Do we know, or at least have a strong argument for the fact that for a given time interval, we can always find a smaller time interval?

Motivation:  In Biology, when, for example, biologists try to model the population dynamics of a population, they say:     Let $N: \mathbb{R}^{nn} \to \mathbb{R}^{nn}$ be a function that   represents the number of individuals in a given population.   And with that they construct some differential equations, which models the interactions of the population with the environment, other populations, etc..However, for a given time $t$, if $N(t)$ is not an integer, say 1.5, it does not mean anything physically - we cannot have 1.5 member in a population. For that reason, even though this model have lots of successes, it is clear that we can make improvements. In fact, it has been already done. They define $N: \mathbb{N} \to \mathbb{N} $, and they use difference equations for describing the changes in the number members in population. Turns out, in this way, we can explain real phenomenas much better (citation needed, but a quick google research can reveal this).  Similarly, in Newton's time, they thought they could move as fast as they can, but it turned out, we cannot have a velocity bigger than $c$, which changed everything.  Explanation:  We always model time with $\mathbb{R}$, which is a dense set; meaning given any two different real numbers $a$ and $b$, we can always find a third real number $c$ s.t $$a<c<b.$$  Now, as far as our measurements imply, we can always measure and look at smaller time intervals - or at least this is what I know. However, as the history of physics have shown, this is not the case with distance, when we look smaller distances - or objects with smaller sizes - the physics get weird, and I'm not sure that quantum physics suggest that we cannot see smaller sizes after at some point.  The actual question:  So, my question is that, is there any argument why modelling time as a real number in any physical theory is sensible?  Note the relation of this question to the motivation given in the beginning .  Edit:  I'm directly going to quote what I have written in the comments:     I do not ask whether time is something or else, but rather, is there   any motivation why we use a dense field to model it, and is there any   counter experimental observations, or any other models who use discreet    time intervals in Physics.   Moreover, I'm talking about Physics in here, not about Biology.


Is there a way to get a background in CSS to stretch or scale to fill its container?


Does there exist a positive irrational number $\alpha$, the number $\lfloor n\alpha \rfloor$ is never a prime?

Does there exist a positive irrational number $\alpha,$ such that for any positive integer $n$ the number $\lfloor n\alpha  \rfloor$ is not a prime?


I searched for ki with * as per the example below and it should have returned the first three lines. I am not sure why it returns the last line when there is no ki matching it.  $ grep "ki*" trial_file.txt kartik,27,Bangalore,Karnataka pulkit,25,Bangalore,Karnataka kit,28,Bangalore,Karnataka kush,24,Pennsylvania,Philadelphia


I have the following:   A PNG or JPG of a random width and height, in pixels, that represents a partial map of the world (i.e. a rectangle of the United States). The four corners of this image are represented by real latitude and longitude values that if plotted, would represent 4 corner points of the United States (LatTop, LatBottom, LongLeft, LongRight). A coordinate that, if plotted, would represent a point somewhere inside of this "rectangle" (Latitude, Longitude).   My question is, what type of projection or formula would I use to calculate the X and Y coordinates (in pixels based off of the original PNG/JPG image) of the coordinate provided in #3 above?  Some example values would be:   ImageWidth = 1312 ImageHeight = 576 LatTop = 30.244381 LatBottom = 29.529928 LongLeft = -96.764958 LongRight = -94.404619 Coordinate Latitude = 30.100000 Coordinate Longitude = 95.100000   I found some information regarding Plate Carrée projections but I could not successfully apply it to this problem. Perhaps I am missing something.


I can't think of an example, so I may be wrong about this, but I think I've seen people replace the prefix "trans" as in transport with an x. "Cross" makes sense, as in "railroad crossing", and I guess "chris" is sort of a punny extension, the extension being like "chris cross" and the example being "xmas", but why trans?


How to change Ubuntu 20.04 Desktop file manager (not gnome)?

Is there anyway to use a different desktop than the one that ships with this Ubuntu? I'm sorry if the question is weak, I understand I can change display managers and so on, but the new desktop is so detached from any file explorer (I use nautilus), it is off putting.


The effect on Nazgul as couriers of the One Ring

This may probably all be speculative, but what effect would the One Ring have upon the Nazgul, who each wore a ring of power, if they had indeed captured it during the hunt for the Ring? Would the Ring move itself to be found/worn in a similar fashion as it had done with Smeagal/Gollum and Frodo, or, as the Nazgul were already in Sauron's service, would there likely be no effect at all?


Does there exist a metric space  $(X,d)$ such that for subsets $A$ and $B$, define $ d(A,B)= inf \{d(a,b): a \in A, b \in B \}$,  $\bar{A} \cap \bar{B} = \phi$, but $d(A,B) \leq 0 $  I think so but don't have an example.


How did Batman build and maintain his Batcave?

It's too big to be built in secret and it requires some maintenance all the time. A single man or even two or three people if you count Alfred and Robin can't keep up with everything.   Where are the workers who built it originally? All dead?  What if there is a leak from the lake?  Okay, it was built by workers who didn't know what they were building. But how they repair it?  By maintenance, I don't mean cleaning the floor or repairing a broken sink. Rather concrete reinforcement or construction/engineering work.


Circuit to adjust -30V to +30V input to 0 to 3.3V for ADC?

Currently working on an oscilloscope design that would require each channel to be able to take in between 30VPP, -30V to +30V, which will go to an ADC which has a maximum input of 3.3V.  What types of designs or specific circuits could I implement to offset the voltage where 0 is -30V and 3.3V is +30V ?  ALSO - Yes, I will also be implementing a voltage divider, but the ADC cannot take in negative voltage.


I meet with term 'empty function' from time to time. It's high time to understand its nature. What is field( set of arguments) and what is image? ( set of value)?


Download old attachment file on Gmail marked as a virus

I have an old file attachment (file.zip) in my Gmail account. I want to download it but now Gmail says that the file that I want to download is blocked because it is a virus. I think one trick is to forward it to another mail provider but I can't forward it for the same reason. Anyone know a trick to download that file?


Is it possible to view the latex code after Lua expansion is made?

When using Lua code inside Latex file, where Lua code sends to Tex Latex code to insert into the document at the location the lua code is made, it will be useful to look at the content of Latex file (internal) after the expansion is made but right before the file is compiled to pdf. This can help in debugging and in many other cases.  Is there an option to do this?  A small example will help explain what I mean.   Given this latex file  \documentclass{article} \usepackage{luacode} \begin{document}  The following is my table  \begin{luacode} i=6 j=8 tex.print("\\begin{tabular}{|l|l|}\\hline") tex.print(i.."&"..j) tex.print("\\\\ \\hline") tex.print("\\end{tabular}") \end{luacode}  \end{document}   Compiling this gives the pdf file:    What I'd like to now see is the Latex file that would resulted after the Lua code expansion, which should be something as follows  \documentclass{article} \usepackage{luacode} \begin{document}  The following is my table  \begin{tabular}{|l|l|}\hline 6 & 8 \\\hline \end{tabular}  \end{document}   I could not find an option to do this so far.  TL 2015    Update  Another example to make clear what is being asked here. I'd like to see not only the latex code that was generated from the lua bits of code, but the full Latex document that would result after all the expansion of all lua code in the original Latex. But this has to be done without modifying the original Latex document itself.   Assuming there is this virtual pipeline:  Latex file -> Lua code expand -> Updated Latex (internal)-> lualatex ->pdf    I'd like to get a copy of the full latex code/file just after all the lua code expanded.  Here is another example. Given this Latex file input:  \documentclass{article} \usepackage{luacode} \begin{document} The following is my table \begin{luacode*} i=6 j=8 tex.print("\\begin{tabular}{|l|l|}\\hline") tex.print(i.."&"..j) tex.print("\\\\ \\hline") tex.print("\\end{tabular}") \end{luacode*}  Our annual budget for the company is \luaexec{tex.print(200*15^3)} dollars as  shown in this list of items \begin{luacode*}  tex.print("\\begin{itemize}")  for i=1,5 do    tex.print("\\item "..i^2)  end  tex.print("\\end{itemize}") \end{luacode*} And so on. \end{document}   The PDF is    I'd like to get a copy of the following latex file, which has all the Lua code expanded and gone and only the Latex code is left in its place. This file can go to a temporary file, or anywhere, as long as it is the complete Latex file as shown and not bits and pieces. This would be very useful in debugging when there is lots of Lua code in different places in the original Latex file.  \documentclass{article} \usepackage{luacode} \begin{document}     The following is my table  \begin{tabular}{|l|l|}\hline 6 & 8 \\\hline \end{tabular}  Our annual budget for the company is 675000 dollars as  shown in this list of items  \begin{itemize} \item 1 \item 4 \item 9 \item 16 \item 25 \end{itemize}  and so on     \end{document}   I hope now the question is even more clear :)


Eager to move up from Mint 19 to ubuntu Maté

Sorry if this the wrong place.  My first computer was the Timex Sinclair 1000 back in the day. and I loved learning the language for it, but after many huge improvements in my subsequent computers, a very bad thing happened... windows. With that, the magic stopped. Well, I'm old now, early 60s, and last week I decided I had to get rid of windows along with google and all their products. I suppose you all know that google is more difficult to divorce than windows, but it is often the #1 computer resource hog in most win based systems. Yes, both google-search and gmail are second to none and is why I keep chrome around during this abrupt transition, though their replacements are soundly structured.  I come to you with my simple question, but please believe me that I have worked all through the night trying to salve it without help, and I'm sure in time I would figure it out, but I'm more anxious than ever to get this done and it is a new day.  I started with slamming in Mint 19, kicking out windows, thank God... It was sooo easy. But now I'm faced with a dilemma. In moving up to ubuntu Maté, I must find a "USB-stick boot Installer" to burn in the ubuntu Maté OS. This was no problem when moving from windows to Mint 19, because all boot installers accommodated windows. But now, I can't seem to find one that is built for Linux Mint. Well, there was UNetbootin, but for some odd reason, I could not get it to run effectively.  Because the memory is only 3.7 GB and HDD 479.8 GB, I downloaded your 18.04.1 LTS {Bionic} release.  By the way, the laptop I'm currently using is a 5-year-old with the following specs:    System: Host: robert-HP Kernel: 4.15.0-36-generic x86_64 bits: 64 gcc: 7.3.0  CPU: Quad core Intel Pentium N3540 (-MCP-) arch: Silvermont rev.8 cache: 1024 KB flags: (lm nx sse sse2 sse3 sse4_1 sse4_2 ssse3 vmx) bmips: 17326  clock speeds: min/max: 499/2665 MHz 1: 499 MHz 2: 499 MHz 3: 851 MHz 4: 721 MHz  Graphics:  Card: Intel Atom Processor Z36xxx/Z37xxx Series Graphics & Display bus-ID: 00:02.0 chip-ID: 8086:0f31 Display Server: x11 (X.Org 1.19.6 ) drivers: modesetting (unloaded: fbdev,vesa) Resolution: 1366x768@60.03hz OpenGL: renderer: Mesa DRI Intel Bay Trail version: 4.2 Mesa 18.0.5 (compat-v: 3.0) Direct Render: Yes  Audio: Card Intel Atom Processor Z36xxx/Z37xxx Series High Def. Audio Controller driver: snd_hda_intel bus-ID: 00:1b.0 chip-ID: 8086:0f04 Sound: Advanced Linux Sound Architecture v: k4.15.0-36-generic  Drives: HDD Total Size: 504.1GB (5.6% used) ID-1: /dev/sda model: TOSHIBA_MQ01ABF0 size: 500.1GB serial:  ID-2: USB /dev/sdb model: STORE_N_GO size: 4.0GB serial:   Info: Processes: 245 Uptime: 4:09 Memory: 2920.6/3835.4MB Init: systemd v: 237 runlevel: 5 Gcc sys: 7.3.0 Client: Unknown python3.6 client inxi: 2.3.56    This is an old laptop I'm using while the keyboard of my usual Sager gaming notebook is being replaced, taking a week or so. I'm not interested in updating this old laptop, though the prospect of using its windows OS is terrible, so now it has Mint 19.  I hope you understand. With Linux, the magic is back!  OH! P.S.  I'd like to thank Joe Collins and his EzeeLinux program. Imma Texan too Joe.  UPDATE!!! I was finally able to install ubuntu Maté once I realize that the .iso.torrent, being recommended, was the wrong choice for me. It was the straight .iso file below it that had the command need to burn it to the USB stick.


BibTeX loses capitals when creating .bbl file

Titles of articles I'm about to cite contain upper case letters and when using BibTeX it converts them to lower case ones. This happens only in the title and only the first letter conserves its case. For example, when I cite an article about HF, the reader won't know if it is about Hafnium (Hf) or fluorine acid (HF).  I know that I can fix it manually in the .bbl file but I would like to avoid it, or fix it automatically.


Restoring with replace going incredibly quickly

So I have a database (on a SQL Server 2008 R2 SP2 instance) that is 2TB uncompressed, with a .bak file that is 500GB compressed. As I have been toying with the fastest way to restore this database after a series of tests, I've tried a couple of things:   Restoring after dropping the database Restoring with Replace   When I restore after dropping the database, the fastest I can get a restore going is 4 hours. This is when I put the .bak on a RAID 10 logical drive, with the data files being written to a separate RAID 10 logical drive on the same server. The log files go to yet another RAID 0 on the same server.  However, if I restore with Replace, the restore process only takes 56 minutes (similar setup). Did I find some sort of turbo button? This is so fast that I am worried.


I have this exercise:     Let $R$ be a Noetherian ring. Let $S\subseteq R$ be a multiplicatively closed set. Prove that $S^{-1}R$ is a Noetherian ring.   First off we claim that given a subset $I\subset R$, $$S^{-1}I \lhd S^{-1}R \quad \Rightarrow \quad I\lhd R\ \land \ I\ \cap S=\emptyset $$ That's true because $$ S^{-1}I \lhd S^{-1}R \quad \Rightarrow \quad (\ \frac {i_k} s \in S^{-1}I \Rightarrow \exists \ d_k\ \mathrm {maximal} :d_k|i_k,d_k\notin S)$$ So if we take the ideal in $S^{-1}R\ $generated by the elements $(\frac {d_1} 1,\frac {d_2} 1,\dots ,\frac {d_k} 1,\dots)$, clearly we obtain $S^{-1}I$, plus $I=(d_1,d_2,\dots,d_k,\dots)\lhd R$. Since every ideal on $R$ is finitely generated, it follows that ideals are finitely generated on $S^{-1}R$ too.  Is this correct? Do I need to be more exhaustive or am I wrong with something? Thank you :)


I'm playing the pc-version of dark souls, does anybody knows what is the equivalent of "rs" for the pc-keyboard? thanks  Sorry, I already saw the other answers, but I couldn't find the key "rs" and his equivalent for pc...perhaps I'm a bit thick :-( .....


As a newbie, I am quite confused how open source software is can/be licensed. I know of licenses like GNU public, Apache, and others.   What is the procedure to license a open source software by developer? What considerations should be made? What choices do I have?


HTML converter possible as a TeX package?

I know there are a lot of threads on existing Tex-HTML converters already, but I have a question about the feasibility of creating one.  Existing tools use other scripting languages to parse raw TeX and output HTML.  Would it be a better idea to write a package for TeX that overrides commands and outputs content to a HTML file?  For instance overriding \section to write a <h1>{content}</h1> tag to another file.  Is this feasible? I'm sure everyone knows more about TeX than me so I'd like to hear your thoughts.


Gksudo alternatives, especially to use in .desktop files

I have wanted to create a .desktop file to create an application icon which would execute a .run file as admin. Since the gksu package is deprecated, I've used  Exec=gnome-terminal --command="sudo /opt/lampp/manager-linux-x64.run"   in the .desktop file. This opens a new terminal window and I type my sudo password to open the application.  So, are there any better solutions, which are more elegant for instance without having a terminal window opened?


Python changing a value in a list changes them all unintentionally

I have a class:  class Tree(object):      def __init__(self):         self.health = 100   And I use it here:  tree_list += [Tree()] * random.randint(4, 12)   This makes the list contain multiple Tree() classes. The problem is that when I change 'health' in one of the items in tree_list:  tree_list[0].health -= 25   It changes the 'health' value in EVERY item in tree_list. Can someone please help me figure out why it changes the value for every item instead of the item I intend to change? Any help would be appreciated. :D


How to strip HTML tags from a string in SQL Server?

I've got data in SQL Server 2005 that contains HTML tags and I'd like to strip all that out, leaving just the text between the tags. Ideally also replacing things like &lt; with <, etc. Is there an easy way to do this or has someone already got some sample T-SQL code? I don't have the ability to add extended stored procs and the like, so would prefer a pure T-SQL approach (preferably one backwards compatible with SQL 2000). I just want to retrieve the data with stripped out HTML, not update it, so ideally it would be written as a user-defined function, to make for easy reuse. So for example converting this: Some useful text&nbsp;      &gt;&nbsp;more text
  to this: Some useful text > more text


$G=\{e,a,b,c\}$, $|G|=4$, non-cyclic, then what are the orders of the elements?

Let $G=\{e,a,b,c\}$, $|G|=4$, non-cyclic.  Then what are the orders of the elements?    I'm thinking that because $G$ is a group, then by non-cyclic and Lagrange's theorem its elements (subgroups) can only have order 1 or 2.  But can I decide on anything else than 1 or 2?


Why would a grad school not want me to defer admission?

I have been accepted to a fairly competitive online computer science-related  (in the US). It is a part-time program geared toward working professionals. During the application process, I was assigned an admissions counselor that worked with me during the application and answered questions, etc. The counselor did mention at one point that I could defer  admission by one trimester, should I be accepted.  Well, long story short, I have a situation with my employer (who would be funding my graduate studies), that is now making me strongly prefer to exercise the deferral option.  I have reached out to my admission counselor seeking guidance on how to do this. I expected this to be a fairly routine, straightforward process. Instead, I am getting aggressive pushback, with the counselor trying to talk me out of it.   After several emails and phone calls with the counselor, I still do not have any instructions on how to actually accept the admission but defer by one trimester. My admission offer is still pending. I would really like to simply accept the offer (and pay the deposits), but with deferral.  All I have are appointments to talk with a current student and a scheduled one-on-one demo of the "courseware" with the counselor. I cannot help but notice the counselor is seemingly dancing around my question on how to defer.  Since this deferral option was mentioned up front when I was still just an applicant, why would I be encountering this kind of resistance? I am truly baffled. Why can't I just do "what is best for me"?  The program has three admission cycles throughout the year: fall, spring, and summer. I applied for fall 2015 and was accepted. I'd like to exercise the option to defer, essentially as if I applied for spring 2016.  I am starting to wonder: Does my request for a deferral reflect badly on someone? On me? On the counselor? Might the school have some aggressive revenue forecast that was expecting my tuition payment, and now this deferral request throws a wrench in it? Does the admission committee and/or counselor have some quota for accepted offers they need to meet? Might they simply be trying to balance class/cohort sizes? I am trying to understand this from the school and counselor's perspective: Why might they do this, and why do so in this aggressive manner?  Furtheremore, does anyone have any advice on how to proceed from this point? Should I just be frank and ask the counselor why the aggressive pushback?


Stuck in nether in creative mode on xbox one and can't find portal to get back

I am on Minecraft in creative mode on xbox one and am lost in nether. I have tried for hours to find my portal and can't. All the responses I see tell you how to get out if you are on a computer and not in xbox one. Anybody have a way to help me get out?


I currently have my rewrite rules in the post_virtualhost_2.conf file this in inserted into the httpd.conf file at the absolute end. I have two blocks that don't seem to be working <IfModule mod_rewrite.c>    RewriteEngine On    RewriteCond %{HTTPS} !=on    RewriteRule ^(.*)$ https://%{HTTP_HOST}/$1 [R=301,L] </IfModule>  <IfModule mod_rewrite.c>     RewriteEngine On     RewriteCond %{HTTPS} !=on     RewriteCond %{HTTP_HOST} !^www\. [NC]     RewriteCond %{SERVER_ADDR} !=127.0.0.1     RewriteCond %{SERVER_ADDR} !=::1     RewriteRule ^ %{ENV:PROTO}://www.%{HTTP_HOST}%{REQUEST_URI} [R=301,L] </IfModule>  The full conf is  What I am expecting is the following in all cases    But when I enter privatmamtora.com it simply get a 200 response. PS. I am hoping that the rules could be subdomain safe. (Not break subdomains) EDIT Rewrite module is loaded.


How to determine wattage of a resistor I found

In general is there a way to know what the wattage rating of a resistor is?  I have a large bin of resistors of varying resistances and physical sizes.  I assume size correlates to wattage as a larger resistor would be able to dissipate more heat.  How would I go about determining what a safe wattage is to pass through a resistor?


Find the interval of convergence for $\sum_{k=0}^{\infty}\frac{x^k}{k!}$.  I tried using the ratio test to find the radius of convergence.  \begin{align} \lim_{k\to\infty}\dfrac{\left|\frac{x^{k+1}}{(k+1)!}\right|}{\left|\frac{x^k}{k!}\right|} &= \lim_{k\to\infty}\left|\dfrac{x}{k+1}\right| =0 \end{align} Doesn't this tell us that we can choose any $x\in\mathbb{R}$ because $\lim_{k\to\infty}\left|\dfrac{x}{k+1}\right| =0$ for any $x$?


I need help on a relatively simple finding a gene program in BlueJ (Java)

Basically, the assignment (on BlueJ) is to fix our program to print out the gene (link) between the startCodon ATG and the stopCodon TAA, but to also allow for the gene output using lowercase DNA (with lowercase start and stop codons). Basically: if CCGATGGCGGCATAAA prints ATGGCGGCATAA the ccatgccgtaagca should print atgccgtaa. I'm a newbie and the best I could do on BlueJ is Gene = ATGcgcacgTAA, when I establish that String startCodon = "ATG" and String stopCodon = "TAA", no matter what I do, it doesn't recognize it. please help...  public class Part2 {                                                       public String findSimpleGene(String dna, String startCodon, String     stopCodon){         int indexStart = dna.indexOf(startCodon);   int indexStop = dna.indexOf(stopCodon, indexStart+3);   String link = dna.substring(indexStart,indexStop+3);   if ((indexStop-indexStart)%3 == 0){      return link;            }     else if((indexStop-indexStart)%3 != 0){     return "";    }         String lowerDNA = dna.toLowerCase();      int lowindexStart = lowerDNA.indexOf(startCodon.toLowerCase());   int lowindexStop = lowerDNA.indexOf(stopCodon.toLowerCase(),lowindexStart+3);   String lowlink = lowerDNA.substring(lowindexStart,lowindexStop+3);      if (dna == lowerDNA && startCodon == startCodon.toLowerCase() && stopCodon == stopCodon.toLowerCase()){          return link = lowlink;            }       return link;  }     public void testSimpleGene() {  String startCodon = "ATG";  String stopCodon = "TAA";    //so it can return a lowercase link, but ATG and TAA must be capital?? //this string below works  String dna =  "GATGTTAGCAAGCTCATAACGCATGACATAA";  System.out.println("DNA strand is " + dna);  String gene = findSimpleGene(dna,startCodon,stopCodon);  System.out.println("Gene is " + gene);       }  }


Placeholder for new question is not properly visible

When you start a new question in the iOS app the placeholder for the title field is partly obscured.   App Version: 1.6.6.2 Device: iPhone 7 OS Version: Version 11.2 (Build 15C114)


Prevent Windows 10 from automatically logging into a passwordless account

We have a Windows 10 Home version 1607 desktop with two user accounts: an administrator account with a password and a limited account without a password. If I shut down the system without logging out of the limited account first, it automatically logs into that account when I start it up again. We'd prefer that it not do that.  I couldn't find a relevant setting anywhere in the system, whether in the Windows Settings app, Control Panel, or even control userpasswords2. There is no access to gpedit.msc. How do I prevent the system from logging in automatically, without setting a password for the limited account?


What is the sum of $\sum\limits_{i=1}^{n}ip^i$?

What is the sum of $\sum\limits_{i=1}^{n}ip^i$ and does it matter, for finite n, if $|p|>1$ or $|p|<1$ ?   Edition :  Why can I integrate take sum and then take the derivative ? I think that kind of trick is not always allowed.  ps. I've tried this approach but I made mistake when taking derivative, so I've asked, mayby I should use some program (or on-line app) for symbolic computation.


Please help me to draw the following diagram:  \begin{displaymath} \xymatrix{ H\ar[r]&H .1={}_HI_Q\supset 1.Q&Q\ar[l]_\epsilon^{\cong}  \\  &R\ar[u]\ar[r]&R\ar[u] } \end{displaymath}


how can I install ubuntu in windows 7 32bit machine?

how do I install ubuntu.iso (downloaded from ubuntu.com[more than 700mb]) in my windows 7 ultimate 32bit. please explain step by step.. thanks


What do You Call Two Siblings That Are Born on The Same Day, But Different Years?

My brother and I were both born on March 18, but he was born in 2000, and I was born in 2002. What do you call that?


How do I write the mathematical equation for ARIMA(0,0,5)(1,0,1) period 12?

I would appreciate if someone could help me write the mathematical equation for the seasonal ARIMA (0,0,5) x (1,0,1) period 12. I'm a little confused with how to go about this.


Infinitive in complex sentence: 'we will do your best in order to ensure the debate be vivid and fruitful.'

Is 'We will do your best in order to ensure the debate be vivid and fruitful.' a grammatically correct sentence?   I am not sure if I used the infinitive correctly, is it better to place simply 'is' instead of 'be'?


xubuntu install from cd on an old laptop

I have found my old Compaq Armada E500 laptop and I thought Xubuntu would run fine on it. I burned a CD with Xubuntu 12.10 32bit and loaded it up, but all I could hear is the constant seeking of the CD head, I couldn't even reach the language selector menu.  I tried burning the CD 3 times, even on RW media. I tried to defragment the ISO before burning it to CD but none of them helped. This is not the first time I encountered this problem with a different laptop (but that was old as well), I thought back then that the CD was poorly written.  Windows XP install, Debian or GParted CD loads fine (so the DVD ROM should be OK) on this E500, and the Xubuntu install CD load fine as well on a Lenovo X230 and does not seek a lot.  Is it possible that I need to write the CD with different settings so that it works well in an older (9-10 years old) DVD-ROM? I burned the CD with 16x speed, with Infrarecorder (in Windows 7).


If a and b are odd integers, then $8\mid (a^2-b^2)$

Prove: If $a$ and $b$ are odd integers, then $8\mid (a^2-b^2)$  So far I have: $$8\mid \left((2n+1)^2-(2m+1)^2\right)\Longleftrightarrow 8\mid \left(4n^2+4n+1-4m^2-4m-1\right) $$ Is this right so far? Where do I go from here? Step by step explanation please!


What is the command to bring up GUI shutdown box?

Unity brings up a window with shutdown/reboot options when pressed my pc power button. But how to do that with a command?


I own the PHB, DMG and MM physically.  I've also downloaded the various free pdfs from the WotC site (Elemental Evil Player's Companion, various Unearthed Arcana, etc).  I find it convenient to be able to search through these pdfs via text matching and that I can carry them around all in my pocket. Not so with the PHB, DMG and MM; they live at home and must be searched through the good ol' fashioned way if ever I need to look something up.  Is there a (legal) way to aquire a digital copy of these core rulebooks (also Volo, SCAG, etc)?    Obviously I won't accept "scan 'em all in yourself" as an answer ('coz I'm a lazy millennial) but I will accept "no, there isn't" if there really isn't anything available to download (legally).   Also note that I am aware of the basic player/DM rules that are available but since it is cut down (understandably since it's free) I don't want that as an answer either.  Finally, there's this suspect looking site, (it's the first hit if you Google "lost mines of phandelver"); given that it appears to offer every D&D book ever for free, I'm guessing this is not legal? Assuming this is the case, I don't want that as an answer either.


What's the name for the property of a function $f$ that means $f(f(x))=x$?

I can think of several examples of functions such that twice application of the function is equivalent to no application of it.   Additive inverse Multiplicative inverse Fourier transform Complex conjugation Any group built up from $\mathbb{Z}_2$, applying (one of) the $\mathbb{Z}_2$ parts' operation.   "Idempotent" came to mind, but that's wrong. It means $f(f(x)) = f(x)$, not $f(f(x))=x$.  What is the word for this "flip-flop" property?


I'm using VMWare, and running debian and whenever I run a new terminal my commands like "ls" seem to be lost. I've tried the solutions listed here for instance:  When I do: PATH=/usr/bin:/bin:/usr/sbin:/sbin:/usr/local/bin:/usr/X11/bin  it works temporarily. When I do: cd ~ nano .bash_profile export PATH=/usr/bin:/bin:/usr/sbin:/sbin:/usr/local/bin:/usr/X11/bin:$PATH  -- the file changes and the save reflects but when I open a new terminal the commands are forgotten again. Edit: rowen@debianRhys:~$ echo $PATH  /home/rowen/bin:PATH   source .bash_profile bash: dircolors: command not found


16 GB USB flash drive capacity down to 938 MB

After writing the FreeNAS IMG to a 16 GB USB flash drive, I can now only use 938 MB. I used the Win32 Disk Imager tool to write the IMG to the device. Then later, when I inserted the the USB drive into my Windows 7 computer it said that it had to be formatted, because it couldn't read it. I believe this is normal. So I formatted it inside Windows using the format option when prompted. So in Windows Explorer now, 938 MB is reported as capacity of this device.    Also, when i check the properties dialog box I can see the same numbers.    And when I check with diskmgmt.msc I can see there are several volumes I don't recognize and unallocated space of 12.79 GB.    Now, I have another 2 GB USB flash drive with the same problem. It too was used for FreeNAS, and it too has a reported capacity of only 938 MB. I thought it was broken there for a while, until I saw the same problem with this 16 GB model.  I tried using diskpart on the 2 GB model, and I saw that there were several partitions there (list partitions) just like on this one. So I used the clean option to try to wipe it, but that wiped off everything so it's totally useless now. I'm not sure how to rebuild it.  Is this a standard routine, like part of the whole "user experience", that whenever you make a bootable USB falsh drive with FreeNAS, it messes up your device? I am new to FreeNAS, so i wouldn't know. But it sure looks like it. Maybe it is in fact the format operation in Windows that messes things up... I don't know. It's not very nice.  How do I restore the capacity back to 16 GB-ish (14.9 GiB)?


Let $f: X \rightarrow Y $ and $g:X \rightarrow Y$ continuous functions and $(X,d_X),(Y,d_Y)$ metric space. Let $E$ by a dense subset in $X$. Prove that $f(E)$ is a dense subset in $f(X)$. If $f(p)=g(p)$ for all $p\in E$, prove that $f(x)=g(x)$ for all $x\in X$.  My attempt: since $E \subset X \Rightarrow f(E)\subset f(X)$ and from the dense property we have $f(X) \subset f(\overline{E})$ and since $f$ is continuous, $f(X) \subset f(\overline{E}) \subset \overline{f(E)}$. Then, $f(E)$ is dense in $f(X)$.  Suppose that $f(p)=g(p), \;  \forall p \in E$. Hence, we have  $$d_{Y}(f(x),g(x)) \leq d_{Y}(f(x),f(p)) + d_{Y}(f(p),g(x)) = d_{Y}(f(x),f(p)) + d_{Y}(g(p),g(x)).$$ By the fact that $f,g$ are continuous, there exist a $\delta_1$ and $\delta_2$ such that $$d_X(x,p) < \delta_1 \qquad d_X(x,p) < \delta_2$$  implies $$d_{Y}(f(x),f(p))<\epsilon /2 \qquad d_{Y}(g(p),g(x)) < \epsilon /2.$$ for all $\epsilon >0.$  Is this correct?


The off topic notice should include option to migrate in the notice, and allow author to do it

I recently googled for a topic, found a very similar question of the same topic in Stack Overflow, and posted my question. After a few days nobody had answered it, but I found the answer on my own and posted it, then accepted the answer. Minutes later the question was marked as off topic, and there was a suggestion that this type of question is better suited for Super User community. In the off topic notice there was no indication that the question could be moved to another community, and being a new contributor, I wouldn't have enough points to do so anyway (unless a change in policy is made in SE to allow authors to move their questions when someone closes them for being off topic). but what should appear there is a button (like the DELETE button that does appear there) The DELETE button doesn't work, by the way, as a vague error message says in general that people have contributed to it. Well, it turns out the contributor of the answer was myself and there was no indication in that message that I should first un-accept my answer, delete it, then delete the original post, or wait for people with higher reputation to move it on my behalf as my hands are tied at that point. It is frustrating for newbies and I suppose many would walk away at that point, but if it's going to be fixed it has to be reported. Is this something that should be changed? And how to go about it without spending a whole lot of time on it - I don't work for SE and can't spend too much time dealing with it.


Is there built-in library can compare float or double  I do not think compare like a == b or a !=b makes any sense. Any suggestion?


Applying for UK visit visit myself and my daughter. Do I need to supply duplicate supporting documents?

I am applying for a UK visit visa for myself and my 6 year old. Can I submit 1 set of supporting documents or will we need to duplicate this for both applications?


How do you find the time to answer questions on SO?

I've been thinking about this many times, that as a person who is spending most of his days coding and learning programming, I should give back of what I learn here and answer questions of other programmers, but due to the lack of time (or maybe discipline), I wasn't successful at this at all. yet I see a lot of professional programmers with astronomically high reputations, people who give accurate responses to though questions at no time.  what is your advice for becoming a useful member of this community?


How to remove a apt-key which I have added?

I added a key like this:  wget -q -O - https://jenkins-ci.org/debian/jenkins-ci.org.key | sudo apt-key add - sudo sh -c 'echo deb http://pkg.jenkins-ci.org/debian binary/ > /etc/apt/sources.list.d/jenkins.list'   Now I want to remove this key. How can I do that? I don't know where it got added and how does it look like.  When I do sudo apt-key list it prints out few things on the console. Not sure which one is related to what I did above?  david@machine:~$ sudo apt-key list /etc/apt/trusted.gpg -------------------- pub   1024D/437D05B5 2004-09-12 uid                  Ubuntu Archive Automatic Signing Key <master@ubuntu.com> sub   2048g/79164387 2004-09-12  pub   1024D/FBB75451 2004-12-30 uid                  Ubuntu CD Image Automatic Signing Key <image@ubuntu.com>  pub   4096R/C0B21F32 2012-05-11 uid                  Ubuntu Archive Automatic Signing Key (2012) <master@ubuntu.com>  pub   4096R/EFE21092 2012-05-11 uid                  Ubuntu CD Image Automatic Signing Key (2012) <image@ubuntu.com>  pub   1024D/D50582E6 2009-02-01 uid                  Kohsuke Kawaguchi <kkiu@kyterty.org> uid                  Kohsuke Kawaguchi <kyterty.iuytre@sun.com> uid                  [jpeg image of size 3704] sub   2048g/10AF40FE 2009-02-01  /etc/apt/trusted.gpg.d//pubring.gpg ----------------------------------- pub   2048R/06634014 2013-01-26 uid                  OSP Team <IET-OSP-IUY@host.com> sub   2048R/732F28E7 2013-01-26


Suppose that $n \geq 1$ is a natural number. (i) Show that for $z$ in $\mathbb{C}$, provided $z \neq 1$, $$ \frac{1-z^{n+1}}{1-z} = 1+z+...+z^n.$$ (ii) Using de Moivre’s Theorem, part (b)(i) and standard trigonometric identities, show that for $\theta$ in $(0,2\pi)$, $$ 1+\cos(\theta) + \dots + \cos (n\theta) = \frac{1}{2} + \frac{\sin((n+\frac12)\theta)}{2\sin(\frac\theta2)}$$  I have set $z=a+bi$ and subbed this into the top equation but dont seem to be getting anwhere with this problem. Any guidance will be great!


What is the difference between malloc and (object*)malloc?

I'm trying to learn about casts and how they work. I have this   (Defined in the Header file)  typedef struct {     int code;     char* name;     float concentration;     int quantity; } Farmacy;   In the .c file when I'm creating a new object when should I use:  Farmacy* f= malloc(sizeof(Farmacy));   or  Farmacy* f= (Farmacy*)malloc(sizeof(Farmacy));


If two coins are flipped and one gets head, what is the probability that both get head?

I have a doubt because I think that once the result of the first coin is obtained, just simply await the outcome of the second, which is completely independent of the previous one, and then we have a chance of $\frac12$ to get a head again.  But someone else tells me that as the possible events are:   Head - Head Head - Tail Tail - Head Tail - Tail   then when we get a head we restrict ourselves to the first three cases, so the probability would be $\frac13$.  What is the right way?    I know there's a difference between saying "first came head" to say "one of the two came head", but if we have the first fact, aren't we supposed to know which one is that came head?


How to ask for help if i know that the answers are (more or less) opinion based, but still helpfull?

I am a programmer, if i get stuck, most of the time the question/answer is easy and already to find here (ie. stackoverflow)   But sometimes there are questions, like 'shall I go right or left' (name a variable like something or not, use a '_' as starting char for a func name, or so)  The point is, I want to ask for other opinions to compleete my picture (this is a basic thing in human kind - I think)    Probably I get only 'go left' or something like 'You have overseen the pit fall, if you go right, you will get stuck')  I understand (and accept fully) why 'plain' opinion based questions are not ok, and not wanted here - like "what is the best IDE/OS/country" ore like  On the other hand - sometimes I want to ask something like 'how would you do that?'  Is there a way/cahnce to ask for others experience, even if it is an other(s)  opinion?


Using an already established SSH channel

I have an already established ssh connection between two machines.    Is there a way to send commands to the remote machine from a shell script that is run on the local machine, using the already open connection, and without starting another ssh session?


Computing the expectation of conditional variance in 2 ways

Same as . Let $X$ be a square integrable random variable on $(\Omega,\mathcal{F},P)$. Let $\mathcal{G}$ be a sub-$\sigma$-algebra of $\mathcal{F}$. Define the conditional variance of $X$ given $\mathcal{G}$ by $$\operatorname{var}(X\mid\mathcal{G})=\Bbb{E}[(X-\Bbb{E}[X\mid\mathcal{G}])^2\mid\mathcal{G}]$$ Prove the formula  $$\operatorname{var}(X)=\operatorname{var}(\Bbb{E}[X\mid\mathcal{G}])+\Bbb{E}[\operatorname{var}(X\mid\mathcal{G})]$$  1 I don't understand part of the presented solution.  2 Is my attempt also correct?  3 Alternate solutions?  1 I don't understand this part of the solution wherein  $$\operatorname{var}(X\mid \mathcal{G})=\Bbb{E}[(X-\Bbb{E}[X\mid\mathcal{G}])^2 \mid \mathcal{G}]$$  $ =\mathbb E[ X^2 \mid \mathcal G] - \mathbb E [X \mid \mathcal G]^2 $. I think it is making use of the fact that $\mathbb E [X \mid \mathcal G]$ is $\mathcal G$-measurable in saying:  $\mathbb E[XE[X\mid\mathcal G]\mid\mathcal G] = \mathbb E[X\mid\mathcal G] \ E[X\mid\mathcal G] = E[X\mid\mathcal G]^2$, but isn't $E[X\mid\mathcal G]$ supposed to be bounded? How to show this?  My attempt:  $E(X^2) < \infty$  $\to E(X) < \infty$  $\to E(X\mid\mathcal G) < \infty$, but I don't think .  2 My own attempt: I tried evaluating $$E(\operatorname{var}(X\mid\mathcal{G}))=E(\Bbb{E}[(X-\Bbb{E}[X\mid\mathcal{G}])^2\mid\mathcal{G}])$$  Is it correct to say that $E(\Bbb{E}[(X-\Bbb{E}[X\mid\mathcal{G}])^2\mid\mathcal{G}]) = E([(X-\Bbb{E}[X\mid\mathcal{G}])^2])$?  After expanding the square I encounter $E[XE[X\mid\mathcal G]]$ and rewrite  $= E[E[XE[X\mid\mathcal G]]\mid\mathcal G]$  $ = E[E[X\mid\mathcal G] \ E[X\mid\mathcal G]]$ (*)  $ = E[E[X\mid\mathcal G]^2]$  (*) Assuming this is all correct, I am still unsure about this part. Is it really bounded?  3 Is there a way to go about this without saying $E[X\mid\mathcal G]$ is bounded?  4 Is this wrong? It's from Stochastic Calculus class notes, though the problem is for an Advanced Probability class (and the notes don't say anything about bounded weirdly).


How can I make sharp geometric 3d models look more realistic?

I'm making a scene in Blender with manufactured mechanical and electrical objects - cylinders, metal objects and so forth. I want to make these look real, be fully present with a sense of mass and substance.  3DCG has a tendency to make everything very sharply geometric, often looking mathematical and artificial. In other scenes, some organic curves, normal maps or particle systems would help make object look real. Like for example, making a simple plastic dog model look more believable, one can add more vertices for better definition, add texture layer, add fur etc.  My scene shows clean resistors, wires, metal strips and such, all sharply geometric. It's tricky to find ways to make the result less mathematical and more substantial, realistic and interesting to the eye.  What are some effective ways to add realism to these objects?


Java Oracle - Result doesn't match varchar2 "NULL" String

I got a database table having a nullable varchar2 column. The value is "NULL" as string. When trying to handle the result-set I'm facing the problem that the string "NULL" doesn't match anything.    I'm using an Oracle 11g XE database and ojdbc6.jar libraries.    What am I doing wrong?   Following an example for reproducing the behaviour:    Sql:    CREATE TABLE jtest (   ID NUMBER(3) PRIMARY KEY,   TEXT VARCHAR2(30) NULL ); INSERT INTO jtest VALUES (1, 'Test1'); INSERT INTO jtest VALUES (2, 'NULL');   nullstring.java    public class nullstring {  final static String JDBC_DRIVER = "oracle.jdbc.driver.OracleDriver";   final static String DB_URL      = "jdbc:oracle:thin:@myhost:1521:xe"; final static String DB_USER     = "myuser"; final static String DB_PASS     = "myuserpw";  public static void main(String[] args) throws ClassNotFoundException, SQLException, UnsupportedEncodingException {     Class.forName(JDBC_DRIVER);      Connection hDB = null;     hDB = DriverManager.getConnection(DB_URL, DB_USER, DB_PASS);      String sCelldata = "";     Statement oStatement = null;      oStatement = hDB.createStatement();     ResultSet oResult = oStatement.executeQuery("SELECT id, text FROM jtest");      while (oResult.next()) {         for (int i = 1 ; i < (oResult.getMetaData().getColumnCount() + 1); i++) {             String test = "NULL";             if ( test == "NULL" ) {                 System.out.println(">> 1111111111111111111111111111111");             }             if ( oResult.getString(i) == "NULL" ) {                 System.out.println(">> 2222222222222222222222222222222");             }             sCelldata = URLDecoder.decode(oResult.getString(i), "UTF-8");              if ( sCelldata == "NULL" ) {                 System.out.println(">> 3333333333333333333333333333333");             }              System.out.println("> [" + i + "] " + sCelldata);             sCelldata = "";          }     }      hDB.close(); } }   Output:    >> 1111111111111111111111111111111 > [1] 1 >> 1111111111111111111111111111111 > [2] Test1 >> 1111111111111111111111111111111 > [1] 2 >> 1111111111111111111111111111111 > [2] NULL >> 1111111111111111111111111111111


I recently installed Ubuntu 18.04 on my desktop and restored my files from a backup drive. Unfortunately it did not restore my applications that I had installed (figured it out that I didn't backup my entire drive, only a few folders). So I had to install most of my applications either through the traditional command-line way or Ubuntu Software program. I had to install VLC as it's way better than the traditional video player.  But I faced a problem, there are two applications with the same name 'VLC' which have the same screenshots but different developers and source. I don't know which one to install. I want a stable version that is managed by the VideoLAN developers.  Information about the two 'VLC' players are below ---  VLC #1 Channel - stable Version - 3.0.7 License - free Developer - VideoLAN (with a tick) Source - Snap Store (I'm not very sure about this)    VLC #2 Version - 3.0.7.1-0ubuntu18.04.1 Updated - never License - free Developer - VideoLAN et al. Source - ubuntu-bionic-updates-universe


Mr. A, Mr. B and 6 more people wants to sit around round table. We need to find out the probability that Mr. A and Mr. B will sit near each other. First of all we need to describe $(\Omega,F,P)$  I think $n= (8-7)!=5040$ than Mr. A and Mr. B we can keep as one because we want them to sit near each other. Tham $m=(7-1)!*2=1440$ Than $P=m/n=1440/5040=2/7$ Is ir right?   And how I should describe $(\Omega,F,P)$?


I use  for draw tangents to an arbitrary plot. For example:  \documentclass[border=5mm]{standalone}   \usepackage{pgfplots} \pgfplotsset{compat=1.10} \usetikzlibrary{intersections}  \makeatletter \def\parsenode[#1]#2\pgf@nil{%     \tikzset{label node/.style={#1}}     \def\nodetext{#2} }  \tikzset{     add node at x/.style 2 args={         name path global=plot line,         /pgfplots/execute at end plot visualization/.append={                 \begingroup                 \@ifnextchar[{\parsenode}{\parsenode[]}#2\pgf@nil             \path [name path global = position line #1-1]                 ({axis cs:#1,0}|-{rel axis cs:0,0}) --                 ({axis cs:#1,0}|-{rel axis cs:0,1});             \path [xshift=1pt, name path global = position line #1-2]                 ({axis cs:#1,0}|-{rel axis cs:0,0}) --                 ({axis cs:#1,0}|-{rel axis cs:0,1});             \path [                 name intersections={                     of={plot line and position line #1-1},                     name=left intersection                 },                 name intersections={                     of={plot line and position line #1-2},                     name=right intersection                 },                 label node/.append style={pos=1}             ] (left intersection-1) -- (right intersection-1)             node [label node]{\nodetext};             \endgroup         }     } } \makeatother  \begin{document}      \begin{tikzpicture}[>=latex]     \begin{axis}[     grid,     axis x line=center,     axis y line=center,     xtick={-5,-4,...,5},     ytick={-5,-4,...,5},     xlabel={$x$},     ylabel={$y$},     xlabel style={below right},     ylabel style={above left},     xmin=-5.5,     xmax=5.5,     ymin=-5.5,     ymax=5.5,     tangent/.style={         add node at x={2}{             [             sloped,              append after command={(\tikzlastnode.west) edge [thick,black] (\tikzlastnode.east)},             minimum width=0.2\textwidth             ]         }           }]         \addplot[color=black,smooth, tangent] coordinates {         (-5,-5)         (-3,-4)         (-2,-1)         (0,0)         (1,2)         (2,3)         (3,3)         (4,1)     };     \end{axis}     \end{tikzpicture}  \end{document}     The problem is that I want more tangents, not only one. For example one more at the point (-3,f(-3)). Is it possible?   I tried some solutions, but I got only errors. Maybe I don't understand Jake's code...  Thank's in advanced!!!


How to compute $\mathbb{Z}_n^*$, the unit group of the integers modulo $n$?

I am trying to wrap my head around calculating residue classes, for example $\mathbb{Z}^*_{12} = [1]...$  Would anyone mind making up an example with a decent explanation. I just wrap my head around things easier seeing the process.  Thanks


$\sum _{k = 0}^ n \binom ka \binom {n-k}b = \binom {n+1}{a+b+1}$

$\sum _{k = 0}^ n \binom ka \binom {n-k}b = \binom {n+1}{a+b+1} $ Can anyone please give me a hint to prove it using combinatorics ? I know that $n \geq a+b$ and $k$ will run from $a$ to $n-b$ . But I think it should be $\binom {n}{a+b} $. Can anyone please help me?


which url is better for google SEO, recursively or directly?

Say I'm building a e-commerce website. I have a lot of products in different categories. For example one of them is:     Flat to Round Power Plug Convertor   So I have two ways to link to this product, directly to it:        or add the categories recursively before it:        According to  it seems it's recommending to put content in their own folders so that both users and robots can understand them easier. Besides if user simply remove the last part of URL flat-to-round-power-plug-convertor-1005874, they can easily get to the category.   The simply question is, when the product is in a 3rd or 4th level directory, the URL gets pretty long. I don't know if this long URL harms SEO or not. Or should I use the first form?  EDIT: The thing that confuses me is the URL should be "descriptive", and it should be "short". Consider the following example:     It would definitely help people find what they want. And when you got tens of thousands of products, this situation would happen a lot. Besides, Google definitely encourages to categorize content in their own folders as referenced above. The problem is, the more descriptive the URL is, the longer it is. How should I make choice between "descriptive" and "short"?


Why there is 2 arms in the tuning fork? It can have 1 or more than 2 arms. If we think to create more resonance, then we can construct a tuning fork having many arms


This link  suggest us to make use of route_callbacks when we are using dynamic routes.Can someone tell me how to make use of this route name in *.links.menu.yml file to make menu? The problem is when we are returning $route_collection in the routes() function then it must be containing multiple routes then how to generate menu for any particular dynamic route.  I did a search inside menu_tree table in the database and find out that no menu has been created with help of dynamic routes so I am beginning to think whether this is possible or not. If it is not possible that what is the possible solution?


Allowing user to edit only certain pages

I would want to allow certain user to edit only one page and it's subpages. How would this be possible? I tried the old Role Scoper, but it seems to have a lot of problems and bugs.


What to do if connection failed during installation

I got the following error while installing Wine from the Terminal.   Err http://za.archive.ubuntu.com/ubuntu/ precise/multiverse wine-gecko1.4 amd64     1.4.0-0ubuntu2                                                                            Connection failed [IP: 41.73.43.3 80] Err http://ppa.launchpad.net/ubuntu-wine/ppa/ubuntu/ precise/main wine1.4-amd64 amd64 1.4.1-0ubuntu1~precise1~ppa4                                                        Connection failed Err http://za.archive.ubuntu.com/ubuntu/ precise/multiverse wine-gecko1.4 i386 1.4.0-0ubuntu2                                                                             Connection failed [IP: 41.73.43.3 80] Err http://ppa.launchpad.net/ubuntu-wine/ppa/ubuntu/ precise/main wine1.4-i386 i386 1.4.1-0ubuntu1~precise1~ppa4   Connection failed   It is installing everything else fine, it just seems to be a select few files that it is not able to download for some reason. Why is this? And what should I do from here to fix the install? Rerun the command in the Terminal?  I apologise if this seems simple or common knowledge but I honestly have no idea what to do from here, as a completely new Ubuntu user.  If there is a way to 'clean up' this action and reverse what I have done that may also be great. I could then just use the Ubuntu Software Center to download and install Wine.   I am running Ubuntu Studio 12.04  Much Appreciated!


How to repair a corrupted FAT32 file system

I'm using the FAT32 file system for my pen drive. It frequently has file/data corruptions.   In Windows, I used the scan disk utility to fix the FAT32/NTFS file systems. How can I do this in Ubuntu?


What are the differences between JOIN statement and one without it?

I am currently learning SQL. I am trying to create Views using Oracle SQL Developer. I came across the JOIN statement but I do not understand why do we need JOIN. According to , the purpose of JOIN is to join multiple rows together. I can do that without the expression JOIN (refer to the following code blocks, both of them produce the same view/table). So what is the purpose of JOIN?  With INNER JOIN:  SELECT      Acc.Cust_Id,     Cus.Address,     Acc.Avail_Balance FROM      Account Acc INNER JOIN     Customer Cus ON     Acc.Cust_Id = Cus.CUST_ID   Without INNER JOIN:  SELECT      Acc.Cust_Id,     Cus.Address,     Acc.Avail_Balance FROM      Account Acc,     Customer Cus WHERE     Acc.Cust_Id = Cus.CUST_ID


How to prove the existence of such an $x \in S^{1}$

Consider this problem :  Let $S^{1}  =\{(x,y)\in \mathbb{R} \times \mathbb{R} \mid x^2 +y^2 =1\}$. Let $f: S^1 \to \mathbb{R}$ be a continuous function. Prove that there exits $x\in S^1$ such that $f(x)=f(-x)$.  I am not able to construct such a function and I am not getting any ideas on which result I should use for construction. Can you please help me with that?


How to sort field_info_instances return value by field weight?

I'm using field_info_instances() to retrieve the information for all the fields used by a content type, for example calling it as field_info_instances('node','bundle_name'). In the returned array, the fields aren't ordered as I expected. I need to get the fields ordered per weight. For example, a field weight is 8, in the Manage fields list.    Despite this, it's shown on the top, in the output from field_info_instances().    Is there any possibility to get the fields ordered?


Samsung M2070W scanner no longer working in 17.10

I own a Samsung M2070W printer/scanner, which worked in 17.04.  After installing 17.10, it prints but is not detected my Simple Scan or Xsane.  The latest drivers from the Samsung website are installed.  It is detected by sane-find-scanner but not scanimage-L. Output from the former:  found USB scanner (vendor=0x04e8 [Samsung Electronics Co., Ltd.], product=0x3469 [M2070 Series]) at libusb:003:003   I tried modifying the .bashrc as suggested in , but it didn't work.  I've seen this issue on several forums but no one seems to have a solution.


Battery drains in about 10 hours when the computer is asleep with Ubuntu 18.04, it is a lenovo y520 (7700hq, 1060 with bumblebee). When I tested no USB devices were plugged in, actually nothing was plugged in. The sleep mode is s2 - deep. I am not interested in hibernation (it is quite slow and takes a lot of space). In windows and Mac OS (hackintosh) sleep mode uses 1 or 2% of battery in a day.


Why is "the set of all sets" a paradox, in Layman's terms?

I've heard of some other paradoxes involving sets (i.e., "the set of all sets that do not contain themselves") and I understand how paradoxes arise from them.  But this one I do not understand. Why is "the set of all sets" a paradox?  It seems like it would be fine, to me.  There is nothing paradoxical about a set containing itself. Is it something that arises from the "rules of sets" that are involved in more rigorous set theory?


Publish own DNS Server and website with own domain name

I'm trying to publish my own website with my own bind9 DNS server running in Ubuntu Server 12.04.3 I've registered the domain name example.com.ar in nic.ar  (entity that registers domains in Argentina) delegated to my own dns ns1.example.com.ar ip 200.44.44.244 and ns2.example.com.ar ip 200.44.44.245. I also need to know how to publish those DNS.  I have the following network configuration:  192.168.0.1 GATEWAY1 ext ip 200.44.44.244 FreeBsd PFSense Firewall 192.168.0.6 GATEWAY2 ext ip 200.44.44.245 Debian Iptables Firewall  192.168.2.111 WEBSERVER Ubuntu Server 12.04.3 BIND9+LAMP+DOVECOT  I need to configure WEBSERVER to be able to reach from the internet the websites allocated there from www.example.com.ar I'm having a lot of trouble with DNS zones and records.  I've tried nslookup example.com.ar from the outside of my network but it's unreacheble.  Any help would be appreciated. Thanks.  EDIT 1:  This is my example.com.ar zone:      $TTL    3h     @       IN      SOA     ns1.example.com.ar. admin.example.com.ar. (                               1        ; Serial                               3h       ; Refresh after 3 hours                               1h       ; Retry after 1 hour                               1w       ; Expire after 1 week                               1h )     ; Negative caching TTL of 1 day     ;     @       IN      NS      ns1.example.com.ar.     @       IN      NS      ns2.example.com.ar.       example.com.ar.    IN      MX      10      mail.example.com.ar.     example.com.ar.    IN      A       192.168.2.111     ns1                     IN      A       192.168.2.111     ns2                     IN      A       192.168.2.111     www                     IN      CNAME   example.com.ar.     mail                    IN      A       192.168.2.111     ftp                     IN      CNAME   example.com.ar.   If I just forward my port I'm able to reach the web site by using my external IP address but I can't by its domain name.  EDIT 2:  I still can't make the entity that registered my domain name example.com.ar to reach my server.


Replies to mod messages go to normal inbox rather than mod inbox?

As a moderator on , I mod messaged a user about a moderation issue.  Weird thing is, when the user replied, I got it in my normal inbox, rather than my mod inbox.  Attached is a screenshot (personal details obviously hidden and freehand circles added):    Another moderator saw it in his mod inbox as normally.  Is this a bug? Or ?


sudo apt-get update command not working what i do

I'm on Ubuntu 14.04 and I tried running:  sudo apt-get update   But I get the below error:  E: Malformed line 59 in source list /etc/apt/sources.list (dist parse) E: The list of sources could not be read.


When we are introduced to waves in school, we are often presented with a picture of a sinusoid (or a cosinusoid). Sinusoids can represent the way many physics phenomena behave, still.... Why are sinusoids so common? When I first started to be more interested in waves, I was confused. According to me a triangular wave, or a square wave seemed to be much more "intuitive". At least "easier". Why aren't we choosing them? Mathematic gives us a little clue, but it doesn't show the full picture. In fact, they form an orthonormal basis of the vector space of functions on $[0,2\pi]$. (More or less, every function in an interval can be written as a linear combination of them). Moreover, sines and cosines are eigenfunctions (eigenvectors) of the second-derivative operator (eigenvalue $=-1$). So sines and cosines are a solution of the [ $x''=-kx$ ] differential equation that is produced by a simple harmonic oscillator, which can be basically anything that obeys $F=-kx$. But how do we glue all these pieces together to understand why are sinusoids such a significant phenomenon of our world? Intuitively, I can guess that given the "apparent" analog nature of our world, physic phenomena presenting a back and forth pattern must go through a smooth transition as they reverse their cycle, and this may be why sinusoids are perfect in embodying this job. Though, my road to get a full picture seems still very long.


Using Free/Open BSD + pf as a DDoS filter

Is using Free/Open BSD + pf a workable option for filtering DDoS? Which of the two would perform better under heavy load? (SYN flood maxing a 1 gbit pipe)  Is this even an option to consider, or is a full hardware DDoS filter needed to get fast enough performance?


A characterization of functions from $\mathbb R^n$ to $\mathbb R^m$ which are continuous

Greets   I came up the other day with the following question: Is it true that $f:\mathbb{R}^n\longrightarrow{\mathbb{R}^m}$ is continuous if and only if $f$ maps compact sets onto compact sets and maps connected sets onto connected sets?  I'm having trouble showing the "if", and I haven't found a counterexample to this part, so I would appreciate ideas to prove or disprove this.  Thanks


I'm trying to store multiple lines in a bash variable, but it doesn't seem to work.  For example, if I list /bin one file per line and store it in $LS, then I pass $LS as stdin to wc, it always returns 1:  $ ls -1 /bin | wc -l 134 $ LS=$(ls -1 /bin); wc -l <<< $LS 1   If I try to output to screen, I get various results: echo prints all the lines on a single line, while printf prints only the first line:  #!/bin/bash LS=$(ls -1 /bin) echo $LS printf $LS   So, a bash variable can contain multiple lines?


Easy way to fit a power function $y=a+b*x^c$

I am writing a program in C++/CLI in which I fit certain functions to some data input (certain number of $x$ and $y$ pairs). I have $7$ models from which one is $y = a*x^b$ and I have the solution for calculating both $a$ and $b$ factors (I have the sum of $ln(x)$, sum of $ln(y)$, sum of $ln(x) * ln(y)$, sum of $ln(x) * ln(x)$ and then $a$ and $b$ are just results of 2 equations).  Then I have the second model which is $y = a + b*x^c$ and I don't know how to get it. Could anyone help? I also have troubles with models $y = a + b*sinh^{-1}(x/c)$ and $y = a*x +b*sinh^{-1}(x/c)$.


I would like to be able to create a convex hull in ArcGIS Desktop 9.x, but I cannot find an appropriate tool.   How does one go about creating one?   I am interested in answers for all license levels: ArcView, ArcEditor and ArcInfo.


I have seen a couple of images in several papers like those attached below. These images are really expressive also nice i.e. look very scientific. I have no idea how to generate such images since I have in the past used powerpoint/excel. I'd appreciate some pointers on the tools for generating such images or even better ones.  UPDATE Just to clarify about duplicated question(s), this question is quite specific to graphs like those that combine several features concisely into a line /bar graph or scatter plot e.t.c. (as provided in the attached images). Some similar questions e.g.  is about illustrations as seen in the answers provided. I think my question is different, so are the answers provided different from those in the referenced question.


Suppose we fix $n$, does there always exist a prime $p$ such that $p\equiv 1$ modulo $n$?

Whilst reading  I found this really nice explanation by Benjamin Peterson. However, I was wondering does there always exist a prime $p$ such that $p\equiv 1$ modulo $n$ for each $n$? I feel like this must follow from some famous result that I do not remember. Thank you so much in advance!


Problem with scipy installation for Sverchok

I'm trying some voronoi with Sverchok and I've see a videa that referes to 3D voronoi node but i found that to run it i need scipy installed. I've tryied to install it from sverchok from comand line and from anaconda but I cant made it work. I have blender 2.92 and I use Win 10


Why multiple length dashes (em, en, hyphen)?

I'm wondering why there are three different sizes (perhaps more?) for lines that separate characters?  I understand the grammatical usage (or rather, I could look it up), but the benefit to readers is not clear to me.


Hibernation on my Ubuntu 18.04 did not work out of the box (I mean sudo systemctl hibernate). So I made several attempts to fix that some time ago and unfortunately can not remember exactly what I did.   But now:  sudo hibernate   successfully hibernates the system and on the next boot the system state successfully restores, except for the login screen does not appear, which is not good. And if I have many applications running than after such a resume the system might be frozen for up to 20 minutes (I see applications' windows, can move mouse pointer, but the system does not respond to clicks) but after that works normally.   sudo systemctl hibernate   does something, shuts down the system, but on the next boot I see several messages delete orphaned node and finally clean boot, as if there were no hibernation.  Please help me clear it up and enable hibernation in the gui interface.  At the same time suspend to memory and resume from memory works fine without a problem, including the login screen on resume.  The primary question I have is: Which of the two mechanisms hibernate or systemctl hibernate should I use with 18.04?  Details  The system has swap partition  $ lsblk | grep SWAP └─sda5   8:5    0  16,8G  0 part [SWAP] $ free -m               total        used        free      shared  buff/cache   available Mem:          15894        3386        9945        1311        2561       11848 Swap:         17163        2150       15013   and in /etc/default/grub it has  GRUB_CMDLINE_LINUX_DEFAULT="quiet splash resume=/dev/sda5" GRUB_CMDLINE_LINUX=""  and  $ cat /sys/power/state freeze mem disk $ cat /sys/power/disk [platform] shutdown reboot suspend test_resume   [SOLVED] :-)  Finally I managed to bring hibernation to work. As long as I do not have deep understanding of the subject, I'd rather describe what I did. So   Completely removed pm-utils and uswsusp, then sudo update-initramfs -c -k all and reboot   After this hibernation attempt ended up in clean boot instead of resume. So then   Reinstalled systemd then changed device names to UUIDs so as    in /etc/default/grub  GRUB_CMDLINE_LINUX_DEFAULT="quiet splash resume=UUID=2c8ec945-6967-4538-93ef-49eb4df6f2a1"  in /etc/initramfs-tools/conf.d/resume  RESUME=UUID=2c8ec945-6967-4538-93ef-49eb4df6f2a1  then   $ sudo update-initramfs -c -k all $ sudo update-grub $ reboot   After this sudo systemctl hibernate and resume succeeded but without login screen, so   In Settings (gui) for power button action I assigned "Hibernate"   Now when I press power button the system hibernates and then restores through login screen.  Many thanks to everyone involved     UPD: Now I have found an even better solution - use swap file  I verified this on fresh Ubuntu 18.10 desktop install and suppose it to work with fresh 18.04 desktop install too as they both use swap file by default i.e. they do not allocate swap partition by default. But the default swap file is 2Gb regardless of the system memory size, so it should be increased.  The complete description is for example .


what does manifold mean in context of surface building

This question is different as I seek to know a particular context of this subject i.e. wrt 3d printing.   It is important for me to know what this means.   " So, projection onto the first coordinate is a continuous, and invertible, mapping from the upper arc to the open interval (−1,1):"  Why is it important ?  It's like doing a self motivated research on this subject. Bump into a doubt and ask here for clarification. How else could I do it ?  ref :


IdP-initiated SSO - modify SAML response based on context

We have setup SFDC as the IdP for SAML 2.0 based SSO with a third party web application called, say, ACME.  The use case is thus:   User navigates to a Contact record User clicks on custom button User is redirected to ACME (SAML authentication happens)   What's special:   The ACME web app takes some data in the <saml:Attribute/> attribute The custom data is based on fields from the Contact the user initiated the process   The proposed design:   Setup VFPage1 to be opened on click of the custom button, pass contact Id While setting up the Service Provider settings for ACME, provide the full URL of VFPage2 as the ACS URL From the controller of VFPage1, invoke the IdP URL (provided by SFDC) and pass any additional parameters received (ie. contact Id) [redirect to a PageReference of this URL] (Assumption) VFPage2 will receive the SAMLResponse as well as the parameters passed from VFPage1 (ie. contact Id) Query contact fields as required, populate  <saml:Attribute/> as required and modify SAMLResponse Do a form post of the modified SAMLResponse to ACME   The challenge:   The assumption in the proposed design is not valid. The IdP URL discards any parameters passed to it unless hard coded in the ACL URL setup   Edit: Another problem is that, the signature/digest is no longer valid because the SAML is now modified. Is there a way to sign it post the change? (Maybe I'll post it as a different question)  The solution:  ??


Skyrim thieves guild influence jobs glitch

So I have completed the thieves guild main story, I returned the key and everything, but I want to fully complete it. So I go back to the guild and try to take influence jobs to eventually become guild master, but I completed one numbers job for Delvin in Whiterun and turned it in, but now it won't give me any more job quests. I talk to both Delvin and Vex and go through the dialogue where they say here's your quest but it doesn't come up in my journal at all, and it's like i didn't ask them... someone please help with this bug? I am a completionist and this is bugging me. pun intended.


Why does Stephen Hawking say black holes don't exist?

Recently, I read in the journal  that Stephen Hawking wrote a paper claiming that black holes do not exist.  How is this possible? Please explain it to me because I didn't understand what he said.  References:   Article in Nature News:  (Zeeya Merali, January 24, 2014). S. Hawking, Information Preservation and Weather Forecasting for Black Holes, .


Star Trek, for being a show about the distant future and extraordinarily high-tech equipment, sure seems to be lacking a lot of computer programmers.   With technology as complex as it is, where are all the starship-based computer programmers responsible for preventing AI malfunctions aboard ships like the Enterprise?    More specifically, we hear plenty of references to having to 'program in' certain things - Picard is dismayed in "All Good Things" that the past Enterprise doesn't yet have an Earl Grey Tea program, and we see plenty of holodeck programming going on, but is all of this programming done explicitly by the crewmember who just wants a cup of tea or a nice stroll along a sandy beach?    In short: Are there any actual dedicated computer programmers in any Star Trek series or movie?  Even one example of a person with such a job would satisfy.


I have problem understanding total angular momentum of earth about center of sun. Consider that earth has an orbital angular velocity of $\omega_0 \hat z$ and a spin angular velocity of $\omega_s \hat s$, distance between the centers of sun and earth as $R$ and radius of earth as $r$ and that earth has mass $m$. My understanding is that total angular momentum of center of mass of earth + angular momentum about CM of earth is $$L = m R^2 \omega_0 \hat z  + \frac{2}{5} m r^2 \omega_s \hat s $$ however a it's given in my text book as  $$L = m R^2 \omega_0 \hat z  + \frac{2}{5} m r^2(\omega_s \hat s + \omega_0 \hat z) $$  Why does the the $\omega_0$ appear when calculating angular momentum about CM of earth?


"make a monkey of someone", " don't monkey with that lock!", and "where have you been, you little monkey!" are examples of sentences where monkey have different meaning.   Should the comma be placed inside the quotes, or outside?  To make it clearer, I am referring to placing the comma when the quoted sentence already has a punctuation like the exclamation mark, or the question mark.


Any word or phrase or idiom that describes a person who takes the pleasure from the misfortunes of others?

Is there any word or phrase or idiom that describes a person who takes the pleasure from the misfortunes of others?


Is it possible to add a list of references at the end of the text in the 'letter' documentclass?


Least expensive way for a tourist to get cash in Israel?

What is the least expensive way for an American tourist in Israel to get cash?  The options seem to be:  Debit card - but there are withdrawal fees, often 5% or more.  Credit card - but interest starts immediately when taking out cash, yet one month fee may be less than the debit card fee  Carry cash - but there is a conversion fee when changing into local currency.  What are the best options to minimize fees?


There are two computers. The first one is the client, the second one is the server. The client needs access to some files on the server.  On the server it is possible for me to install any software (Ubuntu with root access). The client is WindowsXP and I cannot install anything. However there is an USB-port to which I can connect storage devices.  Is there a way (hardware and/or software) which I can use to connect the two computers with USB?  I could imagine a software for my server which uses USB to act as a simple storage device for the client connected to the other end of the USB cable.


I am currently considering a sum $$\sum_{r=0}^{n}{\binom{n}{r} (-1)^{r} (1-\frac{r}{n})^{n}}$$ but have no thoughtful ideas how to start.   Maybe it's worth noticing that $$\sum_{r=0}^{n}{\binom{n}{n-r}(-1)^{r}(1-\frac{r}{n})^{n}} = \sum_{r=0}^{n}{\binom{n}{r} (-1)^{r} (1-\frac{r}{n})^{n}}$$ and apply to the first one the convolution rule, but this doesn't seem productive enough.  Are there any hints that might help? Would be grateful to recieve any.


Korean characters scrambled [XeLaTeX; Noto Sans Korean]?

I was trying to find a font which has obsolete jamo and the right combining behaviour. Yesterday I found out about , which seems to have both of these. However, when I use it in XeTeX, I get some seemingly-arbitrary hanja (or blank spaces) instead of the expected characters.  (I’m guessing the composing behaviour will fix itself when the right characters are selected. And yes, I know that Code2000 is working perfectly in this example, but unfortunately it is the ugliest font in the world. :p)  MWE:  \documentclass{article} \usepackage{fontspec}  % 1. precomposed: U+BB47 % 2. separate jamo: U+1106, U+116E, U+11BA % 3. obsolete [separate jamo]: U+113B, U+119F, U+11EB \newcommand\test[1]{#1 & {\fontspec{#1}{뭇; 뭇; ᄻᆟᇫ}} \\}  \begin{document}  \begin{tabular}{rl} \test{Arial Unicode MS} \test{Batang} \test{Code2000} \test{Gulim} \test{GungSeo} \test{HeadLineA} \test{Nanum Brush Script} \test{Nanum Myeongjo} \test{Nanum Pen Script} \test{Noto Sans Korean} \test{PCMyungjo} \test{PilGi} \test{Adobe Gothic Std} \test{Adobe Myungjo Std} \test{Apple SD Gothic Neo} \test{AppleGothic} \test{AppleMyungjo} \end{tabular}  \end{document}


Close review queue shouldn't use bountied questions as audits

I had  in the close review queue. It clearly shows the question with a bounty, but bountied questions cannot be closed. Either bounty questions shouldn't be used as audits, or don't display the bounty notice.    This is the same problem , except it's happening in the close queue rather than reopen.


Combinatorial Proof Question: Vandermonde convolution identity

I'm really iffy on combinatorial proofs in general and now that there is a sum, it's just confused me even more. Can someone try and walk me through this proof?  $$ \binom{m + n}{r} = \sum_{k=0}^r \binom{m}{k}\binom{n}{r - k} $$


Is it possible to scale up an image to increase the the pixel density?

I have taken a picture whose resolution is less. I can resize the image easily (i.e I can scale to higher resolution) but the image quality goes for a toss, which is true because the image might not have enough pixels to scale properly.   Is resizing a means of increasing the resolution of the image ? Is it possible to increase the pixel density of the image and then resize, so that quality of the image is not affected much?   I mainly use GIMP and Picasa.


Experimental evidence of a fourth spatial dimension?

As human beings, we observe the world in which we live in three dimensions. However, it is certainly theoretically possible that more dimensions exist.  Is there any direct or indirect evidence supporting a fourth dimension?


Proof of x = 0 modulo 3 only if the sum of its digits 0 modulo 3

Okey, lets beggin from a helpfull proposition I've already proved:  $$$$ if $a_i\equiv b_i\:\forall 0\le i\le m$ then to any $m$ numbers: $p_1,p_2,...,p_m\in \mathbb{Z}$  $$\sum _{i=0}^m\left(k_ia_i\right)=\sum _{i=0}^m\left(k_ib_i\right)$$  Now, what I want to prove, is: for number $x$ who's digits are: $x_m...x_0$  $$x\equiv 0\left(mod\:3\right)\:\:<==>\:\:\sum \:_{i=0}^m\left(x_i\right)\equiv 0\left(mod\:3\right)$$ $$$$ I guess the same exmaple with modulo 11 is the same proof.  So, in the first direction, we'll treat $\sum \:_{i=0}^m\left(x_i\right)\equiv 0\left(mod\:3\right)$ as given data and we'll prove $x\equiv \:0\left(mod\:3\right)\:$  That direction of proof is simple: As to the first proposition, we'll take $k_0=10^0,\:k_1=10^1,...,\:k_m=10^m$ and accroding to it: $$\sum \:\:_{i=0}^m\left(x_i10^i\right)\equiv \:\sum \:\:_{i=0}^m\left(0\cdot \:10^i\right)\left(mod\:3\right)$$ then also $$\sum \:_{i=0}^m\left(x_i10^i\right)\equiv 0\left(mod\:3\right)$$ As we want.  Now, in second direction, i have a little trouble: Now we are given: $x\equiv \:0\left(mod\:3\right)\:$ and we want to prove: $$\sum \:_{i=0}^m\left(x_i\right)\equiv 0\left(mod\:3\right)$$  So, from the data that is given we can conclude that: $$x=\sum \:\:_{i=0}^m\left(x_i\cdot 10^i\right)\equiv \:0\left(mod\:3\right)$$  And from here I dont sure how to get rid of the $10^i$, because the first proposition as i understand doesnt work on both directions (am I wrong?), because if n is a devider of a sum, we dont know for sure if it devides every element or only the sum of it, it can be the second case either.   So how do I show that $$\sum \:\:_{i=0}^m\left(x_i\cdot 10^i\right)\equiv \:0\left(mod\:3\right)\:\:\:===>\:\:\sum \:\:\:_{i=0}^m\left(x_i\right)\equiv \:\:0\left(mod\:3\right)$$


What I am trying to do is similar to what was asked here:    I am hoping to use an object's edge for rotation, but instead of simply the one object rotating around that point, it'd be a bunch of stl's I've imported together:     What I'm hoping to do is duplicate everything in that tetrahedron object, rotate the duplicate along one edge like this:    to build a stack of them, like this:   which I would then print.  Any help?


Is it spam or does Stack Overflow have a really stressed/mean community that dislikes questions for fun?

This is a serious question. I carefully wrote a question just so I don't get downvotes, and I still gather 3. Plus I even gave my fix since I fixed the bug on my own.


Q1 - Why is $\sqrt{-x}*\sqrt{-x}=-x?$  Q2 - I was thinking it would be:  $\sqrt{-x}*\sqrt{-x}=\sqrt{-x*-x}=\sqrt{x^2}$ but apparently not (why not?)  Q3 - What are the formal algebra rules to use? Can I calculate this without using i such as in: $\sqrt{-x}*\sqrt{-x}=i\sqrt{x}*i\sqrt{x}=-\sqrt{x^2}=-x$.


Why might Sql Server Agent's Next Run Time value not be what I expect? And is this definitely the next time my job will run?

At times, I'm seeing some inconsistencies with sql server agent's value in the sysjobschedules.next_run_date and time fields.  I have a web interface that interacts with the sql scheduling system.  I've created a test job that started on March 16th 2011 at 9:45am. I've set it up to happen every 4 weeks on a Wednesday.   From today, this should put a next run date and time on January 18th at 9:45 but the Next Run Date/Time value for my job is saying January 4th.  The values in the job properties look good.  The start date says March 16th 2011. The frequency values are all correct. But it seems SQL is failing to land this occurrence properly.  Here is some relevant info for the job in question from the sp_help_jobschedule proc  freq_type   8 freq_interval   8 freq_subday_type    1 freq_subday_interval    1 freq_relative_interval  0 freq_recurrence_factor  4 active_start_date   20110316 active_end_date 99991231 active_start_time   154500 active_end_time 55959 date_created    2011-12-29 20:37:05.737 schedule_description    Every 4 week(s) on Wednesday at 154500 next_run_date   20120104 next_run_time   154500  if the start date is March 16 2011 at 9:45, it doesn't make sense that the next run date would fall on January 4th 2012 based on the properties of the job.    I guess my question is, how much can I rely on this Next Run Date data?


I need to know how i can check if the folder exist, and if it does not exist, create it  For Example:  If File.Exists(File Path) Then     Else        'Create a new folder following the path(Path here) End If   And Thanks for your help.


I've tried to install PHP and Apache2, however when I access the file, it just shows a blank page.  I've installed the packages php, apache2, php-mysql (and some others)  I've already tried pretty much everything that I could find on the Internet.  I'm sorry if I'm not providing enough info, I will give any info that I can.


null pointer exception java accessing nested json object using maven group org.json

this is my depedency    <dependency>     <groupId>org.json</groupId>     <artifactId>json</artifactId>   <version>20160810</version> </dependency>   this is my json object  {    "authorize": {        "balance": "9984.06",        "country": "id",        "currency": "USD",        "email": "xxxx.xxxx@gmail.com",        "fullname": "  ",        "is_virtual": 1,        "landing_company_fullname": "Binary Ltd",        "landing_company_name": "virtual",        "loginid": "VRg4423",        "scopes": [          "read",          "trade"        ]    } }   this is my code  JSONObject jsonObject = new JSONObject(fil); JSONObject jsonChildObject = (JSONObject) jsonObject.get("authorize"); Iterator iterator  = jsonChildObject.keys(); String key = null; while (iterator.hasNext()) {     key = (String) iterator.next();     System.out.println("balance value:" + ((JSONObject) jsonChildObject.get(key)).get("balance")); }   I have no idea why I can't acces all the child node value. It returns null pointer exception there is no "authorize" i can't get the parent value.


Are there any good tabletop RPGs for young beginning players?

I'm looking for a fun, easy to get into RPG for my kids. It could be simple and card-based, or more "normal" tabletop style. I'm looking for something less bloody and dark, and more fun and easy to get into.  What games have you played with pre-teen children that they could easily uptake and enjoyed playing?


Extending figures into the margin on even vs. odd pages

I am using KOMA script for my document.  Occasionally, I have a float that is wider than text width, and I want the float to be pushed into the outer margin.  This is why I defined \widefloat command, that checks if page is odd using command \ifthispageodd and depending on the results pushes the float left or right.  This works fine when float is in the middle of the page.  However, when float is thrown into the next page, \ifthispageodd gives wrong result.  Could you please tell me how to fix this up?  MWE: the first float is correctly pushed into outer margin, the second is pushed into inner margin.  \documentclass[11pt]{scrbook} \usepackage{tikz,lipsum}  \newcommand{\widefloat}[1]{% \ifthispageodd{\makebox[\textwidth][l]{#1}}{\makebox[\textwidth][r]{#1}}}  \begin{document}  \lipsum[1]  \widefloat{ \begin{tikzpicture} \draw (0,0) rectangle (16cm,10cm); \end{tikzpicture}}  \lipsum[3]  \widefloat{ \begin{tikzpicture} \draw (0,0) rectangle (16cm,10cm); \end{tikzpicture}}  \lipsum[2]  \end{document}


Generate permutations of indices of identical items

I have a list  a = ['A', 'B', 'A', 'A', 'C']   and I want to generate all possible permutations of item indices for identical items in a list  [0,1,2,3,4] [2,1,0,3,4] [3,1,2,0,4] [0,1,3,2,4] [2,1,3,0,4] [3,1,0,2,4]   How to do this in a most pythonic way?


What is wrong with my mediaplayer function?

I spent over ten hours on this, trying many solutions I found on the internet, and feeling stupid... This function just loads an ogg file in a MediaPlayer. It gets the url of the file as a string argument. It first extracts the name of the file and tries to load it from res/raw/, if it exists there, else it gets it from the website.  MediaPlayer player ;  void snd_load(String url) {      String id_snd = url.substring(url.lastIndexOf("/") + 1); // name of the file      try{         player.setDataSource( "android.resource://didi.a8bitpocketwrestlers/res/raw/" + id_snd );     }     catch (Exception e){         Toast.makeText(getApplicationContext(), "can't open file, will try to download it"+"\n"+e , Toast.LENGTH_SHORT).show();         try{ player.setDataSource(url); }         catch (Exception e2){ Toast.makeText(getApplicationContext(), "can't download file"+"\n"+e2 , Toast.LENGTH_SHORT).show(); }     } }   I was getting java.lang.NULLPointerException error for both. I understand now, player was only of type MediaPlayer, it pointed to nothing yet. I was mistaken because there are properties inside so I thought the object existed. I must do either player = new MediaPlayer(); or player = MediaPlayer.create();.  Now I fixed this, I still can't load the file.     04-22 15:31:58.018 130-4150/? E/FileSource: Failed to open file   'android.resource://didi.a8bitpocketwrestlers/snd_title.ogg'. (No such   file or directory) 04-22 15:31:58.018   4087-4099/didi.a8bitpocketwrestlers E/MediaPlayer: error (1,   -2147483648) 04-22 15:31:58.018 4087-4087/didi.a8bitpocketwrestlers E/MediaPlayer: Error (1,-2147483648)   And it stops, it does not display the message and does not try to download it.  With player = MediaPlayer.create(getApplicationContext(), R.raw.snd_title ); it crashes because of my player.prepareAsync(); call. I read that .create already takes care of that and so I can't call .prepareAsync(); nor use .setOnPreparedListener(). This is a problem for me, I need to know when it is ready.  Anyway I must use the name in the variable id_snd, not just snd_title.ogg file, so I changed it for player = MediaPlayer.create(getApplicationContext(), getApplicationContext().getResources().getIdentifier(id_snd, "raw", getApplicationContext().getPackageName()) ); and I get     android.content.res.Resources$NotFoundException:Resource ID #0x0   New version  MediaPlayer player ;  void snd_load(String url) {      String id_snd = url.substring(url.lastIndexOf("/") + 1); // name of the file     id_snd = id_snd.substring( 0 , id_snd.indexOf(".") ) ; // to remove ".ogg" or ".aac"      try{         player = MediaPlayer.create(getApplicationContext(), getApplicationContext().getResources().getIdentifier(id_snd, "raw", getApplicationContext().getPackageName()) );     }     catch (Exception e){         Toast.makeText(getApplicationContext(), "can't open file, will try to download it"+"\n"+e , Toast.LENGTH_SHORT).show();         try{ player = MediaPlayer.create(getApplicationContext(), Uri.parse(url)); }         catch (Exception e2){ Toast.makeText(getApplicationContext(), "can't download file"+"\n"+e2 , Toast.LENGTH_SHORT).show(); }     } }


If we want to say "near the river" or "near the lake" which preposition is more accurate by or at?  I think when speaking about a river or lake by is better. Am I right? I mean when we are situated near by, somewhere close to the river or lake, near the bank of the river or on the beach by-side the lake.


Extract email adresses from text using RegEx c#

I have code in console app  reg = new Regex(@"/[a-z0-9_\-\+]+@[a-z0-9\-]+\.([a-z]{2,3})(?:\.[a-z]{2})?/i");   string text = "wjeqklejqwek myEmail@hotmail.com a;lekqlwe anothermail@mail.ru";   parseTextByTagName("", text);   MatchCollection coll =   reg.Matches(text); }   when I debug it it shows that the coll is empty could you tell whats problem I am solving it about an hour


I came across the following problem in Abbott's Understanding Analysis:  Consider the reasonable but erroneous claim that $$\lim_{x\to10} \frac{1}{[[x]]} = \frac{1}{10},$$ where $[[x]]$ refers to the greatest integer value of $x$.  Find the largest $\delta$ that represents a proper response to the challenge of $\epsilon = \frac{1}{2}$ and find the largest $\epsilon$ challenge for which there is no suitable $\delta$ response possible.  A student came to me with the solution to the first part as $\delta = 5$. The reasoning for this was the following:  $$|\frac{1}{[[x]]}-\frac{1}{10}| = |\frac{10-[[x]]}{10[[x]]}| = |\frac{[[x]]-10}{10[[x]]}| < \frac{|x-10|}{10}$$ and so we choose $\delta = 10\epsilon$, which means that for $\epsilon = \frac{1}{2}$, we have $\delta = 5$.  Now to my question on this:   If we consider $|\frac{1}{10}-\frac{1}{4}|=\frac{3}{20}$ and $|\frac{1}{10}-\frac{1}{16}|=\frac{3}{80},$ then would this suggest that there is a larger $\delta$ (namely 6) that is a proper response to the challenge of $\epsilon = \frac{1}{2}$?  I may have some fundamental misinterpretation here and so I welcome any help.   The proposed solution to the second claim is $\epsilon = \frac{1}{10}$. The reasoning is that, as before:  $$|\frac{1}{[[x]]}-\frac{1}{10}|<\frac{|x-10|}{10}.$$ So, picking $\epsilon = \frac{1}{10}$ will do the trick.   I don't feel right about this answer either since $\delta = 1$ will yield $$|\frac{1}{[[x]]}-\frac{1}{10}|$$ as either $\frac{1}{90}$ or $0$ since $|\frac{1}{10}-\frac{1}{10}| = 0$ and $|\frac{1}{10}-\frac{1}{9}| = \frac{1}{90}$.  Again, I might have some sort of fundamental misunderstanding here.  I appreciate any help that can be offered. Thanks in advance!


Can we have the "50 more" link return items of the same type, please?

When working my may through items in , I find it more efficient to handle one flag type at a time.   If there are many items for a flag type, only 50 random posts are shown at a time which is great. However, when I reach the bottom of the list and click "50 more", the selected flag type is forgotten and I end up with 50 random questions of all types.  Feature Request: Can the "50 more" link take into account the selected flag type?    Sure, I can achieve that quickly using CtrlHome + CtrlR (or CtrlL + ENTER), or create a userscript to apply the current querystring to the "50 more" link. However, an official solution would be nice.


Recently I have been receiving down-votes because I do not correct the OP's answer to use "best practice." This has occurred on a few occasions regarding implicit or explicit syntax or deprecation of functions. For this question, I am specifically referring to  regarding deprecation of mysql_ functions.  In a question, the OP posts code that uses the mysql_ function and I post a correct (accepted) answer using those functions and inform the OP regarding the deprecation and alternatives. I would then receive a down-vote because I apparently have not sufficiently discouraged the OP's use of these functions.  Stack Overflow's  states:     Answer the question      Read the question carefully. What, specifically, is the question asking for? Make sure your answer provides that – or a viable alternative. The answer can be "don’t do that", but it should also include "try this instead". Any answer that gets the asker going in the right direction is helpful, but do try to mention any limitations, assumptions or simplifications in your answer. Brevity is acceptable, but fuller explanations are better.   Going off the Answer the question guidelines, I know that my answer provides exactly what the OP is asking as well as a "use this instead".   Stack Overflow's  states:     What is voting down?      Voting down, also known as "casting downvotes", is how the community indicates which questions and answers are least useful.      When should I vote down?      Use your downvotes whenever you encounter an egregiously sloppy, no-effort-expended post, or an answer that is clearly and perhaps dangerously incorrect.   Following the above guidelines, I don't feel my answers meet any of the criteria for voting down.  I certainly attribute down-votes with a negative connotation. I ask, to what degree should "best practice" affect down votes?


How can I pause the download on Mac App Store and then resume it later?

I am downloading macOS Sierra from Mac App Store. But I have electricity problem here. Due to which my iMac will lose power after 2 hours. Now I want to pause the downloading so that I can resume the download later on. How can I do that?  Here is a screenshot.


I am playing a Level 5 Monk/Aarakocra with the monk I get 1d6 + 5 (20 dex) but with Aarakocra’s talons I get 1d4 + 5. Does it become 1d6 + 1d4 + 5?


Having $c\gt0$ $a, c \in \Bbb{R}$ $$(a+b)^2\le(1+c)a^2+(1+\frac{1}{c})b^2$$ I don't know how to solve this inequality, I tried with the AM-GM inequality and I reached this point so far. $$(a+b)^2\le a^2(c+\frac{1}{c})+b^2(c+\frac{1}{c})$$ I don't know how to continue, and I don't even know if this is the right path. If you have any hints, those would be much appreciated. Thanks


Transit visa for Germany when going to Finland

Do I need a transit visa as an Indian passport holder for Germany in order to travel to Finland from Dubai?  Dubai - Germany (2hrs stop) - Finland   Provided I will have a Schengen Visa (Finland)?


Meta alerts in Nagios ? Alert if two other checks are failing

Is there a way in Nagios to do this ?  I want to send a CRITICAL alert if two checks are failing.  For example, if service1 and service2 are CRITICAL send a CRITICAL alert.  To be more precise,  if service1 fails on host1 and host2, then send an alert.


How to detect whether a user is using USB tethering?

Recently a user unplugged their company PC from the network and used USB tethering with their Android phone to bypass the company network entirely and access the internet. I don't think I need to explain why this is bad. What would be the best way, from a zero-cost (i.e. open source, using scripting and group policy, etc.) and technical standpoint (i.e. HR has already been notified, I don't think that this is a symptom of some sort of deeper underlying corporate culture problem, etc.), to detect and/or prevent something like this from happening again? It would be nice to have a system-wide solution (e.g. by using group policy), but if that is not possible then doing something specific to this person's PC could also be an answer.  A few details: The PC is Windows 7 joined to an Active Directory domain, the user has ordinary user privileges (not administrator), there is no wireless capabilities on the PC, disabling USB ports is not an option  NOTE: Thank you for the great comments. I added some additional details.  I think that there are a lot of reasons why one would want to disallow tethering, but for my particular environment I can think of the following: (1) Anti-virus updates. We have a local anti-virus server that delivers updates to network connected computers. If you are not connected to the network you cannot receive the updates.  (2) Software Updates. We have a WSUS server and review each update to approve/disallow. We also deliver updates to other commonly used software programs such as Adobe Reader and Flash via group policy. Computers cannot receive updates if they are not connected to the local network (updating from external update servers is not permitted). (3) Internet filtering. We filter out malicious and, uh, naughty(?) sites. By using a tether you can bypass the filter and access these sites and possibly compromise the security of your computer.  More background information: HR was notified already. The person in question is a high level person so it is a little bit tricky. "Making an example" of this employee although tempting would not be a good idea. Our filtering is not severe, I'm guessing that the person may have been looking at naughty sites although there is no direct evidence (cache was cleared). He says he was just charging his his phone, but the PC was unplugged from the local network. I'm not looking to get this person in trouble, just possibly prevent something similar from happening again.


Is there a place to ask opinion based questions?

I understand and agree that opinion based questions are a bad thing on Stack Overflow, but shouldn't we have a place to ask this kind of question? There are so many times where I look at different frameworks and have to make decisions that will affect the next 3 years of my life without actually having all the pros and cons of both sides.  So my question is: Is there a place to ask these questions?  And if the answer is no, could that be a new Stack Exchange sub-website?