Windows 10 Compressing Memory When Not Needed

I see a lot of posts regarding people asking how to turn off memory compression, whether paging is a good idea etc, with the consensus reply always being that "Windows 10 knows best" and won't compress memory unless it needs to.  I bought a new laptop with 32gigs of ram, and I'd be willing to sign an affidavit in a court of law that the usage has never, ever gone above 19GB of ram, and only then whilst playing a game with a machine learning process training in the background.  Nevertheless, my "in use" and compressed memory right now is 15.GB (2.5GB compressed). Why is Windows compressing memory when it doesn't need to?  Multitasking is still fast, however when I resume some old open applications, it sometimes still takes a few seconds for them to become responsive.  I realize, based on prior discussions, that disabling memory compression, paging etc will most likely not fix this problem and will instead make the system unstable. I realize also that a lot of professionals actually believe that Windows 10 will only compress or page memory when it needs to.  I speak from experience that this is not true. Windows is compressing/paging memory when it does not need to, and when it has never, since its installation, reached close to its maximum capacity.  With this in mind, given infinite ram, is there any way to disable the delay when alt-tabbing to old processes that were never shut? To me this is a fundamental design flaw if there is no way to disable this delay, whatever the cause, if the user were in theory to have an infinite amount of ram, and Windows 10 would nevertheless compress ram anyway.


How can I display a higher precision value in c++

I have an algorithm to calculate pi. However, my console can only display a certain precision value. How can I make it display more digits? I was thinking of using std::to_string() but it only displays one more decimal place. In what way can I make it display more digits? This is my algorithm: double pi15(int precision){     double output = 0;          for (int n=0;n<=precision;n++){         output += (exp(-1.0,n%2)/exp(1024.0,n))*(-(32.0/(4.0*n+1.0))-(1.0/(4.0*n+3.0))+(256.0/(10.0*n+1.0))-(64.0/(10.0*n+3.0))-(4.0/(10.0*n+5.0))-(4.0/(10.0*n+7.0))+(1.0/(10.0*n+9.0)));         std::cout << std::to_string(output/64) << std::endl;     }     return output/64; }


Cannot ping over LAN until a ping is received

I have two OSX machines on a local subnet.  Pings from Machine A to Machine B consistently timeout until Machine B pings Machine A.  After B pings A, A can successfully ping B, but this success is temporary; if there is no communication between the two machines for a half hour or so, pings from A to B begin timing out again (until B pings A again).  How can I ensure that B is always reachable from A, without having to "kickstart" the connection by pinging A from B first?


Admin Post Update Redirection to Posts Screen

Is there a hook I can use that when a post is created or updated it goes back to the list/table page of all the posts. If it is also possible to target a post type as well that would be cracking.  It's a really silly request I know and have argued the toss about it but wanted to make sure it was achievable if not very user friendly.  Steve


Proof that the $(\mathcal P (\mathbb N),\triangle)$ is an abelian group?

I'm stuck trying to figure out how to prove that $(\mathcal P (\mathbb N) \space , \space \triangle)$ is an abelian group? I know the definition, but I'm confused how to incorporate the fact that I'm dealing with a powerset instead of just the integers or natural numbers, so I'm seeking help to understand how proofs on sets works.  Also, I'm using $\triangle$ to mean symmetric difference.


i have a
 element containing multiple lines, each starting with an image, followed by text. I want the text to be next to the vertical center of the image, so i put it inside a div a div and set display:inline-block and vertical-align:middle, but the text is still at the bottom. here is my code:  <!DOCTYPE html>               <meta http-equiv="content-type" content="text/html; charset=UTF-8">         <link rel="stylesheet" href="game.php-Dateien/style.css">

Some describing text


What Does "Tangent to a Point on a Curve" Mean?

Is has been stated in an earlier answer to another question that a "point" is an undefined concept in mathematics.  If this is true, how can we define "tangent to a point on a curve"?


I've never really thought about how the shell actually executes piped commands. I've always been told that the "stdout of one program gets piped into the stdin of another," as a way of thinking about pipes. So naturally, I thought that in the case of say, A | B, A would run first, then B gets the stdout of A, and uses the stdout of A as its input.    But I've noticed that when people search for a particular process in ps, they'd include grep -v "grep" at the end of the command to make sure that grep doesn't appear in the final output. This means that in the command ps aux | grep "bash" | grep -v "grep" it is implied that ps knew that grep was running and therefore is in the output of ps. But if ps finishes running before its output gets piped to grep, how did it know that grep was running?   flamingtoast@FTOAST-UBUNTU: ~$ ps | grep ".*" PID TTY          TIME CMD 3773 pts/0    00:00:00 bash 3784 pts/0    00:00:00 ps 3785 pts/0    00:00:00 grep


I have a form with six different input fields. Two of these fields are an either/both case, i.e. the user does not have to fill out both, but one of them is required. My problem is the design of them. How do I make it clear enough to the user that these two fields are a “group”, and not related to the following two fields?


How prove that $(a_{n})_{n \in \mathbb{N}}$ is convergent with $a_{0}=1$, $a_{n+1}= \sqrt{2a_{n}}$?

Prove that $(a_{n})_{n \in \mathbb{N}}$ is convergent with $a_{0}=1$,   $a_{n+1}= \sqrt{2a_{n}}$ and calculate its limit.      You got the info that the square-root-function is strictly monotonic   increasing and also continuous.   I'm very confused how this could be solved because there isn't really a sequence given here. It seems to be a recursive one and I also don't know how to form $a_{n+1}$.  Could I form it to $a_{n}+ a_{1}$ ?(I don't care if it's useful here but I'd like to know if this would be correct at first.)    I have started by forming to $a_{n}$:  $$2a_{n} = (a_{n+1})^{2}$$  $$a_{n}=\frac{(a_{n+1})^{2}}{2}$$  Then I also formed to $a_{1}:$  $$a_{n}+ a_{1} = \sqrt{2a_{n}}$$  $$a_{1} = \sqrt{2a_{n}} - a_{n}$$  But it seems like this won't lead to anything.. Also I don't know what we can do with the given info, $a_{0} = 1$, the continuity and monotonic increasing...


Ubuntu 17.10 and later: can't change the input switching shortcut to alt+shift

When I try to set the default combo for switching to different language layouts in my keyboard from Shift+Super+Space to Alt+Shift I can't.  I used to have this combo since Ubuntu 14 and even before that when I used to have Windows. Now for some stupid reason it does not allow (actually nothing happens its not like I get an error or the combo is used elsewhere). How could I bypass this bug?


Dark age of universe when all fusion process ceases?

Some say we live in the golden age of the universe because there exits countless number of stars that shines in the dark universe. As the supply of gas for star formation is steadily being exhausted, it is estimated that star formation will cease in 100 trillion years.  Question: Will there be a day that the universe becomes completly dark when all the stars burn out? Does all the cooled bodies eventually collide due to gravitational forces? Will black holes eventually dominate the universe?


Show that the following system of parametric equations describes a line or a parabola: $$\begin{cases} x=a_1t^2+b_1t+c_1 \\ y=a_2t^2+b_2t+c_2 \end{cases}, t\in\mathbb{R}.$$


Creating Digital Terrain Model from Digital Elevation Model using ArcGIS for Desktop?

I have a DEM and I want to create a DTM from that DEM. Is it possible to do this in ArcGIS?


I'm currently reading through Pugh's Analysis (for fun.) I'm currently stuck on this question:  Given two cuts $x=A|B$ and $y = A'|B'$, then $x+y=(A+A')|\text{rest of $\mathbb Q$}$, show that although $B+B'$ is disjoint from $A+A'$, their union might not be $\mathbb Q$.  I understand this question is basically asking why cut addition isn't defined to be $x+y=(A+A')|(B+B')$. I keep trying to find a degenerate case, but can't seem to really get started. Showing that they're disjoint is easy enough, but I haven't really made any progress from there. Hints would be appreciated.


Question about Grassmannian, most vectors in $\bigwedge^k V$ are not completely decomposable?

My question:      Is $e_1 \wedge e_2 + e_3 \wedge e_4 \in \bigwedge^2 V$ not completely decomposable if $e_1$, $e_2$, $e_3$, $e_4$ is a basis for $V$?


When referring to America, one should use the definite article, "the", "the United States".  However, in some titles of posts, the definite article is omitted.       Is that some kind of grammar rule?


finding the number of bit string containing eight 0s and twelve 1s?

How many bit strings containing exactly eight $0$s and twelve $1$s have either all the $0$s consecutive, or all the $1$s consecutive?  My working :  There are $20$ positions $(8 + 12)$   Since there are $2$ possibilities for each position   Thus $2^{20}$


I have an issue where i am trying to write 'Hindi/Chinese' string to MySQL database. PHP is converting that to '????' and that is what i can see in mysql. To isolate issue when i directly put that string in mysql it writes it correctly. does anybody have any idea how i ca resolve this issue.   (my database and tables are in UTF8, PHP configuration set to UTF8)   for every connection to mysql i use set name and set character etc to UTF8  before interacting with mysql, send this two querys:  SET NAMES 'utf8'; CHARSET 'utf8';   When people dont know answer they will not accept the fact but start -ve voting or saying possible duplicate.. without understanding the problem.. which is not good..have great day...   Solution :-  i was using below queries after connection.  SET NAMES 'utf8'  SET CHARACTER SET 'utf8'   which was causing issue somehow i am not able to understand why?? but if i remove  SET CHARACTER SET 'utf8' and only keep SET NAMES 'utf8' everything works fine.  Thank you everyone for your help, for those to who said it is possible duplicate and -ve voted.


I know how to write a usual index with the help of the underscore, but I seem to be unable to find out how to write an (upper/lower) index in front of a letter/text.  These kind of indices are common in chemistry.


Replacing NULL value with Zero in geodatabase table using Python parser of ArcGIS field calculator?

I am having some difficulties to change "NULL" values to zero in geodatabase. I have tried the following python code in ArcGIS 10.1 ("Field Calculator") to change it but did not work.   Pre-Logic Script Code:  def RemoveNULL(x):     if x is None:         return ''     elif x == '':         return '0'     else: return x   Calculation field:  RemoveNULL(str( !DEAD_VOL_PER_HA_SPP1_125!))   Error message:  ERROR: 999999: Error executing function The value type is incompatible with the field type. [dead_pine] Failed to execute (calculate field)


Hii iam learning salesforce Which IDE is mostly used by Salesforce Developers in real time especially in India?


Is “all women who are mothers of daughters” right?

Is the expression      All women who are mothers of daughters are here.   correct? I mean every woman who has at least one daughter is here.


Subject verb agreement in case of sentences having "along with"

In my text, for the question, The dog along with his master ___ for a walk., the answer is marked as "are going" And for another question, The dog, along with his master, ______ for a walk., the answer is marked as "is going" I think both sentences are the same and that the usage of comma in the second sentence is unnecessary. Since 'along with' is not a coordinating conjunction, the part before it, is to be considered subject. So I feel "is going" should be the answer. Am I wrong? Please clarify


Is there a way to change the color of text in a question?

I just asked this question: .  The first answer I got totally missed the point of the question (that answer is now deleted).    I think my question would have been clearer if I could have changed the color of a (non-code) word to red, so I could show an example of what I wanted.  Is there a way to do this?


Let $E$ and $F$ be subsets of some set $S$, which may be finite or infinite. Suppose we are given a bijection $g\colon E\to F$. Is there an explicit way to construct from $g$ a bijection $h\colon S\setminus F\to S\setminus E$?  By explicit, I mean that it is not enough to show that $g$ exists (this is clear, since the cardinalities of $S\setminus F$ and $S\setminus E$ are equal).


How can I vertically align elements in a div?

I have a div with two images and an h1. All of them need to be vertically aligned within the div, next to each other. One of the images needs to be absolute positioned within the div. What is the CSS needed for this to work on all common browsers?

testing...


I'm trying to set a shell variable to $PWD - the path from were the script is executed. This is what I have, setenv.sh:  #!/bin/bash export WORK_AREA=$PWD      #also tried "$PWD", $(pwd), `pwd`   But when I run from the shell  > ./setenv.sh > echo $WORK_AREA   WORK_AREA has no value


Tag markdown in About Me section rendered locally in meta sites

I just noticed . Nothing special but he does have a tag in his About Me:    I clicked it, fully expecting to land , same way as  leads to on Stack Overflow. But I landed  instead, the tag page here on Meta, where of course it contains no questions. It also occurs in all other sites. To top this all, consider his : clicking the tag there leads to  which sends me to search for a panda. Can the tag point to the original site where the user has first wrote the About Me, or at least removed in the network profile? (or just put the tag name, unclickable)


Prove that if $x_n$ converges to $\omega$, $t_n$ converges to $\omega$ too

By the sequence $(x_n)_{n\in\Bbb{N}}$, define a new sequence $(t_n)_{n\in\Bbb{N}}$ such that $t_n:=\frac {x_1+x_2+...+x_n}{n}$. If $\lim_{n\rightarrow\infty}t_n=\omega$, how can I show that $\lim_{t\rightarrow\infty}x_n=\omega$? Original post had ``If $\lim_{n\rightarrow\infty}x_n=\omega$, ..."


Tkinter Frame Disappears after adding a button

I have two frames in the root. And I want to add a button in one of the frames. Both frames have different background colours. When I try to add a button in any of them, the frame that contains the button disappears. Without button from tkinter import *  root = Tk() root.geometry("1600x800+0+0") root.title("ABC")  Rf = Frame(root, width=100, height=800, bg="black") Rf.pack(side=RIGHT)  Lf = Frame(root, width=1500, height=800, bg="green") Lf.pack(side=LEFT)  root.mainloop()  Which results in...  With button But after adding the button, with the following code... from tkinter import *  root = Tk() root.geometry("1600x800+0+0") root.title("ABC")  Rf = Frame(root, width=100, height=800, bg="black") Rf.pack(side=RIGHT)  Lf = Frame(root, width=1500, height=800, bg="green") Lf.pack(side=LEFT)  b1 = Button (Rf, text="Load", fg="red", bg="black") b1.pack(side=LEFT)  root.mainloop()  I get...  Now the button is visible but the frame and background colours are gone. What am I doing wrong? Thanks for your help!


Interpretation of p values for each level of a covariate?

In the output from a cox regression I get several p values from one variate - one for each level of the variate bar one level. I want to know the effect of the variate on the outcome (adjusted by other variates) and therefore one p value would suffice. (I can't seem to use anova because I'm using the R survival function survSplit - although that would be good). I am therefore stuck with trying to interpret the p values for individual levels of the variate. My question is - what exactly do they mean ? - and when do I know that the variate has a significant effect on the outcome ? Do all the p values for each level of the variate have to be significant to conclude that the variate has a significant effect ? The p values seem to be calculated with reference to one of the levels of the variate (presumably treated as a reference level) - but is that useful ? As an example the outcome could be death with genetic-time groups given by survSplit and the variate of interest could be an ordinal variable e.g. the nodal status of a patient. In regression I normally think of whole variates, not different levels, as having a regression coefficient. Does that mean that here each level of a variate has its own regression coefficient which is independent of all levels apart from the reference level ? and if it is significant it can be interpreted as having an association with the outcome/time (=hazard) that is relative to the reference level's association with the outcome/time ? (note that this doesn't seem very useful if I don't know what the reference level's association with outcome/time actually is !?) Unfortunately anova.rms and base anova will not work directly (at least with my data) on one R survival coxph(survSplit) object, presumably because the groups:strata(time_group) parameter which has two levels always gives one of these levels (for each time) with a line of NAs and se(coef) of zero: as in the following results from model coxph(Surv(tstart, time, BCSSsplit) ~ groupsplit:strata(time_group) + Nodal_status_CATEGOR_CATEGOR, data = BCSSsplitdata)                                                                                se(coef)      z        p Nodal_status_CATEGOR_CATEGORa                   2.959e-01  2.071   0.0384 Nodal_status_CATEGOR_CATEGORb                   2.698e-01  5.643 1.67e-08 Nodal_status_CATEGOR_CATEGORc                   2.964e+03 -0.005   0.9959 groupsplitHer2+:strata(time_group)time_group=1  2.774e-01 -4.112 3.92e-05 groupsplitTNBC:strata(time_group)time_group=1   0.000e+00     NA       NA groupsplitHer2+:strata(time_group)time_group=2  3.930e-01  2.563   0.0104 groupsplitTNBC:strata(time_group)time_group=2   0.000e+00     NA       NA  The error given is Error in .rowNamesDF<-(x, value = value) : invalid 'row.names' length anova will however compare two such objects - so I'll have to settle for that unless someone knows a method whereby anova will handle such a coxph object. (The time split (or other adjustment) is necessary following Schoenfeld testing for proportional hazards.)


While Trying to mount a disk image in Raw(dd) format using the following command  mount  nps-2010-emails.dd /media/manu/   I get the following error message   mount: you must specify the filesystem type   I know that using -t we can specify the file system but what is the terminology for  a RAW (dd) file, which can pe passed as an argument to the mount command. If my method to mount this file system is wrong please help me out in doing the same.  On typing the command file -s nps-2010-emails.dd  The output is as follows:  nps-2010-emails.dd: x86 boot sector; partition 1: ID=0xb, starthead 254, startsector 1, 20479 sectors, extended partition table (last)\011, code offset 0x0


SSH Public Key. disable login for specific user. pam?

So today my Server got hacked. But just a non sudoer user.   Nov 26 10:44:18 Ubuntu-1604-xenial-64-minimal sshd[27188]: Accepted publickey for ... from hackerIP port 26394 ssh2: RSA SHA256:...   He started a screen and scanned networks nothing more. History is empty. He connected with some publickey tho I never added any keys. I know I should use ssh-keys instead of password. But my root never got compromised. What I noticed in auth.log is this  Nov 26 19:01:01 Ubuntu-1604-xenial-64-minimal CRON[12360]: pam_unix(cron:session): session opened for user ... by (uid=0) Nov 26 19:01:01 Ubuntu-1604-xenial-64-minimal CRON[12360]: pam_unix(cron:session): session closed for user ... Nov 26 19:02:01 Ubuntu-1604-xenial-64-minimal CRON[12368]: pam_unix(cron:session): session opened for user ... by (uid=0) Nov 26 19:02:01 Ubuntu-1604-xenial-64-minimal CRON[12368]: pam_unix(cron:session): session closed for user ...   I do not know if I am posting it in the wrong section to be honest. I basically just want to know where to find the ssh-keys because my key folder is empty. How to disable remote login for that specific user (so that I only can connect over root and use 'su' command to login). And what to do with pam_unix.   Edit: Firtsly thanks for the huge help. I could undone everything the attacker did. And I disabled ssh-key login in sshd config so only passwords are valid. Failed2Ban is running as well and I am managing auth.log everyday manually.


Interscholastic Mathematics League Senior B Division #2

Points $P$, $Q$, $R$ and $S$ are chosen on the sides of parallelogram $ABCD$, so that $P$ is on line $AB$, $Q$ is on line $BC$, $R$ is on line $CD$, $S$ is on line $DA$, and $AP=BQ=CR=DS=\frac{1}{3}(AB)$. Compute the ratio of the area of $PQRS$ to the area of $ABCD$.


What's the meaning of ?= in a kernel makefile?

I've started learning about building external Linux kernel modules, and in the documentation examples of kbuild () I've come across the line  KDIR ?= /lib/modules/$(shell uname -r)/build   which is then used in  make -C $(KDIR) M=$(PWD)   and sets the directory to the kernel source. Now, what's the meaing of that ?= operator? Google gives me nothing! Is that a conditional assignment? Sort of, "define variable as follows unless it already exists in the environment"?  Thanks!


Biblatex/Biber not resolving citation if more than 3 authors cited

I'm using Biblatex and biber for my citation needs, but I have the problem, that one citation remains undefined, if I cite more than 3 authors, with 3 it shows up, with more than that it is undefined! Anyone had this problem and knows a solution?


Problem: Prove that if $G$ is a finite group, then the number of elements in the double coset $AxB$ is $\frac{|A| * |B|}{|A \cap xBx^{-1}|}$.  So here's what I know, and I don't know if these pieces of information will be useful.  $|AB| = \frac{|A| * |B|}{|A \cap B|}$ and $[G:B] = [G:A][A:B]$.  I am especially caught up on the $xBx^{-1}$ part.  I understand that $xBx^{-1} = B$ if the left and right cosets are equal (that's how the professor explained it anyway) and I know that the left and right cosets are equal if the subgroup is normal.  I don't even know if that is useful for this problem though.  I really don't have any level of understanding when it comes to cosets beyond the definitions as my professor has really not taught this and the textbook does not seem very clear.  There was a preceding problem and the link will be provided in case that is necessary to prove this problem.


Density of states of non-rationally invariant dispersion relations (Energy bands)

When one deals with a dispersion relation of the form $$\epsilon(\vec{k})=\epsilon(|\vec{k}|)$$ then a simple transformation in polar/spherical coordinates is enough to find the density of states.  I read that for electrons in an arbitrary dispersion relation the DOS is given by $$D(\epsilon)\propto\int_{\epsilon(\vec{k}=\textrm{const.})}\frac{dS_\epsilon}{|\nabla_\vec{k}\epsilon(\vec{k})|}$$ Where $dS_\epsilon$ is a surface element of the surface of constant energy. How does on proof this?


On some PCB designs, specific traces are routed in curious ways. This probably has to do with high frequency design considerations and general signal behavior that I am not familiar with.  Let's take this PCB (somewhere from the web) as an example. It shows part of a PCIe card with SATA routing and DDR2 RAM:    I highlighted 4 areas that qualify as unusual trace layout (from my perspective).   What are those shapes supposed to achieve? How do designers come up with what pattern is required? Another example of wave shaped, antenna like routing. This is fairly rare. But obviously the designer deliberately avoided 45° traces. Why? Curves again and a single "pulse" within the trace. How can this have any significant effect?   So what are the use cases and benefits of this techniques?   I want to be able to take those into consideration when doing future PCB designs.


Shortcuts for switch-to-workspace-N for big N

I'm customizing switch-to-workspace settings using dconf write /org/gnome/desktop/wm/keybindings/switch-to-workspace-N "['<Alt>5']"  N 11 works but N 14 doesn't. How could I have this shortcut?


"Questions that may already have your answer" vs. "Related questions"

Lately, my overall impression has been that the list of "Related questions" one sees once a question is posted is usually more relevant that the "Questions that may already have your answer" one is exposed to while typing.  My questions are :    How are the two lists constructed? Are the two lists generated in any significantly different way or am I completely wrong in believing that there is a difference between the two? If there is a difference in the way the lists are constructed, how is the difference justified?


Am I missing something basic in Java Math calculations for float numbers ? I can use Math function round(), However I want accurate value 6.4 as the input given is simple and doesn't have many values after the decimal point.   System.out.println(1.8f+1.0f+1.9f+1.7f); // Expected 6.4 but actual is 6.3999999999999995 how ?


Can we have the ability to flag for reopening?

TL;DR: Grant 500+ rep users (except the OP) the privilege to flag a question for reopening. Currently, you can flag a question for closing, and it automatically enters the  review queue, where 3K+ users can vote to close (or to leave open) the question.  However, there is no ability to flag a closed question for reopening. A <3K user must either:  Flag for diamond moderator attention, causing more workload for the moderators. Create a meta-post on the question, requesting for the question to be reopened. ...  Feature Request Add the ability to flag a post for reopening, just as you can flag for closing. The UI of the flagging dialog for closed post could look like this:  A reopen flag would instantly bring the question into the  review queue, where 3K+ users would vote to reopen (or to leave closed), just like when a reopen vote is cast on a question. This option would be available to everybody except the OP of the question, since he can bring his question to the review queue by editing it. A reputation limit could also be added to prevent abuse, e.g., .


What happened to The Doctor's granddaughter, ? What was her ultimate fate?    Is it possible that she'll make an appearance in the new (2005) Doctor Who?


What is the difference between Early and Late Binding?

What is the difference between early and late binding?


Getting a false Boolean value when I should be getting true

As a condition, I am equating two variables String a and String b. They are exactly the same, in fact I printed the values to the logcat and they are the same string, no extra spaces. But whenever I equate them (a == b), I am getting false back. I even printed out the value with  Log.v("BOOLEAN", Boolean.toString(a == b));   And I got false back. Though when I print out the values sandwiched between the letters I (to make sure there weren't spaces on the end messing the string up), I get  V/BOOLEAN: I123I123I   This is the relevant code  user_pin = USER_PIN.getText().toString();      DatabaseOperations DOP = new DatabaseOperations(ctx);     DOP.open();     Cursor CR = DOP.getRow(id);     CR.moveToFirst();     user_pin_database = CR.getString(3);      Log.v("BOOLEAN", "I" + CR.getString(3) + "I" + user_pin + "I");      if (user_pin == user_pin_database) {...}   Does anyone know what's causing this?


Is a constructor implicitly declared in the case of a abstract class with no data members?

If a class is only used as a base class to derive other classes and therefore has only pure virtual member functions (no data members) - does it get an implicitly declared constructor?      class Object {     public:      virtual void show(std::ostream&) = 0;      virtual ~Object();     };


I have presta valves, and I got tubes with green goo about a year ago. I didn't ride my bike a lot, but I'm riding it more now, but the rear tire can't inflate or deflate. It's full enough that I cant get the wheel tire off the tube, but flat enough that it's hard/dangerous to ride. I'm thinking the green goo clogged up the valve somehow, but I'm not sure how to fix that. Is there a way to get the tire off the tube while it's still mostly inflated? I have thought of trying to poke a hole in the tube somehow, but I can't lift the tire away to do that.


Given a matrix $A_{n \times n}$, which has elements $a_{i,j} \sim \mathrm{unif} \left[a,b\right]$, what is the probablity of $\det(A)$ being zero?  What if $a_{i,j}$ have any other distribution?  Added: Let's assume an extension of the about problem; What is the probability of, $\mathbb{P}(|\det(A)| < \epsilon ), \; s.t. \; \epsilon \in \mathbb{R} $ ?  Thanks!


I plan on spawning Death Trap and letting him get kills for a long period of time for exp. Will any items that are dropped despawn over time (pc)?


Is a melee spell attack also a melee attack?

The  spell says:     The spell captures some of the incoming energy, lessening its effect on you and storing it for your next melee attack. You have resistance to the triggering damage type until the start of your next turn. Also, the fist time you hit with a melee attack on your next turn, the target takes an extra 1d6 damage of the triggering type, and the spell ends.   The  cantrip says:     Lightning springs from your hand to deliver a shock to a creature you try to touch. Make a melee spell attack against the target. You have advantage on the attack roll if the target is wearing armor made of metal. On a hit, the target takes 1d8 lightning damage, and it can’t take reactions until the start of its next turn.   If I absorb fire damage with absorb elements, would I be able to add an extra 1d6 fire damage to my next shocking grasp attack?


How to reinstall Ubuntu 14.04's default login screen

I was playing around with the different Window Managers and I ended up uninstalling the default login screen (I think) How can I reinstall that without reinstalling the whole distro?


How do I solve the problem of black surface forming on an object with 0 alpha transparency adjusted in cycle mode?

In order to give the effect of disappearing the product through video, i made the alpha 0 in the cycle mode to give transparency.  When I proceed the rendering, it's not completely transparent also black surfaces are occured, and I've tried this and that, but I'm asking because it doesn't work. I'd like to ask if there is any way to get rid of this black surfaces and set it to a completely transparent state. The current setting is as follows.


Can the result for $\prod_{p\ge 3}\left(1-\frac 2p\right)$ be extended for general $\prod_{p\ge n+1}\left(1-\frac np\right)$?

In the excellent answer at , the identity $\log\left(1-\frac{2}{p}+\frac{1}{p^2}\right) +\log\left(1- \frac{1}{(p-1)^2} \right)=\log\left(1- \frac{2}{p} \right)$ was put forward as a starting point.  I thought I would try a similar thing for estimating $\prod_{3\lt p\le x}\left(1-\frac 3p\right)$ and thus use some identity which might be along the lines of  $$\log\left(1-\frac 3p\right)=\log\left(1-\frac 1p\right)+\log\left(1-\frac 2p\right)+\log\left(1-\frac 2{p-1}-\frac 2{p-2}\right)$$  but as I work with these quantities I realize that no identity will completely remove the factor $p-3$ from the results entirely.  In my search results I keep finding the same "Euler Product" and "Mertens' Theorem" pages on Wikipedia and Mathworld, but none of those pages has a $p-3$ factor listed that I have noticed, nor any suggestion as to how to approach the broader question.  I am not especially worried about the accuracy of the error term, as long as the error is not asymptotically as big as the rest of the result.  Are there known results that my primitive searches haven't found yet?  Are there any reference materials I could look at that might help me work out some of these bounds myself, or perhaps some simple observation that has a relatively large error term but simplifies the approach in general?


Writing inside the image as in the Figure

I have set my image as you see in the attached figure, is it possible to do so in Latex? and how ?


Find equation of a plane that passes through point and contains the intersection line of 2 other planes

Find equation of a plane that passes through point P $(-1,4,2)$ that contains the intersection line of the planes  $$\begin{align*} 4x-y+z-2&=0\\ 2x+y-2z-3&=0 \end{align*}$$  Attempt: I found the the direction vector of the intersection line by taking the cross product of vectors normal to the known planes. I got $\langle 1,10,6\rangle$. Now, I need to find a vector normal to the plane I am looking for. To do that I need one more point on that plane. So how do I proceed?


Allow Windows Defender to update automatically but not Windows

Windows 8. (Not Windows 8.1)  I have Windows Update set to check for updates but not install them automatically. I get nearly daily notifications from Windows Update to install Defender updates. Can I set Defender to auto-download updates without allowing ALL Windows Updates to auto-install?  Note:  shows up as a similar question. It IS NOT A DUPLICATE because my question is about Win8, not Win7.


put double quote on php variable that holding string value in mysql

<?php $user_id = 23; $abc_username = "orange apple";  "WHERE u.user_type = 2 AND u.status = 1 AND (u.sponsor_id = '".$user_id."' OR u.placement = '".$abc_username."' )"   Syntax error on '".$abc_username."' because '".(only accept integer, not accept string)."'; May you tell me what is the correct syntax to put php variable that holding string value?   I have tried \'".$abc_username."\' as the solution from this page   but still syntax error.


I have the code below which I am having trouble with. I am trying to get a date string and convert to a date object. Then calculate the days between this date and todays date.  The example below should return "6 days" but instead is returning "35 days".  var tmp = '20/11/2013'; var myDateParts = tmp.split("/");                        var oneDay = 24*60*60*1000; var today = new Date(); var secondDate = new Date(myDateParts[2], myDateParts[1], myDateParts[0]); var diffDays = Math.round(Math.abs((secondDate.getTime() - today.getTime()))/(oneDay));  console.log(diffDays+' days');   Can anyone see where I am going wrong.  Thanks


How can i Recover Windows 8 after deleting?

While installing Ubuntu 13.04 I accidentally deleted the Windows 8 system entirely!How and where can i get Windows 8 back?


Can we add a new reason to close a question? Trivial Syntax Error

Currently we have the following reasons to close a question due to being off-topic    Can we add this reason in the list of reasons to close a question?  This question is off-topic because it is about a trivial syntax error.  Background:  Almost daily I see 10's of questions where people post new questions with very simple and trivial syntax errors like     Parse error: syntax error, unexpected '.'   This to a programmer appears like a very lame question. First up because the error is clearly printed in the error message and with little effort OP can find it out. Secondly, we did not force people to use notepad as their editors, they could have used some IDE which would tell them their error. Thirdly, they could have taken hint from SO syntax highlighter after they posted their question. Fourthly, we are not debuggers, we are not here to fix basic issues like oh you missed a comma here, such things don't help people in future and only promote laziness. For me such trivial syntax errors don't justify a question / answer session.  Previously we had too localized as one of the reasons to close a question, but now we don't. Do you think we can have this one then?


Use the values of \title, \author and \date on a custom title page

I am trying to create a title page of my own.  Is there a way to make use of the \title, \author and \date commands inside the title page?  For instance:  ... \title{Something Cool} \author{Cool Dude} \date{\today}  \begin{document} \begin{titlepage}  The title is \title It was written by \author on \date  \end{titlepage} \end{document}   Basically I just want to know if there is a way to leverage the information stored in \title, \author and \date inside the title page.


How can I send visitors to the closest server using DNS?

Is there a way to localize dns entries? Meaning, that users from asia resolve mydomain.com to another ip than users from usa or europe. This would be helpful to give the users the server nearby. DNS is the only technique used so far, meaning I cannot place some softwarerouting or central system replacing the dns to solve this.


My 2-year-old-son is eating small black stones. How to stop this habit?

My 2-year-old son is eating small black stones when he is playing outside. We were really shocked he considered those as "chips", and he tries to bite the stones and swallows them very often. Now we are not allowing him to play outside because we were really scared whether it will hurt his stomach.   Could any one please let us know how to stop this habit? How can we make him understand a "stone" is different from what he is thinking, and he's not allowed to eat it?


Combinatorics leading to fibonacci sequence

I'm trying to generalize the problem that follows oif the number of stairs is "n", the problem is "You climb either 1 or 2 stairs at a time, at any given time. How many ways can you get up 11 stairs?"  Eventually I noticed that as I tried n = 1,2,3,4,5 the number of possible ways are 1, 2, 3, 5, 8.... which is somehow resembling the fibonacci sequence... I tried to prove using pascal triangle since it is comnected to combinatorics and fibonacci but i dunno how to start... any idea?


Is there a way to export my customized settings or copy some xml or config file, in order to install my settings to another computer without me manually changing everything? If this is possible it would make the installation process much easier for people who are not that familier with GIS.  Many people at my workplace are going to be using Qgis in the future and this would make the transition easier :)


Page appears indexed in Google but not findable for any search terms?

(Note that I am going to use screenshots here because I suspect writing about this will change the behavior over time.)  If you do a Google search for     uiviewcontroller best practices   either with or without the quotes, you end up with results like this:      Note that none of these pages resolve to the actual Stack Overflow question containing those words in the title. They resolve to either a) sites that are mirroring our creative commons data and correctly pointing back to the source question without nofollow, as properly specified by  or b) our own internal links to the question, but not the actual question itself.   The actual page with the title ...     Custom UIView and UIViewController best practices?   ... does exist at this URL ...  http://stackoverflow.com/questions/3300183/custom-uiview-and-uiviewcontroller-best-practices  ... and apparently it is present in Google's index!    But why does it not appear when we search for      uiviewcontroller best practices   ?   We know that   Google contains this page in its index Our search terms match the title of the question Stack Overflow has much higher pagerank than the other sites that are    I don't get it. What are we doing wrong here?


How are the wife and kid?   How is the wife and kid?      Which is more correct?


Show that the LU decomposition of matrices of the form $\left[\begin{smallmatrix}0& x\\0 & y\end{smallmatrix}\right]$ is not unique

How can I show that every matrix of the form $\begin{bmatrix}0& x\\0 & y\end{bmatrix}$ has an $LU$ factorization and that even if $L$ is unit lower triangular there is not a unique factorization?  I am completely stuck. Any ideas would be greatly appreciated


StringBuffer or StringBuilder in Servlet's doFilter method?

I'm implementing my custom filter:  public class MyFilter implements javax.servlet.Filter   Which should I use in this doFilter method - StringBuffer or StringBuilder?  I would like to use it in this way:  StringBuffer stringBuffer = new StringBuffer(); stringBuffer.append(MY_CODE_HERE); response.sendRedirect(stringBuffer.toString());   or...            StringBuilder stringBuilder = new StringBuilder(); stringBuilder.append(MY_CODE_HERE); response.sendRedirect(stringBuilder.toString());   I know that StringBuffer is thread safe, but would a StringBuilder be enough?


Is the ring poem slightly inaccurate? Who wrote it?

It is  that the three Elven rings were not made by Sauron. The  on the One Ring, made by Sauron, was in  related to its power, even if we cannot say if it was by fancy (it makes for a nice trick :) ), if it was required by the spell or whatever: it is just like that. What is clear is that when Sauron put it on and the Elves understood the plot, a lot of action started rolling.  Now my point is: the ring poem (while being great, of course) seems slightly inaccurate.  We know that it is a verse "long known in Elven-lore", as Gandalf explains to Frodo in Shadows of the Past.  Was it written by the Elves? Why am I even asking, since Elves clearly love poetry and songs? Because:   It explicitly mentions, at least two times, the (translation of the) evil inscription on the Ring. It is describing the actions and the purposes of the Lord of the Rings: but the Lord only gave out the Seven and the Nine, but not the Three which were exceptional: he had power over them because they were "made" with the same techniques but he had not planned them, they were made independently and one can imagine that they "caught him by surprise".    So, isn't it a bit strange that the verse long known in Elven lore seems to place the Three on the same footing, as if the purpose of the One Ring had been from start to rule them all?  Isn't a bit strange that Elves used for their verses the very words of the spell (which were surely regarded as very evil: in our world it would be similar to quote in a poem words spoken by some dictator...)?  P.S. Yes, it is conceivable that Sauron would make some rings for the Elves, to keep them under his control: but this still had not happened and things went in a different direction.


Context Consider the following scenario for a company selling goods online. A user can purchase several items (i.e. basket of items), some of which are of particular importance and are tracked specifically (let's call them star items). We wish to test a change in an algorithm (e.g. recommendation, risk assessment, add targeting, whatever...) which may influence both the number of star items sold, and the total sales.  This a standard A/B test setup - the randomization unit is at the user level. The purpose of the A/B test is to compare the impact of the algorithm change: the control group has the original algorithm and the variant has the new algorithm One key metric of interest is defined as the ratio of star items sales over total sales. This is a sum of across all transactions of all users in the scope of each A or B group. This means that the analysis unit is at the transaction level, which is different than the randomization unit Metrics are calculated over the entire duration of the test (e.g. 2 weeks)  Detail of the metric used Given group A and a set of users $U_A = \{u_1,u_2,...,u_{N_A} \}$, each user is involved in a number $t_{u_n}$ of transactions. The set $T_A$ of all transactions of all users in group A for the duration of the test is $T_A = \{ t_{u_{11}}, t_{u_{12}}, ... t_{u_{nm} }  \}$. The metric of interest for group A is defined over all transactions in scope of group A. The sums are at the transaction level, not the user level. $$\text{Metric}_A = \frac{\sum_{t_{i} \in T_A} \text{sales star items }$}{\sum_{t_{i} \in T_A} \text{sales }$ }$$ Of course, we could modify the definition to calculate the user level mean and that would simplify everything, but that is not the metric that is being used. Questions What statistical test could be used for such a metric ? An additional consideration is that although we can safely assume that users are i.i.d., it is most likely wrong to assume that individual purchase baskets are i.i.d. for the same user. Here are a few ideas I came across, have any A/B testing practitioners come across similar metrics in the past ?  z-test of proportions Bootstrapping and Jacknife Delta method Change the metric (last resort)   Edit - Some clarifications The reason behind this question is that I have often seen the z-test of proportion being used in this situation. Popular tools used for A/B testing often default on the proportion test and business users rarely check the underlying assumptions required for the test to be valid. @dnqxt's answer below is a good example: "Just use the z test of proportion !" - but I would like to see a rigorous statistical justification as to why (or why not) this test can be used in such a case. I personally don't think that using a z-test of proportions would work here as sales from a purchase event are not Bernoulli trials. I argue that we cannot say that each dollar sold in the denominator can be viewed as a Bernoulli trial resulting in 0 or 1 star item dollar sold in the numerator. Moreover, since the randomization unit is at the user level, purchase events of the same user are not independent (but I would say that is a secondary issue). I could be wrong here, so please feel free to prove this otherwise ! We could also change the metric to make it a Bernoulli/Binomial which converges to Normal by using counts, but that would be a last resort solution $$ \frac{\# \text{sales with star items} }{\# \text{sales}} $$


How can I modify the following command to make it work?  \newcommand{\code}[1]{\begingroup \fontsize{10pt}{10pt}\selectfont \begin{verbatim} #1 \end{verbatim} \endgroup}   I currently get the following error on the close of the following verbatim block:  ! Undefined control sequence. <argument> ...endgroup ^^M^^M$\eta_{xi} = r_{xi} -                                                    q_i \cdot p_x$ \\^^M$q_i ... l.227     \end{verbatim}


Unknown status bar icon (Samsung Galaxy S6, Android 5.1.1)

What does the following icon in my status bar indicate? And how do I remove it?    As far as I know I didn't turn any setting on that triggered it. I can't find the icon online. My first guess was that it was either VoLTE or VoIP or WiFi calling, but I do not have any of these as options on my phone.  EDIT 1:  The icon does not go away, unless I turn off WiFi. Below are screenshots of my full home screen and of the open notification panel.      EDIT 2: The screenshot below is of my phone's "Call Settings". I have no 'Wi-Fi Calling' option. According to guides online, it should come after the 'Vibrate' option.    The screenshot below is the results when searching 'Wi-Fi' in settings. No call options come up.    EDIT 3: It definitely is the Wi-Fi Calling icon (even though I do not have it as an option on my phone) -- I tested it now and I can phone my contacts when in flight mode.


I was trying to install xUbuntu Desktop 14.4 on Lenovo T450s without success. The standard installation freezes immediately after showing the two icons in the beginning never switching to graphics mode.  Did anyone manage to install it from stock installation.


How to automatically install a program bash suggests I install?

I am thinking of the use case of this output:  The program 'tiger' is currently not installed. You can install it by typing: sudo apt-get install tiger   How can I get it to prompt me to install that package? For example it would output this:  The program 'tiger' is currently not installed. You can install it by typing: sudo apt-get install tiger # Confirmation can go here [sudo] password for tim: The following NEW packages will be installed   tiger tripwire 0 to upgrade, 11 to newly install, 0 to remove and 0 not to upgrade. Need to get 8,416 kB of archives. After this operation, 26.5 MB of additional disk space will be used. Do you want to continue? [Y/n]  # and/or confirmation can go here   I don't want to have to run it myself. How can I get it to do it automatically, and give me the option to not install?


Reliability Logistic Regression - train and evaluate the model

I have built an Logistic Regression model in R. The class that I want to predict, is very unbalanced (99 vs 1).   My first finding is that this Logistic model does a better job if I train it on a balanced (50 - 50) train set, instead of on the whole train set (unbalanced (99 - 1). This is, seen the sources on the internet, a common way to deal with unbalanced data ().  But I have doubts about the next two questions:   First Question: To decide my models performance, I used a confusion matrix. I played around with the threshold (when a prediction is classified as 1, or as 0). See this code:   predictions <- predict(mylogit, test_set, type = "response") confusionMatrix(data = as.numeric(predictions > 0.5), test_set$target) # Here I played around with the 0.5 cutoff, to decide when  # my model is performing best on my test set.    So I tweaked the 0.5 until I had the best confusion matrix score on my test set. Is this valid?   In addition,Second question: If my results (in terms of prediction - Confusion matrix) are bad, can I still use the model to see the influence of the factors (coefficients) on the target? So only for describing the data, and not for predicting? And why?


Is it still possible to play Star Craft Brood War online on Battle.net?  What do I need aside from the original game?  Do I need to pay a subscription fee on Battle.net?


git status command doesn't show new untracked directories and I can't git add them.. How can I resolve this? New and untracked files are shown, the problem is only with new directories.


YA fantasy novel about princesses, one must quest to save the other

This is a pretty short YA novel I read circa 2010, although I don't think it was a new book at that time.  I think the author was female and may have authored several additional books about princesses. The story is about two princesses who were sisters. One was shy and the other was outgoing. I'm not sure if these are accurate memories, but I think the shy one had dark straight hair and the outgoing one had curly red hair. One sister gets abducted by a dragon and the other has to make a journey to rescue her from its lair. When she reaches the lair, she is forced to stay there for a few days (I don't remember why). She eventually kills the dragon with a sword and takes her sister home. The book contains the quote "Set your face toward danger, and your heart on victory".


How early should I start learning my baby bedtime routine?

my baby is 2 month old. I want know when I should start "bedtime routine" ? and also when make him sleep in his room ? now he sleep next to me, is it correct to take him sleep on his bed or should I wait?


Csvsimple \csvautotabular and \csvautobooktabular with centered columns' content

I'm using csvsimple for making tables, and csvautotabular and csvautobooktabular are working great. However, I'd like the content of each column to be centered instead of aligned to the left.   An answer using csvautotabular and/or csvautobooktabular simply adding an option would be preferred, if it's possible.   I tried this, but it returns an error.  \csvautotabular[tabular=c]{grade.csv}  \csvautobooktabular[tabular=c]{grade.csv}   Here's a MWE:  \documentclass[11pt,a4paper,oldfontcommands]{memoir}  \usepackage{csvsimple} % For csv importing.  % csv file from another question \begin{filecontents*}{grade.csv} name,givenname,matriculation,gender,grade Maier,Hans,12345,m,1.0 Huber,Anna,23456,f,2.3 Weisbaeck,Werner,34567,m,5.0 \end{filecontents*}  \begin{document} \csvautotabular{grade.csv} \end{document}   And the MWE output.     I want to obtain said output, but with the content of each column centered.    Note  csvautotabular gave me trouble trying to display special characters, but can be solved using the 'respect all' option.  e.g.  \csvautotabular[respect all]{table.csv}   Or with @egreg's custom command.   \csvautotabularcenter[respect all]{table.csv}


Why do physicists believe the "no-hair conjecture" to be true?

The  states that a black hole is completely characterized by its mass, electric charge, and angular momentum. Most physicists take it as given. My question is, why?   It implies the , which violates time reversibility and quantum mechanics in a way that is some what difficult to reconcile. Analogous theorems, such as the four-dimensional equivalent, is outright false, which doesn't lend to the theorem being true. We have no evidence for the no-hair conjecture being true as far as I can tell. It would be difficult to find direct evidence until we could observe a black hole closer.   The only thing in favor of the no-hair conjecture that I can see is Steven Hawking proved that some hard to justify assumptions would imply it. Oh, and a lot of people mistake it for a theorem (which it isn't), which could confuse people into thinking it must be true?  Why is the no-hair conjecture taken as given?  Note: The question "" only addresses why a black hole must have mass and magnetic hair. It doesn't address why there isn't other types of hair.


I am developing simple app to retrieve a string from SQLite database and display it in TextView of my main activity. For that, I created method inside class which handles SQLite database, then inside main activity I called the method, but what it does is only to give NullPointerException.  Method inside my SQLite database handler class.   @Override public void onCreate(SQLiteDatabase db) {     db.execSQL(             "CREATE TABLE " + PERSON_TABLE_NAME +                     "(" + PERSON_COLUMN_ID + " INTEGER PRIMARY KEY, " +                     PERSON_COLUMN_NAME + " TEXT, " +                     PERSON_COLUMN_GENDER + " TEXT, " +                     PERSON_COLUMN_AGE + " INTEGER)"     );  }......////////////   Some  Code...........       public String getAddress(int id) {     // TODO Auto-generated method stub     SQLiteDatabase db = this.getReadableDatabase();       try {         Cursor cursor =  db.rawQuery("SELECT * FROM " + PERSON_TABLE_NAME + " WHERE " +                 PERSON_COLUMN_ID + "=?", new String[]{Integer.toString(id)});          if (cursor != null) {             cursor.moveToFirst();             return cursor.getString (cursor.getColumnIndex (PERSON_COLUMN_NAME));         }     }     catch (Exception e) {          // TODO Auto-generated catch block         e.printStackTrace();     }     return ""; }   My main activity Where I call the method.  button = (Button) findViewById(R.id.addNew);     button.setText(dbHelper.getAddress(8));


Hello i have following problem.  I found regexp expression for email validation like this :   function isEmail(email) {     var regex = /^([a-zA-Z0-9_.+-])+@(([a-zA-Z0-9-])+.)+?.+([a-zA-Z0-9]{2,4})+$/;  return regex.test(email);  }   It looked ok but when i type email address like this  asdasda@asdad   It is valid. Can someone help me why it is valid even without '.' -dot?  Thank You very much


Can a foreign key reference multiple tables?

So I'm doing a bit of practise in database design, and a question arose that I couldn't figure out how to correct.  I'm pretty new at this, so I'm not the best but here it goes.  So I want to create two different tables, one called Team, and one called Player. These tables are pretty different from one another.  I then want another table called Challenge, which I want to reference either Team or Player.  Basically there are competitions, and they are either competed individually, or as a team. I want a foreign key to reference Team, if its a team challenge, or Player if its individual.  I can't combine the two tables, as they contain very different elements.  Im just a bit confused as to how to do it. Can I have just one foreign key, that will reference one table or another. Or shall I have two, with one null.   Or can I add another ID key in the Team and Player. And then in Challenge if a new Type key indicated its a group, it'll reference Team, and if its individual, it references Player.  Again, pretty new at this, so hope I made sense.


Show shutdown messages from last shutdown

Where does Linux store the shutdown messages from last shutdown?


Checking riemann curvature tensor $C^\infty(M)$ linear in $Z$ with $R(X,Y)Z=\nabla_X\nabla_YZ-\nabla Y\nabla_XZ-\nabla_{[X,Y]}Z$

Let $M$ be a smooth manifold. Given affine connection $\nabla:\Gamma(TM)\times\Gamma(TM)\to\Gamma(TM)$, I want to check that curvature tensor field $R(X,Y)Z=\nabla_X\nabla_YZ-\nabla_Y\nabla_XZ-\nabla_{[X,Y]}Z$ is $Z$  $C^\infty(M)$ linear.   So I want to check $R(X,Y)fZ=fR(X,Y)Z$. I can surely check this in local coordinates.   Q: Is there any trick I can use to simplify my checking?


Let $r$ be the smallest positive integer such that $a^r \equiv 1 \bmod{n}$. Prove $r \mid \phi(n)$.

Let $a \in \mathbb {Z}$, $n > 1$ a natural number with $\gcd(a, n) = 1$, and let $r$ be the smallest positive integer such that $a^r \equiv 1 \bmod{n}$. Prove that $r \mid \phi(n)$.  Euler's generalization of Fermat's Little Theorem: If $n \in \mathbb {N}$ and $m \in \mathbb{Z}$ such that $\gcd(m, n) = 1$, then $m^{\phi(n)} \equiv 1\bmod(n)$.  By Euler's generalization I would have $a^{\phi(n)} \equiv 1\bmod{n}$.  Then I could say $a^r \equiv a^{\phi(n)} \equiv 1 \bmod{n}$. At this point I can see that $r$ clearly must be some multiple of $\phi(n)$.  If I want to show that $r \mid \phi(n)$, then I can show that $\phi(n) = rk$, for some $k \in \mathbb {Z}$.  However, I am a bit stuck about how to make this last step showing that  $\phi(n) = rk$, where $k \in \mathbb {Z}$.


I've been trying to understand how the second order derivative "formula" works:  $$\lim_{h\to0} \frac{f(x+h) - 2f(x) + f(x-h)}{h^2}$$  So, the rate of change of the rate of change for an arbitrary continuous function. It basically feels right, since it samples "the after $x+h$ and the before $x-h$" and the $h^2$ is there (due to the expected /h/h -> /h*h), but I'm having trouble finding the equation on my own.  It's is basically a derivative of a derivative, right? Newtonian notation declares as $f''$ and Leibniz's as $\frac{\partial^2{y}}{\partial{x}^2}$ which dissolves into:  $$(f')'$$ and $$\frac{\partial{}}{\partial{x}}\frac{\partial{f}}{\partial{x}}$$  So, first derivation shows the rate of change of a function's value relative to input. The second derivative shows the rate of change of the actual rate of change, suggesting information relating to how frequenly it changes.  The original one is rather straightforward:  $$\frac{\Delta y}{\Delta x} = \lim_{h\to0} \frac{f(x+h) - f(x)}{x + h - x} = \lim_{h\to0} \frac{f(x+h) - f(x)}{h}$$  And can easily be shown that $f'(x) = nx^{n-1} + \dots$ is correct for the more forthcoming of polynomial functions. So, my logic suggests that to get the derivative of a derivative, one only needs to send the derivative function as input to finding the new derivative. I'll drop the $\lim_{h\to0}$ for simplicity:  $$f'(x) = \frac{f(x+h) - f(x)}{h}$$  So, the derivative of the derivative should be:  $$f''(x) = \lim_{h\to0} \frac{f'(x+h) - f'(x)}{h}$$  $$f''(x) = \lim_{h\to0} \frac{  \frac{ f(x+2h) - f(x+h)}{h} - \frac{ f(x+h) - f(x)}{h}  }{h}$$  $$f''(x) = \lim_{h\to0} \frac{  \frac{ f(x+2h) - f(x+h) - f(x+h) + f(x)}{h}  }{h}$$  $$f''(x) = \lim_{h\to0} \frac{  f(x+2h) - f(x+h) - f(x+h) + f(x)  }{h^2}$$  $$f''(x) = \lim_{h\to0} \frac{  f(x+2h) - 2f(x+h) + f(x)  }{h^2}$$  What am I doing wrong? Perhaps it is the mess of it all, but I just can't see it. Please help.


Newbie question re multi-dimensional dictionaries

I need to define and use a "3-dimensional" dictionary.  I don't fully understand dictionaries, so I'm sure what I'm doing is, at best, flawed ... and probably just outright dumb. Code: # Set up and initialize two-dimensional dict maxR = 3 R = {"one": [0] * maxR,      "two": [0] * maxR      }  # Set up and initialize three-dimensional dict maxE = 4 E = {"alpha": [[0] * maxE] * maxR,      "beta" : [[0] * maxE] * maxR     }  # change some individual values R ["one"][2] = 11 R ["two"][0] = 13 E ["alpha"][2][3] = 17 E [("beta", 1, 2)] = 29  # Print out contents for i in range (maxR):     print ("R [one][", i, ", ] = ", R ["one"][i]) for i in range (maxR):     print ("R [two][", i, ", ] = ", R ["two"][i]) print () for i in range (maxR):     for j in range (maxE):         print ("E [alpha][", i, "] [", j, "] = ", E ["alpha"][i][j]) for i in range (maxR):     for j in range (maxE):         print ("E [beta][", i, "] [", j, "] = ", E ["beta"][i][j])  Results: R [one][ 0 , ] =  0    R [one][ 1 , ] =  0 R [one][ 2 , ] =  11 R [two][ 0 , ] =  13 R [two][ 1 , ] =  0 R [two][ 2 , ] =  0  E [alpha][ 0 ] [ 0 ] =  0 E [alpha][ 0 ] [ 1 ] =  0 E [alpha][ 0 ] [ 2 ] =  0 E [alpha][ 0 ] [ 3 ] =  17 E [alpha][ 1 ] [ 0 ] =  0 E [alpha][ 1 ] [ 1 ] =  0 E [alpha][ 1 ] [ 2 ] =  0 E [alpha][ 1 ] [ 3 ] =  17 E [alpha][ 2 ] [ 0 ] =  0 E [alpha][ 2 ] [ 1 ] =  0 E [alpha][ 2 ] [ 2 ] =  0 E [alpha][ 2 ] [ 3 ] =  17 E [beta][ 0 ] [ 0 ] =  0 E [beta][ 0 ] [ 1 ] =  0 E [beta][ 0 ] [ 2 ] =  29 E [beta][ 0 ] [ 3 ] =  0 E [beta][ 1 ] [ 0 ] =  0 E [beta][ 1 ] [ 1 ] =  0 E [beta][ 1 ] [ 2 ] =  29 E [beta][ 1 ] [ 3 ] =  0 E [beta][ 2 ] [ 0 ] =  0 E [beta][ 2 ] [ 1 ] =  0 E [beta][ 2 ] [ 2 ] =  29 E [beta][ 2 ] [ 3 ] =  0  The two-dimensional version ("R") works as I expected.  However the three-dimensional version ("E") does not -- it appears to set values in a slice rather than an individual element. Note the "17" and "29" values above.  What am I doing wrong?  [note: my actual application is not homogeneous so I can't use arrays]


What is a safe way to upgrade over multiple releases without losing installed programs?

I currently have Ubuntu 10.10 installed and I would like to upgrade to 11.10 (i.e. upgrading by two versions).  There are a couple of issues:    Firstly, I have Matlab installed, and I can't install this myself (I need to get it done by  IT support, which can sometimes be quite difficult).  So I'll need to keep Matlab installed across upgrades.  Secondly, I have custom drivers installed (the NVidia developer drivers for using CUDA) and I'm not sure if this is a problem.  I don't mind reinstalling this however, as they are freely available.   I could click the "upgrade now" button in the update manager, but I will have to do this twice (10.10->11.04->11.10).  Is it possible to put in an Ubuntu 11.10 CD and upgrade my 10.10 install?  Will this leave Matlab installed?    Reinstalling and copying over data might not be an option due to my need for Matlab (proprietary software, eh? :P).


Which lenses should be included in a travel photography kit?

On a crop sensor camera, e.g. Canon EOS 7D, what would be the best kit to travel with around Europe for a few weeks? My shooting style will focus on landscape, architecture, and general travel shots (of note would be my lack of interest for portraits).     Limit to around 1-3 lenses, and I prefer light ones.   Crop sensor camera chosen to save on weight over a full frame option. Question is open to all brands for general guidance, but I will be using a Canon body.   Cost is not a factor, I will rent the lenses I do not already own.   Quality is of paramount importance. I will not have a tripod.   I understand some may consider this subjective, but I do believe that for a crop sensor body, with weight as a consideration, and a limit to the amount of lenses, a true best kit can be determined.


Moderator elections are here. I voted.  However, I find the voting page very biased. It's based on a feed, so if there's 30 people, I won't time nor the memory to read everyone's full description of why I should vote for them.   I doubt most users take the time to read each and every single candidates message.   A small synopsis/message that is written by the user and a different design would DEFINITELY make a huge difference in the way these elections took place and how effective they ultimately are.    Suggestion:    Required Meta Description of why we should vote for a moderator. 140 characters.   Different Design Tile view design where the candidates go across the screen (10 at a time for example) completely randomly (based on the refresh) and NOT based on the time they applied for the election.  Expand Details: "Click to Read More" sign or 3 sentences of the candidates "message" to their potential constituency/voters.   Hide the # of votes until the user voted. This is so biased. Heard Mentalty: feeling more secure voting for someone who has 50+ votes than with someone who has 30 even if they are much stronger than the other candidate. Pure herd mentality.    This would keep the election less biased and surely more effective giving us better moderators on stack exchange!


How to read/write a text file in javascript?

i am an amateur programmer and I'm trying to make a javascript game. I am not going to post this game to the internet, so don't bother with servers and stuff.  The game has a simple score keeping system and every time the game is over, I want the all-time-high score to be shown, and if a new highscore is obtained, I want the previous highscore to be overwritten with the new one.  I searched a lot but couldn't find a proper read/write in javascript tutorial anywhere.  Also, if it can be written to a file that cannot be edited by anyone like txt files, it would be better.  I use plain javascript only, no Jquery or JSON or anything like that.


Story about the first person to be resurrected

I remember reading a short story that takes place in the future in which the leading scientist brings his father back to life as the first "test" of resurrection technology. His father was chosen based on his optimism about the future, and the son said that everyone else was watching to see how someone would react to the news that they had died and were brought back to life. The implication was that technology had advanced quite far, and people from the past would be shocked to see the world as it truly is, so the father was shown a "fake" world designed to look like what he was used to so that he could be eased into reality. From what I remember of the story, it takes place entirely as a conversation between the father and son.  I feel like this story was written by a fairly famous author, but I cannot be sure.  Can anyone help me find this story?


How to pass values from a file to a variable when I run "cat example.txt"

I'm trying to use values from one file and pass them as inputs for variables of another file. Essentially I'm trying to create another file while reusing values from the first file.   When I perform "cat example.txt" I get to see the contents of the example1.txt. Now, from the contents I would like to GREP the lines that I need and pass the values of those lines to a variable. I will then use that variable in subsequent script which will get the values from memory.   contents of example1 file is..  key:value key2:value2 key3:value3 Key4:value4   Now I want to pass key1,key3 to a variable $value1,$value3 and then reuse in example2 like below..  key:"$value1" key2:value2 key3:"$value3" key4:value4   This way the second file can use the values from first commmand output.


Getting error while opening /etc/profile: Error reading lock file /etc/.profile.swp: Not enough data read

I am getting this error while opening /etc/profile file using nano.  Error reading lock file /etc/.profile.swp: Not enough data read   How can I fix this?


I really need help to not let my parents get a divorce

I'm 13 and yes, I know I'm young and don't understand marriage and stuff, but I can't let my parents get a divorce, my mom is the only one who has mentioned wanting a divorce ever, my dad at least wants to some how work it out, they are always fighting about the dumbest things, they are both just so head strong, neither of them wants to even listen to the other persons side, when ever they fight, it's like hours of literal yelling and screaming at each other,some times, they have even gone so far as to hit each other before,  the neighbors think we are crazy, my mom is a house mom, no job, my dad go's on 3-5 day work trips around the area making our money, I have 3 other siblings,  2 younger brothers and a 18 year old sister who moved out last year, and I know that when they aren't fighting about stupid stuff, they absolutely love each other, you can tell from just the way they look at each other, but then the fighting starts and they turn into completely different people... please help me to get them to stop and use some common sense...


I have thousands of episodes that I want to rename which are all in a similair format.  This would take a really long time if I had to do it manually.  So I'll need a simple way to batch rename the following examples:  [Source]SeriesName_-_001_EpisodeName_[480p][DVD][Uploader]  [Source]SeriesName_-_010_EpisodeName_[720p][BD][Uploader]  [Source]SeriesName_-_100_EpisodeName_[1080p][BD][Uploader]  to just:  SeriesName Episode 1 - EpisodeName  SeriesName Episode 10 - EpisodeName  SeriesName Episode 100 - EpisodeName  How would I be able to achieve this?


\documentclass{mwrep} \usepackage[font=small,compatibility=false]{caption} \usepackage[chapter]{minted} \usepackage{lipsum} \begin{document} \chapter{Test} \lipsum[2-3] \captionof{listing}{Caption of listing}  \lipsum[2-3] \end{document}   In the provided example, using of \captionof causes all paragraph indents to disappear (after \captionof). How can it be fixed?


Auto-expand @username in comments to keep the username up-to-date

Comment-discussions are becoming very inconsistent if users change their names, so it might be a good idea if @username would be automatically replaced by @userno on submission and autoexpanded to the current username on loading the question. Since this lookup is also done when the replied-to user's comment is loaded it wouldn't require additional loading anyway.  edit (in reply to @Mark Hurd 's answer) ok, I thought the userid is stable. But as long as there is a way to internally connect comments to its poster, the same mechanism could be used for the @-expansion  update Since questions now have a , I assume the userid is now stable, so this could now be implemented...


Pgfplots Cycle List results in no Colors

I'm trying to use cycle list name = MyCyclelist in order to give my graphs all the same color/style scheme. However all lines are shown in black. I hope, somebody can help. Many thanks!  I've defined the cycle list in my header like this:  \pgfplotscreateplotcyclelist{MyCyclelist}{% {darkgray, mark = none, thick}, {Green, mark = none, thick}, {MidnightBlue, mark = none, thick}, {Mahogany, mark = none, thick}, {RedOrange, mark = none, thick}, {RoyalPurple, mark = none, thick}, }   My pgfplot file is pretty standard:  \tikzsetnextfilename{nextfilename1} \begin{tikzpicture}  \begin{axis}[ axis on top, xlabel = abc, ylabel = def, xmin=0, xmax=194, ymin = 0, legend style = {nodes=left, font =\footnotesize}, legend pos = north east, height=0.5\textwidth, width=\textwidth, cycle list name=MyCyclelist ] \pgfplotstableread{pictures/data.txt} \datatable \addplot[legend image post style={sharp plot, line width=1pt, mark=none}, thick] table[x index = 0 , y index = 1 ] from \datatable; \addlegendentry{abc} \addplot[legend image post style={sharp plot, line width=1pt, mark=none}, thick] table[x index = 0 , y index = 3 ] from \datatable; \addlegendentry{def}     \end{axis}   \end{tikzpicture}   data.txt looks like this:  0   6.21E-11    5.40E-11    8.73E-11 1   6.04E-11    4.86E-11    8.49E-11 2   5.16E-11    5.54E-11    7.30E-11 3   6.46E-11    4.63E-11    8.12E-11


If the function $f(z)$ is analytic and one valued in $|z-a|<R$, How do we prove that $0<r<R$, $f^{'}(a)$ = $\frac{1}{{\pi}r}\int P(\theta)e^{-i\theta}d\theta$, where $P(\theta)$ is the real part of $f(a+re^{i\theta})$. I am guessing Cauchy's integral formula can be used but that has lead me to $f^{'}(a)$ = $\frac{1}{2{\pi}r}\int f(a+ re^{i\theta})e^{-i\theta}d\theta$. How to proceed from here.


How does one get a command to execute on startup on Ubuntu 18.04?

I would like a command to execute when my PC starts up. My OS is Ubuntu 18.04 LTS. The command is:  xrandr --newmode "1920x1080_60.00"  173.00  1920 2048 2248 2576  1080 1083 1088 1120 -hsync +vsync && xrandr --addmode VGA-1 1920x1080_60.00 && xrandr --output VGA-1 --mode 1920x1080_60.00   It works perfectly when I execute it (from the Terminal) after the pc has booted up. I have tried various options (after internet searches) but can't get any of them to work - have tried both command line and GUI profferings - none has worked.


A Word that means "to adapt or improve, to conform to a higher standard"?

I need to find or invent a word that suggests a system might be "adapted or improved to conform to a higher standard". A verb, noun, adjective or even adverb would be acceptable, but so far I haven't found quite what I'm looking for.  Context Examples:  "We are upgrading the current system for greater Enterprise [conformity to a higher standard]."  "I believe we need to change our approach. We need to [adapt to conform to a higher standard]."  "It will take some time to write an article that's more [improved to conform to a higher standard] than I've written before."


Sufficient conditions for $x, Ax, A^2x, ...$ being linearly indepedent

Suppose $x\in\mathbb{R}^n$ and $A\in\mathbb{R}^{n\times n}$. What is a sufficient condition for $$x, Ax, A^2x, ..., A^{n-1}x$$ being linearly independent?


Its the wavelength of the reflected light that gives us the perception of color? But how is this possible while we know also that electrons emit the absorbed photons? so we get 1 color from the emitted and 1 color from the reflected light?


How can I embed the FolderBrowserDialog into my "form1"?  I don't want a popup dialog, how can I achieve this?


How can I know if an attempt is UB and how can I avoid them?

Is there a way to understand a behaviour whether it's undefined-unspecified-implementation defined?   If we can't know, how can I avoid using these statements?  Also, if there is a source that I can find these kind of common UB's can you share?


How to solve $\int_0^\pi{\frac{\cos{nx}}{5 + 4\cos{x}}}dx$?

How can I solve the following integral? $$\int_0^\pi{\frac{\cos{nx}}{5 + 4\cos{x}}}dx, n \in \mathbb{N}$$


Computing $\text{lim}_{n \rightarrow \infty}\frac{n!}{n^{\lfloor y\sqrt{n} \rfloor}(n-\lfloor y \sqrt{n}\rfloor)!}$

We fix $y \ge 0$. What is the following limit?  $$\text{lim}_{n \rightarrow \infty}\frac{n!}{n^{\lfloor y\sqrt{n} \rfloor}(n-\lfloor y \sqrt{n}\rfloor)!}$$  My attempt so far is as follows:  By Stirling's formula, $n! \approx e^{-n}n^{n+1/2} \sqrt{2\pi}$, so that we can compute:  $$\text{lim}_{n \rightarrow \infty}\frac{e^{-n}n^{n+1/2} \sqrt{2\pi}}{n^{\lfloor y\sqrt{n} \rfloor}e^{-n+\lfloor y\sqrt{n} \rfloor}(n-\lfloor y\sqrt{n} \rfloor)^{n-\lfloor y\sqrt{n} \rfloor+1/2} \sqrt{2\pi}} \\   = \text{lim}_{n \rightarrow \infty}e^{-\lfloor y\sqrt{n} \rfloor} \left( \frac{n}{n-\lfloor y\sqrt{n} \rfloor} \right)^{n-\lfloor y\sqrt{n} \rfloor+1/2}$$  upon cancellation and rearrangement of terms.  This is endlessly confusing for me to compute at this point.  Does anyone know how to deal with the limit from here?  I'm asking this question as part of another:  for reference.


After entering the US on a B-1 visa for a program, are tourist activities permitted?

I am traveling to the USA on B-1 visa to attend a 6-day leadership program, from the 13th to the 18th of November. However, I have booked my flight tickets so that I arrive on the 6th of November and depart on 28th November. The total stay will be 23 days. The university invitation letter only states the program dates.   I have booked a room for the 6th to the 13th in Boston, will be staying in university housing during the program, and I will again book the room from the 18th to the 28th.  My question is whether is fine to stay that long on a B-1 visa. I have 10-year visa.  What will I be asked on arrival at the airport? What documents should I carry?


Men go outside Arda to the Timeless Halls when they die. Elves and Dwarves to the Halls of Mandos, i assume Hobbits have the same fate as Men. so where do Orcs go after they die or are Killed? do they stay within the confines of Arda? rot where they lie? leave the world? is there information pertaining to this?


I'm having this problem where objects look transparent but I don't know why. in the shader editor, they look like this.  And when I render it looks like an alpha mask? I don't know.  I don't know what to do, I've already reinstalled Blender.


Prove that if $P$ is a $p$-Sylow subgroup of $G$ and $N \triangleleft\> G$ then:    $ PN/N $ is a $p$-Sylow subgroup of $G/N$ $P \cap N $ is a $p$-Sylow subgroup of $N$


Unlike British English and other varieties, American English does not double the letter "l" in words such as "traveled", "canceled", etc. However, it does with the word "controlled". Is there any logical explanation for this contradiction?


Existence of angle functions on the proper open subsets of $S^1$

Here is the problem 1-8 in Lee's introduction to smooth manifolds:          An angle function on a subset $U \subset S^1$ is a continuous     function $ \theta: U\to \mathbb R$ such that $e^{i\theta(z)}=z$ for all $z \in U$. Show that there exists an angle function on an open subset $U\subset S^1$ if and only if $U \neq S^1.$ For any such  angle function, show that $(U,\theta)$ is a smooth coordinate chart for $S^1$ with its standard smooth structure.      I wonder if $U\ne S^1$ is sufficient for the existence of such a continuous angle function(I feel that the statement should be "there exists an angle function on an open subset $U\subset S^1$ if and only if $U$ is not dense in $S^1.$").    Let's take a special case when $U=S^1-\{-1\}$. Suppose there is such a continuous angle function $ \theta: U\to \mathbb R$ such that $e^{i\theta(z)}=z$ for all $z \in U$. Then we must have $\theta(z)=arg(z)+2k\pi$. However, It seems that there will always be a "jump" somewhere on the circle making $\theta$ discontinuous. For example, if we define $\theta(z)=\arg(z)$, then when $z$ approaches $-1$ from the first quadrant and the four quadrant separately, $\theta(z)$ approaches to $\pi$ or $-\pi$.(This argument turns out to be wrong, see the answers and comments given below by repliers)    Since professor Lee doesn't make any corrections to this problem, it should be correct as given. But how to define such a continuous angle function for arbitrary proper open subset of $S^1$? Thanks in advance!


Ok, I was misunderstanding the problem. After reading it a couple of times I figured out randInt is actually the method itself i am using to populate the array. So when it says to call randInt its some sort of recursive call I think. This is somehow what it should look like:     static int[] randInt(int i, int j) {     int[] temp = new int[(j - i) + 1];     for ( i = 0; i < j; i++) {         temp[i] = i + 1; // here i populate the array     }     System.out.println(Arrays.toString(temp)); // this prints [1, 2, 3, 4, 5]     for ( i = 1; i < j;i++){         swapReferences(temp[i], temp[randInt(0,i)] ); //this is some sort of recursive call that swaps the references          // btw that statement does not compile, how can i pass a method as a parameter?        }     return temp; }  static void swapReferences(int a, int b) { //these parameters are wrong, need to be changed    //Method to swap references  }   Sorry for the confusion, but I think thats how it should be correctly.


Quadratic with integer roots and coefficients in arithmetic progression

Question : Suppose the quadratic polynomial $p(x)=ax^2 + bx + c~$ has positive coefficients $a, b, c$ in arithmetic progression in that order.If $p(x)=0$ has integer roots $\alpha$ and $\beta$, then what is the value of $\alpha + \beta + \alpha \beta$ ?   My attempt: I am not aware of any inequality of some sort if it exists, but I could not get far by trying substitutions over these unknown variables.


Does the empty set have a supremum or infimum?

I actually dont need this question to be answered for university or something, it was just a discussion I had with a friend.  Does the empty set have an upper or lower bound?  Since the supremum is the minimal bound it must be $-\infty$ since  there is no element in the empty set such that it is bigger than $-\infty$. It somehow makes sense. On the other hand the infimum is $\infty$.   Can one define something like that for the empty set? Or is it just heuristic...?


Linux Ubuntu CUDA rendering not available

I am using Linux Ubuntu 15.04, Blender 2.74, I have NVIDIA GeForce GT 610 which supports CUDA and 346.59 driver (latest driver available in my OS). When I open user preferences, CUDA is still not available. Why and how to fix that?


What scale of shutter speeds actually lies behind the numbers?

On nearly every camera I've used, the scale of shutter speeds goes something like:  1s, 1/2s, 1/4s, 1/8s, 1/15s, 1/30s, 1/60s, 1/120s, 1/250s, 1/500s, 1/1000s, 1/2000s  whereas clearly a scale of halves actually runs:  1s, 1/2s, 1/4s, 1/8s, 1/16, 1/32s, 1/64s, 1/128s, 1/256s, 1/512s, 1/1024s, 1/2048s.  That's close enough, but still, there's a difference, and I imagine that with high-precison electronic shutters it's quite possible to be right on the mark with timings.  Where on the scales are the marked, nominal values generally intended to be true (i.e. where are the shutter makers aiming for true accuracy, even if it's only an aim):   along the up to 1/8s range (where they match the actual scale of halves) along the 1/15-1/120s range (where they are off at a ratio of 0.9375) along the 1/250s and faster range (where they are off at a ratio of 0.9765625)?   I am well aware that mechanical and even electronic tolerances may in most circumstances render quibbles over tiny fractions of a second moot. I am equally well aware that many of the scales and numbers used in photography are convenient approximations, and not intended to be taken at face value.   Even so, the fact remains that in design and manufacture an approximation of an ideal still requires a conception of that ideal. Just because a standard is an ideal and can't be met, or it doesn't really matter if it's not met, doesn't mean that design and manufacture don't need ideals, or don't work with them.   I guess that the point of truth in the shutter timings scale is 1s=1s, and all the other numbers are allowed to be approximations if necessary, but it would be nice to know.


Programmatically add more 'paragraphs' in form alter ajax call

I have a content type called repair that has a multi paragraph field (field_products) called Products.  In the create new repair form I have an ajax button that fetches N number of products and returns the $form['field_products'] for re-render.  By default the form shows only 1 paragraph subform.  My question is how do I programmatically show N number of paragraph subforms based on the number of products fetched. The behavior I want is the equivalent of clicking the Add Product (add more) button N times.


So, I don't really have much knowledge about the coordinate system and sometimes I get stuck in certain things that I just can't get around it. For example, whenever I'm working with a vector that is in UTM and I need to see a raster of that place, I use the plugin to see the google satellite in the background. But how can it be perfectly placed with the vector? Wasn't it supposed to have like a difference between the two since the vector is in UTM and Google works in another coordinate system? How does that work? I am doing something wrong? Could someone explain that to me or give me some references that I could be reading to fully understand the subject?


What happens if the Death Star comes out of hyperspace in the middle of an asteroid field?

As , I wonder what happens if the Death Star comes out of hyperspace in the middle of an asteroid field... Or in the middle of a space fleet? Would it be destroyed?  Edit: My main question purpose was originally to know what kind of hyperspace travel the Death Star performs, but since this was edited out, I created a . This secondary question is not a duplicate of the , it is in fact the opposite of it. So in order to clarify it better I will add this:  When the Death Star comes out of the hyperspace, if its entire mass occupies, for instance a group of ships spread around part or the entirity of its area, would they just be pushed out by it, or would they still remain in that area and probably overlapsed by the Death Star mass?


Where can I read the rules on the algabraic manipulation needed to finish this inductive proof that $133$ divides $11^{k+1}+12^{2k-1}$?

Prove: 133 | $11^{k+1}$ + $12^{2k-1}$ , $\forall$ k > 0  Basis: Let k = 1  133 | $11^{2}$ + $12^{1}$ $\implies$ 133 | 133, True  Hypo: Assume true for k = n  133 | $11^{n+1}$ + $12^{2n-1}$  Need to Prove: k = (n+1)  133 | $11^{(n+1)+1}$ + $12^{2(n+1)-1}$  $\implies$ 133 | $11^{n+2}$ + $12^{2n+2-1}$  $\implies$ 133 | $11$($11^{n+1}$) + $12^2$($12^{2n-1}$)  ???  I know that by the hypothesis, 133 divides what is in the parenthesis, and that $11+12^2$ is also divisible by 133, but how can I manipulate the equation to make it so? If you guys can refer me to where I can read about this, or explain to me how and why, I would appreciate it. Thank you.


What happens if dd encounters errors while output of dd is being piped to gzip?

Suppose that   dd if=/dev/sda bs=100M | gzip -c > somefile.img.gz    is done. If errors occur in dd, do I get to see error messages in terminal, or do they get ignored?  Also, suppose that dd encounters a read error. Will dd just skip the block, or will it print out error messages?


I'm confused on my calculations on analytic geometry with probability. Things I learned on these were messed up since I was a newbie on these subjects. Here's my problem:  Three points are chosen uniformly at random from the perimeter of circle. The probability that the triangle formed by these is acute can be expressed as $a/b$  where $a$ and $b$ are coprime positive integers. What is the value of $a+b$?  You may provide explanations so I would know how it was solved. Thank you


Getting the IP address of a given interface

I need the IP (v4) address of a device I specify. The response will be later used in a script. This is what I have:  $ IFACE=eth1 $ ifconfig $IFACE |grep "inet " | awk '{print $2}' 10.0.0.33   Is there a cleaner (shorter) way of doing this?  EDIT: ifdata is exactly what I need. Solution found here:


Code examples, like in the TikZ/PGF manual

I like very much the 'side-by-side' code examples in the TikZ/PGF manual...    ... and I would like to use the same thing in a manual I'm writing. I have found the source code for the codeexample environment that the TikZ/PGF manual uses for this purpose (specifically, it's located at /usr/local/texlive/2012/texmf-dist/doc/generic/pgf/macros/pgfmanual-en-macros.tex).  My (probably rather basic) question is: how can I use the same codeexample environment in my own documents? I ask because I tried compiling the example in the related question below, but the file couldn't be found.


Is it always possible to replace "where" with "in which"?

I read on this site, that we put the words "in which" instead of "where". (Now I don't find the cite). Is that true?


Does divergence of $\sum a_k$ imply divergence of $\sum \frac{a_k}{1+a_k}$?  Note: $a_k > 0 $  I understand that looking at the contrapositive statement, we can say that the convergence of the latter sum implies  $\frac{a_k}{1+a_k}\rightarrow 0$ but from here is it possible to deduce that $a_k\rightarrow 0$ because it is not completely straightforward. If we assume $a_k$ to be convergent, this trivially follows but it could diverge in which case this is nontrivial to me.


if 'statement' : 'statement' if 'statement' else 'statement' How this double if and else work?

I cant understand this double if and else statement   full code is below and where is cant understand is    if not imgs[i].startswith('.'):                 label[j]=0 if imgs[i].split('.')[0]=='cat' else 1     def LoadDirImgList(sampleNum,path):      data = np.empty((sampleNum,3,32,32),dtype="float32")     label = np.empty((sampleNum,),dtype ="uint8")     imgs = os.listdir(path)     num = len(imgs)     j=0     for i in range(num):         if not imgs[i].startswith('.'):             label[j]=0 if imgs[i].split('.')[0]=='cat' else 1             img = Image.open(path+imgs[i])             arr = np.asarray (img, dtype ="float32")             data [j,:,:,:] = [arr[:,:,0],arr[:,:, 1],arr[:,:, 2]]              j=j+1     return data, label


How to create complex conditional clauses / queries?

I've been reading the documentatoin on  and also studied the api description for  and  but I fail to create a $query with 3 ->conditions:   select all between 0 and 100 but exclude 23, 48 and 97 select also 107, 123, 126 and 128   That's what I have tried so far:  $query->db_or()   ->condition('my_field', array(107, 123, 126, 128), 'IN')   ->condition(db_and()->condition('my_field', array(0, 100), 'BETWEEN')                       ->condition('my_field', array(23, 48, 97), 'NOT IN'));   But I get the following error:  PHP Fatal error:  Call to undefined method SelectQuery::db_or() in [... first line]   I've tried to play around with the syntax like that:  $query->condition(->db_or()   ->condition('my_field', array(107, 123, 126, 128), 'IN')   ->condition(db_and()->condition('my_field', array(0, 100), 'BETWEEN')                       ->condition('my_field', array(23, 48, 97), 'NOT IN')));   But again getting errors like that:  PHP Parse error:  syntax error, unexpected T_OBJECT_OPERATOR, expecting ')' in [... first line]   I also tried working with variables:  $cond01 = array('my_field', array(107, 123, 126, 128), 'IN'); $cond02 = array('my_field', array(0, 100), 'BETWEEN'); $cond03 = array('my_field', array(23, 48, 97), 'NOT IN'); $db_and = db_and(); $db_and->condition($cond02); $db_and->condition($cond03); $db_or = db_or(); $db_or->condition($cond01); $db_or->condition($db_and); $query->condition($db_or);   But this again yields drupal errors like that:  SQLSTATE[42S22]: Column not found: 1054 Unknown column 'Array' in 'where clause'   How to create a complex conditional database query with both AND and OR statements?


IGBT ratings, I don't understand how this is possible

I found the  at Digikey.  The datasheet says the device is rated for 400A @ 25C, 1200A @ 25C for 1ms, with a voltage rating of 300V and PD of 1000W.  Really?  This TO-264 package can control 400A of current all day long?  I can short out my TIG welder with it in DC mode?  How do those leads even carry 400A of current?


Obtaining the likelihood of an individual observation

In Likelihood and All That Ben Bolker states " the joint likelihood of the whole data set is the product of the likelihoods of each individual observation". Is there a way that someone could explain to me, in simple terms, how we obtain the likelihood of an individual observation?


Please make pending edit suggesters be @reply-able in comments

When reviewing suggested edits, it often happens that I'd like to say something to the edit suggester, but I can't. The ability to reply to them would be a way to solve edit problems much more amicably, rather than rejecting possibly approvable edits without giving them a reason. Commenting on unrelated posts is clearly not okay. Rejecting the edit with a custom "causes harm" reasoning is also not a good solution, because:  This doesn't notify the edit suggester; they would need to dig out the review for that, which rarely happens. It can only happen when rejecting the suggestion, which is often not my intent.  Besides that:  past approved and binding editors of posts are already reply-able1, there is already an ongoing  to allow replying to rejected editors in comments it's possible for users with pending edit suggestions to edit their edit proposals, so that those edits are also incorporated into the same review (i.e. an unlimited grace period while the edit is still pending) the "Improve Edit" option may not be the right option, as the reviewer may not be entirely aware of what the edit proposer is on to in some cases, or they may need further clarification of the edit before making a decision  I am asking to allow @reply-ing to users who have a pending suggested edit on the post. Note, this does not mean the overloading of their inbox - they won't be notified of all comments, only ones that @-mention their name. Only the post owner would get a notification from all the comments on their post, as normal. Another use case of this feature would be in case someone who has accidentally created a second account or has lost access to their original account suggests an edit to one of their own posts; since the user won't (be able to) see notifications on the first account, one can mention to their second account with the fact that they have another account and instructions to have their account merged. 1As @Glorfindel mentions, they are already pingable. But pending and rejected suggested editors are still not.


According to       Unaccepts should show up in your reputation history. I do remember seeing those notifications for a brief few months in the past, but not for a long time now (it is a rare occurence, so I have to wait for it to happen...).   Just now, I got greeted with another one of these mystery rep transactions:    Question:  Is this feature broken, or is something else at play?  Could it be that it has to do with the new (black) site banner/header/menu thing? It seems to me that the notification system in general is kinda broken/quirky since then. E.g. I seem to get the same notifications at least 3 or four times, sometimes unable to clear them at all, except by clicking on the "colored tab" notification counts in the profile page. I don't really mind that, but it might point at an issue?     and also  *   *  etc...


How to find original community description

Before joining a community you can easily see the community description. For example, for example before joining the Programming Puzzles & Code Golf Stack Exchange you see the description:     Programming Puzzles & Code Golf Stack Exchange is a question and   answer site for programming puzzle enthusiasts and code golfers.   However, after joining I can no longer see this description. I can go to the on-topic page and see a different description:     Programming Puzzles & Code Golf is for programming contests and   challenges. We welcome questions from beginners and experts alike.   Yet, I cannot seem to find the original description anywhere. Is there a way to find the original description while being logged into a Stack Exchange site?  Based on Rene's answer, I can click the Tour link on each site, but StackOverflow (and maybe other sites) do not have a tour link. Instead, I'd have to go there by manually typing it in the address bar. Is there a reason that this has been removed from the Stack Overflow page?


A zombie process, which should not be using any resources (RAM and CPU), is hogging up an entire core on my 8-core 64-bit Ubuntu 11.10 Desktop installation.  This is the output of ps -el|grep Z:  F S   UID   PID  PPID  C PRI  NI ADDR SZ WCHAN  TTY          TIME CMD 0 Z  1000 10317     1 99  80   0 -     0 exit   ?        19:27:15 java <defunct>   ... and here is an excerpt from top:    PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND                                                                                10317 deltik    20   0     0    0    0 Z  100  0.0   1170:17 java <defunct>  1424 root      20   0  612m 193m 158m S   14  2.4 287:17.11 Xorg 12580 deltik    20   0  710m 135m  46m S    5  1.7  27:31.07 compiz   This is how the zombie process came to existence:   I opened a Java JAR called . This launcher downloads another JAR file to ~/.minecraft/bin/minecraft.jar That JAR was executing when I locked my computer with xscreensaver. Then, I entered my password to unlock the computer, and I saw that the Minecraft window was frozen. I tried killing it (PID 10317) with gnome-system-monitor. It became a zombie. kill -9 10317 was ineffective. xkill only closed the window titled "Minecraft"; it didn't close the underlying java process.   Relevant information:   The graphics driver is FGLRX, and it has caused notorious issues with  of  and , including sometimes high CPU usage of Xorg and compiz.   I want to know:   What way is there to destroy this process of java without restarting, if any? Why is this issue happening? What can I do to prevent this issue from happening again?


I'm trying to prove that if $M$ is a simple module over $M_n(D)$ where $D$ is a division algebra, then $M\cong D^n$. I know that if $M$ is a simple module over $R$ then it is isomorphic to $Rv=\{rv|r\in R\}$ for all $v\in M$. I'm trying to find a $M_n(D)$ module isomorphism $f:M_n(D)v\rightarrow D^n$. I've been told to try the map that maps $Xv\mapsto Xe_1$, where $e_1$ is the column vector with 1st entry 1 and the rest 0. I can prove that this is a homomorphism but I'm stuck on the injectivity. Any help would be well appreciated!


How can I customize the highlight colors in Preview?

Is it possible to change the default highlight colors used by macOS's Preview? Only yellow here is usable, other colors are toooo deep/dark that I think they didn't highlight, but de-highlight what I think important...


The force between two sections of uniformly charged line

A line is charged uniformly with the linear density $\lambda$ . What is the force between two sections with lenghts $l_{1}$ and $l_2$ if their end points are separated with distance $r_{0}$?  I have calculated that the electric field from the section on the right is:  $$ E(x)=-k \lambda \frac{l_{2}}{(l_{1}+x)(l_{1}+l_{2}+x)}  $$  I am not sure how to get the force. I tried:  $$ dF=E(x)dq=\lambda E(x)dx \Rightarrow F=\int_{0}^{l_{1}}-k \lambda^2 \frac{l_{2}}{(l_{1}+x)(l_{1}+l_{2}+x)} dx $$ But probably it isn't the right way.   Thank you for any help in advance.    ------------------------------------------------------------------------------  propposed solution:      $$ dF(x_1)= (\lambda dx_1) \int_{l_{1}+r_{0}}^{l_{1}+r_{0}+l_{2}} \frac{\lambda dx_2 }{4\pi \epsilon_0 (x_2-x_1)^2}=k\lambda^2\frac{l_{2}}{(x_{1}-l_{1}-r_{0})(x_{1}-l_{1}-l_{2}-r_{0})}dx_1 $$ The net force:  $$ F=\int_{0}^{l_{1}} F dx_1=\int_{0}^{l_{1}}k\lambda^2\frac{l_{2}}{(x_{1}-l_{1}-r_{0})(x_{1}-l_{1}-l_{2}-r_{0})}dx_1=k\lambda^2log(\frac{(l_{1}+r_0)(l_2+r_0)}{r_0(l_1+l_2+r_0)}) $$