How to get Nvidia graphics working on Sony Z laptop?

I have an older Sony VAIO Z 590 laptop with switchable graphics between Intel and Nvidia GeForce 9300M. It is NOT Optimus. I did a clean install of Ubuntu 12.04. Everything works, but it's using Unity 2D with the Intel drivers. I've tried loading the Nvidia drivers from "Additional Drivers", but it says "this driver is activated but not currently in use".   When I run "nvidia-settings", an error window pops up to say "You do not appear to be using the NVIDIA X drivers." "lspci" shows both graphics cards. Let me know if I should add more info.  How do I get the Nvidia graphics and Unity 3D working?   More info:  $ lshw -short -class display  H/W path       Device  Class       Description ==============================================  /0/100/1/0             display     G98 [GeForce 9300M GS]  /0/100/2             display     Mobile 4 Series Chipset Integrated Graphics C  $ glxinfo name of display: :0 Xlib:  extension "GLX" missing on display ":0". Xlib:  extension "GLX" missing on display ":0". Xlib:  extension "GLX" missing on display ":0". Xlib:  extension "GLX" missing on display ":0". Xlib:  extension "GLX" missing on display ":0". Error: couldn't find RGB GLX visual or fbconfig  Xlib:  extension "GLX" missing on display ":0". Xlib:  extension "GLX" missing on display ":0". Xlib:  extension "GLX" missing on display ":0". Xlib:  extension "GLX" missing on display ":0". Xlib:  extension "GLX" missing on display ":0". Xlib:  extension "GLX" missing on display ":0". Xlib:  extension "GLX" missing on display ":0".   Excerpts from :  [    16.373] (II) LoadModule: "glx" [    16.373] (II) Loading /usr/lib/x86_64-linux-gnu/xorg/extra-modules/libglx.so [    16.386] (II) Module glx: vendor="NVIDIA Corporation" [    16.386]    compiled for 4.0.2, module version = 1.0.0 [    16.386]    Module class: X.Org Server Extension [    16.386] (II) NVIDIA GLX Module  295.49  Tue May  1 00:09:10 PDT 2012  [    16.608] (II) NVIDIA dlloader X Driver  295.49  Mon Apr 30 23:48:24 PDT 2012 [    16.608] (II) NVIDIA Unified Driver for all Supported NVIDIA GPUs  [    17.693] (EE) Failed to initialize GLX extension (Compatible NVIDIA X driver not found)


Using the Squeeze Theorem on $\lim_{x\to 0}\frac{\sin^2x}{x^2}$

$$\lim_{x\to 0}\frac{\sin^2x}{x^2}$$  I'm trying to evaluate this limit using Squeeze Theorem. However, looking at the graph I know it approaches $1$, but I am getting $0$ using the Squeeze Theorem.  $$-\frac{1}{x^2} < \frac{\sin^2x}{x^2} < \frac{1}{x^2}$$  when I sub in $0$ it's just $0$. What am I doing wrong?  Edit: Wait, it's not zero! The upper and lower bounds are indeterminate. So I can't use squeeze theorem, correct?


Cannot find Gnome-shell.css default file

Where can i find a vanilla version of that file, i find it really odd that in dosent come up when you search it on google and such  The link in the answer for a similar question does not exist ("")


Is there any difference between GROUP BY and DISTINCT

I learned something simple about SQL the other day:  SELECT c FROM myTbl GROUP BY C   Has the same result as:  SELECT DISTINCT C FROM myTbl   What I am curious of, is there anything different in the way an SQL engine processes the command, or are they truly the same thing?    I personally prefer the distinct syntax, but I am sure it's more out of habit than anything else.  EDIT: This is not a question about aggregates. The use of GROUP BY with aggregate functions is understood.


Magnetic field due to a charge having uniform velocity

Faraday's law states that "Any change in electric field induces a magnetic field and vice versa". I don't see exactly where these fields are induced, but I assume that these fields are induced at each and every point in space.  Now, let us consider a charge Q, moving with a uniform Velocity V. Obviously this movement of the charge creates a change in the electric field everywhere. As such it should induce a magnetic field.  Subsequently, this change in the magnetic field should also bring about an electric field, an induced one, owing to further changes induced in the magnetic field.   Apparently this machinery seems to be similar to an EM radiation. But we know that an EM radiation can only be produced by charges in accelerated movement. Why this chain of events can't be seen as an EM wave propagation?


Best Method to Format Currency in Python

I'm trying to figure out the best/easiest method to format number into currency in python.  If the number is negative I want the minus sign to be before the dollar sign (ex.  -$123,323). Otherwise the number should appear in this form  (ex $123,323,323). Is there a built in python method to do this?


When calling abstract method from concrete class throwing NullPointerException

I am testing a method in a class. Which is calling a method of abstract class.  Eg:  class abstract Abstract {   public ReturnObject abstractMethod(SomeObject value) {     // do something     return returnObject;   } }  class Concreate extends Abstract {    public ReturnObject concreteMethod(SomeObject value) {    //do something    returnObject = abstractMethod(value);    return returnObject;    }  }  My UT is   class ConcreateTest {   @InjectMocks   private Concreate conctrete;    @Mock   private Concreate conctrete2;    @Test   public void test_method() {      when(conctrete2.abstractMethod(value)).thenReturn(returnObject);      conctrete.concreteMethod(value);   }  }   This way it is returning me NullPointerException.


How do I stop the screensaver from turning on when watching videos online?

My screenlock is set to five minutes. So while playing YouTube videos after five minutes the screen locks even though the video is playing. Any solutions?


How to implement a prepared statement into mysql query

I'm currently using the following query to insert data into a table $query = mysqli_query($connection, "SELECT * FROM booked_activities INNER JOIN activities ON booked_activities.activityID = activities.activityID WHERE booked_activities.customerID LIKE $_SESSION['customerID']"); I've been instructed to use prepare statements for the $_SESSION['customerID']. Does this mean by just naming $_SESSION['customerID'] = $db_id? Or do I need to do something else to protect the data.


Is there a way to specify style for part of a path in tikz?

When I need a partially dashed path as below     I have to write two \draw commands:  \documentclass{minimal} \usepackage{tikz} \begin{document}     \begin{tikzpicture}         \draw (0,0)--(1,1);         \draw[dashed] (1,1)--(1,2);     \end{tikzpicture} \end{document}   That is basically OK, but can the job be finished in a single \draw command?  I have tried  %\draw (0,0)--(1,1)[dashed]--(1,2);   % dashes both segments %\draw (0,0)--(1,1){[dashed]--(1,2)}; % no effect %\draw (0,0)--(1,1){[dashed]--}(1,2); % fails   but they either fail or do not work as desired.


Does newer card text on a Magic: The Gathering card override the old wording?

While going through the Gatherer database I noticed that the Alpha version of  says,     {1}: You may tap any land, creature, or artifact in play on either side.   whereas the Tenth Edition of the  says,     {1}, {T}: Tap target artifact, creature, or land.   This has me wondering, does the newer Tenth Edition card text retroactively apply to the Alpha card or does the Alpha text still apply when that card is in play? In other words, if I were to play the Alpha version, would I play by its rules, or the newer rules on the Tenth Edition card?


How to properly use unit-testing's assertRaises() with NoneType objects?

I did a simple test case:  def setUp(self):    self.testListNone = None  def testListSlicing(self):    self.assertRaises(TypeError, self.testListNone[:1])   and I am expecting test to pass, but I am getting exception:  Traceback (most recent call last):      self.assertRaises(TypeError, self.testListNone[:1])  TypeError: 'NoneType' object is unsubscriptable   I thought that assertRaises will pass since TypeError exception will be raised?


How to grab a my current Salesforce instance in an Apex class and reference it to my VF page

I know this should be a piece of cake but I am not a developer and just started today learning Apex. I have created an Apex class that supposedly grabs my current Salesforce URL instance then passes the variable into my VF page. After grabbing the instance of the URL, I am trying to append the rest of the restOfMyDomain link for the Object. I plan on doing this for multiple objects so once I get the first one down, the rest is set sail.   I have run into the error: Unknown property 'getInstance.link' when I get go to my VF page.  Here is my Apex class:  public Class getInstance {  public String link; public String getLink(String link) {     link = URL.getSalesforceBaseUrl().toExternalForm();     return link; }   }  And here is my VF page code:  <apex:page controller="getInstance">   <apex:variable var="string" value="{!link}"/>   <apex:outputLink value="string + restOfMyDomain" id="groupLink"> Groups - UI</apex:outputLink> </apex:page>


Number of $\alpha\in\Bbb{F}_{27}$ such that $|A_{\alpha}|=26$ equals $12$

Question: Let $\Bbb{F}_{27}$ denote the finite field of size $27$. For each $\alpha\in\Bbb{F}_{27},$ we define $$A_{\alpha}=\{1,1+\alpha,1+\alpha+\alpha^2,1+\alpha+\alpha^2+\alpha^3,\dots\}.$$ Then show that number of $\alpha\in\Bbb{F}_{27}$ such that $|A_{\alpha}|=26$ equals $12$. What I could conclude is, $0\in A_{\alpha}$ if and only if $ \alpha\neq0$. Then I thought that, $|A_{\alpha}|=26$ implies $A_{\alpha}=\Bbb{F}_{27}^*$, but I am not sure. Then some guess what I was making from the fact $\phi(26)=12$, but no progress. Help me with this, because I not getting any clue from the structure of $A_{\alpha}$.


Prove that there is no positive rational number a such that $a^2 = 3$.

I solved a similar question $a^4 = 2$ but I didn't find it hard. This one is taking a lot of my time and I still don't understand how to solve this. Here's what I have tried so far. edit: \begin{align} a^2 &= 3 \\ a &= \left(\frac mn\right) \\  a^2 &= \left(\frac mn\right)^2 = 3 \\ m^2 &= 3n^2 \\ m &= 3p \\ m^2 &= (3p)^2 \\ 9p^2 &= 3n^2 \end{align} In another similar question $a^3 = 2$, I had to divide a common number from each side to finally solve the problem. But with this problem, I don't know how to continue.


Weird colored stripes around windows - Ubuntu 16.04

So recently I noticed that, around the windows, and the right click menu of all applications, there are these weird colored stripes. They disappear after I restart Ubuntu or Unity, but then appear again shortly after.    My laptop used NVIDIA GeForce 960M, and for those who knows, I just started CUDA programming a few weeks ago.  These are the installed packages related to nvidia:  quan@quantran:~$ sudo apt list --installed | grep nvidia  WARNING: apt does not have a stable CLI interface. Use with caution in scripts.  nvidia-367/xenial,now 375.39-0ubuntu0~gpu16.04.2 amd64 [installed] nvidia-367-dev/xenial,now 375.39-0ubuntu0~gpu16.04.2 amd64 [installed,automatic] nvidia-375/xenial,now 375.39-0ubuntu0~gpu16.04.2 amd64 [installed,automatic] nvidia-375-dev/xenial,now 375.39-0ubuntu0~gpu16.04.2 amd64 [installed,automatic] nvidia-cuda-dev/xenial,now 7.5.18-0ubuntu1 amd64 [installed,automatic] nvidia-cuda-doc/xenial,xenial,now 7.5.18-0ubuntu1 all [installed,automatic] nvidia-cuda-gdb/xenial,now 7.5.18-0ubuntu1 amd64 [installed,automatic] nvidia-cuda-toolkit/xenial,now 7.5.18-0ubuntu1 amd64 [installed] nvidia-modprobe/unknown,now 367.48-0ubuntu1 amd64 [installed,automatic] nvidia-opencl-dev/xenial,now 7.5.18-0ubuntu1 amd64 [installed,automatic] nvidia-opencl-icd-367/xenial,now 375.39-0ubuntu0~gpu16.04.2 amd64 [installed,automatic] nvidia-opencl-icd-375/xenial,now 375.39-0ubuntu0~gpu16.04.2 amd64 [installed,automatic] nvidia-prime/xenial,now 0.8.2 amd64 [installed,automatic] nvidia-profiler/xenial,now 7.5.18-0ubuntu1 amd64 [installed,automatic] nvidia-settings/xenial,now 378.09-0ubuntu0~gpu16.04.1 amd64 [installed,automatic] nvidia-visual-profiler/xenial,now 7.5.18-0ubuntu1 amd64 [installed,automatic]   Result of lspci:  quan@quantran:~$ lspci 00:00.0 Host bridge: Intel Corporation Xeon E3-1200 v3/4th Gen Core Processor DRAM Controller (rev 06) 00:01.0 PCI bridge: Intel Corporation Xeon E3-1200 v3/4th Gen Core Processor PCI Express x16 Controller (rev 06) 00:02.0 VGA compatible controller: Intel Corporation 4th Gen Core Processor Integrated Graphics Controller (rev 06) 00:03.0 Audio device: Intel Corporation Xeon E3-1200 v3/4th Gen Core Processor HD Audio Controller (rev 06) 00:14.0 USB controller: Intel Corporation 8 Series/C220 Series Chipset Family USB xHCI (rev 05) 00:16.0 Communication controller: Intel Corporation 8 Series/C220 Series Chipset Family MEI Controller #1 (rev 04) 00:1a.0 USB controller: Intel Corporation 8 Series/C220 Series Chipset Family USB EHCI #2 (rev 05) 00:1b.0 Audio device: Intel Corporation 8 Series/C220 Series Chipset High Definition Audio Controller (rev 05) 00:1c.0 PCI bridge: Intel Corporation 8 Series/C220 Series Chipset Family PCI Express Root Port #1 (rev d5) 00:1c.1 PCI bridge: Intel Corporation 8 Series/C220 Series Chipset Family PCI Express Root Port #2 (rev d5) 00:1c.2 PCI bridge: Intel Corporation 8 Series/C220 Series Chipset Family PCI Express Root Port #3 (rev d5) 00:1c.3 PCI bridge: Intel Corporation 8 Series/C220 Series Chipset Family PCI Express Root Port #4 (rev d5) 00:1d.0 USB controller: Intel Corporation 8 Series/C220 Series Chipset Family USB EHCI #1 (rev 05) 00:1f.0 ISA bridge: Intel Corporation HM86 Express LPC Controller (rev 05) 00:1f.2 SATA controller: Intel Corporation 8 Series/C220 Series Chipset Family 6-port SATA Controller 1 [AHCI mode] (rev 05) 00:1f.3 SMBus: Intel Corporation 8 Series/C220 Series Chipset Family SMBus Controller (rev 05) 01:00.0 3D controller: NVIDIA Corporation GM107M [GeForce GTX 960M] (rev a2) 04:00.0 Network controller: Intel Corporation Wireless 7260 (rev bb) 05:00.0 Unassigned class [ff00]: Realtek Semiconductor Co., Ltd. Device 5287 (rev 01) 05:00.1 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller (rev 12)   Thanks everyone in advance!


"for all ... do in parallel" without "end for"

I am using  approach to have a for all ... do in parallel using the algcompatible package.   \documentclass{article} \usepackage{algorithm} \usepackage{algcompatible}  \algblockdefx{FORALLP}{ENDFAP}[1]%   {\textbf{for all }#1 \textbf{do in parallel}}%   {\textbf{end for}}  \begin{document}  \begin{algorithm} \caption{A test algorithm} \begin{algorithmic}[1] \FORALL {$v \in V(G)$} \STATE $l(v) \leftarrow \infty$ \ENDFOR \FORALLP{$v \in V(G)$} \STATE $l(v) \leftarrow \infty$ \ENDFAP \end{algorithmic} \end{algorithm}  \end{document}   How can I  get rid of the end for at the end of the block?


How far back can German Genealogy normally be traced?

I've been researching my family history, and I hit a roadblock. The oldest records I can find are from German church records in the early eighteenth century. I can find nothing older. Is this a reasonable amount for German ancestry?


We were taught in school that gerund comes after 'for', while infinitive follows 'to'.   However, I came across this sentence :"Thank you for devoting your time to reading my letter"  Whatever research I try to do on the subject, the only results I get are 'ways to thank people for their time' and 'how to write formal letters' , but it's the given grammar structure i'm interested in.   So can you please help out?   Thank you so much! :)


How is it that the estimated duration of a SYD-SCL flight (7060 miles) on a 747-400 (cruise speed Mach 0.85) is 12:40, but SCL-AKL flight (6011 miles) on a 787-8 (same cruise speed) takes 13:20.  My first thought was perhaps wind direction. So I ran a quick calculation assuming SYD-SCL always has a 10m/s tail wind, and SCL-AKL has a 10m/s head wind. The numbers come out as:  7060 miles / (252.1m/s + 10m/s) = 12:02 6011 miles / (252.1m/s - 10m/s) = 11:06   So it's probably not wind, so why does it take longer for a 1000 mile shorter flight?


Can I use an altered art card in tournament?

I have investigated a lot but I'm still not sure if I can use an altered art card in a tournament. I know that the golden rule is: The head judge will determine if the altered card is legal or not. But I don't want to paint my card if it will obviously be rejected.  To be more specific I want to make a border extension of my commander. The tournaments in which I am interested are mainly FNM and local shop little tournaments.  If someone doesn't know what border extension is, here is an example:    Here, Iona, Skithiryx and Thundermaw Hellkite have a pure border extension with no further modifications.  I have read  in this site but it doesn't clarify if this can be done or not because for one side it says:     If the card is legal then the card has black or white borders   and then it says:     Artistic modifications are acceptable in sanctioned tournaments, provided that the modifications do not make the card art unrecognizable, contain substantial strategic advice, or contain offensive images. Artistic modifications also may not obstruct or change the mana cost or name of the card.   Moreover I've read that if I use sleeves the card is most likely to be accepted by the judge. Considering that Commander is a more casual format and the commander(or general) almost never go into the deck I would like some help to decide if I do this art extension or not.  Maybe one judge can point me in the right direction.


Prove that for every $x,y\in\mathbb{R},$   $$\dfrac{|x+y|}{1+|x+y|}\le\frac{|x|}{1+|x|}+ \frac{|y|}{1+|y|}.$$   I really don't know how to start. I thought to dividing it into 4 parts when $(x<0) \land (y>0)$, $(x>0)\land (y<0)$, $(x>0)\land (y>0)$, $(x<0)\land (y<0)$ but I didn't get much from this.


What should the standard spelling be - British or US?

I just saw someone edit the title of  question to  the spelling from favourite (The British spelling) to favorite (The US-English spelling).  Does SOFU have an accepted standard on language and spelling? Which is it?


Why are sperm cells not attacked by the female immune system?

Whenever a foreign particle enters into someone's body, it is attacked by the white blood cells. I just want how it is that, when sperms enter the female body, they are not attacked by the the woman's immune system?


How can we avoid big money in casual games?

My girlfriend and I have recently discovered the Big Money strategy in Dominion, and it's killing the game for us. We're not very competitive, so we don't want to spend a lot of time and effort trying to play even better than Big Money (as the answers to  propose). But Big Money is so easy that it's hard to not just play it, and then we lose all the fun of the kingdom cards.  Are there any house rules we could add to simply keep us from being able to play Big Money, so that we can go back to casual games with plenty of kingdom card excitement? I know that if we really wanted to we could learn to play better than Big Money, but the games wouldn't be as fun and easygoing.  We also have almost all the Dominion expansions so we can use them.


I don't want any answer saying that there's no need, please!


using outside smtp to deliver cron generated emails

I want to deliver cron generated emails to my id, abc@example.com instead of being saved on /var/spool/clientqueue  I've done the following:  echo "set smtp=smtp.example.com" > /root/.mailrc echo "set from=abc@exmaple.com" >> /root/.mailrc  but nothing happen.   Any help ??  No I don't want to run MTA on my machine. I want to using external smtp instead of running a smtp on my machine. this is what i want.  I don't want to use postfix or sendmail. I want to use a smtp server as normally we use smtp in outlook express as outgoing server. Same like that i want to use an external smtp for cron.  I want to deliver emails on behalf of other MTA which would be use as smtp for all of the emails delivery.


Did Gandalf have a teacher/mentor?   If yes, who was his teacher/mentor? If no, from where did he get his knowledge? How did he became so wise?   This question doesn't ask if he had a teacher to learn to become a wizard, though that may be implied. Gandalf is knowledgeable in things beyond just magic. Even a mentor may be considered a teacher, even if he is not taught about magic in specific.


How much time would it take for a black hole size of a proton to suck up a pen?

Suppose a black hole size of a proton appeared.Would it take it a lot of time to suck up a pen and eventually earth? What formulae should i use to calculate that?


Why isn't my EC2 Instance online after reboot?

I rebooted my Amazon EC2 Linux Instance today, though Amazon's AWS website.  Now if I go to my website Safari says it can't find the server, AWS says my IP has stayed the same.  What is wrong here?  My website is  and my IP is 54.213.219.247  Thanks for your effort!


How to end do while loop with user input with if statement

import java.util.Scanner; public class main {      public static void main(String[] args) {     boolean a = true;          do {                 Scanner input = new Scanner(System.in);                 System.out.println("Press any on keyboard:");                 String keys = input.nextLine();                 System.out.println("You pressed:");                 System.out.println(keys);                 System.out.println("Your hash is:");                 String B = "#B";                 String hash = B+keys;                 System.out.println(hash);                 System.out.println("To end loop press f");                 //End Loop                 Scanner exit = new Scanner(System.in);                 String end = exit.nextLine();                 if (end=="f") {                     a=false;                     }             }                while(a);     }            }   I've been using python and I decided to start learning java since android studio requires it. I'm learning how to do loops again. I can't get this to work. I already looked this up I couldn't find it. How would I end this by pressing 'f'? My thought process was that once it was done going though the first lines of the do loop, it would go though the if statement changing the value of a ending the loop.


I'm planning to build a new bike from scratch.  Part of that is buying a new frame, and possibly facing/reaming it. That's actually the part I'm scared of the most.  Fortunately, the brand I'm targeting, Surly, seems to do that in the factory. But as they state, there may be some paint left where it should not be:     Since Surly frames are faced prior to painting, it is possible to   shave the paint off the head tube and BB shell ends with a carpet   knife blade.  This usually results in an acceptable result, saving you   money, but we still recommend having it done the proper way to ensure   longest life from your components.   So what is the "proper way" to remove the extra paint, if the frame is properly reamed/faced already?  Should I choose not to do it the proper way, which components are going to suffer? I suppose at least the headset and bottom bracket, but could the frame suffer as well?


I worked in the US this summer and I received a paper check from tax returns on my address in the US. But I live in Europe now, and I don't have an American debit card.  Can a friend of mine who has the check cash it out for me on his bank account? Or is there another way to get the money to me?


For each positive integer n, let $\gamma_n = 1+\frac12+ \cdots + \frac1n -  \int_1^n \frac1x \, dx$. Prove that the sequence $\{\gamma_n\}$ converges.


Why Data Recovery Block needs to operate at 16 times the baud rate

The data is received on the RXx/DTx pin and drives the data recovery block. The data recovery block is actually a high-speed shifter operating at 16 times the baud rate, whereas the serial Receive Shift Register (RSR) operates at the bit rate.


Feminine form of “son” when used as term of endearment

It seems natural and appropriate for an older man to call a non-relative boy/young man “son” to convey endearment. Although I’m not sure, I think it’s unofficially reserved for men’s use only (the older person is male).  However, if he younger person was female, “daughter” seems awkward.  Is there a analogous term of endearment for young females? If so, it is reserved for older women’s use? Or is “daughter” used?


Why is my python 2D list being created with duplicated rows

I've trying to write code that finds the distances between 3 atoms (code below), where their coordinates are given by the 2D list water_coords, where water_coords[0,:] is the x,y,z coordinates of the first atom, etc. I tried writing the following code where the distance between two atoms would be stored in a 2D array dist (where dist[0][0] is the distance from the 0th atom to the 0th atom, dist[1][0] is the distance from the 0th atom to the first atom, etc.) For some reason whenever I run my code, though, the rows just end up duplicating every loop. I thought it might be a reference / deep copy issue, but using dist[i][j] = copy.deepcopy((x*x + y*y + z*z) ** .5)  Didn't change anything. Any help would be really appreciated!


Would I use who or whom in this scenario?

I know there are numerous examples of who vs whom. But I can't find anything that really makes me feel confident in how to write this.  The sentence is     The two most important are the satisfaction level of the person whom   opened the ticket and the number of days a ticket was open.   I broke it down so I could use the He/She/Him/Her test. What I came up with is      The ticket was opened by her/him.   But that doesn't really match the sentence structure at all and really just rearranges it such that I can make that particular substitution. I could, if I wanted, rearrange it as     She/he opened the ticket.   which also works but still doesn't follow the sentence structure.  I suppose the best way to really clarify it is to say     The two most important are the satisfaction level of the person by whom the ticket was opened and the number of days a ticket was open.   Is that actually the correct way or are they both correct with the latter simply being less cumbersome than the former?


A product is defined for $n\in\mathbb{N},$ as  $$a_n=\left(1-\frac{1}{2^2}\right)\left(1-\frac{1}{3^2}\right)\cdot...\cdot\left(1-\frac{1}{n^2}\right).$$  a) Show that the limit $\lim_{x\rightarrow \infty}a_n$ exists.  b) Compute the limit $\lim_{x\rightarrow \infty}a_n$.    a) For the limit to exist, we have to show that the decreasing sequence is bounded below. We have that $a_n>0$ and  $$\frac{a_{n+1}}{a_n}=\left(1-\frac{1}{n^2}\right)<1\Longleftrightarrow a_{n+1}=a_n\left(1-\frac{1}{n^2}\right)<a_n,$$  This shows that the limit exists.  Is this line of thought correct?  b) Here I'm stuck. I'm not sure what to do next. I tried to express $\ln(a_n)$ as a sum but to no avail.  NOTE: No expansions of any sort is to be used. Only elementary calculus.


Why comment when it's practically a spot-on answer?

Why do people comment when it's a spot-on answer? I often get useful comments like , but wonder why they don't post those as answers. If they post them as answers, I can boost their reps by upvoting and choose "solved" but I can't do that with comments. Is it for readability or something? I don't have to scroll much to see comments, and that's convenient, but are there other reasons why people do this?


What minimal SMTP client will allow me to relay cron output to an external email address?

I would like to have cron output sent to an external email address, via a minimal SMTP client that sends via Gmail. I think I need this client to support TLS and /etc/aliases, and I would like configuration to be as simple as possible.


Calculation of $\sum_{m=1}^{\infty}\sum_{n=1}^{\infty}\frac{m^2n}{3^n\left(m\cdot 3^n+n\cdot 3^m\right)}$

Calculation of $\displaystyle \sum_{m=1}^{\infty}\sum_{n=1}^{\infty}\frac{m^2n}{3^n\left(m\cdot 3^n+n\cdot 3^m\right)}$.  $\bf{My\; Try::}$   Let $\displaystyle S = \sum_{m=1}^{\infty}\sum_{n=1}^{\infty}\frac{m^2n}{3^n\left(m\cdot 3^n+n\cdot 3^m\right)}=\sum_{m=1}^{\infty}\left[\frac{1}{3}\cdot \frac{m^2}{ \left(3m+3^m\right)}+\frac{1}{3^2}\cdot \frac{2m^2}{(3^2m+2\cdot 3^m)}+.........\right]$  Actually I did not understand how can i solve it, Help me  Thanks


How do you avoid network conflict with VPN internal networks?

While there's a wide variety of private non-routable networks across 192.168/16 or even 10/8, sometimes in being thoughtful of potential conflict, it still occurs. For example, I set up an installation OpenVPN once with the internal VPN network on 192.168.27. This was all fine and dandy until a hotel used that subnet for floor 27 on their wifi.  I re-IP'd the VPN network to a 172.16 network, since that seems to be all but unused by hotels and internet café's. But is that an appropriate solution to the problem?  While I mention OpenVPN, I'd love to hear thoughts about this problem on other VPN deployments, including plain ol' IPSEC.


Destruction order of static objects in C++

Can I control the order static objects are being destructed? Is there any way to enforce my desired order? For example to specify in some way that I would like a certain object to be destroyed last, or at least after another static object?


Prove $(1-a)(1-b)(1-c)(1-d)>1-a-b-c-d$ and $ a,b,c,d$ are real and between 0 and 1.    I can do this with $$(1-a)(1-b)>1-a-b  \\ 1-a-b+ab>1-a-b  \\ ab>0  $$  But with $c$ and $d$, this becomes much more difficult. Can someone nudge me in the right direction?


OpenSSL get's the server SSL key instead of the website SSL key

If I navigate to my site, it shows in the browser that my ssl key is correct for my site hosted at WP Engine. It is showing and validating my certificate. However, if I connect with openssl, it get's the underlying servers ssl key.  openssl s_client -connect mysite.com:443  How do I get the SSL command to resolve the ssl key using the domain name instead of the ip address only.  This isn't a WP Engine issue. I have reproduced it on Amazon servers as well.


What's the frequency of filesystem check on boot?

What is the maximum number of times the root filesystem on this computer can be mounted before it is automatically checked?


Sacrificing a creature I control that my opponent owns

If I were to cast  on one of my opponent's creatures then, while that creature is under my control for the turn, I cast  choosing to sacrifice the creature I took from him/her, does that creature go into my graveyard (since I control the permanent), or does it go into my opponent's graveyard?   This happened recently while playing with friends and we just decided to put it in the original owner's graveyard.


Find $\|T\|_{\ell^\infty \rightarrow \ell^2}$

Let $(v_n)_{n \geq 1} \in \ell ^2$ be a fixed bounded sequence of real numbers. Define a mapping $T$ on $\ell^\infty$ using the formula $$T(a_1, a_2,\ldots)=(v_1a_1,v_2a_2,\ldots), \qquad x=(a_1,a_2,\ldots) \in \ell^\infty$$  We can use the fact that, $Tx \in \ell^2 $ for every $x \in \ell^{\infty}$ and $T: (\ell^\infty,\|\cdot \|_\infty) \rightarrow (\ell^2,\|\cdot \|_2)$ is a linear operator and $\|Tx\|_2 \leq \|(v_n)\|_2 \cdot \|x\|_\infty$ for all $x \in \ell^\infty$    $$||T||_{\ell^{\infty} \rightarrow \ell^2}= \sup _{*}||Tx||_{\ell^2}$$  Where $*$ can be $||x||_{\ell^{\infty}}$ $\leq 1$ or $<1$ or $=1$ according to my notes. There is also the infimum definition of it. I don't know which one is best to use but I also have no idea how to evaluate it because of stuff like $||x||_{\ell^{\infty}}$, I have no idea what the subscript would mean because it is a set - not a number (or infinity).


Integrable Functions in Lebesgue Integration

Definition: Let $(X, \mathcal{A}, μ)$ be a measure space. Let $f:X \rightarrow \mathbb{R}$ be a measurable function. We say $f$ is integrable if $$\int_X |f| dμ < +∞. $$ Suppose that $f$ is a non-negative integrable function on a measure space $(X, \mathcal{A}, μ)$. Prove that $$\lim_{t \rightarrow ∞} tμ(\{x \in X: f(x)≥t\})=0.$$ I need its proof by using above definition.


Meta Descriptions not working for google search

I have unique meta descriptions on each of my pages, and when I search my site in google it will come up with no description.  Any idea what I might have done wrong?


Low pass filter cutoff frequency calculation

The cutoff frequency is defined as the frequency where the amplitude of \$H(j\omega)\$ is \$\frac{1}{\sqrt{2}}\$ times the DC amplitude (approximately -3dB, half power point).  I wish to understand why it is \$\frac{1}{\sqrt{2}}\$, and not \$\frac{1}{\sqrt{3}}\$ or some other value. Can we derive the cutoff frequency in any other way?


Can I remote desktop to another user on the same machine?

On my work Mac, which stays physically in my work office, I want to keep my work stuff separate from my personal stuff by using two different user accounts.  I normally stay logged in as the 'work' user.  But I want to have them visible at the same time, since I have a large screen.  I think I could get a nice setup if I could use the built in remote desktop client or a 3rd party VNC client to connect to the login screen of the existing machine, so that I can select a different user.  Or if I could connect as a specific user, even though the physical machine is already logged in as someone else.  I normally use my system with "remote management" mode enabled (not just remote desktop), and I often use a VNC client at home to access my Mac desktop at work.  Although this is not my daily routine.  In this mode the VNC client immediately connects to the existing desktop.  Is there a way I can force this connection to go to the login screen instead?  When I use a VNC client to connect to the existing screen, I can see it trying (you get the kind of infinite regress that you might expect), so the basic connection works.  I just want it to let me select another user.  Edit: I think part of the problem is that the system might be running a VNC server session in the background waiting for me to connect.  It connects to the active session.  It seems to happen either when I have "remote management" turned on or just "screen sharing".  Using an alternate user in an "open" command results in an error about not being able to control your own screen.  To be clear, both accounts are on my work computer.  From home I want to connect to my "work user" on my work computer.  From my desk at work, logged in as my "work user" I want to be able to connect to the "personal user" on my work computer.  I think my real problem is related to what happens on the server side of the connection.  I want the OS to fire up the login window even through there is a user logged in on the main screen/keyboard.   I know that is some circumstances a remote-login user can receive the login screen.  It might be necessary for me to give up the idea of sometimes connecting to the logged-in user and sometimes connecting with a fresh login.  If I can switch completely to the fresh-login mode that would be a start.  How does Mac OS decide whether to show the login-screen for a remote connection versus just connecting you to the running desktop?  I thought it was related to having "remote management" turned on vs "screen sharing".  But with just "screen sharing" turned on, I still get the connect-to-existing behavior.


Singleton Class or Class with only static fields?

what is the better approach?   Let us assume a scenario in which there is a utility class that is used by other classes. What is better to use in this case, a singleton class which can be instantiated exactly once or should i make all the fieds static?


How Can I add an Object so that is not facing the current the view?

I was following a tutorial on blender ( I dont remember which now, as I have watched a lot ). I some how  set up this feature and now I dont know how to turn it off.   Each time I apply an object in to my scene, it applies facing whichever direction my camera is facing. How can I get this back to the default of applying the object in the center?  Thank you in advance.


Is it possible for me to exclude certain sites from my view of Hot Network Questions?

There are some SE sites I am simply not at all interested in, and never will be.   Is it possible for me to filter certain sites from showing up in the Hot Network Questions list, and if not, can this be considered?  Perhaps a setting in the profile?  Also, once I view a certain Hot Question - Can it be prevented from showing up in the future days?


I have download Scrivener Appimage on Ubuntu 20.04 but it not integrate on the menu using Appimage Launcher. What’s the problem? Settings on the launcher or the application? Hope for some help Thanks Josef


A standard way for getting variable name at compile time

Is there some way in C++11 or higher to achieve a similar behavior to:  int some_int; std::string x=variable_name<some_int>::value; //Theoretical code  std::cout << x;   Result should be:      some_int   If not, is there a compiler specific way to do it? I am targeting MSVS.


How do I get a sound played at startup on XFCE4?

My goal is to play a welcome melody each time I log in into the graphical environment (xfce4). I think I can realize it with the sessions-and-startup program and a short script, which starts  vlc from the command line.  However, I am not able to start VLC without its GUI.  I read here here some answers to this problem, but they did not work,  for instance: vlc -I null does not work and vlc --intf dummy does not work either.  My VLC version is 2.2.2


How to apply Gaussian kernel to smooth density of points on 2D (algorithmically)

I have a set of points on a 2D surface and need to build a heatmap. However, I also need to smooth out the density/distribution by applying some sort of kernel (Gaussian kernel, for example).  I Know what Gaussian distribution is, and I have no idea, how mathematically apply the Gaussian kernel to the points on 2D so I can get a smooth distribution or density of points. I know there are functions in Wolfram to do that, but this is more like a research problem, so I need to understand the THEORY of it. Let's say, I am a theory person, and I am NOT in needs of programming. I just need to understand the underlying math of it, why it is still   Can someone, please, explain to me, possibly with an example? Or take me to a website that I can read about it?   I'd much appreciate that.  Thanks


By induction, show that for ∀n∈N, it is true that:

$$\sum_{i=1}^n 2^i=2+2^2+2^3+.....+ 2^n=2(2^{n}-1)$$ Any help/explanations would be REALLY appreciated.  Also in the same vein:  By induction, show that   $$∀n∈\mathbb N: 11^{n+2} + 12^{2n+1}$$ is divisible by $133$.  Thank you so much.


Prove $\sum\limits_{i=0}^n\binom{i+k-1}{k-1}=\binom{n+k}{k}$ (a.k.a. Hockey-Stick Identity)

Let $n$ be a nonnegative integer, and $k$ a positive integer. Could someone explain to me why the identity $$ \sum_{i=0}^n\binom{i+k-1}{k-1}=\binom{n+k}{k} $$ holds?


Client's website is not showing up as expected in Google local searches or maps

I'm working for a client who runs a wellness center. He has a website as well as a Google Places account for the business. The Google Places account has a lot of tags associated with it that are relevant to the offerings from the center, and yet it doesn't show up on Google maps or in the local search results for really obvious searches like "massage [name of city]".   I don't have access to the Google Places account yet, but I'm wondering if there's any way to check to see if there's some obvious problem with how things are set up. I can include the link to the website/Google Places pages. I didn't want to do that right away in case it wasn't allowed.  Thanks in advance for any help!  It doesn't seem to me like this question is a duplicate of the one indicated. In this case there is a Google Places account, but it's not showing up in the local search results or anywhere on the map for anything other than the name of the wellness center itself. If this Google Place account isn't working properly, would it be advisable to create a new one for the same location, re-verify with google, mark the old one for deletion and then hope the new one works better? Are there any obvious configuration issues I should look for that might explain why this center doesn't even show up on the map for a search of "[name of first listed category] [name of city]"? I have worked with Google Places before and never encountered this type of problem.


Are personal information stored in the project file?

How risky is it to share a .blend file?  Does it hold a variable some where with your computer name?  If Blender is installed through Steam does it hold your Steam username as a variable somewhere in your blend files?   I searched around and couldn't find any information about this. If this is the case, how can I remove my personal information from the project file.


In one project, I am trying to adopt marvellous styles for flow maps created by @underdark. At this moment I have the following output  Shapefile was created with the usage of  Plugin. Lines have different directions, i.e. the starting point of first is the ending point of the second and vice versa. So basically the table includes lines with both directions but without any description of those directions.   However, I faced several issues 1. Varying buffers' sizes Buffers around points shall inherit parameters from a different layer, i.e. they are not the same size. How to make them respond to the size of the circles' radiuses? Is there any kind of scaling factor, so to make my buffers "dynamic"? difference(   difference(     $geometry,     buffer(start_point($geometry), 500)   ),   buffer(end_point($geometry), 500) )  Maybe I to apply layer_property() or dbvaluebyid() or represent_value() if I want to extract the dynamic value from a different layer? I know that the buffer values in the expression above only produce appropriate results for line datasets which use a CRS in meters and will have to be adjusted for other units. 2. Proper allocation of arrows I am using an expression for Arrow type > Plain CASE     WHEN x(start_point($geometry)) - x(end_point($geometry)) < 0 THEN 1     ELSE 2 END  but still, I can not properly allocate orange halves of Arrows on the opposite side of blues. 3. The width of the arrows I want to adjust the line width accordingly to the values of a field "FLUX". For that reason, I am using an expression for Arrow width. scale_linear("FLUX",0,10,0.1,3) * CASE WHEN  "FLUX" > 1000 THEN 1 ELSE 0 END  How shall I handle those issues?  My desired output should look like this, curved lines can be ignored.   References:


In the final confrontation between Aang and Ozai. Aang touches Ozai and their bodies become blue and orange color respectively, with blue/orange lasers shooting out of their eyes. Can someone explain this phenomenon ?


Effect of VISA refusal reason quoted on Denmark green card visa application?

One or more Member State(s) consider you to be a threat to public policy, internal security or public health as defined in Article 2(19) of Regulations Ec No 562/2006 (Shengen Borders Code) or to the international relations of one or more of the Member States.  will my denmark green card application is prone to decline due to the past schegen visa refusal reasons?   With the above refusal reason, I am not sure whether my name is listed in SIS.  Is there a way to clear the name out of the record.. whom should i contact and what it takes in terms of time and money?  Please advice.


Are US universities generally reluctant to admit PhD students who already hold a PhD?

I am planning to do a Ph.D. in Math Education from one of the prominent universities in western Europe, and then do a Ph.D. in EEE/CSE. The reason being, I have a STEM background but due to clinical depression and weak math background, I decided to drop out of the MSc in CS program. My age is running out and I feel that getting a Ph.D. in Education is a safer option, as Education is based on social science, and it is relatively less risky than getting involved in Ph.D. in CSE as science research regularly fails, and there is also a risk that some other guy may be already working on what I am getting started with. However, I am feeling a deep obsession with studying CSE and getting a Ph.D. in CSE. My plan is to start a Ph.D. in math Education and repair my math and CS background simultaneously. Are US universities reluctant in admitting Ph.D. students who already hold a Ph.D.? If Yes, why and how to bypass that?


Javascript - testing for non-numeric text input

I have a text input for a calculator that is already set up to only accept numbers, and I want to allow for both positive and negative integers, but when the input is used, I want to disallow + and - to be entered. Instead, I want to have those inputs cause operations to be performed.  display.keypress(function() {   if (temp === 0 && $(this).val().isInteger()) {     temp = $(this).val().toString();   } else if ($(this).val().isSafeInteger()) {     temp += $(this).val().toString();   } });


How does finder sort folders when they contain digits and characters?

I can't figure it out how to sort folders by name in Finder.   My expected results should look like this:  0629e7bc-8110-4db9-aaa9-b67b0b73743d 06a409e1-98c6-4bf4-afa4-c814f7899d82 0a3a5c12-e459-4aa0-b9cb-30b544013215 0c14581f-31d8-4961-a14f-11afc40e47f9 0fe8970c-6338-46ca-bc16-f7867b271480 129855c4-7dbe-4a9f-a100-28b1d3d02340 1522e288-8a81-4298-aefc-f334cb088a53 180d430b-76f9-401f-845a-cb395bc1eba0 1a01a936-bedf-4758-971a-d4886ee8d281 ....   But instead it looks like this:    Here are my settings:    Grouping is turned off.  I think this is a bug.  (grouping doesn't change anything here). I've deleted .DS_Store files.   I am running macOS Mojave 10.14.5 (18F132)  Even if I switch to another view, it does not work.    What else could I try to fix this?


"Any help will be appreciated." - appropriate or not?

I don't know what to call these sentences that are often written at the end of questions, but here are some examples:   "Could anyone give me some explanations on this problem? Thanks a lot!" -  "Thanks in advance!" -  "Thank you and More Power!" -  "Please help" -  "any suggestions?" -    Is it OK for questions to contain these messages?  I've also seen some edits adding these, even when the original question did not have them. Is this OK as well?


Is there any way to disable below warning that Chrome throws sometimes when you are trying to close a tab?


can you please help me? I need to fix this to make weapons for my game, I use boolean operators, and then active the smoothing, after activating the smoothing appears strange artifacts in my mesh, an example image - first image:    Then I add the Edge Split modifier or activate Auto Smooth, so the artifacts disappear, but when I add bevel, the artifacts appear again, only weaker or stronger, example image - second and third image:     these artifacts are visible in unity, and in other programs, and this is very bad, is there any method that can fix this, please help me, can solve using flat shader, instead of smooth shader, it seems that the problem is smooth shader, but I need to use smooth shader.  sorry about my english, I'm from Brasil.


I am semi-new to Linux and Ubuntu, I recently just got a NVMe drive dedicated to my Ubuntu itself and I am running into troubles with using ubuntu on this SSD (I did not have any trouble installing) it just keeps freezing and when I try to log in nothing happens I type my password and acts like it logs in but then doesn't and just brings me back to the log in screen. Anyone else run into this problem?


Expected number of trials to get 5 heads

Say I have a fair coin. I want to know the expected number of trials to get 5 heads. What is the relationship to the following idea: $E[$number of heads in n trials$]= (1/2 \cdot 1+1/2 \cdot 0) \cdot n= 5$ $\rightarrow$ n= 10


How do you go about comparing two servers in order to figure out how many of one, you could replace with a newer one?  In particular, I have the following  Old server: ProLiant BL460c G6 (1.86 GHz, Intel Xeon E5502) New server: ProLiant BL460c Gen9 (1.80 GHz, Intel Xeon E5-2630L v3)  I can go onto CPU benchmarking website and compare the CPUs   (for a direct comparison)   (for benchnmark)  However, I am not sure how to be able to say that my G6s can be replaced by x G9s? How do I factor in core count and memory? Anyone know a smart way of doing this, or any other metrics to use?


a question of element commutative algebra

Let $A$ is a commutative ring with $1$ and $a$, $b$ are the elements of $A$ such that $a+b=1$ and there is some $n>0$ , $(ab)^n=0$. Prove: $(1)=(a^n)+ (b^n)$.    I would say it's kind of easy one, but somehow I got stuck on it too long. Please help me !


Can someone explain how integration by parts was done?

I just would like someone to identiy u and dv.


Finding DEM for Greece (in high resolution) in order to calculate road slopes?

I want to calculate the slope of road segments and I need dem for Greece. Where can I find it? I have found another one but the slopes were huge which is impossible.


Using Flash Drive to Give Extra Memory to Computer?

I am running on a bad 4g Windows-8 Gateway laptop. I have a lot of files and coding scripts. This is causing my memory to drain. I was wondering if I could clean a flash drive (Which I know how to do) and convert it to extra memory on my computer?


Help figuring out this Standard Normal Problem

Need to somehow prove P(Z less then z) is less then equation2  I dont know where to get started with this problem. Please help me figure out how to go about doing this problem. Thank you  So do i need to just integrate the equation given in part a from z to infinity ... how does that show its greater then P(Z less then z)?


How to sort 2 arrays while keeping them connected to same element?

My program sorts alphabetically by last name and places the first name beside it, however I want it to also sort by first name as well. How would I go about this?      // Before sort     for (int i = 0; i < NUM_PEOPLE; i++) {        cout << first_names[i] << "\t" << last_names[i] << endl;     }      string temp;      for (int pass = 0; pass < NUM_PEOPLE - 1; pass++)         for (int i = 0; i < NUM_PEOPLE - 1; i++)             if (last_names[i] > last_names[i + 1]) {             temp = last_names[i];             last_names[i] = last_names[i + 1];             last_names[i + 1] = temp;             temp = first_names[i];             first_names[i] = first_names[i + 1];             first_names[i + 1] = temp;         }      cout << "After sort:" << endl;      for (int i = 0; i < NUM_PEOPLE; i++)         cout << last_names[i] << "\t" << first_names[i]<< endl;


Supposing $a^{n}\cong1(mod\,m)$ and $t \cong r(mod\,n)$. How to prove that $a^{t}\cong a^{r}(mod\,m)$?

I've been looking at this question but I can't figure out any ways to approach it. This is from a first year undergraduate number theory class.


How to set multiple list values via Entity Metadata Wrapper?

Field creation code:  if (! field_info_field(MY_FIELD_NAME)) {      field_create_field(array(         'field_name => MY_FIELD_NAME,         'type' => 'list_integer',         'settings' => array(             'allowed_values' => some_allowed_values(),         ),         'cardinality' => FIELD_CARDINALITY_UNLIMITED,     ));      field_create_instance(array(         'field_name' => MY_FIELD_NAME,         'entity_type' => MY_ENTITY_NAME,         'bundle' => MY_ENTITY_BUNDLE_NAME,         'widget' => array(             'type' => 'options_select',         )     ));  }   Setter code:  //posted options are list values keys e.g (3,4) $wrapper->{MY_FIELD_NAME}->set(array_values($values['posted_options'])); //not work too: $wrapper->{MY_FIELD_NAME}->set($values['posted_options']); $wrapper->{MY_FIELD_NAME}->set(array($values['posted_options'])); //in for loop $wrapper->{MY_FIELD_NAME}[] = $option_key;   Error:     EntityMetadataWrapperException: Invalid data value given. Be sure it   matches the required data type and format. in   EntityMetadataWrapper->set()   or     Fatal error: Cannot use object of type EntityValueWrapper as array   It works only when I set single value:  $wrapper->{MY_FIELD_NAME}->set($option_key);   This is not related to:    because this is different field type.  Found solution:     field_create_field(array(         'field_name' => MY_FIELD_NAME,         'type' => 'list_integer',         'settings' => array(             'allowed_values' => options_values(),         ),         'default_widget' => 'options_select',         'default_formatter' => 'list_default',         'cardinality' => FIELD_CARDINALITY_UNLIMITED,     ));      field_create_instance(array(         'field_name' => MY_FIELD_NAME,         'entity_type' => MY_ENTITY_NAME,         'bundle' => MY_ENTITY_BUNDLE_NAME,         'widget' => array(             'type' => 'options_select',             'formatter' => 'list_default',         )     ));


Given positive integers $a,m$, let $a_1=a,\ a_{n+1}=a^{a_n}, \forall n\in\mathbb Z_{\ge 1}$. Show that the sequence $(a_n)$ eventually becomes constant $\pmod m$.  A solution given is as follows:  Suppose that there is a counterexample.  Then there is a counterexample for which $ m$ is minimal. Trivially, $ m\neq 1$.  Note that the sequence $ \{ a^j\}_{j=0}^{\infty}$ eventually becomes periodic $\pmod m$; let the length of this period be $ k$.  Evidently, $ 1 \le k \le m-1$.  Since $ \{a_j\}_{j=2}^{\infty} = \{ a^{a_j}\}_{j=1}^{\infty} $ does not become constant mod $ m$, it follows that $ \{a_j \}_{j=1}^{\infty}$ does not become constant mod $ k$.  Thus $ k$ is a smaller counterexample than $ m$.  Contradiction.   I do not understand how the bold part follows. Can someone help?


What is physical significance of product of Inertia?

I have read in available sources that  is just a term that is defined because it is useful in calculating the minimum and maximum moments of inertia of a body and also in finding the moments of inertia about a rotated system of axes with respect to the original system of axes. But does not there stand any physical significance of ?


On login to EC2 (Ubuntu) instance, I see   *** /dev/xvda1 should be checked for errors ***   I can't fsck /dev/xvda1 because it is mounted, and sudo umount /dev/xvda1 fails because it is in use.  lsof shows   jbd2/xvda  172               root  cwd       DIR              202,1     4096          2 / jbd2/xvda  172               root  rtd       DIR              202,1     4096          2 / jbd2/xvda  172               root  txt   unknown                                        /proc/172/exe   and kill -SIGKILL 172 is ineffective.  What to do?


Software Center doesn't work after installing Python 3.4.3

I have a problem with my Ubuntu 15.04, after installing Python 3.4.3 I couldn't run the Software Center and this message appears:  File "/usr/bin/software-center", line 140      print time.time() SyntaxError: invalid syntax


If you have expertise in a skill, is only your initial proficiency bonus doubled, or does it scale as you level up?

I understand that having expertise in a a skill doubles your proficiency in it, but is it just the initial proficiency that's doubled or does it include proficiency you gain from leveling up?  e.g. If I had +2 persuasion and expertise in it it would be +4. If I then level up would it now be +6 or +8?


In Windows, you can run android application using BlueStack.   I was wondering, is there any way these apps can be run on Ubuntu 12.04?


How to run a headless VM with VBoxManager as a windows service

Objective  I want to run this command VBoxManage startvm MyVM --type headless at the boot system just like a service (postgres, apache) does.  What i've tried  1. I've tried to create a service using sc command  I've found over the internet that could be the solution so i tried all this versions:   sc create "vboxMyVMService" binPath= "C:\Progman Files\Oracle\VirtualBox\VBoxManage.exe startvm MyVM --type headless" sc create "vboxMyVMService" binPath= "C:\Progman Files\Oracle\VirtualBox\VBoxManage startvm MyVM --type headless"   No success, so i tried to suppress the verbose output of the command   sc create "vboxMyVMService" binPath= "C:\Progman Files\Oracle\VirtualBox\VBoxManage.exe startvm MyVM --type headless > NUL" sc create "vboxMyVMService" binPath= "C:\Progman Files\Oracle\VirtualBox\VBoxManage startvm MyVM --type headless"   Still no results. All this version returned me a 1053 error. So the last call was to add the Virtualbox command to the Path     sc create "vboxMyVMService" binPath= "VBoxManage.exe startvm MyVM --type headless" sc create "vboxMyVMService" binPath= "VBoxManage startvm MyVM --type headless"   suppressing output   sc create "vboxMyVMService" binPath= "VBoxManage.exe startvm MyVM --type headless > NUL" sc create "vboxMyVMService" binPath= "VBoxManage startvm MyVM --type headless > NUL"   No positive result always 1053 error.  2. Assign Computer Startup Scripts  I followed this  with my last hope, but no success.  What left  I'm thinking about to download the Visual Studio and try something related to .    So guys, where is my mistake? Is there hope to me?    FAQs   Can you switch you OS to linux?   No. It's out of question.  Why you need this VM to startup at with the system?   Unfortunately this windows 7 host is a small server for the application running over the VM. The machine it's not mine and it's the only option they gave to me to make the deploy.  Why you are not making the deploy of the application inside the windows host?   I'm not running PHP, or any .NET stuff, so no.


I am looking at adding a new javascript library to drupal 8. I want the ability to call this library from other modules / libraries.  The way WordPress does this is by the use of wp_enqueue_scripts. Using a common library would make sure that my library is loading just once.  An existing implementation of this in drupal is the way you can add dependencies into your the yml files  js:  dependencies:   - core/jquery   Is there a way I can add my own javascript library as the dependency that can be used throughout my drupal instance (all modules and themes should be able to use this as a dependency)


For some reason it won't let me install skype! I looked at this link   typed these:  sudo apt update sudo apt install skype   and got these error messages:  Reading package lists... Done Building dependency tree        Reading state information... Done E: Unable to locate package skype   Thank you for all the help!


How can I list all man pages that have certain text without displaying contents?

I'd like to search for a certain string in all system man pages, but I only want to get a list of the man pages where this text appears.  The first 2 pages of results Google returned do not provide the answer I'm after, if at all such an answer exists.  Let me explain:  I'd like to see all man pages where the word hairpin appears.  I proceed to type man -K hairpin, and the contents that appear are akin to me having typed man nmcli.  When I exit this man page via q, the following then appears on my screen:  --Man-- next: bridge(8) [ view (return) | skip (Ctrl-D) | quit (Ctrl-C) ]   From here, I can continuously type Ctrl+D and eventually return to the command prompt with the following displayed above the prompt:  --Man-- next: bridge(8) [ view (return) | skip (Ctrl-D) | quit (Ctrl-C) ] --Man-- next: lldptool-evb22(8) [ view (return) | skip (Ctrl-D) | quit (Ctrl-C) ] --Man-- next: systemd.network(5) [ view (return) | skip (Ctrl-D) | quit (Ctrl-C) ] --Man-- next: nm-settings(5) [ view (return) | skip (Ctrl-D) | quit (Ctrl-C) ] --Man-- next: nm-settings-ifcfg-rh(5) [ view (return) | skip (Ctrl-D) | quit (Ctrl-C) ] --Man-- next: systemd.directives(7) [ view (return) | skip (Ctrl-D) | quit (Ctrl-C) ]   What I'm asking is, is it possible to get a listing of the man pages where hairpin appears such as below?:  man -<some-option> -K hairpin nmcli(1) bridge(8) lldptool-evb22(8) systemd.network(5) nm-settings(5) nm-settings-ifcfg-rh(5) systemd.directives(7)   Edit: Searching Google using a sentence doesn't always return the results where the specific query is addressed.  This is obviously the case for this question, as pointed out by several that it is indeed a duplicate.  However, it would be best not to delete it as it shows the specific output returned on Ubuntu systems.  A user on Ubuntu may benefit from this question.  Edit 2: Searching for skip (Ctrl-D) now has this question appearing in the first page of Google results where previously nothing was returned!


How to allow some special characters and how to insert them into MySQL using PHP pdo

I've been having issue allowing some special characters and when inserting them into database they are showing up incorrectly.


What's so special about the speed of light?   Why do many equations in physics include the speed of light in vacuum $c$?   Why do so many thing depend upon it?  Why can't it be the speed of sound?   Or as a matter of fact any other variable?   For example, in mass-energy equivalence $E=mc^2$, why the speed of light $c$?


I have the following proof that I would like to be walked through because I'm not intuitively seeing what to do:  If $A$ is $n\times n$, prove $\det\left(\operatorname{adj}(A)\right) = \det(A)^{n-1}$.  I know the property of $A\operatorname{adj}(A) = \det(A)I$ is important but I don't know how to apply it to get an answer. Any help is much appreciated.  Thanks,


If it's "yourself", why isn't it "hisself"?

There seems to be a bit of inconsistency with "-self" pronouns. Some are possessive while others are objective/subjective:  Consider:        Yourself   Ourselves   Itself(?)      vs:        Himself   Herself   Themselves   Itself(?)      The first set use the possessive pronoun; the second don't. Why?  Similarly, is "itself" "it"+"-self" or "its"+"-[s]elf"?


Is it possible to only share specific games through Steam Family Sharing?

On my steam account, I have some games that I don't particularly want my sister to play, but I want to share my Terraria game with her so she can play with her friends.  Is it possible to only share Terraria with her through Family Sharing but no other games?


Give two integer vectors in c++ (same size and type), I'd like to sort one from smallest to largest element and change the order of the second vector

Give two integer vectors in c++ (same size), I'd like to sort one of my vectors from smallest to largest element and change the order of the second vector respectively.  How can I achieve this without using boost library?  Thanks.


Go to XY tool not working when clicked in ArcMap?

I am using ArcGIS 10.3. When I click on 'Go to XY tool', located on toolbar, it doesn't open.  What is the possible solution to fix this problem, so I could open 'Go to XY tool' in ArcGIS 10.3?


We can see our face in a mirror, but why not clearly in a aluminium or steel?

We can see our face in a mirror. But why can't we see our face clearly in a aluminium or steel?


$$\gcd(\text {lcm}(x, y), \text {lcm} (x, z)) = \text {lcm}(x,\gcd(y, z))$$ where $x,y,Z$ are three integers. I came across this property on GCD but was not able to prove this.Can anyone suggest me a method.


question about p values and significance comparison

I am under the impression that you have to set your alpha value before the experiment, and once the experiment is done, your p value, based on the alpha value, is either significant or not.  It's dichotomous.  There is no "almost significant" or anything like that.  So if I set my alpha at 0.04, but my p value is 0.05 then my results are insignificant.    I do not understand why.  Imagine a beginner researcher who really wants to get significant result, setting alpha at 0.2 and gets 0.19 p so its significant.  Or imagine a researcher so sure that a treatment works that sets alpha at 0.001 but his p value is 0.002 so its insignificant. Why has the significance of the result have anything to do with the researcher's guess about alpha levels?    Why can't we treat p value as a continuous variable, instead of randomly picking some alpha significance level before we start?


Can I add schema.org markup with JavaScript after page load?

My webpages show products. The product data (title, price, reviews, etc.) is fetched with an XHR and added to the DOM at run-time.  Does it make sense to add schema.org markup with JavaScript after the page load, or will Google completely ignore that markup?


When I know gallons and I know total area how to I get total inches

If I know total gallons of oil spilled is 94,000 gallons and area is 5 miles by 2 miles long how do I find total thic


Find the unit vector $\vec{b}$ if $-\hat{i}+\hat{j}-\hat{k}$ bisects the angle between $\vec{b}$ and $\vec a=3\hat{i}+4\hat{j}$  The unit vector along the angle bisector is $$\frac{-\hat{i}+\hat{j}-\hat{k}}{\sqrt3}=\frac{\vec{b}+\left(\frac35\hat{i}+\frac45\hat{j}\right)}{|\vec{b}+\frac35\hat{i}+\frac45\hat{j}|}$$ Im not able to extract $\vec b$ from here


How to create nested lists with random numbers?

Please if you know how to solve this: I need to add nested lists, each list with randomly generated numbers, but within the same range. If I run my code like it is, it adds nested lists, each list with the correct length of 6 numbers, but the problem is that all numbers in the lists are identical! the output is like that: [     [27, 2, 23, 12, 9, 2, 28, 31],     [27, 2, 23, 12, 9, 2, 28, 31],     [27, 2, 23, 12, 9, 2, 28, 31],     [27, 2, 23, 12, 9, 2, 28, 31] ]  How can I manage to generate new numbers each time I call the function in the for loop? lottery_numbers = [] numbers_list = []  def num_generator():    for num in range(0, 2):       random_number = random.randint(1, 40)       numbers_list.append(random_number)       lottery_numbers.append(numbers_list)     for number in range(0, 4):   num_generator()


How to extract title from php file get contents?

<?php        $content=file_get_contents('example.com');     // it would return html <head>.....    <title>Example.com</title>   I want to extract example.com from title    $title=pick('<title>','</title>',$content);     Echo $title;   And it would show Example.com


Does the gravitational field of the photon create a gravitational wave and a red shift?

Another thread on this site established that the photon has a gravitational field of its own. Then the photon must loose energy to the gravitational wave the photon makes when it travels through space, I assume? But I have never seen a calculation of the red shift due to this effect by mainstream astronomers. But prof. Jian-Miin Liu (Nanking University) has some interesting papers on this subject on the internet, using the GTR as his theoretical background. I would be very glad to hear of your views on this.


Subtle difference in two (almost) similar structures

So, there are two 'almost' similar structure in 'C' code  1st:  struct P1 {     int i;     char c;     char d;     int e; }; printf("3. size of struct is, %d\n", sizeof(P1));   Gives a console Output: 3. size of struct is, 12  2nd:  struct P2 {     int i;     char c;     int e;     char d; }; printf("4. size of struct is, %d\n", sizeof(P2));   Gives the console output: 4. size of struct is, 16  Can anyone explain the discrepancy? (Even though both the struct have 2 int and two char)  Thanks in advance!


Unfortunately I have clicked on the edit button in the attributes table and the spreadsheet with the polygons and their attributes has disappeared (see picture).  It is likely that I am making a mountain out of a molehill but I really do not know how to make the spreadsheet reappear.  Thank you in advance


Can you recover a deleted message or chain of messages from iPhone?

I see all of these software that claim that they can recover messages deleted from your iPhone. Do they actually work?  For example, if I received 2 text messages from my friend and I immediately deleted them. Is it possible to recover them?


confusing behavior of emacs-style keybindings in bash

Bash offers many useful emacs-style keybindings for simple commandline editing. For example, Ctrl+w deletes ("kills") word left from the cursor.  Another keybinding, Alt+d is supposed to be a "mirror" of the first one. It is supposed to delete a word right from the cursor.  However, I have noticed, these two keybindings do not act completely symetricaly. Whereas Ctrl+w treats foo.bar as one word, Alt+d treats it as two words  Even more annoyingly, # echo are two words for Ctrl+w, but one word for Alt+d.  Is there some logic in this? Is there some reason why they don't treat words in the same way?  Is there any way for me to change this?  I am using bash on Debian Wheezy


Deletion banner by underage deleted user displays the original username

On  (10k only, of course), the user self-deleted the question, then their account was deleted for being underage. The account name displays as "user106595" in the question and comments, but the deletion banner says "deleted by <original username> yesterday." It should say "deleted by user106595 yesterday."


Following java programs gives me this outcome like [I@4554617c  public class Firstlast6 {      public static void main(String[] args) {         int testnums[] = {6,1,5,3};         firstLast6(testnums);          System.out.println(testnums);     }      public static boolean firstLast6(int[] nums){         if (nums[0] == 6){             return true;         }else if (nums[nums.length-1] == 6){             return true;         }else {             return false;         }     } }


Error when installing gimp from Ubuntu Software Center

Last night my internet connection was slow so I canceled Gimp installation (4.5 Mb/53Mb). But today when I try to click on Gimp install button in Ubuntu Software Center, this error came up "Requires installation of untrusted packages". What should I do now?


Non-trivial groups pairwise non-isomorphic with isomorphic direct products

Are there four non-trivial groups $G_1,G_2,H_1,H_2$ pairwise non-isomorphic but such that $G_1 \times G_2$ is isomorphic to $H_1 \times H_2$?  My idea was to consider the abelian groups and something related to their decomposition as direct product of cyclic groups, but it doesn't work.


There seems to be a "follow" button in other people's posts that I can click on and receive notifications from. However, I seem to always receive notifications for my own questions without the ability to unfollow them. (The "follow" button is replaced by a "delete" button respectively.)  As a comparison, on GitHub, you can watch/unwatch a repository (which determines whether you receive notifications from that repository). You are initially watching your own repository, but you have the ability to unwatch your repository.  Given that I don't want to receive any notifications from my own questions, what should I do? (This isn't necessarily disassociation, I need to be able to receive reputation from upvotes/people need to know that it was me who posted this question.)


Moving from HTTP to HTTPS in Google Search Console

I'm moving from HTTP to HTTPS for my entire site. The site is currently added to Google Search Console (formerly Google Webmaster Tools) as www.example.com and all the pages are indexed without using SSL.  How do I go about moving to the new HTTPS URLs on Google Search Console?   Do I just submit an updated sitemap which has the HTTPS URLs or do I add a new site as https://www.example.com and submit the sitemap with HTTPS URLs? All current URLs are set to redirect to their HTTPS counterparts. Do I add multiple properties to Google Search Console?


(DUPLICATE) Get for loop to be executed on first x number of tuples in a list

I have a VERY long list of tuples e.g. [(1,2), (18,485), (284,475)....]. I also have a for loop, which will perform a function on groups of these tuples. I want the loop to be executed on the first 68 tuples, then the next 68 tuples, then the next 68 tuples, and so on until it has been done on all tuples (the total number of tuples is divisible by 68, by the way).  I thought first to group the tuples into separate lists of 68, but then wondered if it is more efficient to do something using the "in range(68)" function? I just do not know how to get the for loop to then move onto the next set of 68 tuples and to not re-read the first 68 tuples.   I do not yet have much code, just       tuple1= new_tuple # changing tuple of tuples to list of tuples     list_of_tuples = list(tuple1)      # here I want to either split the list into mini-lists of 68, or start the for loop for the first 68 tuples, then the next 68 etc.       #the for loop:       for z in SOMETHING?       d = z       mdata = []        for p, k in combinations(d,2):          distance = math.sqrt( ((p[0]-k[0])**2)+((p[1]-k[1])**2) )         mdata.append(distance)   I dont think this helps much though. Would really appreciate any help or even just advice. Thanks in advance.


How can a pion with neutral charge exist?

A $\pi^0$ consists of an up and anti-up quark. However, I also learned that when a particle and its anti-particle meet, energy is produced.  So, my question is that how can $\pi^0$ exist? Won't it turn to energy instantly if it is formed?


Confusion regarding direction of electric field and dipole moment

So we know electric field is directed away from a positive charge and is towards a negative charge. But in an electric dipole we define a quantity called electic dipole moment which is directed from negative to positive (arbitrarily fixed direction). But then later it is also told that the electic field in a dipole(along axial line) is also in the direction of dipole moment. But how can electric field be directed from negative to positive? Shouldn't it be the opposite that the direction is directed from positive to negative charge?  I'm sorry if my question sounds naive. I'm currently in initial stages of learning.


Is $2^{2n} = O(2^n)$?  My solution is:  $2^n 2^n \leq C_{1}2^n$  $2^n \leq C_{1}$,  TRUE.  Is this correct?


Do you capitalise words like 'Liberalism'?

Do you capitalise words like 'Liberalism', 'Communism', 'Socialism'?  I'm presuming that such words are proper nouns because they are the specific names of ideologies. If they are not capitalised, why not?  And if they are capitalised, are words like mathematics capitalised? I am led to believe they are not unless they are the name of a specific course subject like 'Maths 101', but isn't mathematics the proper noun of a specific concept?


I want to know if you can have the offspring mate with one of his or her own parents. It's odd, yes, but I'm curious if Bethesda thought this through.  Edit: I'm going to cross breed, by this I mean like this   Parent 1 + Parent 2   Parent 3 + Parent 4     = Child 1            = Child 2  Parent 1 + Child 2    Parent 2 + Child 3     = Child 3            = Child 4   I hope this visual (somewhat) representation will show what I'm planning to do.


Let $\phi$ be a scalar field and then I see the following expression (1) for the square of the normal ordered version of $\phi^2(x)$.   \begin{align} T(:\phi^2(x)::\phi^2(0):) &= 2 \langle 0|T(\phi(x)\phi(0))|0 \rangle^2 \\ &+ 4\langle 0|T(\phi(x)\phi(0))|0 \rangle:\phi(x)\phi(0): \\ &+ :\phi^2(x)\phi^2(0): \tag{1} \end{align}  It would be great if someone can help derive the above expression - may be from scratch - and without outsourcing to Wick's theorem - and may be help connect as to why the above is related (equal?) to the Wick's theorem?    Isn't the above also known as OPE (Operator Product Expansion)? If yes, then is there at all any difference between OPE and Wick's theorem? Is there a systematic way to derive such OPEs?  Can one help extend this to Fermions?


"expected expression" when trying to define nested template member function

I have a templated class that has a templated member function.  Currently, I give the definition as:  template <typename... Ts> template <size_t Column> At<Column, Ts...> & tuple_reference<Ts...>::at(void) {   return array.at<Column>()[row]; }   But I get this error:  $ g++ example.cpp -o example -Wall -Werror -Wextra -std=c++1y -stdlib=libc++ example.cpp:42:27: error: expected expression   return array.at<Column>()[row];                           ^ 1 error generated.   Which confounds me, as that method of array works fine elsewhere in my code (see ic_arr.at<1>() below).  Here's my full source:  #include <iostream>  // Provide a Array-of-Structs (AoS) interface to a collection that // is actually implemented as a Struct-of-Arrays (SoA). namespace soa {  template <typename... Ts> class tuple_array;  // index into a parameter pack to get the N'th type listed template <int N, typename... Ts> using At = typename std::tuple_element<N, std::tuple<Ts...>>::type;  // the "Struct" the API provides template <typename... Ts> class tuple_reference {  private:   tuple_array<Ts...> &array;   size_t row; public:   tuple_reference(tuple_array<Ts...> &array, size_t const &row)       : array{array}, row{row} {}   // extract the value for a given index   template <size_t Column>   At<Column, Ts...> & at(void); };  // The toplevel interface template <typename... Ts> class tuple_array {  private:   std::tuple<Ts *...> arrays;   size_t size{}; public:   tuple_array(Ts *... arrays, size_t const &size)       : arrays{arrays...}, size{size} {}   // extract the array for a given index   template <size_t Column> At<Column, Ts *...> &at(void) {      return std::get<Column>(arrays);   }  };  template <typename... Ts> template <size_t Column> At<Column, Ts...> & tuple_reference<Ts...>::at(void) {    return array.at<Column>()[row]; }  }  int main() {    int five_ints[]{0, 1, 2, 3, 4};   char six_chars[]{"abcde"};    soa::tuple_array<int, char> ic_arr{five_ints, six_chars, 5};   soa::tuple_reference<int, char> ic_ref{ic_arr, 0};    // outputs "abcde\n"   std::cout << ic_arr.at<1>() << std::endl;   // should output "0 a\n"   std::cout << ic_ref.at<0>() << " " << ic_ref.at<1>() << std::endl; }   I'm using Apple LLVM version 6.0 (clang-600.0.57).


I discovered several (about around 100) loop processes in memory of my Xubuntu 18.04 LTS desktop. What are these for and can I safely remove them?

loop processes (over 100) in memory:    I can see them in taskmanager.  Can anyone tell me what these processes are for, and what uses them? They are all called  loop (with an increasing number (up to above even 100)). I have more Linux PCs, but of all 4 of them only 1 other has a few loop# processes (about 8 or so).  I suspect these loop# processes take up  a lot of my desktop PCs CPU processing power the system is not really as fast anymore as when I just installed Xubuntu 18.04. What can I do to remove these, and is it safe to do so?  loop processes above 100 in task manager:


I want a cam to zoom out and stop. but it looks silly when it goes from moving to full stop in a frame, so I need it to slow down a few frames before the end.  I found a  few guides, where I should edit the speed in the graph editor window but mine looks nothing like the ones others show.   mine:    why is it not the same ?


How is it possible for a standing wave to exist in a tube with both sides open?

A standing wave is the result of the interference of 2 opposing waves right? Then how can this diagram on the upper left be true?  One sound wave is created by the musician, the other is supposed to come as a reflection, how?  And if the second, opposing wave is somehow generated by reflection, shouldn't the point where it was created be a node, not an anti node?


prove that for $0<r<R$ , $f'(a)=\frac{1}{r\pi}\int_{0}^{2\pi}P(\theta)e^{-i\theta}d\theta$

If function $f(z)$ is analytic and one valued in $|z-a|<R$ , prove that for $0<r<R$  $$f'(a)=\frac{1}{r\pi}\int_{0}^{2\pi}P(\theta)e^{-i\theta}d\theta$$  where $P(\theta)$ is real part of $f(a+re^{i\theta})$  EDIT : As pointed out by @Kavi Ram Murthy the question has been answered correctly here :   Since the answer has not been accepted I will copy the answer and mark this as closed (with due credits to @Kavi Ram Murthy)  My approach :  We know that $$f'(a)=\oint\frac{f(z)}{(z-a)^2}dz$$ subsituting $z=a+re^{i\theta}$ and simplifying i get   $$f'(a)=\frac{1}{2r\pi}\int_{0}^{2\pi}f(a+re^{i\theta})e^{-i\theta}d\theta$$  I am struck here I dont know how to procced further and prove first equation is equal to last equation . Any hints or sugestions ? (Also I may be be totally wrong in approaching the solution please let me know if I am


Sentences that do not contain the classic subject and predicate structure

I understand the classic definition of a sentence is one that contains a predicate and a subject, but is it okay to have shorter sentences that don't follow this structure for effect?  For example, if I was to write something like the following:      Inside was something ancient. Something powerful. Something mysterious. Something that...   I realize I could put the 'Something ancient' and 'Something mysterious' between commas, but would it be okay to use them as stated (between periods) for a kind of more dramatic effect even though they don't fit the classic definition of a full sentence?


Why does ffmpeg accept .txt files as input?

I just learned ffmpeg accepts .txt files and renders the content. See:  ffmpeg -i bees.txt -r 2 bees.gif     Where can i find more information about this behavior (docs/sourcecode ?), and are there other "magic" file endings like this ? It looks like ffmpeg ignores the file ending in almost all other cases.


My friend is receiving a lot of Stack Overflow account recovery emails. When I checked I came to know that for triggering account recovery only email id is needed. So anyone knows his email ID can send a recovery email to his inbox. Since email ID is something public should we ask some private info like date of birth before sending account recovery email?


MySQL select distinct not getting desired query result


Automating file transfer using Bash scripts in SSH on my new server from old server

How can I connect to a remote host using SSH and create one Bash script to copy all files and folder from my old server to my new server for backup every day?


How are Anonymous inner classes used in Java?

What is the use of anonymous classes in Java? Can we say that usage of anonymous class is one of the advantages of Java?


I was following a tutorial on YouTube beginner, and when I added quick smoke and hit play, nothing showed up.  I tried a bunch of different things but still cannot see smoke. If its not showing do you think that means my laptop isn't able to support it, or is there something else going on that I'm not doing.


Validity of status in USA after expiration of visa

If I enter the USA before the expiration of a ten-year multiple-entry visa, can I stay after the date of expiration of the visa?


How to create a global style? (like drop shadow)

I have created multiple objects, while testing I applied a drop shadow style on one object and its looking very good. Now I want to apply the same style to all other objects (around 20). Is there any way like global color to create a style once and apply to other objects with single click automatically?  Or I have to apply that drop shadow effect on each object one by one manually?


Using the MacLaurin series of $\ln(1-x)$ to find a series representation of $\ln2$

Background  In a previous problem, I have shown that the Taylor polynomial around $x=0$ for $f(x) = \ln(1-x)$ is $$T_nf(x) = -\sum_{k=1}^{n}\frac{x^k}{k}$$  Problem  Use this Taylor expansion to show that $\displaystyle \ln2 = \sum\limits_{k=1}^{\infty}\frac{1}{n2^n}$.  My thoughts  I figured, hey, $\ln(2) = \ln(1-(-1))$ so with $x=(-1)$ I can just plug it into that Taylor expansion. But apparently that Taylor polynomial is only valid for $x\in(-1, 1)$, so I can't do that.  So that's where I'm stuck.  Any help appreciated!


Does a law for A in boolean algebra hold true for not A as well?

Okay, so according to associative law: (A + B + C) = (A + B) + C So, could I also assume that ~(A + B + C) = ~A + ~B + ~C = ~(A + B) + ~C Where "~" means NOT and "+" means OR. Thank you very much.


cryptsetup: cryptsetup failed, bad password or options?

Today I installed Ubuntu 14.04 on my laptop running Windows 8.1 using Universal-USB-Installer-1.9.6.1.exe. When I finished the installation, I was asked to reboot. I did so but the passphrase wasn't accepted. I had the same password for my user and the disks which I had encrypted with Ubuntu's own tool. I am sure my password is correct as I tried it many times. On every 3rd try I am redirected to a page with lots of command lines. At end of that page I see:  Gave up waiting for root device. Common problems:  -Boot args (cat /proc/cmdline)        -Check rootdelay= (did the system wait for long enough?)      -Check root= (did the system wait for the right device?) -Missing modules /cat /proc/modules; ls /dev) ALERT! /dev/mapper/ubuntu--vg-root does not exist. Dropping to a shell!  BusyBox v1.21.1 (Ubuntu 1:1.21.0-1ubuntu) built-in shell (ash) Enter "help" for a list of built-in commands.  (initramfs)   I am totally new to Linux and I need help with this. I have already tried various things on this site but they didn't help me. I have no risk of losing files as I have them on my other computer which I am currently using.  I could totally re-install Ubuntu but i don't know how to do it. Can anyone help with it?


AJAX send multiple variables, including JSON, to php for database insert

I am trying to send two variables to my PHP file to insert them into a database. One variable is called 'skuLabel', which is just text and the other is 'jsonString', which is a JSON representation of a canvas design. When I just try to send the 'skuLabel', it works fine and inserts it like I would expect. But, when I send either just the 'jsonString' or both, my PHP errors that the two indexes do not exist when I try to access them. I've been working on this for several days now, trying many different methods, all with the same result. This is my first attempt at using AJAX, so I am sure I am doing something simple wrong. I appreciate any help anyone can give!   Here is my code:  var skuLabel = document.getElementById('sku').value; var jsonString = JSON.stringify(canvas.toDatalessJSON()); $.ajax({     type:   'POST',     url:    'uploadDesign.php',      dataType: 'json',     data:   {sku: skuLabel, json: jsonString},     success:              function(data){                 alert(data);             } });   And PHP:  $sku = $_POST['sku']; $jsonData = $_POST['json']; if($mysqli->query("INSERT INTO designs (sku, jsonData) VALUES($sku, $jsonData)")===TRUE){     printf("Inserted successfully.\n"); }


Find conditions on positive integers so that $\sqrt{a}+\sqrt{b}+\sqrt{c}$ is irrational

Find conditions on positive integers   $a, b, c$    so that $\sqrt{a}+\sqrt{b}+\sqrt{c}$ is irrational.    My solution: if $ab$ is not the square of an integer, then the expression is irrational. I find it interesting that $c$ does not come into this at all.  My solution is modeled (i.e., copied with modifications) from dexter04's solution to  .  Suppose $\sqrt{a}+\sqrt{b}+\sqrt{c} = r$ where $r$ is rational.  Then,  $(\sqrt{a}+\sqrt{b})^2  = (r-\sqrt{c})^2  \implies a+b+2\sqrt{ab}  = c+r^2-2r\sqrt{c}$.  So, $a+b-c-r^2+2\sqrt{ab} =-2r\sqrt{c}$. Let $a+b-c-r^2 = k$,  which will be a rational number.  So, $(k+2\sqrt{ab})^2 = k^2+ 4ab+4k\sqrt{ab} = 4cr^2$ or $4k\sqrt{ab} = 4cr^2-k^2- 4ab$.  If $ab$ is not a square of an integer, then the LHS is irrational  while the RHS is rational.  Hence, we have a contradiction.


Finding a normal and not normal subgroup of $S_3$

I'm being asked to find 2 subgroups of $S_3$, one of which is normal and one that isn't normal. I guess, to find the non normal subgroup is easier. I would do this by trial and error, but since the group is $S_3$ and easily visualizable, I guess that there should be a geometrical property that makes it easy to find a normal subgroup. Any of you guys know one? Or should I try this by brute force?


If $a$ is an odd integer, prove that $24 \mid a(a^2-1)$.  I proved in my class that $a^2=8k+1$ for some $k$, provided $a$ was odd.  So $$a(a^2-1)=(2k-1)(8k+1-1)=8k(2k-1)$$ but I can't pull a $24$ out of it.


I have 2 large files (3000 columns, 15000 rows) of the following format  file1 (tab-separated):  1/0 0/0 0/0 0/0 1/1 0/0 1/1 0/1 0/0   file2 (tab-separated):  3 5 2 1 7 10 3 4 3   I'd like to combine the values from the first column of each file with a ":" separator, then move on to the second, third, etc. columns.  Desired output (tab-separated):  1/0:3 0/0:5 0/0:2 0/0:1 1/1:7 0/0:10 1/1:3 0/1:4 0/0:3   Efficiency isn't critical, so any language is fine. I apologize if this has been asked before.


What is an intuitive explanation of units like $N \cdot m$?

Every quantity in Physics has a unit. These units can be in 3 forms:   A single unit. An example is kg or m or J A division of two or more units. An example is $\frac{m}{s}$ or $\frac{m}{s^2}$ A product of two or more units. An example is $N \cdot m$ or $J \cdot s$   The first case is simple. A person whose mass is 70 kg simply has a mass of 70 kg, simple enough.   The second case is also very simple. A speed of 1 $\frac{m}{s}$ means that 1m of distance is covered per second/every second.  The third case, however, has eluded me for a long time. What does it mean to have a unit like $N \cdot m$? What does the multiplication sign between the newton and meter mean? I tried stripping down the unit to the fundamental parts and I got $\frac{kg \cdot m^2}{s^2}$, which does not help.  Can someone please provide me with an understanding of a unit made of a product of two or more other units?


How to Join 2 existing website into 1 without killing SEO?

I have a good trafic website (with a nasty domain name) and a low trafic site (with a good domain name)  My idea is to join both websites and finally have 1 website with the good domaine name (where I would import the posts from the good trafic website)  What would be the smart way to achieve that and keep a good trafic ?  regards


I want to be able to reference a captionless figure (e.g. \ref{figure1}). Based on , it appears that labeling a figure (e.g. \label{figure1}) actually labels the caption. How do I reference my captionless figure? I tried adding an empty caption (e.g. \caption{}) but this create an undesired Figure 1.


JavaScript closure using function declaration

I saw closure being declared using function expression and not function declaration. Being new to java script i have below queries. i tried referring similar question but it didn't helped me.   Do closure always need to be declared using function expression and not function definition Do closure need to be self invoked in function expression I understand key difference between Function declaration and function expression id hoisting. can anyone help me when and which in situation i should decide whether i should go with function declaration or function expression. what are the other advantages and disadvantages of using any one of them   Sorry some questions might be answered previously or kind of basic but being new to it i feel its confusing  below is the example i have done using function declaration but its not giving me proper result    function counter() { var count = 0;  return function() { return count++; } } <!-- using function declaration -->  <button onclick="alert(counter())">Counter</button>       var counter = (function() {   var count = 0;  return function() { return count++; }   increment(); })(); <button onclick="alert(counter())">Counter</button>


If there is already an EFI partition for windows, do I need to create a new EFI partition for Ubuntu?

I'm trying to do a dual-boot installation of Ubuntu and I've noticed that there is already an EFI partition in my SSD. Do I need to create a new one for my Ubuntu Partition?


Considering a field tower $K \subset E \subset L $, $E/K$ is separable extension,$L/E$ is normal extension, is ture that $L/K$ is normal extension?


Not sure why this is producing error.  This is a test code emulating my real code.   I want to write a wrapper for find and want to allow for any argument, so I'm wrapping each arg in single quotes.  #!/bin/bash  function find2 {     ARGS="/usr/bin/find"    while [[ $# -gt 0 ]]; do       ARGS="$ARGS '$1'"       shift    done    echo CALLING:  $ARGS    $ARGS  }  find2 /tmp/test -name "hello.c"    # THIS IS THE DESIRED IMPLEMENTATION (doesn't work)  find '/tmp/test' '-name' 'hello.c'     # THIS IS FOR DEBUGGING (works)   I want to "find2" work, but it doesn't work.  I get the following output:  CALLING: /usr/bin/find '/tmp/test' '-name' 'hello.c' /usr/bin/find: `\'/tmp/test\'': No such file or directory /usr/bin/find: `\'-name\'': No such file or directory /usr/bin/find: `\'hello.c\'': No such file or directory   however, if I use the exact same command (produced by find2) directly, it works fine:  /tmp/test/hello.c   Not sure what is going on.


I am very new to beamer, but not new to LaTeX, and for the life of me cannot find my error when trying to get started building in Beamer. I have read numerous intro guides, and I still just don't get it. This should be SUPER simple, but for some reason it will not build. I know it is a problem when I add the math environment, but not sure why.  \documentclass{beamer} \usetheme{Boadilla} \usepackage{amsmath,amsthm,amssymb,graphicx,tabularx,array,enumitem,multicol,tikz,wrapfig,float} \usepackage{subfigure} \usepackage{collcell}  \title{A Review of Functions} \subtitle{Section 1.1} \author{Ethan Lightfoot} \institute{Gateway STEM} \date{\today}  \begin{document} \begin{frame} \titlepage \end{frame}  \begin{frame} \frametitle{Do Now} I am just trying to type some functions $f(x)$ \end{frame} \end{document}


How to center image horizontally and vertically inside a div

How to center Image both horizontally and vertically inside a div   HTML :

   CSS :  .main-item {   height: 95vh;   margin-top: 6rem;   background-color: $color-grey-light; }    What I have now :    The result I want :   I want the result to be responsive , so that the image stay in the center no matter what is the width of the device screen. The most important thing I want the image to be responsive.


Meaning of fields in "Enable Wi-Fi verbose logging"

Does anyone have a link to clear docs on the meaning of all the fields for Wi-Fi networks when I Enable Wi-Fi verbose logging in the developer options?  I can guess a few and worst case I can read the source, but I was hoping for a clear and simple table.  Specific fields are:   rssi (this is about the only one I'm 100% clear on) score tx rx   Also, the extra data after the mac address of each access point, e.g.  [(1){FF:FF:FF:FF:FF:FF*=2462,-49,4s};]


How to Install Grub after Installing Windows

Yes, I know this question maybe has asked often. I searched a lot everywhere and really tried to fix it without annoying you, but I couldn't fix it with boot repair with entering in Ubuntu with a test Version.  So, I installed Ubuntu after I had Windows already everything was fine. I set up Ubuntu really nice I was happy then it happen Windows got full of Bugs and I had to reinstall it. So, it destroyed GRUB and I can't enter Ubuntu any more... the extra thing I have done: I used GParted and formatted the partition on which Grub was installed. So I need help. How do I install only the GRUB the thing that lets me choose what to boot and to choose Ubuntu. When I tried Boot Repair it says I have to deactivate Secure Boot. I deactivated it and it still didn't work.  Best would be if someone would help me get a finished GRUB Copy and Paste and format the partition into the right format to then select it from Windows with something like this:  bcdedit /set {bootmgr} path \EFI\ubuntu\grubx64.efi


Informed badge not visible on my profile

I have gone through the entire about page for meta.stackexchange.com site thoroughly but I can still find no Informed badge awarded in my profile; why is that so? Is it some kind of technical error on the website?


how to color specific strings in standard output and standard error

How do you color specific strings in standard output and standard error?  For example:  gpg --verify   Outputs either a good signature or a bad signature string.  How can I color the good one, green; and the bad one, red, using GNU software only?  In: , the developer talks about a wrapper script.  I want to do this without adding code to the source code of gpg to colorize those strings.


I wrote a proof for a problem in my textbook. Can someone please verify it or offer suggestions for improvement?  $\textbf{Problem:} $If $u$ and $v$ are $m$-vectors, the matrix $A = I+uv^*$ is known as the rank-one perturbation of the identity. Show that if $A$ is nonsingular, then its inverse has the form $A^{-1}=I+\alpha u v^*$ for some scalar $\alpha$, and give an expression for $\alpha$. For which $u$ and $v$ is $A$ singular? If it is singular, what is null($A$)?  Suppose $A$ is singular. Then, there exists a nonzero $x \in \mathbb{C}^m$ such that $Ax=0$. That is, $(I+uv^*)x=0$. This implies that $u(v^*x) = -x$. For this to be true, $x$ has to be a multiple of $u$. So, let $x = c_1u$ for some nonzero scalar $c_1$. Then, $Ax = c_1u(v^*u) = -c_1u$. Note that $u = 0$ if $v^*u = 0$. Therefore, $A$ is singular if and only if $v^*u \neq 0$, and null($A$) $=$ span($u$) if it is singular.  Now, set $\alpha = -1$. By the reasoning in the above paragraph, $v^*u = 0$ for $A$ to be invertible. Now, $(I+uv^*)(I-uv^*) = I - uv^*uv^* = I - u(v^*u)v^* = I$. Therefore, $A^{-1} = I - uv^*$.


Restore xorg.conf file in Ubuntu 16.04LTS

Checking the content of /etc/X11 dir, I saw that xorg.conf file is missing. Is that normal? I only have xorg.conf.failsafe configuration file with the following lines:   Section "Device"     Identifier  "Configured Video Device"     Driver      "vesa" EndSection  Section "Monitor"     Identifier  "Configured Monitor" EndSection  Section "Screen"     Identifier  "Default Screen"     Monitor     "Configured Monitor"     Device      "Configured Video Device" EndSection   Is, the one above, a correct configuration file? Or, I have to restore the xorg.conf file? If yes, how can I do that? The current driver used is:  sudo lshw -c display | grep driver [sudo] password di michele:         configuration: driver=i915 latency=0   and   lspci | grep -E 'VGA|Display|3D' 00:02.0 VGA compatible controller: Intel Corporation 2nd Generation Core Processor Family Integrated Graphics Controller (rev 09) 01:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Whistler [Radeon HD 6730M/6770M/7690M XT] (rev ff)   A few hours ago, after rebooting my OS, I got a black screen with message:      your system is running in low-graphics mode   but after restarting the pc, all strangely returned as before.  Thanks!