I'm currently building a private servers farm with a thousand and thousand hosts, and I suddenly faced a really interesting question that I was unable to answer at the moment.  Is there a Standard ISO/Whatever for servers hostname attribution into a really large environnement?  For now, my puppet generate a random alphanumeric hostname that it not relevant for anyone connecting on the host.  That fine, and I'm able to connect to the correct server and service for maintenance because my puppet is managing all my host and link them to Nagios which has category etc.  But I'm really interesting to know if someone already faced this kind of question AND/OR if you have personal experience and testimony.  Many thanks!


Trigger Task Scheduler in Windows 7 when computer wakes up from sleep/hibernate

I don't want task scheduler or whatever to wake the computer, but when I open the laptop back up and the machine wakes I'd like that to be the trigger that task scheduler or something uses to run an app.


Show that four points given by vectors lay on a circle

I'm stuck on problem 2.10 from Vector Analysis and Cartesian Tensors by Kendall:      Show that the four points with position vectors $\vec{r_1}$, $\vec{r_2}$, $\frac{r_2}{r_1}\vec{r_1}$, $\frac{r_1}{r_2}\vec{r_2}$ , where $r_1\neq0$ and $r_2\neq0$, lie on a circle.   I tried supposing that there exists some vector $\vec{d}$ which gives the position of the circle centre and then trying to prove that the distance from each point to this centre is equal. But I just arrive at the condition that $\hat{r_1}=\hat{r_2}$.   Any suggestions for another strategy, am I just messing something along the way?


Ubuntu: How to execute a script without using terminal?

This is my dilemma. I have a program that can only be launched through terminal. So, right now I am always having to first open the terminal and then do the following ./theGUIScript. It runs but I want to have a link or a executable script or application on the desktop that does the same thing but with double click. So, whenever I want to start this program, I double click on this link or script. I have looked at all the self-help online on this issue, but there seems to be no definitive answer. And whatever I try it doesn't seem to help. When I think I solved this issue, Ubuntu opens the file with gedit or popups a message saying there is a problem with the shortcut or link.


How can I download Ubuntu onto a mac, then use it on a Windows PC?

I found an older question saying to download Unetbootin which I did.  BUT when I get to this part...     Select the Ubuntu ISO file you downloaded and click the Open button.   HOW does one select the ISO file?      I clicked the bullet for disk image but the button with three dots that SHOULD let me see the desktop is showing a blank desktop.  Isn't it suppose to show me what's ON my desktop including the file I need it to see?   It's not. What do I do now?


How can I check multiple check boxes in jQuery?

I have a table with a checkbox at the start of each row. Each Checkbox has the ID of #tablecheckbox. The table header row has a check icon which should check all boxed in the table. How can I do this with jQuery?


Is it possible to boot from the hard drive of a dead Linux machine on another machine?

My 5 year old pristine laptop decided to die. Every time I plug in the power it shorts the adapter so I think my motherboard is gone. Is it possible in anyway to boot into that install from another different Intel based laptop? Through a virtual machine? Or some sort of safety mode?  I know there is naturally a driver issue here but it's there any way to overcome it? I'm running fedora 25.


Workflow related to field update scenarios

If we create2 work flows( field update)on same object which workflow rules will exceute first ?


What is the distance allowed for the goalkeeper to be off the line during penalty kick?

Recently, I saw a video showing a penalty kick replayed twice because the goalkeeper advanced from the goal line.  My question is: what is the distance allowed for the goalkeeper to be off the line during a penalty kick? And generally, have these kind of incidences happened before?


What is f(n), g(n) and real constant in The Big-Oh Notation

The definition in a book said   The "Big-Oh" Notation Let f(n) and g(n) be functions mapping nonnegative integers to real numbers. We say that f(n) is O(g(n)) if there is a real constant c > 0 and an real constant n0 ≥ 1 such that f(n) ≤cg(n), for n ≥ n0.   I couldn't able to understand terminologies used in formula and definition can somebody explain in plain English.


I'm writing a paper and I am not sure how to word this sentence. Which is the correct sentence:      I am able to avoid a pitfall into which many a student has fallen.     I am able to avoid a pitfall into which many a student have fallen.    I think the correct one is the first one since has agrees with student, but both sort of 'sound right' to me. Maybe because have agrees with many, you know? Can anyone tell me which is the correct wording?


Global option to turn on/off section numbering

Suppose I want to change from numbering my \sections, \subsections, and so on to not numbering them.  As far as I know, the only way is to manually change (e.g.) \section{Foo} to \section*{Foo} and so on, all through the document... one by one.  That seems at odds with the LaTeX philosophy.  It is also a very manual and tedious process, especially when one has a master document and sub-files.  I know there are tricks within editors and the command line to globally replace text with replacement text... but a cleaner solution would be a LaTeX option.  In other words:  Is there a global LaTeX option one can set to swap from numbered to unnumbered sectioning (and vice verse)?  P.


Prove that for any prime p, there is a complete set of mod p residues {q1, . . . , qp}, where each qi is prime. I used the theorem {a, a+n, a+ 2n, . . .} contains infinitely many primes if gcd(a, n) = 1 but haven't got much progress. Any comment will be helpful!


I have a file named Overview-2015.xlsx and no matter what I do, my computer keeps telling me the file is still in use.  Here's what I have tried:   COMPUTER RESTART - The only reason I could possibly think that this wouldn't fix the issue is something is opening and running the program upon startup. Although, I have been using this file for the past 3 months and now all of the sudden it does this. Process Explorer - I used this program, as suggested by other threads, to try and fish out a program that may be using this file... couldn't find a single thing running an open file with the name Overview-2015 let alone an excel file   Any idea why this may be happening or a way that I could delete this file?


Making REST API calls from Salesforce to Marketo

I am new to both making API calls and coding in Apex and feel way over my head.  How can I make a call to the Marketo REST API through Salesforce? Is this possible through Apex?  For example, hypothetically, say I didn't want to use the automatic sync of Marketo and Salesforce for some reason. Would it be possible to use Apex to push a lead to Marketo manually using something similar to this:   When a new lead is created, trigger Apex class "syncLead" syncLead requests token and logs in to Marketo from Salesforce, so I can use the Marketo API syncLead makes an SOQL to Salesforce, and stores data for Lead01 as, for example, Map m syncLead makes POST to create a new lead in Marketo using the information from Map m   Otherwise, is there another way to do this? Perhaps by linking to an external database through Salesforce?


Easiest and most complex proof of $\gcd (a,b) \times \operatorname{lcm} (a,b) =ab.$

I'm looking for an understandable proof of this theorem, and also a complex one involving beautiful math techniques such as analytic number theory, or something else. I hope you can help me on that. Thank you very much


How to make a disk image and restore to another, the hardware between the servers are the same

Currently there is an issue happening on the production environment and not happening in dev. so I would like to recreate it in dev by creating a image of prod and restore it in dev. the hardware are the same as well as the RAID. My question is  a. what the best tool to use to do that? b. when creating the image, does it require any downtime? c. I presume that i need to do some configuration changes once the restore is done? d. after the restore, would the logic/physical mount be eased?  Plus I am new to Ubuntu, have tried tar way to do. it seems that it caused lots of issues. I have gave up on that due to time limitation.   Thank you so much.   Bing


Fist off - I am not going to do this job myself, I would just like to try to do this without cutting open the ceiling. We have a 110 GFCI outlet in our garage and I would like to add a 30 amp plug that would come from it's own breaker for our Airstream trailer when I'm working on it in the driveway. The distance from breaker box to the garage wall is about 20 feet. What is the possibility of tying on the new wiring to the existing wiring, pulling it back to the breaker using the existing wiring, and then pulling it all back to the garage together? Is this an unreasonable request to ask the electrician?


I need to prove this inequality using AM-GM. Any help would be appreciated.     Let $a, b, c, d$ be non-negative numbers such that    $a +b + c + d = 4$. Prove that:   $$\frac4{abcd} \ge \frac ab +   \frac bc +  \frac cd +  \frac da$$


How was the Stack Exchange community born?

It is clear that, for Stack Exchange to work, it is necessary for there to be a big community of people like it has now. In general this is necessary for a lot of other websites like Wikipedia.   But there was a moment when they didn't have a big enough community that made it work so well.  My questions are:  How did the Stack Exchange community reach the critical mass necessary to work well?   What is the best way, in general, to create a site that needs a big community working on it and what steps should follow the small community to make it thrive?   Assume the site is interesting enough so a lot of people in the world would be willing to join to the community but the site is not known (like happened with Stack Exchange when it was small).


My first post,pretty excited.I want to make a soap api call which insert multiple records. I am using 2 different salesforce instances. destination side  global with sharing class SoapDemo1 {    global class AccountWrapper    {       webservice string Name;       AccountWrapper(Account a)       {         this.Name=a.Name;       }    }     webservice static List<Account> CreateMultipleAccounts(List<Account> accs)    {        List<Account> FinalList=new List<Account>();         for(Account a:accs)        {           Account a1=new Account();           a1.Name=a.Name;            FinalList.add(a1);           }         if (FinalList.size() > 0)        {           Database.Insert(FinalList);        }         return FinalList;     }     }   I generated the class wsdl file and also partner wsdl file  ****source side:**** I upload the class wsdl file generated from destination, when I parse no errors, but when I click Generated Apex code, it shows error as:     Unable to find complexType for   {}anyType    I changed anyType to string and again repeated the process but it shows error as:     Unable to find complexType for   {}JunctionIdListNames   Please help me out


To refer to singular/plural items without knowing the actual quantity

Sometimes we need to refer to something without knowing will it be singular or plural. How to write such things in formal writing?  Version 1     No valid input files found.         Make sure the input field contains at least one ".adoc" file.   Make sure this file (these files) does exist.      Version 2     No valid input files found.         Make sure the input field contains at least one ".adoc" file.   Make sure this file(s) does exist.      Or something different?


Terminate a 3rd party windows application and the apps that it started

Lets call the app I need to close A. The problem I have is that A starts an other application, lets call it B.  So if I close A, B is still running.  The reason why I need to also close B is because if I restart A after I closed it, it does not work properly, because a B app is already running because a previous A started it.  I only know the path to the A application.  Sysinternals Procmon can see that they have this starter-started relationship, but how can I?    I'm writing my closer app in Delphi, but I'm open to any alternative solutions.  Thanks.


I am taking Real Analysis in the Fall and the Professor recommended Spivak's Calculus to prepare for the course. Unfortunately, someone was faster than me and already borrowed the book from the library and I don't want to buy it. Does anyone have a similar book they recommend, covering advanced calculus as a preparation for real analysis? I already have Abbott's "Understanding Analysis" (he's a professor here, really nice guy, plays electric guitar in the faculty band).


Dirac delta function as a limit of sinc function

I'm looking for a rigorous proof of the statement: $\delta(x) = \lim_{\epsilon->0} \frac{\sin(x/\epsilon)}{\pi x}$ (see ).  For any non-zero value of x, LHS of the above is by definition zero. But, for any non-zero value of x, the limit in RHS simply does not exist. So, how is this statement proved?


What does $2^x$ really mean when $x$ is not an integer?

We all know that $2^5$ means $2\times 2\times 2\times 2\times 2 = 32$, but what does $2^\pi$ mean? How is it possible to calculate that without using a calculator? I am really curious about this, so please let me know what you think.


Running 3 External Monitors off a Mid 2014 MacBook Pro

I have a MacBook Pro retina 15 inch. It's a retina model with a i7 4980HQ 2.8Ghz quad core processor, a 2GB Nvidia GTX 750M graphics with 2GB VRAM and 16GB ram.   I was wondering if I would be able to connect 3 monitors to it to use mostly for coding, but perhaps also some occasional gaming.   would the best way to do it be through the two Thunderbolt ports using a 2 Thunderbolt-> DVI adapter and one monitor through the HDMI?   Will they all work properly, will there be any difference in quality if I'm using 3 monitors of the exact same model.


I am looking for more information about my graphics card whether it will support Ubuntu or not. I have GeForce GT 640_(). I would really appreciate any information could be provided by the community.


For $f \in L^2 (\mathbb{R}), g(x) = \int_x^{x+1}f(t)\mathrm{d}t$ show $\lim_{x \to\infty} g(x) = 0$

This is a question on an old exam I'm studying from and I'm not really sure how to approach it.  $f \in L^2(\mathbb{R}) \rightarrow \sqrt{\int_{-\infty}^\infty f^2(t)\mathrm{d}t} < \infty$.  I'm guessing the argument is something along the lines of "as $x \rightarrow \infty, \int f^2(t)\mathrm{d}t \rightarrow 0$ so $\int 0 = 0$, but I'm not entirely sure how to show that.  Is it because it is the infinite integral of a positive number going to zero the integrand must go to zero?


After repeatedly losing data on encrypted drives due to some trivial combination of software and hardware failure, I would like to know if there is a simple tool that keeps local folders synchronized. Like a local "cloud" service that runs on one computer and synchronizes any changes in one folder to the other folder as soon as both folders are available. That way I can keep a copy of the most important files on a different hard-drive.


Identify novel where gamers enter RPG theme park environment to play game

I read this in the 80's, probably published around the same time.    The book had two principal strands, a group of professional or semi-professional gamers enter a theme park which exists to provide "real life" RPG experiences. They are playing a new "game".  The second strand of the book was the theme parks security chief tracking a murderer and/or burglar, who ends up being one of the players.   The two strands merge when the security guy is inserted as a PC in the game, so he can investigate the group. There is so much riding on the success of the new scenario that the operators are unwilling to shutdown the game for any reason.  I remember the cover had the party on a raft, possibly in white water, a scantily clad female (a magic user PC) was holding a rune inscribed staff, fighting an enormous snake in the river. The POV of the picture was of someone in the water looking up at the characters on the raft.  The beasties they fought were mechanical, the people they fought were actors playing roles.  The "rune etched staff" was actually a computer, which the "mage" used to give instructions to the operators regarding the spell/alteration she was casting.  Another detail I remember is one of the characters being shocked when their faux sword cut actually appears to cut off someones arm, but that actor had lost the limb previously and the gimmick was setup to enhance the realism of the story setting.  It was English language, set in America, decades before MMORPGs were considered possible.


Repeatedly used snippets of code - how to shortcut?

I use LaTeX and TexStudio.  I work with transripts and have so far found \longtable to be my best friend, e.g.:  \begin{longtable}[H]{p{1.7cm}p{11.5cm}}     Ignoramus  &  Richard, what are your favourite animals? \\     Richard    &  Gnus, penguins and deers, of course! \\     \caption*{(Animal talk)}  \end{longtable}   I have to make (yet another) dozens of such dialogues. Soe of them are quite long - that's one reason to use longtable.  I have tried to figure out how I can make a macro or something to let me insert a template like:  \begin{longtable}[H]{p{1.7cm}p{11.5cm}}        &   \\     \caption*{()}  \end{longtable}   but to no avail.  It seems that in   It seems that kileuser have this option:   What is the simple solution for a TexStudio user?


How to add display resolution for an LCD in Ubuntu 12.04? xrandr problem

I am new to Ubuntu. I have installed Ubuntu 12.04 and am stuck trying to set up the correct resolution for my LCD display.  The native resolution for the LCD is 1920x1080  here is the output from xrandr:  $ xrandr Screen 0: minimum 320 x 200, current 1280 x 720, maximum 4096 x 4096 LVDS1 connected 1280x720+0+0 (normal left inverted right x axis y axis) 0mm x 0mm 1280x720 60.0*+ 800x600 60.3 56.2  640x480 59.9 VGA1 disconnected (normal left inverted right x axis y axis)   Then I create new modeline:  $ cvt 1920 1080 60 1920x1080 59.96 Hz (CVT 2.07M9) hsync: 67.16 kHz; pclk: 173.00 MHz Modeline "1920x1080_60.00" 173.00 1920 2048 2248 2576 1080 1083 1088 1120 -hsync +vsync   So far so good. Then I create new mode using xrandr:  $ xrandr --newmode "1920x1080_60.00" 173.00 1920 2048 2248 2576 1080 1083 1088 1120 -hsync +vsync   But for some reason that new mode was created for VGA (VGA1) output instead of LCD output (LVDS1):  $ xrandr Screen 0: minimum 320 x 200, current 1280 x 720, maximum 4096 x 4096 LVDS1 connected 1280x720+0+0 (normal left inverted right x axis y axis) 0mm x 0mm 1280x720 60.0*+ 800x600 60.3 56.2  640x480 59.9  VGA1 disconnected (normal left inverted right x axis y axis) 1920x1080_60.00 (0xbc) 173.0MHz <---------- ????!!!!!! h: width 1920 start 2048 end 2248 total 2576 skew 0 clock 67.2KHz v: height 1080 start 1083 end 1088 total 1120 clock 60.0Hz   So, if I try to add mode to LVDS1, I get an error:  $ xrandr --addmode LVDS1 "1920x1080_60.00" X Error of failed request: BadMatch (invalid parameter attributes) Major opcode of failed request: 149 (RANDR) Minor opcode of failed request: 18 (RRAddOutputMode) Serial number of failed request: 25 Current serial number in output stream: 26   Adding that new mode to VGA1 works fine, but I don't use that VGA1 output.


I have a class with a nullable int? datatype set to serialize as an xml element.  Is there any way to set it up so the xml serializer will not serialize the element if the value is null?    I've tried to add the [System.Xml.Serialization.XmlElement(IsNullable=false)] attribute, but I get a runtime serialization exception saying there was a an error reflecting the type, because "IsNullable may not be set to 'false' for a Nullable type. Consider using 'System.Int32' type or removing the IsNullable property from the XmlElement attribute."  [Serializable] [System.Xml.Serialization.XmlRoot("Score", Namespace = "http://mycomp.com/test/score/v1")] public class Score {     private int? iID_m;     ...      /// <summary>     ///      /// </summary>             public int? ID      {          get          {              return iID_m;          }          set          {              iID_m = value;          }      }      ... }   The above class will serialize to:  <Score xmlns="http://mycomp.com/test/score/v1">     <ID xsi:nil="true" /> </Score>   But for IDs that are null I don't want the ID element at all, primarily because when I use OPENXML in MSSQL, it returns a 0 instead of null for an element that looks like


Has technological progress stopped or reached a peak in the Star Wars universe?

In the last 30 years, human technology has developed massively.  Every year a new smartphone is released with a faster processor, more memory, better features.  Why hasn't the same level of progress happened in the Star Wars universe?  In The Phantom Menace, we see a number of droids - R2 units, C-3PO, Pit Droids, etc.  In Return of the Jedi - the droids we see pretty much have the same capabilities.  I would have thought that technology would still be progressing in the Star Wars universe - but it appears to have stopped.  During wars on Earth, our technology capabilities grow - so it can't just be the effect of a massive war which is causing the stagnation of development.  So, what gives?


What's the value of this limit? I keep getting half, but the answer's 1/3. I think there might be a problem with writing ${x\cot x \over x^2 }$  as $ {\cos x \over x^2}$. Is there ? I get (1-cosx)/x^2 on using this substitution, and if I use L'hôpital's Rule on this, I get the answer as sinx/2x = 1/2.  Edit: I can only use results like $\sin x=x$ and L'Hospital's rule. No series expansion.  Edit 2: Here's my attempt:  1/x^2 - cosx/(x*sinx) = 1/x^2 - (cosx/x^2)(x/sinx) = 1/x^2 - (cosx/x^2)(1)  {Since sinx/x=1} = (1-cosx)/x^2 Being a 0/0 case, L'hôpital's Rule: sinx/2x = (1/2)(sinx/x) = 1/2, since sinx/x=1


NullPointerException error in Runtime.getRuntime().exec

I'm trying to make some processes to do one task and I use Runtime.getRuntime().exec and any process read some long number from one file then use xor operand and write in another file. Finally main process should read each long number in files has produced and xor all again. Here is my code but when I run it I get NullPointerException in line that include Subprocess[i].waitFor() == 0. Why? Thanks for any help. I know what is NullPointerException and I don't want to ask about it!      Process[] Subprocess;     Subprocess = new Process[processCount];     for (int i = 0; i < processCount; i++) {         try {             String[] command = {"java", "-cp", pathSubProcess, "SubProcess", p, String.valueOf(i), String.valueOf(processCount), String.valueOf(size)};             Subprocess[0] = Runtime.getRuntime().exec(command);          } catch (IOException e) {             System.out.println(e.getMessage());         }     }     /////////////////////////////////////////////////////////////////////////     long xor = 1;     for (int i = 0; i < processCount; i++) {         if(Subprocess[i].waitFor() == 0){             xor = xor ^  pp.readFiles(i);         }     }     xor = xor ^ 1;


A famous problem:  A lady is in the center of the circular lake and a monster is on the boundary of the lake. The speed of the monster is $v_m$, and the speed of the swimming lady is $v_l$. The goal of the lady is to come to the ground without meeting the monster, and the goal of the monster is to meet the lady.  Under some conditions on $v_m,v_l$ the lady can always win. What if these conditions are not satisfied?  Edited: the monster cannot swim. If the conditions are not satisfied, then monster can always perform a strategy such that the lady will not escape the lake. On the other hand this strategy is not desirable for both of them because they do not reach their goals. As there was mentioned, this deals with undecidability of the problem. On the other hand, if you imagine yourself to be this lady/monster, you can be interested in the strategy which is not optimal. What is it? If there are such strategies in the game theory?  Edited2: My question is more general in fact. If we have a game with one parameter $v$ when two players $P_1, P_2$ are enemies and if $v>0$ then for any strategy of $P_2$ the player $P_1$ wins. If $v\leq 0$ then for any strategy of $P_2$ there is a strategy of $P_1$ such that $P_2$ does not win and vice versa. I am interested in this case. From the mathematical point of view as I have understood the problem is undecidable since there is no an ultimate strategy neither for $P_1$ nor for $P_2$. But we are solving somehow these problem IRL. Imagine that you are a lady in this game - then you would like to win anyway even while knowing that your strategy can be covered by the strategy of the monster. On the other hand, the monster knows that if he will cover all strategies of the lady she will never reach the shore and he will never catch her. I mean they have to develop some non-optimal strategies. I hope now it's more clear.


Commenting on a closed post should dismiss the flag asking for a comment

Note how the info to the right of the flag says I've commented    If it knows I've commented, it really shouldn't tell me to comment.  I'm in the habit of commenting immediately after I close, so I can see this happening a lot.  Even for mods who normally comment before closing, the rare occurrence of this flag when they forget or whatever should be dismissed on a comment just like deleting a post clears flags.  I also disagree with the general premise that mods should be nagged instead of being taught up front what to do when closing, but that's a subject for a different post.  There's also the occasional question which is about apples or something, and it's not exactly necessary to leave a comment when closing as off-topic.  As noted in the comments:  Given the newer clearer close reasons and the help center, sometimes a comment is not even needed. Mods would basically be repeating whats mentioned on the close banner just a few lines below.


I want to find 3 natural  numbers  a, b and c such that  $\frac{4}{193}=\frac{1}{a}+\frac{1}{b}+\frac{1}{c}$. Also I want the see the decomposition  of 4/313 too.  I need to see these decompositions for my research on E-S problem.


let P$_n$ be the following statement: Every group of n persons that contains at least on male contains only males. What is wrong with the following proof by induction that this statement is true for all n? Certainly P$_1$ is true. Now assume that P$_n$ is true, and take any group of n+! persons containing at least one male. Let G={p$_1$,p$_2$,p$_3$,...p$_n$,p$_n$$_+$$_1$} denote this group, with p$_1$ being known male. The subgroup {p$_1$,p$_2$,p$_3$,...p$_n$} of G must contain only males, by the induction assumption. Furthermore the n-person group {p$_2$,p$_3$,...p$_n$,p$_n$$_+$$_1$}, which we now know contains some males, must also contain only males, again using the induction assumption. Thus G consists of all males; p$_n$$_+$$_1$ follows from p$_n$.  I don't know where to start or anything. Any help or hints would be helpful.


Automorphism group of the direct product of cyclic groups

I was wondering what the order of the group $Aut(Z_{p^a} \times Z_{p^b})$ is, where $p$ is prime and $a $ and $b$ are natural numbers, eventually equal. I had found a way on internet that was using matrices, but it looks like I cannot find that topic anymore, and I think I hadn't really understood that explanation, could someone please explain how to count them?  By the way, it seems that using matrices is the best option (as I clearly remember the explanation I had found wasn't very long and looked like it didn't require many calculations), but couldn't I just calculate how many  "good" possibilities there are? I mean, I would send the generator of $Z_{p^b}$ in another element of order $p^b$, then the generator of $Z_{p^a}$ in another element of order $p^a$. The problem is that the cyclic subroups generated by the images of the generators must have a trivial intersection. So I was hoping to find how many choices I had for the second generator, but here it gets tricky and I don't know how to proceed, how to count how many "good" choices I have.  Thanks for the help


I'm trying to find a counterexample to the statement that a graph that has cycles containing x and y and a cycle with all 3 I know this is a false statement


How to evaluate the integral $\int_0^{\infty} e^{-\frac{1}{2}\left(x^2+ \frac{c}{x^2}\right)}dx$?

I am wondering how one would calculate the integral:  $$ \int_0^{\infty} e^{-\frac{1}{2}\left(x^2+ \frac{c}{x^2}\right)}dx $$  where $c$ is a constant. I have tried to reparametrize by letting $u = x^2$ to get:  $$ \int_0^{\infty} \frac{1}{2\sqrt{u}} e^{-\frac{1}{2}\left(u+\frac{c}{u}\right)}du $$  and then trying to use integration by parts. However, I am getting nowhere with that approach.


Is there a way to have latex detect forward references?

I've got a very large document (which I've broken into "chapters" and such) which I've recently moved a few things around in.  Is there a nice way to get latex to output a list of forward references? (like, things in chapter 5 that reference a result in chapter 10)


Why during annihilation of an electron and positron 2 gamma rays are produced instead of 1?

$1 \gamma \rightarrow 1 e^- + 1 e^+$       (pair production)  Then why  $1 e^- + 1 e^+ \rightarrow 2 \gamma$       (annihilation of matter)  instead of  $1 e^- + 1 e^+ -> 1 \gamma$ ?


What are the steps and resources I can use to publish a math paper?

I've spent years writing a math paper I call "A study of Pythagorean Triples" and I would like to publish. I've written and re-written for accuracy and clarity and I ported it from Word to TexShop after having found that most publications require that format.  My paper is currently 14 pages long including 8 [ small ] graphic Exhibits in .png format.  How do I begin to get peer review as a total amateur and how do I proceed from there?  Update: My work was original to me but comments have led me to links showing that some of it has been done by others. The only distinction my work still has is in showing how this or that function was developed and how it works. I should rename my paper something along those lines and reflect that in my abstract.


Not able to get the expected Assert statement in my test Class

My Assert Statement is failing in the below logic and i am not able to get the proper expected value ,   Please find the Codes in the Screenshots.    Logic:  public static void wmgRemoveOldGroupQueue(Map<Id,case> newMap,Map<Id,Case> oldMap){  string WmgRecordTypeId = Schema.SobjectType.case.getRecordTypeInfosByDeveloperName().get('WMG_Operations_Workflow').getRecordTypeId(); for(case o: newMap.Values()){    if(o.RecordTypeId ==  WmgRecordTypeId && !((String)o.OwnerId).startsWith('005') && (o.ownerId != oldMap.get(o.Id).OwnerId)){                o.ANN_Accepted_From_Queue__c='';   }  } }   test Class :   static testMethod void wmgRemoveOldQueueTest(){  //setup  user thisUser = [select Id FROM user where ID = :UserInfo.getUserId()]; string WmgRecordTypeId = Schema.SobjectType.case.getRecordTypeInfosByDeveloperName().get('WMG_Operations_Workflow').getRecordTypeId(); string assertMessage = 'Accepted From Queue did not clear out'; QueueSobject q = [Select QueueId,Queue.Name From  QueueSobject Where SobjectType = 'Case' and Queue.Name = 'WMG Ops - Licensing' limit 1];  Case c = new Case(); c.ownerId = q.QueueId; c.RecordTypeId =  WmgRecordTypeId; insert c;  c = [SELECT OwnerId, ANN_Accepted_From_Queue__c, RecordTypeId FROM Case WHERE Id = c.Id]; c.ownerId = thisUser.Id; update c;  c = [SELECT OwnerId, ANN_Accepted_From_Queue__c, RecordTypeId FROM Case WHERE Id = c.Id]; c.ownerId = q.QueueId; c.RecordTypeId =  WmgRecordTypeId; update c;  ///This is Failing System.assertEquals(null,[SELECT ANN_Accepted_From_Queue__c FROM Case Where Id=:c.Id].ANN_Accepted_From_Queue__c, assertMsg);


Is there a way to disconnect eth0 (wired connection) for just until I reboot? Or even a way to just bring it down then up again before I shut the computer down? I want to do this because sometimes I want to be on Wi-Fi and when the signal gets low, it hops back to eth0, even if I manually disconnected from it. Using Ubuntu MATE 15.04


Moment of inertia: why $\mathrm{dI}=r^2\mathrm{dm}$ instead of $\mathrm{dI}=m\mathrm{dr^2}$?

When computing the moment of inertia, I observed that people usually use the following logic:  $$d I=r^2 dm,\\ \therefore I=\int r^2 dm$$  My question here is, why not use $dI=m  ~d(r^2)$?   I acknowledge that integrating $dI$ means that I am summing up all the small I's ($\Sigma I_i$). What I find strange is that viewing $dI$ as $md(r^2)$ seems to make no sense when viewed from such perspective.  Is there a reason why no textbook seems to view $dI$ that way?


How to correctly add bibtex bibliography with latex?

I have added bibliography in my latex file like so :  ...to the literature \cite{ahu61} \bibliography{bibliography}   and my bibliography.bib looks like this :   @article{ahu61,        author={Arrow, Kenneth J. and Leonid Hurwicz and Hirofumi Uzawa},        title={Constraint qualifications in maximization problems},        journal={Naval Research Logistics Quarterly},        volume={8},        year = 1961,        pages = {175-191}      }   If i keep the citation I get   Texification succeeded: no errors!  However, there were warnings in your LaTeX source  ./main.tex:231: LaTeX Warning: Citation `ahu61' on page 4 undefined on input line 231. ./main.tex: LaTeX Warning: There were undefined references.   and no bibliography.  If I remove it I get no warnings but no bibliography either.


C# Image file information read location details and date

I have images(Jpg, gif ,png etc..) local hard disk. What I need to read all file information such as location details latitude longitudes or location name and photos created date  each images. Please help me how do I read location details and date.  This is my C# code it not display location details or created date   string directory = (@"C:\Photos");  var AllImages = Directory.GetFiles(directory, "*.jpg",                                    SearchOption.AllDirectories)                          .Select(Image.FromFile).ToList()   This is one of my photo example  .


I have killed all of the Brotherhood of Steel - what now?

in FO:NV, i killed all of the Brotherhood of Steel in the Hidden Valley Bunker. I then went to Deathclaw Promontory and picked up the power armour. I try to wear it and it says i have to have Power Armour Training. I've heard that i can only get the training from the Brotherhood, what are my options?  Thanks


Consider the irreducible polynomial $g = X^4 + X + 1$ over $F_2$ and let $E$ be the extension of $F_2 =$ {0, 1} with a root $α$ of $g.$  Could $E$ have a subfield of order 8  When working through my work Ive come across this question which has stumped me and I cant get my head aound if this is true of not so any help will be appreciated.


How to explain spin for a 14-year old teen

How do you explain the concept of spin in QM to a 14-year old teen, and why it isn't a vector as in the classical notion of angular momentum?


How can I have 150 or more credits? I mean I want to have '150/150 credits'.


On Dec 23, 2013 I edited two of my questions on Physics.SE:         Then I flagged them because one was marked duplicate and other as closed. The flags remained active for nearly four days. I left a comment on  asking the moderator to take some action on my flags, for I was worried that mods had forgotten my flags. Then eventually both of the questions got deleted by the "community moderator".   I suspect the posts deleted by the "community moderator" are indeed deleted by the human moderators. Because my questions were deleted before 9-days I had edited them. That very moderator wanted to show me an action which I requested from him.    Still no action was taken by moderatorss on my flags. After my questions were deleted by the "community moderator" one more surprise came to me: Question 1 was completely removed by moderator. when I tried to enter its URL, I was denied access to it. After this removal the moderator took action on my flags explaining that I need to edit them more.    After some time another weird thing happened: Question 2 was undeleted by the community and Question 1 was unremoved but it is still deleted by the community.    Consequently, I have two questions:     How can a question deleted by community be undeleted? It seems impossible because a question is automatically deleted when it becomes outdated  as explained here:()   How is a removed question unremoved?         Through the constructive comments of some nice users i got another question:    Does Community♦ represents a bot or the present working moderators of Stack Exchange websites?         Addendum: Question 1 has been deleted by the "community moderator" by Dec 28 '13 at 13:15


Maximum number of subsets of $\{1,\ldots,n\}$ such that the intersection of every two of the subsets has cardinality $\geq r$.

Let $S=\{1,2,\ldots,n\}$ and $\mathcal{F}=\{A_1,A_2,\ldots,A_k\}\subseteq\mathcal{P}(S)$ such that $|A_i\cap A_j|\geq r$ for all $1\leq i<j\leq k$, where $r\in\mathbb{N}_+$ and $1\leq r\leq n$. Find the maximum of $k$.   The special cases $r=n-1,n$ are trivial, where $\max k=2^{n-r}$. The case $r=1$ is easy. We pair each $A\subseteq S$ with $S\setminus A$. There are $2^{n-1}$ such pairs and the answer again is $\max k=2^{n-r}$ by the pigeonhole principle. However, $k\leq 2^{n-r}$ does not hold for all $r$. An example is $n=6$, $r=2$ and $\mathcal{F}$ consists of all subsets of $S$ of cardinality $\geq4$, in which case $k=22>2^4$. Is it possible to find the maximum for the general case and how do I proceed?


I am getting below error when I tried to install the WSP in staging environment.     Add-SPSolution : Operation is not valid due to the current state of   the object. At line:1 char:1   + Add-SPSolution  -LiteralPath "D:\StagePackage\SharePoint.ServiceSett ...   + ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~       + CategoryInfo          : InvalidData: (Microsoft.Share...dletAddSolution:SPCmdletAddSolution) [   Add-SPSolution], InvalidOperationException       + FullyQualifiedErrorId : Microsoft.SharePoint.PowerShell.SPCmdletAddSolution   I am not sure what is the exact issue here, I tried to install the same package in my dev/test environment its working fine  Below is the ULS log     Deleting the SPPersistedObject, SPSolutionLanguagePack   Name=0.   5f1402fb-84e7-41d1-abeb-da9cdc500246      Deleting the SPPersistedObject, SPSolution   Name=sharepoint.mysettings.wsp.   5f1402fb-84e7-41d1-abeb-da9cdc500246      System.InvalidOperationException: Operation is not valid due to the   current state of the object.     at   Microsoft.SharePoint.Administration.SPConfigurationDatabase.Microsoft.SharePoint.Administration.ISPPersistedStoreProvider.GetParent(SPPersistedObject   persistedObject)     at   Microsoft.SharePoint.Administration.SPSolutionLanguagePack.get_DisplayName()   at   Microsoft.SharePoint.Administration.SPSolutionLanguagePack.SetSolutionFile(SPFarmSolutionPackage   solnPackage, String path, String solutionName, Boolean isRestore)   at   Microsoft.SharePoint.Administration.SPSolution.AddLanguagePack(SPFarmSolutionPackage   solnPackage, String path, UInt32 lcid, String name, Boolean isRestore)   at Microsoft.SharePoint.Administration.SPSolutionCollection.Add(String   path, String name, UInt32 lcid, Boolean isRestore)     at   Microsoft.SharePoint.Administration.SPSolutionCollection.Add(String   path, UInt32 lcid)     at   Microsoft.SharePoint.PowerShell.SPNewCmdletBase`1.InternalProcessRecord()   at   Microsoft.SharePoint.PowerShell.SPCmdlet.ProcessRecord()  5f1402fb-84e7-41d1-abeb-da9cdc500246      Error Category: InvalidData    Target Object    Microsoft.SharePoint.PowerShell.SPCmdletAddSolution  Details  NULL    RecommendedAction NULL    5f1402fb-84e7-41d1-abeb-da9cdc500246   I tried deploying the package with stsadm command also and there also I am getting error. Its 2013 solution and scoped at farm level  I am completely running out of ideas can anyone please help me on this.


Ckeditor toolbar not entirely showing up

I have just moved my site from local machine to production, the wysiwyg editor based on ckeditor no longer show the complete toolbar. I have a minimal list of element. Can someone help, am trying everything, edit profile, check if all files are uploaded, i don't see any problem !


Error log is :  016-02-21 21:22:34 GET DETAIL:  Connection matched pg_hba.conf line 83: "host    all             all             ::1/128                 md5" .... .... 2016-02-21 21:22:37 GET DETAIL:  Connection matched pg_hba.conf line 83: "host    all             all             ::1/128                 md5" 2016-02-21 21:22:37 GET FATAL:  password authentication failed for user "postgres" 2016-02-21 21:22:37 GET DETAIL:  Connection matched pg_hba.conf line 83: "host    all             all             ::1/128                 md5" 2016-02-21 21:22:37 GET LOG:  CreateProcess call failed: A blocking operation was interrupted by a call to WSACancelBlockingCall.       (error code 299) 2016-02-21 21:22:37 GET LOG:  could not fork new process for connection: No error 2016-02-21 21:22:37 GET LOG:  incomplete startup packet 2016-02-21 21:22:38 GET FATAL:  password authentication failed for user "postgres" 2016-02-21 21:22:38 GET DETAIL:  Connection matched pg_hba.conf line 83: "host    all             all             ::1/128                 md5" 2016-02-21 21:22:42 GET FATAL:  password authentication failed for user "postgres" 2016-02-21 21:22:42 GET DETAIL:  Connection matched pg_hba.conf line 83: "host    all             all             ::1/128                 md5" 2016-02-21 21:24:26 GET LOG:  could not receive data from client: An operation on a socket could not be performed because the system lacked sufficient buffer space or because a queue was full. 2016-02-21 21:24:26 GET LOG:  incomplete startup packet 2016-02-21 21:24:29 GET FATAL:  password authentication failed for user "postgres" 2016-02-21 21:24:45 GET PANIC:  could not write to log file 000000010000000100000041 at offset 4259840, length 8192: Invalid argument 2016-02-21 21:24:45 GET STATEMENT:  COMMIT 2016-02-21 21:24:53 GET LOG:  server process (PID 470944) was terminated by exception 0xC0000409 2016-02-21 21:24:53 GET DETAIL:  Failed process was running: COMMIT 2016-02-21 21:24:53 GET HINT:  See C include file "ntstatus.h" for a description of the hexadecimal value. 2016-02-21 21:24:53 GET LOG:  terminating any other active server processes   Can anyone help to solve the problem ,I spent many hours but dont find solution. PG VERSION is 9.4   Operating System: Windows  PostgreSQL.conf: is :  listen_addresses = '*' port = 5432  max_connections = 100 shared_buffers = 128MB   dynamic_shared_memory_type = windows   pg_hba.conf is :  # IPv4 local connections: host    all             all             127.0.0.1/32            md5 host    all             all             0.0.0.0/0               md5


What is the proper way to name a bundle identifier.?

As there are so many ways to create an app bundle-identifier, which or what is the professional or proper way to be considered while naming an bundle-identifier.?  I used to follow this  com.companyname.appname   Is there any better way to do this or it depends.?  Thanks in advance.!


Why are my meshes showing up as invisible when I open a new file

I know that there are issues with AMD GPUs on versions 2.9 and above. I recently reinstalled 2.82 and this happens everytime I open a new file. My default cube shows up as what I can only describe as a transparent mesh. In rendered view, there is a black texture which seems to stay static when you adjust the camera angle. I'm very confused as 2.82 worked perfectly for me for over a year. It's really only started having issues since I installed version 2.92 which had a lot of issues and then reverted back to this version. I'm happy to provide more info, but I'm really not sure what info to provide because I'm so confused right now.


Is it possible to dual boot i5 8th generation (HP) laptop?

I wish to buy the HP cc130tx model laptop which has an i5, 8th gen processor with Win 10 pre-installed. But the tech guy at the shop said that I might not be able to successfully dual boot the laptop with Ubuntu 14. Same goes for the models released in the last 6-7 months, and that I should rather buy a 4th or 5th generation.  Is this true? If so, what is the reason behind not being able to successfully dual boot a system? And which processor, etc. requirements should I look for in a laptop, as a result?  P.S.: I specifically want to install Ubuntu 14 (LTS) since the software I want to work on does not have a stable release for the latest versions, yet. I shall upgrade later.


I have one folder in my internal HDD. I need to copy the folder to multiple external HDD. If the copy can happen simultaneously, it will help me gain time.  Folder name is "AllFiles" Folder is located at the root of the internal HDD. /AllFiles  No to copy it to /dev/sdb, /dev/sdc and /dev/sdd  I saw some command lines using cat and tee. I couldn't test it because it was for a specific purpose and the destination was a network folder.


Probability to calculate the birthday match

Is there any intuitive way to calculate the probability that in a randomly chosen group of r people at least three people have the same birthday


Is there always an equilibrium point in space for gravity?

For instance, for a two-body system, there will always be a point in-between the two in which the forces of gravity completely cancel, and if I were there then I would experience no net force. I believe there is also a point, or a region, for three body systems as well. Assuming we treat the stars or planets as simply point-masses, will there always be, for any number of objects, a point, or a region, of equilibrium? Or no?


Show that $f_n=(1+\frac{x}{n})^n$ converge uniformly on all compact of $\mathbb R$

Let $f_n(x)=\left(1+\frac{x}{n}\right)^n$. Show that it converges uniformly to $e^x$ on every compact $K\subset \mathbb R$.    This is how I would like to do:  Let $K$ a compact. Let $g_n(x)=\left(1+\frac{x}{n}\right)^n-e^x$. Since $g_n$ is continuous on $K$, it take it's maximum on $K$. Let denote $a_n\in K$ s.t. $|g_n(x)|\leq g_n(a_n)$ for all $n$. Set $b_n=g_n(a_n)$. How can I show that $$\lim_{n\to\infty }b_n=0\ \ ?$$  I tried to show by induction that $(b_n)$ is decreasing, but it looks very complicate. And even if it converge, it looks complicate to show that it converge to $0$ as well.


How do this two gate able to give an output if in the first place they both doesn't have a second output... in which will be the input of the other...  Both cannot get a second input because they don't have a second input themselves to provide an input to the other...    Conversation:  Gate 1: Hey gate 2, I'll give you your second input... oh wait, I don't have my second input... I can't provide you your second input.. you don't have a second input as well that I need, now we're stuck.  Gate 2: I know right.


Redefining multiplication so that $\mathbb{Z}$ is a field?

My book (Finite Dimensional Vector  Spaces by Halmos) says to redefine (if possible) addition and/or multiplication in order to make $\mathbb{Z}$ a field. The only field proprety that $\mathbb{Z}$ lacks is the existence of a multiplicative inverse. I defined multiplication as normal, with the exception that $\forall ( a \not = 0) a \cdot 2 = 1)$. Since $a \cdot 2 = a \cdot (1+1) = a+a$, I also redefined addition as normal, except in the case of $a+a$, which is always equal to $1$. But I noticed that this gives me a contradiction because we cannot have $0+0=1$.   What is a better way to solve this problem, and more importantly, how can I know that it won't give me a contradiction somewhere?


de morgan law $A\setminus (B \cap C) = (A\setminus B) \cup (A\setminus C) $

First part :  I want to prove the following De Morgan's law :  ref.(dfeuer)  $A\setminus (B \cap C) = (A\setminus B) \cup (A\setminus C) $    Second part:  Prove that $(A\setminus B) \cup (A\setminus C) = A\setminus (B \cap C) $    Proof:  Let $y\in (A\setminus B) \cup (A\setminus C)$     $(A\setminus B) \cup (A\setminus C) = (y \in A\;  \land y \not\in  B\;) \vee (y \in A\; \land y \not\in C\;)$      $\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;= y \in A\ \land (  y \not\in B\; \vee \; y \not\in C ) $      $\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;= y \in A \land  (\lnot ( y\in B) \lor \lnot( y\in C) )$   According to De-Morgan's theorem :  $\lnot( B \land C) \Longleftrightarrow (\lnot B \lor \lnot C)$ thus     $y \in A \land (\lnot ( y\in B) \lor \lnot( y\in C) ) = y \in A \land y \not\in (B \land C)$   We can conclude that  $(A\setminus B) \cup (A\setminus C) = A\setminus (B \cap C)$


Can I make some of my hard drives invisible to certain programs?

On Windows 7.  I have a lot of hard drives which are used for storage.   When launching certain programs (e.g. some games, Photoshop, etc.) the program will automatically try to query/access all of the system's drives for whatever reason (presumably to enumerate them, see how much free space is on them, or access some other property of them).  This means that every time I launch these programs all of my drives have to (slowly!) spin-up even though no files on the drive are actually being used.  This is extremely annoying.  So is there a way I can restrict access to these hard drives, and/or make them invisible to certain programs?


I think the following sentence is incorrect  Leena is a most intelligent student.  because in such constructions the must come before most But I found this sentence in a book. I think it should be  Leena is the most intelligent student.  or even better way to write this will be  Leena is the most intelligent student in the class.


Is there a time operator in quantum mechanics?

The question in the title has been asked many times on this site before, of course. Here's what I found:    in 2011. Answer states time is a parameter.  in 2012. Answer by Arnold Neumaier cites surveys in the literature, and very briefly summarizes Pauli's 1958 proof: if a time operator satisfied a CCR with the Hamiltonian, it would imply spectrum of Hamiltonian is unbounded below.  in March 2013. Closed as duplicate without answer.  in Nov 2013. Answer confusingly states there is no time operator, then describes a time operator. Then closed as duplicate.  in Feb 2016. Answer describes an explicit time operator, but points out that multiplication by $t$ does not yield an $L^2(\mathbb{R})$ function since norm is preserved in time.  Let me also link , , , and  which address slightly different questions, but contain related discussions. We also have , where Valter Moretti points out that a sensible construction of coordinate operators in relativistic QFT yields the Newton-Wigner operators, but only for the spatial coordinates, since none exists for the timelike coordinate by Pauli's theorem. And off of physics.se, a great resource is John Baez's website, where he has a note  which mentions that by  a time operator satisfying a CCR with the Hamiltonian would necessitate the Hamiltonian have unbounded spectrum.   Should Pauli's theorem (which is probably a corollary of Stone-von Neumann theorem), as it's referred to in some of the answers, be taken as the definitive answer? Most of the sources seem to agree.  But some of these answers seem to be ignoring an elephant: in a relativistic theory, time and space are treated on an equal footing. If there are spatial operators, surely there must be a time operator. Indeed, some of the comments in the above questions refer to chapter 1 of . Let me quote the relevant passage:     One [option to combine quantum mechanics and relativity] is to demote position from its status as an operator, and render it as an extra label, like time. The other is to promote time to an operator.       Let us discuss the second option first. If time becomes an operator, what do we use as the time parameter in the Schrödinger equation? Happily, in relativistic theories, there is more than one notion of time. We can use the proper time τ of the particle (the time measured by a clock that moves with it) as the time parameter. The coordinate time $T$ (the time measured by a stationary clock in an inertial frame) is then promoted to an operator. In the Heisenberg picture (where the state of the system is fixed, but the operators are functions of time that obey the classical equations of motion), we would have operators $X^\mu(τ)$, where $X^0 = T$. Relativistic quantum mechanics can indeed be developed along these lines, but it is surprisingly complicated to do so.   In a subsequent paragraph, he points out that promoting all the coordinates to operators, including time, is exactly what string theory is, though with the additional complication that there is an additional parameter.  So how do we reconcile these two camps? Is Pauli's theorem incompatible with relativistic considerations? Is it really a problem if your Hamiltonian's spectrum is not bounded below? Why is there no timelike Newton-Wigner operator? Does there in fact exist a relativistic quantum theory which includes an operator whose eigenvalues are time coordinates?   I feel like the existing answers on the site did not address this issue, so I'm hoping for some new answers which look at it from that perspective.


How do I clean up my "home" drive or "/" to get some free space?

I need to free some space on my drive:  Not enough free disk space: The upgrade has aborted. The upgrade needs a total of 2,807 M free space on disk '/'. Please free at least an additional 1,396 M of disk space on '/'. Empty your trash and remove temporary packages of former installations using 'sudo apt-get clean'.    It's different from , as the solutions for that question weren't sufficient


Cardinality of "$x-y\in\Bbb Q$"-equivalence class of $1/\sqrt2$

For $x,y\in I:=[0,1]$ define the relation on $I$ as $x-y\in \Bbb Q$. How big (using cardinal number) is the cardinality of the equivalence class $[1/\sqrt2]$?  I have tried to solve it by finding the equivalence class but I'm not sure about the method that I can solve the question. Please, can you help me to solve it.


Is it considered good practice to avoid using `sudo su`?

The root password is disabled by default so nobody can directly log into the root account.  However I can still log into root another way by doing sudo su and entering my own password, given that I am a member of the sudo group in /etc/group (as far as I know this is the only necessary condition).  Is this considered a bad practice to "backdoor" my way into the root account by using sudo su? Is it something to be avoided, and instead rely on using sudo command instead?


With every pair of Bluetooth headphones I've owned I've had a latency of about 50 ms.  How do I get rid of or reduce this delay?  MacBook Pro with Retina, Mid 2015, macOS Mojave 10.14.3 (but I had the problem on earlier OSes).


How do wizards cast spells which appear on their spell list when it has a divine focus component?

What does a wizard do to cast a spell which contains a DF component? Take  for example,  Components V, S, DF    A divine focus component is an item of spiritual significance. The divine focus for a cleric or a paladin is a holy symbol appropriate to the character's faith. The divine focus for a druid or a ranger is a sprig of holly, or some other sacred plant. If the Components line includes F/DF or M/DF, the arcane version of the spell has a focus component or a material component (the abbreviation before the slash) and the divine version has a divine focus component (the abbreviation after the slash).  So do wizards have holy/unholy symbols in their spell components pouch or what?


In an auditorium a comperer announces and asks the audince to take their seats on the left side. What does it mean?

In an auditorium the announcer asks the audience to be seated on the left side seats.  Doesnt it mean the left side of the audience??


A woman has $n$ keys, one of which will open a door. a)If she tries the keys at random, discarding those that do not work, what is the probability that she will open the door on her $k^{\mathrm{th}}$ try?  Attempt: On her first try, she will have the correct key with probability $\frac1n$. If this does not work, she will throw it away and on her second attempt, she will have the correct key with probability $\frac1{(n-1)}$. So on her $k^{\mathrm{th}}$ try, the probability is $\frac1{(n-(k-1))}$ This does not agree with my solutions.   b)The same as above but this time she does not discard the keys if they do not work.  Attempt: We want the probability on her $k^{\mathrm{th}}$ try. So we want to consider the probability that she must fail on her $k-1$ attempts. Since she keeps all her keys, the correct one is chosen with probability $\frac1n$ for each trial. So the desired probability is $(1-\frac{1}{n})^{k-1} (\frac1n)^k$. Again, does not agree with solutions.  I can't really see any mistake in my logic. Can anyone offer any advice? Many thanks


I have 2 array as below :  Array 1 (   [0] => c1   [1] => c2   [2] => c3 )  Array 2 (    [0] => Son    [1] => Daughter    [2] => Son )   Output required :  Array (   c1  => Son   c2  => Daughter   c3  => Son  )   Can anyone please guide to generate this output ? Thank you.


This is a pretty simple request.  I'm looking to format the timestamp string - '2016-08-02T18:43:58Z' into a date format that I can compare on with Python.   I made it to here:     (datetime.strptime(each_element['sentAt'], "%Y-%m-%d'T'%H:%M:%S'Z'"))  but I'm still getting the error  ValueError: time data '2016-08-02T18:43:58Z' does not match format "%Y-%m-%d'T'%H:%M:%S'Z'"  Pretty sure the error is in the inclusion of the 't' and 'z' but I am stuck as to how to fix. Help?


How do I delete strings from a list in a certain order without typing its value?

I already know how to delete strings, but the question here is: How do you delete them in a certain order without typing its value, for example, "Mathew", but I want to remove it without actually typing "Mathew" and without removing the value "Paul"? Is there a way behind this?  Note that "Paul" is the first string in the list, so I do not want to remove this, but the second string if it is possible.  usernames = ["Paul", "Mathew"] del_username = usernames.remove("Mathew")   I have tried adding a '1' to the .remove function, but it can't find the value somehow.  del_username = usernames.remove(1)


I am trying to understand a C++ code. The Following is written in the *.h file   Sys(int w, int h, Eigen::Matrix3f K, bool enableSys = true); Sys(const Sys&) = delete; Sys& operator=(const Sys&) = delete; ~Sys();   What is the interpretation of Line 2 and Line 3?  Are those destructors? Why are they needed? Is this a good practice?


What is the name for the little numbers that appear over characters' heads when they lose health?

...you know the ones. Something like "value overlays" or "value pop-ups" describes them quite well, but I was thinking they might have a real name?


Stop prompting for password every time I do something requiring privileges

I didn't see this answered satisfactorily anywhere, so I figured I'd ask.  Every time I go to do something requiring privileges, such as install a program, open restricted folders, etc., I'm prompted for the account password, even though my user account is an administrator.  How do I get it to stop prompting me for my password when doing such actions?


So I wanted to hide the Finder icon on my Dock.  According to this answer -  I am suppose to edit DockMenus.plist file. When I tried I had no permission to do that. I tried to use chmod (also with sudo) on that file with no effect, same message from terminal - Unable to change file mode on DockMenus.plist: Operation not permitted. I ran ls -lOe on that file and I learned that apparently there is new permission flag called restricted.  I still don't know how to get permission to edit that file. Does anyone have any solution?


multibrowser chatting with flas-socketio

I am trying to create a simple multi browser chat web application. I thought I finished creating it. But when I try run it I get 500 status and  Internal Server Error  The server encountered an internal error and was unable to complete your request. Either the server is overloaded or there is an error in the application.   Not really sure why this is occurring. I am doing this project in Flask and I am currently learning at the same time. Because I am currently learning Flask and Flask-socketio and websockets.   chatty.py:  from gevent import monkey # Do all of the default monkey patching (calls every other function in this module. monkey.patch_all()  from threading import Thread from flask import Flask, render_template from flask.ext.socketio import SocketIO, emit from time import strftime  app = Flask(__name__) app.config['SECRET_KEY'] = 'secret' socketio = SocketIO(app) thread = None   @app.route('/') def index():     global thread     if thread is None:         #thread = Thread(target=background_thread)         thread.start()     return render_template('index.html')  # handle messages @socketio.on('send message') def handle_message(message):     #msg = strftime("%H:%M:%S") + ': ' + str(message)     emit('response',              {'data': strftime("%H:%M:%S") + ': ' + message['data']},              broadcast = True)  @socketio.on('connect') def conn():     emit('response', {'data': 'Connected'})  if __name__ == '__main__':     socketio.run(app)   index.html:                                <form id="broadcast" method="POST">         <input type="text" name="message" id="msg" placeholder="Enter message here...">         <input type="submit" value="Send">     </form>
Chat


I have taken code from .  I ran the code in ide provided in gfg itself.  I have edited code a bit , sizeof(int) is showing 4 but it is shown to take 8 bytes in struct through offset  #include <stdio.h>   #define OFFSETOF(TYPE, ELEMENT) ((size_t)&(((TYPE *)0)->ELEMENT))   typedef struct PodTag  {      int   i;      double d;      char  c;  } PodType;   int main()  {      printf("%ld", OFFSETOF(PodType, d) );       getchar();      return 0;  }


Converting field to string with leading zeroes using Python Parser of ArcGIS Field Calculator?

I would like to create an expression using the field calculator in ArcMap to be able to convert an Int field to a string and add leading zeroes.  I am able to do it in a python window with an example  x=450 print str(x).zfill(4) >>>0450   I have tried:  !Time!.str().zfill(4)   but that gives me invalid syntax errors.


Quantum eraser: How does photon detection in an interference pattern "dark spot" not affect the state of the remaining photon?

I have read time and time again that there is nothing mysterious going on in the , but I can't get the math to add up. Please help me: Consider these two simplified illustrations from : The experimental setup, with emission points A and B, beam splitters BS_ and detectors D_    and the measurement results    The point I often hear made is that since the interference patterns only happen once you correlate a statistical amount of data from the two sides of the experiment, there is no retro-causality at play, just good old correlation. Which sounds good.   But let's say that a dark spot in the interference pattern, e.g. in the center of the $D0$ correlated with $D2$ data, is perfectly dark - zero photon detections happen at the center which are correlated with a $D2$ detection, no matter how many times we do the experiment. And say that the right photon is detected long before the left photon. Then let us say we run the experiment with a single photon in each direction, and the right photon is detected while $D0$ is in the center position. It would then seem like we can use this to predict that the left photon will not be detected in $D2$. But that would mean that the detection of the right photon influences the path of the left photon, which is of course not possible. What am I missing?  Let me try to restate the question mathematically: Let us describe the state of the left photon, $| \psi_L \rangle$ right before it is detected,  $$| \psi_L \rangle = \frac{1}{\sqrt{2}} (| A \rangle + | B \rangle) = \frac{1}{\sqrt{4}} (| D_1 \rangle + | D_2 \rangle + | D_3 \rangle + | D_4 \rangle ),$$  so it is equally likely to be detected by any detector. This would be true if it was propagating independently of the right photon. Detection of the right photon does not collapse it into $| A \rangle$ or $| B \rangle$, but it does mean that $\langle D_2 | \psi_L \rangle = 0$, which is not true according to the definition above.  How can this be described without saying that the detection of the right photon "tells" the left photon to avoid $D_2$?


Why is there steam in a hot shower even though the water is not boiling?

When I take a hot shower, there is normally a fair amount of steam. However, I don't think the water coming out of the shower-head is actually boiling (unless I am mistaken).      Why is there water vapor in a hot shower?


Using xargs in msysgit to remote prune all doesn't seem to work

I have multiple remote references, and there's no "git remote prune --all" so I attempted "git remote show | xargs -n 1 git remote prune" but it doesn't work. I'm running msysgit 1.7.4. I know it works in Linux (well "git remote show | xargs git remote prune" does) but I just get no output in msysgit, and I know it's not working as I can still prune after running that.  "git remote show | xargs -n 1 echo git remote prune" shows me it's compiling the "git remote prune public1" commands correctly.  Any ideas?


I've looked at several videos and webpages explaining how to color individual faces, but none of them work for me.  When I select a face and change the material in v2.8, the entire object changes color. This is in solid mode, rendered, and look dev.


Seek Steering Behavior with Target Direction for Group of Fighters

I am implementing steering algorithms with group management for spaceships (fighters). I select a leader and assign the target positions for the other spaceships based on the target position of the leader and an offset. This works well. But when my spaceships arrive they all have a different direction. I want them to keep to look in the same direction (target - start).   I also want to combine this behavior with a minimum turning radius that is based on the speed. The only idea I have is to calculate a path for each spaceship with an point before the target position, so the ships have some time left to turn into the right position. But I dont know if this is a good idea. I guess there will be a lot of rare cases where this can cause a problem.  So the question is, if anybody knows how to solve this problem and has some (simple code) or pseudocode for me or at least some good explanation.


What's an effective way to remove this stubborn burnt-on oil from a saucepan?

I have a stainless steel saucepan that has dark burnt on oil around the sides. I'm assuming it's from cooking oil since I use oil in this saucepan a lot.  It seems to just keep building up and up and I can't get rid of it.  This morning I tried boiling 1cup water with 1cup distilled vinegar for 5 minutes, then adding baking soda. I emptied the water, then tried to scour it clean but it made very little difference.  Is there some industrial strength stuff I can buy to help me out here?  Here's a pic:


$Z$ is Normal$(\sigma,1)$, find UMVUE of $P(Z\leq 0)$.

Given i.i.d. samples $X_1,...,X_n$ from Normal$(\sigma,1)$, find the UMVUE of $g(\sigma)=P_\sigma(Z\leq 0)$.  I tried to use Lehman-Scheffe theorem. We now that $\sum_1^nX_i$ is sufficient and complete for $\sigma$, and we could take $T(X)=1_{\{X_1<0\}}$ as an unbiased estimator for $P(Z\leq 0)$. Then by this theorem, $S(X)=E[T(X)|\sum_1^nX_i]$ is the unique UMVUE for $g(\sigma)$. The point I got stuck is calculating the conditional expectation $E[1_{\{X_1<0\}}|\sum_1^nX_i]$.  Thanks in advance for any help/hint/suggestion.


I've looked at all the relevant topics on the site and this particular gotcha does not seem to be covered  I exported a Word 2016 document (in French) as filtered HTML ( filtered= no office specific stuff included). If I show the file in my browser as html, everything is fine - all the accents show correctly. ( Charset is utf-8 and it's not coming from a database). But when I change the extension to .php and run it, all the french characters are shown as black diamonds with a question mark inside.  If I express the french characters as html entities, they show correctly, but I don't want to do this as the fix - there are hundreds of them in there, and I don't want to edit the text - it's not mine and the author would have to proof read it all again just to check the accents.  So I figured it's a PHP (5.5.26) issue - but I can't see anything in the ini file which might affect this - it looks like UTF-8 is the default charset if you don't change anything,  What's the fix ??


Is there a way to hide pictures from being shown in Gallery

How can I hide a jpeg image in Android Gallery? or is there a way to hide a folder of pictures for Gallery only?


order of infinite countable ordinal numbers

I'm trying to understand ordinal arithmetic.  If one had an ordered list of the some subset of countable ordinal numbers, what order would the following 6 countably infinite ordinals be in?  If the following order is not correct, what is correct order and why is that the correct order?  $$\omega\;<\; \omega^2 \;<\; 2^\omega \;<\; \omega^\omega \;<\; {^\omega}2 \;<\;{^\omega} \omega$$  I know $\epsilon_0 = {^\omega} \omega$ is the largest, but is still countable, but I'm not sure where the powers of $2$ fit in versus the powers of $\omega$.  I understand why $\omega^2$ or $\omega^n$ for any finite value of $n$ needs to be countable.  But, why does $\omega^\omega$ need to be countable?  For cardinal numbers, $2^{\aleph_0}$ is uncountably infinite.  Presumably, there would be some contradiction in mathematics if any finite ordinal arithmetic equation involving $\omega$ generated an uncountable infinity.


Is "helter skelter" a word or two words or two non-words? What do we call it?

The phrase "helter skelter" is strange because you don't see the word "helter" or "skelter" used anywhere, and when I searched Merriam-Webster dictionary for either word it links me to the definition of "helter skelter."    Since helter and skelter are separated by either a space or a hyphen whenever it's used, it seems like a "compound word," but compound words are made up of other words, whereas "helter skelter" is made up of two "non-words" (for lack of a better word (so far)).   What do we call this?  Is there a term for a word like "helter" that is only a word when it's paired with another, "skelter?"


Does "singular" have a common meaning across matrices, decomposition, vectors and values?

Saying a matrix is "singular" means that it cannot be inverted. Separately "singular value decomposition" factors a matrix into three matrices, one that contains "left-singular" vectors as columns, one that contains "singular values" on the diagonal, and another that has "right-singular" vectors as columns. And ironically, SVD works on a matrix regardless of whether or not it is singular.  Is there some underlying sense in which singular describes something common to all of these? If I accept that "singular values" was an arbitrary choice, then I can accept that SVD has singular in the name because it uses them, and that left and right singular vectors are just so called because they appear on either side of the matrix that contains singular values, but then I'll still left wondering how we get from there to singular matrices.


If there were infinite many stars, is the sky then always full of light so is there than even night?


What is the function of bash shebang? What is the difference between executing a file using ./file or sh file?   How does bash understand it?


Why is underline red in jsp and how to iterate list correctly

I don't understand what I do wrong. I'd like to iterate list in jsp. (In class it's working)          public static void main(String[] args) throws ClassNotFoundException {     List<SprawdzanieCen> PaS = SprawdzanieCenLista.PS();      for (SprawdzanieCen ob : PaS ) {         System.out.println("nrFaktury: "+ob.nrFaktury);     } }   But as I wrote I'd like to do it in jsp jsp code is as follows:          <%  out.println("Lets Start"); List<SprawdzanieCen> PaS = SprawdzanieCenLista.PS(); for (SprawdzanieCen s : PaS) {     s.nrFaktury; }  %>   I do not understand why "nrFaktury" is underline on red. Hot to iterate this list. Help,


Pandemic, Global Epidemic, Epidemic, Endemic

I really want to hear from the experts the definitions of all 4 terms especially whether global epidemic is equivalent to pandemic. Or should this question be directed to the epidemiologist?   Pandemic Global Epidemic Epidemic Endemic   I have Googled the terms and I understand the definition of 1), 3) and 4). In short the definition is based on geographical location and scale of outbreak, Pandemic is an outbreak of disease on a global scale (e.g. HIV). Epidemic is an outbreak of disease on a localised area. Endemic is a disease in a localised area. However, a definition for Global Epidemic is not available online.  Recently, WHO mentioned that "“It is important to put this on the table: this virus(Covid19) may become just another endemic virus in our communities, and this virus may never go away,” WHO emergencies expert Mike Ryan told an online briefing." Isn't covid19 considered a pandemic since it is on a global scale and is spreading rapidly?  Another term that I come across often is Global Epidemic. For example in the WHO website, HIV is listed as Global Epidemic. Does that mean Pandemic and Global Epidemic are the same?


why are integrals called anti derivatives rather than inverse derivatives

If the integral of a derivative of a function produces the original function (within a constant), why are integrals referred to as anti derivatives rather than inverse derivatives?


Only half of the display works, can I set to display only in that region?

I have a Macbook with a cracked screen, only the top left half of the screen works, is there anyway to reduce the screen resolution, keep the DPI the same, and thus have the entire OS visible in the top left section of the screen which works?  The below photo demonstrates what I mean, with parts of the creen totally unusable, it would make sense to be able to display the whole screen in the remaining usable part.


Biblatex - Undefined control sequence with specific source

As soon as I try to cite a specific source, the bibliography causes an "Undefined control sequence" error. When I cite a different source, no problems occur.  A minimal working example:  \documentclass[]{scrbook} \usepackage[style=chem-angew, backend=bibtex, sorting=none]{biblatex} % chem-angew \addbibresource{literature.bib} \begin{document}     \cite{Maitlis.2013a}     \printbibliography \end{document}   The specific entry from the bib-file:  @Book{Maitlis.2013a,   title =     {Greener Fischer-Tropsch Processes for Fuels and Feedstocks},   date =      {2013},   editor =    {Maitlis, Peter M. and de Klerk, A.},   publisher = {WILEY-VCH Verlag},   location =  {Weinheim},   file =      {Maitlis.2013a.pdf:Books\\Maitlis.2013a.pdf:PDF},   keywords =  {Fischer-Tropsch} }   This is the output from the log-file:  ! Undefined control sequence. <argument> ...ibnameprefix {de}\isdot \ifprefchar                                                {} {} {\ifuseprefix {\bibn... l.10    I have no idea how to solve this issue? Have I missed something? Thank you for your help!


Please let us keep the reason for community-deleted posts

I just noticed this (on , but seemingly applying to all Community-deleted posts):    This is awesome, and I'm concerned that it's an oversight and is meant only to be enabled for developers.  If it was an oversight... can we please keep it? Humanizing the deletion reasons would be great, but even in its current form I want it to stay.


I have a HashMap<Object, Student> where the Object is the ID of the Student, and the Student is an object from Student.  How can I resort the HashMap by the Students name, student->getName()?


Is “Paul’s and my ideas” *really* the correct possessive?

Do you always have to put other people before yourself?  When you are telling a story about yourself and another person, it is correct to reference the other person first.  For example,     Tim and I went shopping.     Given that rule, then is this also the case in the following type of sentence, where you’re forming a possessive of two people, one of whom is you yourself:     Please see attached Paul's and my ideas on this subject.   This doesn't look at all right to me, but aside from rearranging the whole sentence I can't see how to make it right. Can I write:     Please see attached myself/my/mine and Paul's ideas on this subject.   or does that go against the whole rule about putting the other person first?  I know I can make the sentence work by changing it around but I would like to know if there is a rule for this type of sentence.


Minimum of two random variables with exponential distribution

Let $X,Y$ be two random variables with exponential distribution and their rates are $\gamma, \beta $. Let $Z$ be a random variable such that $Z = min\{X, Y\}$.  How do I prove that the density function of $Z$ is $(\gamma+\beta)e^{-(\gamma+\beta)x}$ for $x\geq0$ and $0$ for $x<0$?


What’s wrong with this way of fitting time-dependent coefficients in a Cox regression?

I have a Cox proportional hazards model. Judging by Schoenfeld residual vs. time plots and corresponding tests for zero slope, there is clear violation of the PH assumption for several of the variables (too many to stratify).   If we take the single-covariate case for simplicity, the original model looks like:  $$ \hat\lambda(t) = \lambda_0(t)*\exp(X_1\hat\beta_{X_1}) $$  Given the violation of the PH assumption, I want to try fitting time-dependent coefficients for the problem variables. It seems intuitive to fit this:  $$ \hat\lambda(t) = \lambda_0(t)*\exp(X_1\hat\beta_{X_1}+X_1t*\hat\beta_{X_1t}) $$  which simplifies to  $$ \hat\lambda(t) = \lambda_0(t)*\exp(X_1(\hat\beta_{X_1}+t*\hat\beta_{X_1t})) $$  So, effectively, this would parametrically fit a coefficient $\hat\beta^\prime_{X_1}$ that is a linear function of time: $$ \hat\beta^\prime_{X_1} = \hat\beta_{X_1}+t*\hat\beta_{X_1t} $$  Before I could happily dance off into the sunset with this model, I learned it's invalid ( and ). But WHY is it invalid? Why do we have to construct a dataset with start-stop times instead?


This is first of my few questions coming up on cameras. I cannot ask all in one question as they relate to different topics.   My first question:     What is Aperture in Camera?   Why Having a bigger aperture makes images blurred?  Can anyone clear my question? I read it on some blogs and wiki, but they are all to confusing to me. It is too complicated on Wiki for me to understand it.


There are a lot of questions asking what happens if you change the current, but keeping the same voltage. If more current is flowing to me it means you can damage the device. But what if it is the other way around? What happens if you increase the voltage, but have the same current?  Let's say I power on a device with an adapter that outputs 5 volts @ 2 amperes. If I would like to connect that same device to an adapter that outputs 20 volts @ 2 amperes, will I burn it? I think you burn a device by passing too much current, no? Could increasing the voltage also burn it if you are passing the same current?


Fibonacci sequence: Prove the formula $f_{2n+1}=f_{n+1}^2 + f_n^2$

I can't seem to figure out this proof. I'm using weak induction and always get stuck during the inductive step.  Prove for n > 0:  $$f_{2n+1} = f_{n+1}^2 + f_n^2$$


How does a bowl of hot water move by itself?

I think everyone should have seen a bowl of hot water moving by itself on a flat surface such as glass(seems like it is moving by itself but maybe there are some external force applied to it when it moves). What is the explanation of this phenomenon?  Hypotheses :   Since the bowl is heavy, for it to move the friction between the bowl and the surface must be very very low. I have heard that water may form a thin layer between the bowl and the surface, but l'm not sure whether it is the case or not. I think the bowl can move by itself because heat makes the air below the bowl expand.   Edit : I will re-experiment those again and update the question in few days. Maybe I will take a video clip too. and I am not talking about a magic trick whatsoever.


Why is my JPanel Background image not displaying?

I am trying to add a background image to a Jpanel. Below is the code I'm using      private void createUIComponents() {         JPanel panel1 = new BgPanel();     }      class BgPanel extends JPanel {         Image bg = new ImageIcon("image.png").getImage();         @Override         public void paintComponent(Graphics g) {             g.drawImage(bg, 0, 0, getWidth(), getHeight(), this);         } }   I am using IntelliJ so most of the GUI code is hidden. Shouldn't the custom created JPanel be a BgPanel and therefore display the image? Where have I gone wrong?  I am getting the following when trying to compile:  Exception in thread "main" java.lang.NullPointerException     at testGUI.$$$setupUI$$$(testGUI.java)     at testGUI.<init>(testGUI.java:4)     at testGUI.main(testGUI.java:11)   Full Code:  import javax.swing.*; import java.awt.*;  public class testGUI {     private JButton button1;     private JPanel panel1;      public static void main(String[] args) {         JFrame frame = new JFrame("testGUI");         frame.setContentPane(new testGUI().panel1);         frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);         frame.pack();         frame.setVisible(true);     }      private void createUIComponents() {         JPanel panel1 = new BgPanel();     }      class BgPanel extends JPanel {         Image bg = new ImageIcon("imagelink.png").getImage();          @Override         public void paintComponent(Graphics g) {             g.drawImage(bg, 0, 0, getWidth(), getHeight(), this);         }     } }


I am from India and learning blender from few weeks.  When I render demo file bmw27 it takes 22 minutes with CPU and 11 minutes with GPU (gtx 750ti). Default settings.  I see some video on YouTube same GPU and same file within 2 minutes.  I want to know that this time is ok or there is problem.  My pc is  I5 3330 H77m-d3h (gigabyte) 8gb ddr3 ram Gtx MSI 750ti 2 GB ddr5  Windows 7 64 bit


Entire function f which satisfy $|f(z)| \leq |\exp(z)|$

Can someone confirm whether or not my solution to the following question is okay? Or if I'm missing something  Question: Let f be an entire function satisfying: $|f(z)| \leq |\exp(z)| ,\: \forall z \in \mathbb{C}$. Show that there exist a $c \in \mathbb{C}$ such that $|c|\leq 1$ and $f(z) = c \cdot \exp(z), \: \forall z \in \mathbb{C}$.  Solution: Note that $\exp(z) ≠ 0, \: \forall z \in \mathbb{C}$. Hence the function $\dfrac{f(z)}{\exp(z)}$ is an entire function, with $\dfrac{|f(z)|}{|\exp(z)|} \leq 1$. Since it is bounded it must be constant and therefore $f(z) = c \exp(z)$ for some $c \in \mathbb{C}$. It is then seen that $\dfrac{|c \cdot \exp(z)|}{|\exp(z)|} \leq 1 \Leftrightarrow |c| \leq 1$  Thanks


If statement using == gives unexpected result

private void refineWords() {     for(String word : words){         Log.i("word", word);         if (word == "s" || word == "t" || word == "am" || word == "is" || word == "are" || word == "was" || word == "were" || word == "has" ||              word == "have" || word == "been" || word == "will" || word == "be" || word == "would" || word == "should" || word == "shall" ||              word == "must" || word == "can" || word == "could" || word == "the" || word == "as" || word == "it" || word == "they" ||             word == "their" || word == "he" || word == "she" || word == "his" || word == "her" || word == "him" || word == "its" ||             word == "in" || word == "on" || word == "a" || word == "at") {              Log.i("step", "step Success!!");             words.remove(word);         }     } }   I have a List called "words" and it contains strings. Here the Log.i works for the "word" tag fine but the "step" Statement does not executes. Seems the If condition does not work well. like this method never goes into it although the "words" list contains similar strings. What would be the problem. pleas help..


Tools to measure the nonrandomness of databases

I was working on historical data looking for anomalous patterns that we would not expect to occur at random. I'd like to create a scheme to analyze data and markets to test for statistical significance and consistency over time.  Question : Are there some tools we could use to evaluate the nonrandomness of a database? What do we use usually to say that something is random or not (statistically)? Figure we work with change in some value over time.  Question : Does the Benford's law could answer in part this question?


Why does cancellation of dots $\frac{\partial \dot{\mathbf{r}}_i}{\partial \dot{q}_j} = \frac{\partial \mathbf{r}_i}{\partial q_j}$ work?

Why is the following equation true? $$\frac{\partial \mathbf{v}_i}{\partial \dot{q}_j} = \frac{\partial \mathbf{r}_i}{\partial q_j}$$ where $\mathbf{v}_i$ is velocity, $\mathbf{r}_i$ is the displacement, and $q_j$ is the generalized coordinate into which $\mathbf{r}_i$ is transformed. In reading further, I find that it's related to $$ \mathbf{v}_i \equiv \frac{\mathrm{d}\mathbf{r}_i}{\mathrm{d}t} = \sum_k \frac{\partial \mathbf{r}_i}{\partial q_k}\dot{q}_k + \frac{\partial \mathbf{r}_i}{\partial t} $$ I know that in transforming the virtual displacement $\delta\mathbf{r}_i$ into generalized coordinates, I can use $$ \delta\mathbf{r}_i = \sum_k \frac{\partial\mathbf{r}_i}{\partial q_k}\dot{q}_k $$ The first equation above is of course equivalent to $$\frac{\partial \dot{\mathbf{r}}_i}{\partial \dot{q}_j} = \frac{\partial \mathbf{r}_i}{\partial q_j}$$ I'm not sure why the dots vanish just like that. How do these all connect? In a non-mathematical explanation, I can understand that as $q_j$ changes, $\mathbf{r}_i$ changes as well. In the same way, as $\dot{q}_j$ changes, $\mathbf{v}_i$ changes, too. I'd like to know, mathematically, how these changes (for $\mathbf{r}_i$ and $\mathbf{v}_i$) turn out to be equal.


Intuition of Distance covered when accelerating

When you're moving at $5$ m/s for $1$ second, you have traveled $5$ m.  When you're moving at $5$ m/s (initial velocity) and you accelerate $2$ m/s for $1$ second, you have traveled $5$ m + $1$ m (distance traveled because of acceleration).   But does this hold true in real life? If I was to test this out, would the distance traveled because of acceleration equal $1$ m?


Why can't I buy the Windhelm house (Hjerim)?

I've finished the Stormcloak storyline, and now cannot become a Thane of Windhelm without buying Hjerim. The Steward keeps saying something has happened and he can't sell it right now.  What the heck am I missing? I've been doing every random little quest from people in town I can find, hoping to unlock the house. I'm well over the 5/5 requirement of helping people.  Any ideas?


I have following class structure  public class OfferModelCollection {     List<OfferModel> offers = new List<OfferModel>(); }  public class OfferModel {      public int ID { get; set; }      public ProviderModel Provider { get; set; }      public ProviderType ProviderType { get; set; }   //Enum  }  public class ProviderModel : BaseModel, IIdentity {      public string ProviderCode { get; set; }      public string ProviderName { get; set; }    }   I am now trying to update ProviderType of those offers whose Provider.ProviderCode matches to some string value. How can I achieve it in LINQ?  Something like this:  offersVM.Offers.Where(x=>x.Provider.ProviderCode.Contains("p10"))).ProviderType = ProviderType.Default;


Why can't the entropy of an isolated system decrease?

I read that heat cannot flow from cooler body to hotter because for that entropy of the system becomes negative. Why is that so? Why we cannot have negative entropy?


Using capital case on every word of a title

I have to write a post for my college website and it is the format of a "listicle". An introduction followed by short paragraphs with each paragraph getting a heading. My question is regarding these headings and the article title.  I am doing research on the listicle format and I see most have titles where every word is in the capital case. Even are headlines through the articles are given the same treatment.  For example,   20 Crushes Who Made Your Heart Soar In 2018 Who Said It: Harry, Ron, Or Hermione? Choose Your Dream Wedding And We'll Reveal How You'll Meet Your Soulmate Eat A Ton Of Food At A Buffet And We'll Tell You Which Disney Channel Star You Actually Are   Why is this done and more importantly is this correct?


How much money I need to show while entering the US for a one week trip?

I'm planning to enter the United States for vacation. My nationality is Indian but I'm a graduate student in Europe and I'm planning to travel to Boston, NYC and NJ for a total of 7 days. I've already pre-booked my flights and my airbnb but I came to know that you have to inform the CBP officer at the port of entry about the amount of money you're carrying with you.   I'm taking around 550 in cash with me and I will also carry my bank card which will give me access to another 200-300 dollars for my stay. Since I do not plan to do any shopping, I was wondering if this will be enough to convince the CBP officer that I do not wish to abuse or violate my visa terms? Or should I carry even more money?   I am really not sure if there is a specific amount that they're looking for.


Every surjective function has a right inverse

I am studying the counterpart of the axiom of choice in ETCS which is that "Every surjective fucntion has a right inverse". I am trying to see why it implies the axiom of choice and this is the paragraph i am studying at the moment. Let  $f: X \rightarrow Y$ be the surjective function and $g: Y \rightarrow X$ be the right inverse. Noticing that a surjective function represents a non empty set  of a disjoint non empty set and that disjoint sets are  $f^{-1}(y)$ for each $y$ in $Y$. Then $g: Y \rightarrow X$ is a choice for every $y$ in $Y$ as $g$ picks out one element of $f^{-1}(y)$. Therefore, the existence of $g$ is equivalent to the axiom of choice. I can't make sense of the "$g: Y \rightarrow X$ is a choice for every $y$ in $Y$ as $g$ picks out one element of $f^{-1}(y)$". I studied the definition of the axiom of choice as "given a non empty set $A$,  it is possible to choose an element from each subset $a$ in set $A$" I would greatly appreciate any help with this.


Programmatically add a taxonomy term as entity reference in a custom entity

I'm really struggling to add a taxonomy_term as an entity reference to a custom entity I've created programmatically.  Here is my configuration based on BaseFieldDefinition (the name of the vocabulary is "specialite":  $fields['speciality_field'] = BaseFieldDefinition::create('entity_reference')   ->setLabel(t('speciality'))   ->setRevisionable(TRUE)   ->setSetting('target_type', 'taxonomy_term')   >setSetting('handler_settings', ['target_bundles' => ['specialite' => 'specialite']])   ->setSetting('handler', 'default')   ->setTranslatable(TRUE)   ->setDisplayOptions('view', array(     'label' => 'hidden',     'type' => 'author',     'weight' => 0,   ))   ->setDisplayOptions('form', array(     'type' => 'entity_reference_autocomplete',     'weight' => 5,     'settings' => array(       'match_operator' => 'CONTAINS',       'size' => '10',       'autocomplete_type' => 'tags',       'placeholder' => '',     ),   ))   ->setDisplayConfigurable('form', TRUE)   ->setDisplayConfigurable('view', TRUE);   This piece of code doesn't work, would you please help to find what I am missing, or redirect me to a good documentation explaining different values for handler_settings  Thank you so much.


If $f(x)$ is continuous and differentiable function , prove that $f(x) \geq e^{3x}, \forall x \geq 0$

$f(x)$ is continuous and differentiable function defined in $x \geq 0$. If $f(0)=1$ and $f'(x) >3 f(x)$, then prove that $$f(x) \geq  e^{3x}, \forall x \geq 0$$  Could someone give me little hint as how to proceed in this question? I am not able to initiate.


Who vs whom in "Who is the right person to turn to?

Take the sentence:     Who is the right person to turn to?   I'm not sure whether who or whom should be used in this position.


Differentiation of $x^{2}$ by writing it as $ x \: + \: x \: + \: ... \: + \: ... \: + \: x \: \: (\text{as many as x}) $ gives paradox $2=1$

Regards. I would like to pour out something that I found on Youtube, and test my view on this.  $$ f(x) = x^{2} $$     $$ f'(x) = 2x $$   $$ x^{2} = \: x \: + \: x \: + \: ... \: + \: ... \: + \: x \: \: (\text{as many as x})$$     $$ \frac{d(x^{2})}{dx} = \: 1  \: + \: 1 \: + \: .... \: + \: 1 \: = 1 \cdot x  $$   So we get from the results above : $$ 2 = 1 \: \: (??) $$  But in another way   $$ x^{2} = x \cdot x $$     $$  \frac{d(x^{2})}{dx}  = (1 \cdot x) + (x \cdot 1) = 2x $$   This refers to the video :    The mistake in the 2nd paradox in the video is clear, but for the 1st one .. some insightful thoughts?  My argument is that the 'summation'  $$ x \: + \: x \: + \: ... \: + \: ... \: + \: x \: \: (\text{as many as x}) $$ may not be seen as a function of $x$. But also because this only holds when $x$ is a positive integer, and we count the limit as below   \begin{align*} \frac{d(x^{2})}{dx}  &=  \lim \frac{(x + \triangle x)^{2} - (x)^{2}}{\triangle x} \\ &= \lim \frac{(x^{2} + 2 x \triangle x + \triangle x^{2}) - (x)^{2} }{\triangle x}  \\ &= \lim \frac{(x + x) \triangle x + \triangle x^{2}  }{\triangle x}  = (x+x) = 2x  \end{align*}  Thanks, all the best.


sql server stored procedure - collection of data for fields as input

I have a stored procedure to add a collection of values to a field in table. How I implement it now: from my .net app, I create a string of comma separated values from an array( eg: resource1, recource2, resoource3...). This string is then send to stored procedure, where it is split and each value is inserted into a table. my code below ALTER PROCEDURE  [dbo].[resourcetrackerupdate] @resources varchar(max)  as begin  SET NOCOUNT ON;   DECLARE @MyCursor CURSOR; DECLARE @ReourceName varchar(max); BEGIN     SET @MyCursor = CURSOR FOR     select [name]  from dbo.splitstring(@resources)      OPEN @MyCursor      FETCH NEXT FROM @MyCursor      INTO @ResourceName      WHILE @@FETCH_STATUS = 0     BEGIN               BEGIN TRY                 INSERT INTO resourcetracker ([ResourceName]) VALUES (@ResourceName)              END TRY             BEGIN CATCH                   END CATCH        FETCH NEXT FROM @MyCursor        INTO @ResourceName     END;       CLOSE @MyCursor ;     DEALLOCATE @MyCursor; END;  Now, my requirement is that I need to send multiple field data (as opposed to just one - resourcename - now). So , I will need to send resourcename, resourcesize, assignedto etc to stored procedure to insert into the table as new records. FYI, these arrays are size of few thousands records. The long comma separated string approach might not work anymore. How can I change my stored procedure to process all that data?


Find $\lim_\limits{x\to 1^-}{\ln x\cdot \ln(1-x)}$. I can't even start because I don't really know what $x\to 1^-$ means. If you know what it means it would really help me. I would as well if you helped me with finding the limit, hinted or thorough.


I have webservice which is passed an array of ints. I'd like to do the select statement as follows but keep getting errors. Do I need to change the array to a string?  [WebMethod] public MiniEvent[] getAdminEvents(int buildingID, DateTime startDate) {         command.CommandText = @"SELECT id,                             startDateTime, endDateTime From                             tb_bookings WHERE buildingID IN                             (@buildingIDs) AND startDateTime <=                             @fromDate";      SqlParameter buildID = new SqlParameter("@buildingIDs", buildingIDs); }


I would like to restore LightDM to its default state, because for some reason /etc/lightdm/unity-greeter.conf is now an empty file.  Deleting /etc/lightdm/unity-greeter.conf and then running sudo apt-get install --reinstall unity-greeter doesn't create a new config file as you might expect.   How can I restore a missing config file?


Review of Low Quality answers offers unsatisfactory choices of actions

According to , answers that are earnest attempts at an explanation, but that are technically incorrect, should be downvoted but not deleted.  However, the Low Quality review queue does not offer an easy way to do the right thing:     "Looks OK" is inappropriate: "nothing is wrong" doesn't apply to a wrong answer. "Edit" is inappropriate: Any edit that corrects the answer would also radically alter the meaning of the post. "Recommend Deletion" is inappropriate since it is an earnest but misguided attempt at an answer. "Skip" is, unfortunately, the only way to clear this item from the queue.  However, skipping items isn't letting the reviewer be helpful.   Therefore, the Low Quality review queue needs to offer better choices of actions.


Upgrading to Ubuntu 18.04 on a dual bootable OS: Ubuntu 17.10 and Windows 10

I'm currently using dual boot Windows 10 + Ubuntu 17.10. I wanted to upgrade Ubuntu 17.10 to 18.04 stable release. By doing so I don't want to harm anything and end up with nothing. I've created live CD for that. Live CD is the only source to upgrade system.