getting NullPointerException in onPostCreate of Google play console

I am having Null Pointer Exception in Play Console and unable to find the issue in my code.  I have tried every possible way to find that exception. I have also tried it on several devices but all in vain.  This is my onPostCreate Code:   @Override protected void onPostCreate(@Nullable Bundle savedInstanceState) {     super.onPostCreate(savedInstanceState);      pageRange= (EditText)findViewById(R.id.pageRange);     pageRange.addTextChangedListener(new TextWatcher() {         @Override         public void beforeTextChanged(CharSequence charSequence, int i, int i1, int i2) {         }          @Override         public void onTextChanged(CharSequence charSequence, int i, int i1, int i2) {             String text = pageRange.getText().toString();             for (int x = 0; x < selected.size(); x++)                 selected.set(x, false);             textChanged(text);         }          @Override         public void afterTextChanged(Editable editable) {             String text = pageRange.getText().toString();             for (int x = 0; x < selected.size(); x++)                 selected.set(x, false);             textChanged(text);         }     });     img_recycler = (RecyclerView) findViewById(R.id.recycler);     recyclerAdapter = new RecyclerAdapter();     img_recycler.setLayoutManager(new GridLayoutManager(this,3));     img_recycler.setAdapter(recyclerAdapter);     Thread t = new Thread(){         public void run()         {             getImages();         }     };     t.start();     // fileName=getFileName(SplitFiles.path);     // fileName = SplitFiles.filePath.lastIndexOf("/");     String path=SplitFiles.filePath;     fileName=path.substring(path.lastIndexOf("/")+1);     AdView mAdView = findViewById(R.id.adView);     AdRequest adRequest = new AdRequest.Builder().addTestDevice("41B2730621B6EDDB8BF5E8148E0CC1CE").build();     mAdView.loadAd(adRequest); }   This is the log details in Google Play Console..  java.lang.RuntimeException:  at android.app.ActivityThread.performLaunchActivity  (ActivityThread.java:2974) at android.app.ActivityThread.handleLaunchActivity  (ActivityThread.java:3059) at android.app.ActivityThread.-wrap11 (Unknown Source) at android.app.ActivityThread$H.handleMessage (ActivityThread.java:1724) at android.os.Handler.dispatchMessage (Handler.java:106) at android.os.Looper.loop (Looper.java:164) at android.app.ActivityThread.main (ActivityThread.java:7000) at java.lang.reflect.Method.invoke (Native Method) at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run  (RuntimeInit.java:441) at com.android.internal.os.ZygoteInit.main (ZygoteInit.java:1408) Caused by: java.lang.NullPointerException:  at com.skytek.pdf.creator.SplitFiles2.onPostCreate (SplitFiles2.java:121) at android.app.Instrumentation.callActivityOnPostCreate  (Instrumentation.java:1292) at android.app.ActivityThread.performLaunchActivity  (ActivityThread.java:2956)


How to prove $x_n$ converges as $n \to \infty$.

Let $x_n = \sum_{k=1}^{n} \frac{1}{k} - \log n$. Prove that $x_n$ converges as $n \to\infty$.


How to choose color palette for text on top of an image?

Im assigned to collateral, ad design, web banners, etc.  It gets frustrating when the image im gonna put a text on top of has a wide range of color. And sometimes, it gets frustrating to choose what color of the text should be.  Is there a secret to this?


What are the differences in using 32 bit and 64 bit Windows 10 on 2GB RAM?

The system has only 2 GB of soldered RAM and can't be upgraded. It is a Intel Celeron processor. A similar system works fine with 32 bit of Windows. I plan to use the "Bash On Linux" on windows. It first came on 64 bits. I do not know if 32 bit supports it.  I prefer Chrome (and have usually 20+ tabs open) and not Firefox (which uses significantly less RAM).   My primary usage comprises programming (on light editors mostly) and lots of tabs open in the browser.  CPU does support 64 bit. Celeron 2840:


$M_1 \to M_2 \to M_3 \to 0$ exact iff $0 \to \text{Hom}_A(M_3, N) \to \text{Hom}_A(M_2, N) \to \text{Hom}_A(M_1, N)$ is exact.

Let $M_1 \to M_2 \to M_3 \to 0$ be a sequence of homomorphisms of $A$-modules. Is this sequence exact if and only if the induced sequence of abelian groups$$0 \to \text{Hom}_A(M_3, N) \to \text{Hom}_A(M_2, N) \to \text{Hom}_A(M_1, N)$$is exact for every $A$-module $N$?


PDF of X is $f_X(u)=c(1−u^2)$ for some suitable constant c. Find c & PDF of Y where $Y=X^2$.

Let $X$ be a continuous random variable defined on the interval $[0,1]$ with density function $f_X(u)=c(1−u^2)$ for some suitable constant $c$.   Find: (a) the value of $c$, (b) (i) the expectation and (ii) the variance of $X$. Also find (c) the density function of the random variable $Y = X^{2}$.   Found $c=\frac{3}{2}$,  $E(X)=\frac{1}{4}$ &   $E(X^2)=\frac{1}{8}$, so:   $Var(X)=\frac{1}{8}-(\frac{1}{4})^2=\frac{1}{16}$  Have I done parts (a) & (b) correctly? If so how do I go about finding the PDF for Y and if not same question but also where did I go wrong?  Thank you.


How to boot to external monitor to see BIOS?

My laptop screen is working but I can only get the secondary display working when I close the laptop lid after turning on power. I believe external monitor starts up after the windows logo and such so much too late to go to BIOS.


If $(a,n)=d>1$ and $k$ is any positive integer, then $a^{k} \not\equiv 1 \pmod n$

Show that if $(a,n)=d>1$ and $k$ is any positive integer, then $a^{k} \not\equiv 1 \pmod n$.   I know that the order divisibility property states the following.  If $(a,n)=1$ and $k$ is the order of $a \pmod n$, then for any positive integer $j$, we know that $a^{j} \equiv 1 \pmod n$ if and only if $k \mid j$.  It seems like I could somehow use the "if an only if" part to prove that $k$ does not divide $j$, which would imply the conclusion. But how can I show it formally?


my 3d view window seems to cut off the view   is there a way to fix this


To show the group $Aut(V)$ of algebra automorphisms of a finite dimensional algebra $V$ is a Zariski closed subgroup of $GL(V )$.

My aim is to proceed with a Heuristic calculation of the Tangent space to Aut(V) at the identity. However, I will have to prove the problem statement before I can proceed with that. My problem, Understanding the polynomial structure on the group Aut(V). The proper way of doing that would have to do with the symmetric algebra on the dual space, I don't wish to proceed this way. And I have been told to visualize the "coordinates" of the matrices as polynomials and work with that. If that is so, what would it mean for the "coordinate" to be "zero". Once this is certified I can proceed. This is what I have thought. Any other procedure, please, please let me know.


Clone partitions and content of an SD card onto another one

Let's assume that I have an SD card with different partitions and files or filesystems on them and I want to reproduce it on another non-partitioned SD card (the new card will be of the same size). Is there a command or set of commands that could be put together in a bash script to automate the process? So far I can only copy the content of one partition with the dd command.


How do melee spell attacks interact with the Mobile feat?

The Mobile feat states that:     When you make a melee attack against a creature, you don’t provoke opportunity attacks from that creature for the rest of the turn, whether you hit or not.   Does that include melee spell attacks like green-flame blade or even steel wind strike?  So let's say you are surrounded by enemies and you cast steel wind strike and attack everyone around you. can you then safely walk out without provoking opportunity attacks?


Often, crontab scripts are not executed on schedule or as expected. There are numerous reasons for that:   wrong crontab notation permissions problem environment variables   This community wiki aims to aggregate the top reasons for crontab scripts not being executed as expected. Write each reason in a separate answer.  Please include one reason per answer - details about why it's not executed - and fix(es) for that one reason.  Please write only cron-specific issues, e.g. commands that execute as expected from the shell but execute erroneously by cron.


How to make tikzposter work with lmodern font?

I have problems making tikzposter work with lmodern font. The resulting document is  using textsyle for sums and integrals. This does not happen, when using another class like article or when removing lmodern.  \documentclass{tikzposter} \usepackage{lmodern}  \begin{document} \block{Test}{ \begin{equation}     \sum_{i=0}^{n}{abc} \end{equation}     } \end{document}   LaTeX Font Info:    Try loading font information for   some parts that might be related from the log:  OT1+lmr on input line 4. (/net/TeXLive/2018/texmf-dist/tex/latex/lm/ot1lmr.fd File: ot1lmr.fd 2009/10/30 v1.6 Font defs for Latin Modern ) LaTeX Font Info:    Try loading font information for OML+lmm on input line 4.  (/net/TeXLive/2018/texmf-dist/tex/latex/lm/omllmm.fd File: omllmm.fd 2009/10/30 v1.6 Font defs for Latin Modern ) LaTeX Font Info:    Try loading font information for OMS+lmsy on input line 4.  (/net/TeXLive/2018/texmf-dist/tex/latex/lm/omslmsy.fd File: omslmsy.fd 2009/10/30 v1.6 Font defs for Latin Modern ) LaTeX Font Info:    Try loading font information for OMX+lmex on input line 4.  (/net/TeXLive/2018/texmf-dist/tex/latex/lm/omxlmex.fd File: omxlmex.fd 2009/10/30 v1.6 Font defs for Latin Modern ) LaTeX Font Info:    External font `lmex10' loaded for size (Font)              <17.28> on input line 4. LaTeX Font Info:    External font `lmex10' loaded for size (Font)              <12> on input line 4. LaTeX Font Info:    External font `lmex10' loaded for size (Font)              <10> on input line 4. LaTeX Font Info:    External font `lmex10' loaded for size (Font)              <24.88> on input line 9. LaTeX Font Info:    External font `lmex10' loaded for size (Font)              <20.74> on input line 9. LaTeX Font Info:    External font `lmex10' loaded for size (Font)              <14.4> on input line 9. LaTeX Font Info:    External font `lmex10' loaded for size (Font)              <29.86> on input line 9.  [1


I was stuck by a combinatoric question. Can someone give me a hint?

In the game "Don't Fall Off The Cliff," you may move forward any positive number of steps, not move, or move one step backward. Each of these three options takes one turn. How many ways can you finish and come back to the point where you started after 𝑛 turns, while never going behind where you started? It looks like a Catalan Number. But l am only familiar with the two-dimensional one. This problem should be 3-dimensional. X refers to go forward any positive number of steps, y refers to stay there, z refers to move one step backward


How much voltage I need to light up this led

I have a RL80-UR543 LED 8MM. How much voltage I need if I use a resistor of 100Ohm?


Intermediate Value Theorem Prove\Disprove Question

I would appreciate your help regarding this prove/disprove: -- Let $f:(0, \infty) \to R$ be a continuous function at $x_{0}=1$ which $f(x)\cdot f(\frac{1}{x})<0$ for every $0 < x \neq 1$. So $f(1)=0$. -- I have tried to prove it with no luck, than tried to find a counter-example with no luck... Any help will be amazing! Thank you so much!


Get list of ZSH commands from ~/.zsh_history with regex separator and multiline fields

I want to get a list of all commands from the ZSH history in ~/.zsh_history.  The file is formatted like so:  : 1467892191:0;cd /usr/share : 1467892276:0;lsrc : 1467892743:0;logout : 1467892751:0;reload : 1484284548:0;echo 'multiple \ line \ test'   Commands may span multiple lines.  The initial format is the same for every command, e.g the regex ^: \d{10}:\d;.  Here's the desired output  cd /usr/share lsrc logout reload echo 'multiple \n line \n test'   Any standard Unix command is fair game.  The purpose of this is so I can pass the list of commands to my $EDITOR to for easy selection for documentation or write-ups.  Here's as far as I got with awk, which prints mostly empty lines.  awk -F': [0-9]{10}:[0-9];' '{ print $1 }' ~/.zsh_history


Tyre loosing air pressure despite having no puncture

The front tyre on my bike looses air pressure despite there being no punctures. There is no leak via the Schrader valve either. If I fill up the tyre, it looses a considerable amount of pressure by day 3. What could be causing this?


Script executed from cron doesn't display GUI notifications

The script below has the name notifyrssh.sh.  1:  File=/home/vaios/Desktop/tempcron/liveusers.txt    //OK 2:  cd /home/vaios/Desktop/tempcron                      3:  ps -aux | grep sshd > liveusers.txt                //OK file is being updated  4:                                                     //   every minute  5:  for name in gus tom max    //***crontab-problem***                          6:  do 7:     notify-send "$name" "DEBUG_MSG" 8:     if grep -q $name "$File"; then 9:             notify-send  "$name" "ONLINE" 10:    fi 11: done   The above script is being run in crontab. I open crontab list with :  crontab -e   And then i add the line :   * * * * * bash /home/vaios/Desktop/tempcron/notifyrssh.sh   Execution from shell prompt  The script seems to be executing fine when i run it regularly from the shell prompt. Being in the directory where the executable script is, i execute it like this :  ./notifyrssh.sh   ...and it works as i expect (updates the file liveusers.txt and gives me all the notification messages) . I again execute it like this :  bash /home/vaios/Desktop/tempcron/notifyrssh.sh   ...and again the results are correct (update file liveusers.txt etc and gives me the notification messages).  Execution from crontab, every minute  The problem when the script is being executed every minute by crontab begins from line 5 and onwards until the end. The file liveusers.txt is being updated regularly every minute (I check this with : cat liveusers.txt) but then it doesn't give me the notifications i expect.   Let me explain what the above script actually does:   In the first 3 lines it updates the file liveusers.txt with the contents of the command :  ps aux | grep sshd From line 5 onwards it checks a list of names (gus tom max) and then if it finds the name in the file liveusers.txt it gives me the notification message from line 9.  The notification message from line 7 is being put for debugging purposes exclusively. I expected that crontab script will give me at least the notofication from line 7 but that didn't happen also.   Any ideas?


How to prepend numbers to typed values in column

I need to manually enter a list of six-digit codes in a column. Each code starts with the same two-number prefix, 03.  e.g.:  030144 030289 030283   Is there a way that I can type just the last four digits of the code but have the cell AND formula bar show the full six-digit code?  In other words, a custom number format will not do because the full six-digit code won't be displayed in the formula bar.


ArrayList returning null after it's already been filled

So I'm playing around with a number-sorting program, trying to write the most efficient way possible to order a random list of numbers from lowest to highest.  I'm having trouble after the first number sorting method has been run, the ArrayList passed to the second method is empty. I figure it has something to do with the first methods sorting technique; which finds the lowest value, places it in a new ArrayList, removes it from the mixed one, then starts again.  What I don't understand is that I pass the mixedArray to sortingMethod1, which is in an entirely different class, yet somehow it still edits the local variable in the main method... help please?  P.S. All of this uses ArrayLists, even though I reference array.  Inside The Main Method:  List<Integer> mixedArray = sorter.generateNumbers(numbers, range); sorter.printArray(mixedArray); //The Random Numbers sorter.printArray(sorter.sortingMethod1(mixedArray)); //This prints them out ordered sorter.printArray(sorter.sortingMethod2(mixedArray)); //This receives a null array   Here is sortingMethod1:  public List<Integer> sortingMethod1(List<Integer> mixedArray){  //Finds the lowest, places it into a new array.     List<Integer> sortedArray = new ArrayList<Integer>();     while (!mixedArray.isEmpty()) {         int lowest = mixedArray.get(0);         for (int i = 1; i < mixedArray.size(); i++) {             if (mixedArray.get(i) < lowest) {                 lowest = mixedArray.get(i);             }         }         sortedArray.add(lowest);         mixedArray.remove(mixedArray.indexOf(lowest));     }     return sortedArray;   As requested, sortingMethod2, however it is still untested   public List<Integer> sortingMethod2 (List<Integer> mixedArray) {   // Finds the lowest, places it at beginning         for (int i = 0; i < mixedArray.size(); i++) {             int lowest = mixedArray.get(i);             for (int x = i; x < mixedArray.size(); x++) {                 if (mixedArray.get(x) < lowest) {lowest = mixedArray.get(x);}             }             Collections.swap(mixedArray, i, mixedArray.indexOf(lowest));         }         return mixedArray;     }


Converting sums of square-roots to nested square-roots

When solving different equations, I have realised, that some roots containing only arithmetic operations and square roots (4th, 8th roots too, because they can be represented using only square roots) can be converted to nested square roots form. Examples (these are roots of equations of 2nd, 4th, 4th and 8th degree): $$\sqrt{2}+\sqrt{3}=\sqrt{5+\sqrt{24}}$$ $$\sqrt{2}+\sqrt{3}+\sqrt{6}=\sqrt{15+\sqrt{160+\sqrt{6912+\sqrt{18874368}}}}$$ $$1+\sqrt{2}+\sqrt{3}+\sqrt{6}=\sqrt{21+\sqrt{413+\sqrt{4656+\sqrt{16588800}}}}$$ $$\sqrt{2}+\sqrt{3}+\sqrt{5}=\sqrt{14+\sqrt{140+\sqrt{4096+\sqrt{8847360}}}}$$ However, I have failed to convert to such form following root (8th degree equation): $$3+\sqrt{2}+\sqrt{3}+\sqrt{5}$$ Performing any operations with it, number of square roots inside increases, what makes me think that converting that root is impossible.  So, question: Can it be done with that root and with what roots in general?  Some forms I was able to get: $$\sqrt{19+6 \sqrt{2}+6 \sqrt{3}+6 \sqrt{5}+2 \sqrt{6}+2 \sqrt{10}+2 \sqrt{15}}$$ $$\sqrt{19+2\left(\sqrt{33+6 \sqrt{30}}+\sqrt{37+6 \sqrt{30}}+\sqrt{51+6 \sqrt{30}}\right)}$$  If one don't know how I got those expressions, here you are an example.  $$\sqrt{2}+\sqrt{3}+\sqrt{5}=\sqrt{\left(\sqrt{2}+\sqrt{3}+\sqrt{5}\right)^2}=$$ $$=\sqrt{10+2 \left(\sqrt{15}+\sqrt{6}+\sqrt{10}\right)}=\sqrt{10+2 \left(\sqrt{15}+\sqrt{\left(\sqrt{6}+\sqrt{10}\right)^2}\right)}=$$ $$=\sqrt{10+2 \left(\sqrt{15}+\sqrt{16+4 \sqrt{15}}\right)}=\sqrt{10+2 \left(\sqrt{15}-a+a+\sqrt{16+4 \sqrt{15}}\right)}=$$ $$=\sqrt{10+2a+2 \left(\sqrt{\left(\sqrt{15}-a\right)^2}+\sqrt{16+4 \sqrt{15}}\right)}=$$ $$=\sqrt{10+2a+2 \left(\sqrt{15+a^2-2a \sqrt{15}}+\sqrt{16+4 \sqrt{15}}\right)}=$$ $$[2a=4 \Rightarrow a=2]$$ $$=\sqrt{14+2 \left(\sqrt{19-4\sqrt{15}}+\sqrt{16+4 \sqrt{15}}\right)}=$$ $$=\sqrt{14+2 \sqrt{\left(\sqrt{19-4\sqrt{15}}+\sqrt{16+4 \sqrt{15}}\right)^2}}=$$ $$=\sqrt{14+2 \sqrt{35+4 \sqrt{16+3 \sqrt{15}}}}=\sqrt{14+\sqrt{140+\sqrt{4096+\sqrt{8847360}}}}$$


I don't know if this is appropriate for math.stackexchange, or whether philosophy.stackexchange would have been a better bet, but I'll post it here because the content is somewhat technical.  In ZFC, we can prove that the (second-order) Peano axioms have a model, call it $\mathbb{N} = (N,0,S)$. Furthermore, $\mathbb{N}$ is unique up to isomorphism. Thus, it would seem that we've pinned down $\mathbb{N}$.  However, if ZFC is consistent, then it has some very peculiar models. In particular, it has a model $(V_0,\in_0)$ whose "native" $\mathbb{N}$, let call it $\mathbb{N}_0$, is a model for the sentence "ZFC is consistent," and another model $(V_1,\in_1)$ whose "native" $\mathbb{N}$, lets call it $\mathbb{N}_1$, is a model for the sentence "ZFC is inconsistent."  But in reality, in other words, for the "real" $\mathbb{N}$, only one of these can be sentences can be true. Furthermore, the objects $\mathbb{N}_0$ and $\mathbb{N}_1$ aren't isomorphic, since the set of sentences they satisfy are different.  So it seems to me that $\mathbb{N}$ cannot truly be pinned down. Furthermore, its categoricity is, in some sense, illusory. Is this correct, or am I missing something?


When a car's non-driving wheels are turned, what is the frictional force vector that actually causes the vehicle to turn in that direction?

I am almost a little embarrassed to be asking this question since my education and experience is in mechanical engineering.  However, I've drawn a few diagrams, but am still a little puzzled by this question...  In my diagrams, the vectors I've drawn don't seem to actually produce a resultant force that would actually push the vehicle one way or the other when a turn is desired....    From everyday experience, the short answer is that the actual forces that cause a vehicle to turn are due to frictional forces.  Anyone that has driven a car on reduced traction roads due to slush and ice can attest that those conditions result in a car usually not wanting to turn in the direction the steering wheels are turned.  Furthermore it isn't hard to imagine a car already in motion on a totally frictionless surface - turning the front wheels one way or the other would not make the vehicle turn in that direction at all...  For this case, please only consider a car with rear wheel drive and front wheel steering.  It seems rather obvious that in vehicle configurations where the steering wheels are also driving wheels (that is, front wheel drive, AWD, or 4WD), then the vehicle turns in the direction the steering wheels are turned because the actual forces the road surface exerts on the wheels are turned relative to the centerline and CG of the vehicle.  In a car with front steering and rear driving wheels, every part of the car forward of the rear driving wheels is being pushed forward by the rear driving wheels.  The car wants to go in a straight line.    Imagine that the car is in motion going forward and that the front wheels are turned only very slightly to left or right (a few degrees left or right of directly straight ahead), what force vectors and resultant actually produce the 'kick' that causes the entire front end of the vehicle to turn in the desired direction?  It is obvious that a rolling tire wants to continue rolling and that turning the wheel relative to its initial straight-ahead path would produce a scuffing situation - a high friction situation compared to rolling.    In a related situation, we can examine when a car is not in motion, but stopped. When a vehicle is at a complete stop and the front wheels are turned in the direction of an intended turn and obviously not rolling in the forward direction, what are the force vectors that result in the front of the vehicle turning in the direction of intended motion?  In my diagrams, I've isolated and examined the forces on the steering tires' contact patch with the road, but still cannot resolve a frictional force vector that would explain why the front end of the car turns...  I've even considered the gyroscopic effect of rotating wheels and thought that it might be due to a force that is exerted on a rotating wheel that has its rotating axis deflected when the wheels are steered - again I wasn't able to find anything and the gyroscopic restoring force would not explain how a stationary turned wheel causes a vehicle to turn anyway...  Please help me understand this seemingly simple concept....


cannot uprgade from 19.04 to 19.10 thence to 20

At this point in time (Nov. 2020) I am unable to get 19.04 to upgrade to 19.10, as a halfway point to 20. What to do? The various tools simple say 'can't upgrade to focal' but we are trying to get to 19.10 first, as I understand that is necessary.


Can I use a SRAM Powerlink on a Shimano chain

Have 9 speed Shimano chain that I need to shorten.     I don't have the Shimano pin so I need to go buy one. Could just reuse the regular pin but I already broke one chain tool trying that.  I think the SRAM Powerlink would be more convenient.       Is it safe to use the SRAM Powerlink on a Shimano chain? Or is there some other reusable connector (master link) for a Shimano chain?


I am a Pakistani citizen and applied for PLAB 2 UK visa (for 6 months) on 15th October 2015 and was refused a visa based on the fact that the visa officer was not satisfied that I would leave the UK at the end of my visit.   My contract at work expires 2nd December 2015 and my exam is on 6th January 2016. I stated in the application form I will be staying for 3 months and I will be flying to UK on 1st December 2015. I work on an annual contract basis and according to the hospital policy the contract is renewed only a month before expiry.   So there was no way for me to show them my new contract which would be renewed in November 2015. Now my exam fee and the my career are at jeopardy. I assumed they would understand that I will be staying for at least 3 months because in case I fail my exam I will re-apply from within UK within that valid 6 month period of the visa.   I have not been given any right of appeal or administrative review. Please guide on when can i make my new application. My new contract is ready now.


Can I block with my Llanowar elves and then tap it for mana immediately afterward?

My opponent attacks with a 3/3. I block with my 1/1 , and have all of my land tapped from my last turn. Can I now tap my Llanowar Elves after it has been declared as a blocker to play  on it, make it 4/4 until end of turn, and destroy my opponent's attacking creature when damage is dealt?


How to create blurring layer in adobe illustrator

I'm interested in Gaussian blur layer that blurring all inside of some figure located on this layer.  I mean, blurred background of some exact area. And in case of I move this area, blurred image must be updated. If I move some object in background - blur must be updated. etc.


Showing that $y$ is irreducible in $\mathbb R[x,y]/(x^2+y^2-1)$.

Let $B = \mathbb R[x,y]$ where $x^2 + y^2 = 1$ which is called the coordinate ring of the unit circle. I am trying to prove that $y$ is irreducible in $B.$ I have the following information about $B$: 1- $B$ is an integral domain. 2- $B = \mathbb R[x] \oplus \mathbb R[x]y$ and multiplication by $y$ is a map of $B$ as an $\mathbb R[x]$-module. And $y$ is integral over $\mathbb R[x]$ and so there is a ring inclusion $B \rightarrow M_2(\mathbb R[x]),$ called a representation of $B$ described below: $$\phi:B \rightarrow M_{2}(\mathbb R[x]), \phi (a_{1} + a_{2}y) =  \begin{pmatrix} a_{1} & a_{2}(1-x^2) \\ a_{2} & a_{1}  \end{pmatrix} $$ 3- Also, I know that $B^* = \mathbb R^*$ I am trying to use  Eisenstein criterion for showing that $y$ is irreducible. Here is my try: We need to find a prime $p$ such that $p$ divides $0$ because we have only 1 coefficient which is the leading coefficient and every other coefficients are $0$ and any prime can divide zero trivially. Also any prime does not divide 1. But now I do not know why $p^2$ does not divide $a_0$ which is zero in our case ...I need $p^2$ to divide $a_0$ to fullfill the conditions for Eisenstein Criterion. Could anyone explain this to me please? Also, is there any use for the fact that $y$ is integral in this proof?


Why does my dock keep moving back to my other monitor?

I have a larger, external monitor connected to my MacBook Pro and have arranged it such that the dock is in the external monitor (via System Preferences > Displays > Arrangement, by dragging the white bar to the larger screen). This works fine, except for the fact that every now and then, the dock will suddenly shift back to my MacBook screen, but when I open up Displays to change this back, the white bar is still on the external monitor. So I have to drag it to the smaller screen, and then drag it back to the external monitor.   It's a minor issue, obviously, but I've noticed that it has been happening more and more frequently and it's getting quite annoying. Perhaps there's something I've been doing unintentionally for this to happen?   I'm using Mavericks, 10.9.5.


W: Failed to fetch http: //ppa.launchpad.net/picaso/octave/ubuntu/dists/trusty/main/binary-amd64/Packages  404  Not Found  W: Failed to fetch http: //ppa.launchpad.net/picaso/octave/ubuntu/dists/trusty/main/binary-i386/Packages  404  Not Found  W: Failed to fetch http: //ppa.launchpad.net/kilian/f.lux/ubuntu/dists/trusty/main/binary-amd64/Packages  404  Not Found  W: Failed to fetch http: //ppa.launchpad.net/kilian/f.lux/ubuntu/dists/trusty/main/binary-i386/Packages  404  Not Found  E: Some index files failed to download. They have been ignored, or old ones used instead.   I`m not being able to update  my ubuntu 14.04 And i face some 404 not found too.


What's with the bat branding and its consequences?

Why do the prisoners attack the guy with the bat brand in Batman V Superman: Dawn of Justice?  I'd think many of them are in there because of Batman.  Why would a person branded by Batman be especially in danger?


Electrons belong to a group of elementary particles called leptons. There are charged and neutral leptons. And electron is the charged one. But how come it got charged?  The negative or positive charges were assigned by convention. But it is a fact that electrons are charged. My question is why electrons? and not neutrons?  Also while reading , I saw that "Independent electrons moving in vacuum are termed free electrons. Electrons in metals also behave as if they were free. In reality the particles that are commonly termed electrons in metals and other solids are quasi electrons, quasiparticles, which have the same electrical charge, spin and magnetic moment as real electrons but may have a different mass  ( or Effective mass - extra mass that a particle seems to have while interacting with some force )."  What does this mean?


My domain name is not in search but few other pages are in search

This is really weird but its happening. The domain is about 6 months old and was built with wordpress. It was hacked (a lot of pages were appending after domain name in chinese language etc. I could see using site:domain.com) but I am not getting any clicks from those hacked pages anymore.  Now it is in different hosting and built from scratch, not using wordpress anymore. I submitted new site to google and it shows indexed. One of the page (domain.com/certification) is even appearing in google search on page 1/2.   However when I type domain name 'domain' in search. Its not there. It shows whois domain, domain.sg or some other extension but not domain.com. Seems like my domain does not exist at all?  Does deleting domain from search console and starting from scratch helps? Does verifying domain ownership with different methods help?  Even brand new site shows up after a week or two but something is going on here. Can anyone help me how to fix this issue?


Windows/Installer and Windows/winsxs using up 25% of my 60gb SSD

I'm wondering if anyone knows a safe way to clean these two folders or even clean the Windows folder so that I can get some space back as it's eating 25% of my SSD, the entire windows folder is taking 30%    Any help would be much appreciated


Today I saw this "try and avoid" phrase in a sentence .  "Try and avoid repeating the problems with the images dataset". What does "try and avoid" in this sentence mean? Is it the same with "try to avoid ? "


How to fix corrupted bash-completion in command substitution?

it seems my bash-completion got corrupted. Every time I try to use command substitution, for example when I type  ls $(ls Deskto<Tab>   ..result is..  ls $(ls Desktobash unexpected eof while looking for matching ")".   I tried removing my .bashrc file and cp /etc/skel/bashrc ~/ to get a new one. That works until I add something into my new bashrc. Even when I do echo '#" >> ./.bashrc it breaks again. Removing my bash_aliases did not help either.  Also sudo apt-get install --reinstall bash-completion did not do the trick.  However there are some threads about similar problem, nothing works.  ANY hint will be greatly appreciated! :)


Show $f(x)=\sqrt{x}$ is uniformly continuous on $[0,\infty)$     Let $\epsilon>0$, then there exists a $\delta=\epsilon^2$ such that $|x_1-x_2|<\delta$ for all $x_1,x_2\in[0,\infty)$.  $\begin{align}|f(x_1)-f(x_2)|&=|\sqrt{x_1}-\sqrt{x_2}|\\&<\sqrt{|x_1-x_2|}\\&<\sqrt{\delta}\\&=\epsilon\end{align}$    Can someone tell me where I did wrong? I don't see where the error is. Thanks    EDIT  From comment, people said the argument I have is right, I want to know how to show $|\sqrt{x_1}-\sqrt {x_2} |\leq\sqrt {|x_1-x_2|} $ is true.


Uploading a csv and losing a connection results in lost disk space and table bloat

I have a server with 150GB of diskspace. Today I uploaded a dataset of 30GB. I cancelled the import due to internet dying, then noticed there was 29GB of space missing in the database (meaning the CSV was uploaded, but not deleted when I broke the operation). When uploading the data once again, it broke again and I lost another ~25GB. Now there isn't enough free space to upload the data.  This is hosted on AWS RDS, Postgres 10.6.  Is there a way to fix this? But will this delete records? I'm hosting at the moment ~70GB of data and don't want to lose any records. What's the best way to go about this?


Is there an upper limit to a rocket's size/payload?

It's obvious that as you increase the payload of a rocket, you need to also increase the amount of rocket fuel. Yet, as you increase the amount of rocket fuel, you are also increasing the overall mass of the rocket and, therefore, require even more fuel to get the rocket off the ground.  From this observation, one could potentially conclude that as you double the payload of a rocket, you must roughly quadruple its fuel (I am making an assumption here, so correct me if I'm wrong on that one). With that said, is there a theoretical/practical upper limit to the size and payload of a chemical rocket?


Can I use null conditional operator instead of classic event raising pattern?

C# 6.0 adds this new ?. operator which now allows to invoke events like so:  someEvent?.Invoke(sender, args);   Now, from what I read, this operator guarantees that someEvent is evaluated once. Is it correct to use this kind of invocation instead of the classic pattern:  var copy = someEvent  if(copy != null)   copy(sender, args)   I'm aware of  where above version of pattern would require additional locks, but let's assume the simplest case.


Is the physics engine capable of reproducing this effect of a ball oscilating due to a water jet? [video]

So I have this video:   I'm wondering, is it possible in a scene to add a water source on top and a rigid-body ball on the floor, and with the correct viscosity and friction between the floor and the ball, would the Blender physics engine by itself be capable of reproducing this effect?  That last part is important. I don't mean if it is possible to reproduce doing the animation by hand, I mean if the physics engine itself is capable of doing the animation just by having the initial parameters.  For this it's necessary for there to be friction due to viscosity between the liquid and the ball, and friction due to surface irregularities between the ball and the floor.  Any comment is appreciated, thanks.  Edit: this question () was posted on 2013, as well as its answer, and I wanted to see if something had changed.


I have already download Firefox for Lubuntu a (Firefox.tar.bz2 file) and I have extracted the file after downloading. I have lot of files in that folder. from there, which file do I need to select for installation? can you please help me with the installation steps  I have no idea about Linux please help in detail


PHP switch statement showing file type meaning

The input $filetype is the file extension, so if we say it's PHP $def should be equal to "Web". But the output is just "Image" no matter what filetype is in the input.  $filetype = "PHP"; switch(strtolower($filetype)) {     case ("jpeg" || "jpg" || "png" || "ico" || "gif" || "svg" || "ps" || "psd" || "tif" || "tiff" || "ai" || "bmp"):         $def = 'Image';         break;     case ("aif" || "cda" || "mid" || "midi" || "mp3" || "mpa" || "ogg" || "wav" || "wma" || "wpl"):         $def = 'Audio';         break;     case ("7z" || "arj" || "deb" || "pkg" || "rar" || "gz" || "tar.gz" || "z" || "zip"):         $def = 'Archive';         break;     case ("bin" || "dmg" || "iso" || "toast" || "vcd"):         $def = 'Disc';         break;     case ("csv" || "dat" || "db" || "dbf" || "log" || "mdb" || "sav" || "sql" || "tar" || "xml"):         $def = 'Data';         break;     case ("apk" || "bat" || "cgi" || "pl" || "com" || "exe" || "gadget" || "jar" || "py" || "wsf"):         $def = 'Executable';         break;     case ("fnt" || "fon" || "otf" || "ttf"):         $def = 'Font';         break;     case ("asp" || "aspx" || "cer" || "cfm" || "css" || "htm" || "html" || "js" || "jsp" || "part" || "php" || "rss" || "xhtml"):         $def = 'Web';         break;     case ("key" || "odp" || "pps" || "ppt" || "pptx"):         $def = 'Presentation';         break;     case ("c" || "class" || "cpp" || "cs" || "h" || "java" || "sh" || "swift" || "vb"):         $def = 'Programming';         break;     case ("ods" || "xlr" || "xls" || "xlsx"):         $def = 'Spreadsheet';         break;     case ("3g2" || "3gp" || "avi" || "flv" || "h264" || "m4v" || "mkv" || "mov" || "mp4" || "mpg" || "mpeg" || "rm" || "swf" || "vob" || "wmv"):         $def = 'Video';         break;     case ("doc" || "docx" || "odt" || "pdf" || "rtf" || "tex" || "txt" || "wks" || "wps" || "wpd"):         $def = 'Document';         break;     default:         $def = ''; } echo $def;   How do i get the correct $def output from the switch?


How to make temperatures with decimal comma?

I was asked to write a document where I have to put temperatures like -51,4 degrees celcius. How can I do that in LaTeX? I tried   \usepackage{siunitx} ... \SI{-51{,}4}{\celsius}   but it turns the comma to the dot.


How to compute $\sum_{k=1}^{+\infty}kq^{k-1}$?

Another task from former tests of my basic course on probability...     Each time a cup of coffee is requested, a coffee express:         Brews coffee with probability $p_c=0.9$;   Pours hot water to the cup with probability $p_w=0.09$;   Gets out of order and refuses this and any subsequent requests with probability $p_f=0.01$.         Let $X$ denote the amount of coffees the express prepares before it gets out of order. Compute $\operatorname{E}X$.   My solution attempt:  On $k$th request, assuming the express is not broken, let $c_k$ denote the event that it prepares coffee, $w_k$ mean that it prepares boiling water and $f_k$ mean that it fails. We have $\operatorname{P}(c_k|\neg f_k)=\frac{\operatorname{P}(c_k\wedge\neg f_k)}{\operatorname{P}(\neg f_k)}=\frac{p_c}{1-p_f}$  Let $F=k$ mean that the express went out of order while handling the $k$th request. Now by the law of total expectation we have:  $\operatorname{E}X=\sum^{+\infty}_{k=1}\operatorname{P}(F=k)\operatorname{E}(X|F=k)$  $F$ has geometric distribution, so we have $\operatorname{P}(F=k)=(1-p_f)^{k-1}p_f$  $X|F=f$ has binomial distribution with $k-1$ experiments, each having probability of success equal to $\operatorname{P}(c_k|\neg f_k)=\frac{p_c}{1-p_f}$; thus $\operatorname{E}(X|F=k)=(k-1)\frac{p_c}{1-p_f}$  Therefore:  $\operatorname{E}X=\sum^{+\infty}_{k=1}\operatorname{P}(F=k)\operatorname{E}(X|F=k)=\sum^{+\infty}_{k=1}(1-p_f)^{k-1}p_f(k-1)\frac{p_c}{1-p_f}=\\p_cp_f\sum_{k=1}^{+\infty}(1-p_f)^{k-2}(k-1)=p_cp_f\sum_{k=1}^{+\infty}(1-p_f)^{k-1}k$  Here is were I'm stuck. How to compute this sum? I've really forgotten much from discrete mathematics :(


How can I reduce the margin between the first line of my document and the headerline?  \documentclass[12pt, a4paper]{article} \usepackage[ top=0.6in,bottom=0.6in,left=0.7in,right=0.5in]{geometry} \usepackage[utf8]{inputenc} \usepackage[misc]{ifsym} \usepackage{amsmath} \usepackage{amsfonts} \usepackage{mathtools} \usepackage{amssymb} \usepackage{forest} \usepackage[parfill]{parskip} \renewcommand{\baselinestretch}{1}  \usepackage{tikz} \usepackage{tkz-euclide} \usetkzobj{all} \usetikzlibrary{intersections} \makeatother \usepackage{fancyhdr} \pagestyle{fancy} \usepackage{lastpage} \lhead{LH} \rhead{RH} \chead{CH} \rfoot{Page \thepage \hspace{1pt} of \pageref{LastPage}} \lfoot{LF} \cfoot{CF} \renewcommand{\headrulewidth}{0.4pt} \renewcommand{\footrulewidth}{0.4pt} \begin{document} \large First Line of my document......... \end{document}


Why is my profile messed up on a single site and how can I revert it?

I was just asking a question on Gardening SE and suddenly my user name there is a25bedc5-3d09-41b8-82fb-ea6c353d75aand my picture is replaced by a Gravatar. My location is also left blank.  Here's a   Curiously, my profiles on all other sites are fine.  I don't have a separate login for SE, I log in using my Google account. Nobody other than me has access to my Google account. I use two step authentication and I can see on "recent devices" in Google that no one but me has accessed my Google account. I only access SE from home, and nobody other than me has used my devices.   I tried to edit my Gardening SE profile back to the way I want it to be and I got the following message:     Oops! There was a problem updating your profile:   Display name may only be changed once every 30 days; you may change again on Jun 20 at 10:49   I'm assuming this is because I changed the "about me" on all SE sites two days ago.  I never edit my profiles individually. I always apply changes to all sites, using the same profile on all sites.  I have certainly not made such strange (or any) edits to my profile on Gardening SE.  Why did this happen, and how can I get my proper user name and picture back on Gardening SE? Do I really have to wait for a whole month? I want to use the site, and I want them to recognize me as the user they know. I don't want to wait a whole month.  Update: The Gardening SE moderator Niall C. helped me out, and he offered the following potentially relevant information:     I changed your display name on Gardening & Landscaping back to "Fiksdal". Your profile history shows that your profile image (from your headshot on imgur.com to a gravatar), email, about me also changed at the same time as your display name on May 21. It also shows that I changed your profile image to a different gravatar when I changed your display name just now... weird! – Niall C. 1 hour ago


With office 2010 I would like to open two excel document on different monitor. The only way I achieved to do this was to widden the Excel main window over the both screen which is not very convenient because:   the mouse operation is not so easy. it hides what is between the two excel sheet.   Excel 2007 used to perform this very easily with a multi window system. Is there a tricks for 2010?


I have a shapefile with city areas, but unfortunately the shapefile only contains single lines. The shapefile looks like this:  I want to convert those lines to an area-polygon shapefile in QGIS. I tried it with the "Lines to polygons" tool (Vector > Geometry Tools > Lines to polygons), but it didn't work correctly. After using this tool, the shapefile looks like this:  Is there any other way to convert the line shapefile to an area polygon shapefile in QGIS? I am using QGIS 2.14.3 Essen.


is there an instruction manual for ubuntu 16.04.2?

Is there a book or instruction manual for ubuntu 16.04.2, other than the ubuntu desktop guide, that has all the commands for the terminal with definitions and uses for each one clearly defined?


Imagine a scenario where Jim provides a piece of information to Sue. Jim believes this information to be true and correct, but is later proven to be mistaken. Some might say that Jim lied to Sue. I believe this to be the wrong word, because the misinformation was unintentional.  Is there a better word for this type of unintentional "lie"?


I'm dynamically adding <script> tags to a page's <head>, and I'd like to be able to tell whether the loading failed in some way -- a 404, a script error in the loaded script, whatever.  In Firefox, this works:  var script_tag = document.createElement('script'); script_tag.setAttribute('type', 'text/javascript'); script_tag.setAttribute('src', 'http://fail.org/nonexistant.js'); script_tag.onerror = function() { alert("Loading failed!"); } document.getElementsByTagName('head')[0].appendChild(script_tag);   However, this doesn't work in IE or Safari.  Does anyone know of a way to make this work in browsers other than Firefox?  (I don't think a solution that requires placing special code within the .js files is a good one. It's inelegant and inflexible.)


Integrability of the Hilbert transform of a Schwartz function

Given a Schwartz function $f\colon\mathbb{R}\to\mathbb{R}$, define its Hilbert transform by $$(Hf)(x)=\frac{1}{\pi}\left(\int_{|t|\leq 1}\frac{f(x-t)-f(x)}{t}\,dt +  \int_{|t|\geq 1}\frac{f(x-t)}{t}\,dt\right)$$ (the first integral is interpreted as an appropriate limit/principal value).  It can be shown that $Hf$ is continuous and that  $\lim_{|x|\to\infty}x(Hf)(x)=\frac{1}{\pi}\int_{\mathbb{R}}f(t)\,dt=\frac{1}{\pi}\hat{f}(0)$. Using this, it is easy to prove that, if $Hf$ is absolutely integrable, $\hat{f}(0)$ must be $0$. I want to prove the converse.  So assume $\lim_{|x|\to\infty}x(Hf)(x)=0$. This by itself doesn't guarantee integrability of $Hf$, since $Hf$ might behave like $\frac{1}{x\log x}$ at infinity. A stronger decay condition for $Hf$ is needed, but I'm not sure where to get it from. The fact that $f$ is Schwartz should be important; does this imply $Hf$ decays faster than any polynomial?  Note, since this is a homework question, please don't be overly explicit in your answers.


Proving knowledge of a preimage of a hash without disclosing it?

We consider a public hash function $H$, assumed collision-resistant and preimage-resistant (for both first and second preimage), similar in construction to SHA-1 or SHA-256. Alice discloses a value $h$, claiming that she (or/and parties she can communicate with or/and devices they have access to) knows a message $m$ such that $H(m)=h$. Can some protocol convince Bob of this claim without help of a third party/device that Bob trusts, nor allowing Bob to find $m$? At Crypto 98 rump session, Hal Finney made a 7-minutes presentation  which seems to be intended for that. This remarkable result is occasionally stated as fact, including  and . But I do not get how it is supposed to work. Update: This talk mentions using the protocol in the Crypto'98 paper of Ronald Cramer and Ivan B. Damgård:  ( is very similar, or there is ).


ArcMap Crashes with ArcGIS has encountered serious error when Accessing Classified Symbology

Whenever I select classified symbology for a raster layer ArcMap will crash/close and give the message/ prompt to send error report: "ArcGIS has encountered a serious error.."  The problem is not associated with the data itself as it happens for any raster.  I have uninstalled ArcGIS 10.3 and reinstalled ArcGIS 10.4 and reset my normal file and the error still happens. There doesn't seem to be any issues with the install and the issue is new. I had been using ArcGIS 10.3 for a while with no issues.  The only change on my computer I can think of is I updated my AMD Radeon Display driver recently. However I have tried disabling it and running ArcMap and the same error occurs.


Was there ever a vaccine candidate that showed negative side effects many months or years after the patient was injected?

The current prognosis for a COVID-19 vaccine to become available is "12-18 months" and a big part of the reason for such a long timeline is the fact that scientists want to ensure that the vaccine is safe enough. But did this ever happen in practice? An article on CNN mentions the :      In 1976, President Gerald Ford's administration reacted at speed to a novel swine flu outbreak, ignoring the World Health Organization's words of caution and vowing to vaccinate "every man, woman and child in the United States." After 45 million people were vaccinated, the flu turned out to be mild. Worse, researchers discovered that a disproportionately high number of the vaccinated -- roughly 450 in all -- had developed Guillain-Barré syndrome, a rare disorder in which the body's immune system attacks the nerves, leading to paralysis. At least 30 people died. Upon discovery of the risk, the program was terminated in late 1976. A crush of lawsuits against the federal government followed.   However this looks like a very rare complication, only causing problems for 1 in 100,000 patients. And even that complication could've been detected :     About a week after getting the swine flu shot, she recalled, “I was so weak I couldn’t push down the toaster button.” She spent a month in the hospital, paralyzed from the neck down, before gradually recovering.   So has there ever been a vaccine trial satisfying the following conditions?   Significant side effects were detected Those side effects appeared in otherwise healthy candidates after more than 3 months since they were injected with the vaccine These side effects were something other than birth defects (those obviously take up to 9 months to show up)   If not, what causes scientists to be so cautious about testing a new vaccine quickly?


Something changed in QgsVectorDataProvider().changeAttributeValues() in QGIS 2.8?

I have a plugin that works with QGIS 2.2 but does not work with 2.8. Only deleteFeatures() works fine, but changeAttributeValues(), changeGeometryValues() and addFeatures() not.  I receive r == False on the code below. The layer is an SpatiaLite table.  for feat_vias in lay_vias.getFeatures(req):      if  feat_vias.attributes()[idx_pkvia] == div_rowid:         fid = feat_vias.id()         attrs = { idx_setvia : s_geocodi }         r = lay_vias.dataProvider().changeAttributeValues({ fid : attrs })   I'm using QGIS 2.8.1 - Windows  In another question () I found an Matthias Kuhn's answer that solve this question too.  I put the commit sentence outside the loop as below. Work fine!  for feat_vias in lay_vias.getFeatures(req):      if  feat_vias.attributes()[idx_pkvia] == div_rowid:         fid = feat_vias.id()         attrs[fid] = { idx_setvia : s_geocodi }  r = lay_vias.dataProvider().changeAttributeValues(attrs)


Would like to use different passwords for initial login and sudo for encrypted home folder

I just encrypted my home directory using ecryptfs and the instructions from .  In order to really benefit from the encryption, however, I needed to change to a stronger and longer password for login. Typing in a long password once at login doesn't bother me, but it does get annoying to have to type in such a long password every time I use sudo.  How can I set my account to use two passwords: a strong long password for login and a weaker shorter password for sudo (with an ecryptfs encrypted home folder)?


Do you reject the null hypothesis when $p < \alpha$ or $p \leq \alpha$?

This is clearly just a matter of definition or convention, and of almost no practical importance. If $\alpha$ is set to its traditional value of 0.05, is a $p$ value of 0.0500000000000... considered to be statistically significant or not? Is the rule to define statistical significance usually considered to be $p < \alpha$ or $p \leq \alpha$??


Woman Discovers she was a Male Astronaut

Looking for a short story where Happily Married woman discovers that she was a male astronaut on a Medical Ship and that her Husband is the Pilot. As I remember the Ship crashed during a war and She is drugged to feel that she has a happy life. One day the Drug (In the shape of an egg) is boiled, thus rendering it ineffective. Can't quite remember how the story ends except I recall her continuing to take the drug to remain happy whilst her "Husband" will live with the knowledge that they will never be rescued.


I want to install selenium webdriver in my Ubuntu 16.04 system for python

When I install Selenium I get the following error:  Shubham@Shubham-To-be-filled-by-O-E-M:~$ sudo apt-get update     Get:1 http://security.ubuntu.com/ubuntu xenial-security InRelease [107 kB]     Hit:2 https://repo.skype.com/deb stable InRelease                            Hit:3 http://in.archive.ubuntu.com/ubuntu xenial InRelease                          Get:4 http://in.archive.ubuntu.com/ubuntu xenial-updates InRelease [109 kB]     Get:5 http://in.archive.ubuntu.com/ubuntu xenial-backports InRelease [107 kB]       Fetched 323 kB in 8s (38.6 kB/s)                                                    Reading package lists... Done     Shubham@Shubham-To-be-filled-by-O-E-M:~$ sudo pip install selenium     Traceback (most recent call last):       File "/usr/bin/pip", line 9, in <module>         from pip import main     ImportError: cannot import name main   How should I proceed?


How to download and install a single package with all it's dependencies?

How to download a package with all its dependencies So that it can be installed later on another computer without the internet. I tried at . But it also needs to be download individually all dependencies.


I have an issue with cycles render where it doesn't seem to be rendering fully the eye just look dotty.    Here is a image of the rendered mesh and eye. I would prefer if it can be fully rendered instead of a dotty look. How can I achieve that?


I receive an error when trying to install Google Chrome

I am receiving a '403 forbidden error' when running sudo apt-get update. I have used the following commands to add the Google Chrome repository :  Add key:  wget -q -O - https://dl-ssl.google.com/linux/linux_signing_key.pub | sudo apt-key add -    Add repository:  sudo sh -c 'echo "deb [arch=amd64] http://dl.google.com/linux/chrome/deb/ stable main" >> /etc/apt/sources.list.d/google-chrome.list'   Install package:  sudo apt-get update  sudo apt-get install google-chrome-stable   Output of apt-get update:    sudo apt-get update    Ign http://dl.google.com stable InRelease   Ign http://dl.google.com stable Release.gpg                                        Ign http://dl.google.com stable Release                                            Err http://dl.google.com stable/main amd64 Packages  403  Forbidden [IP: 172.217.26.206 80]                             Ign http://dl.google.com stable/main Translation-en_IN                             Ign http://dl.google.com stable/main Translation-en                                Ign http://extras.ubuntu.com trusty InRelease                                      Hit http://security.ubuntu.com trusty-security InRelease                           Ign http://in.archive.ubuntu.com trusty InRelease                                  Hit http://ppa.launchpad.net trusty InRelease                                      Hit http://in.archive.ubuntu.com trusty-updates InRelease                          Hit http://extras.ubuntu.com trusty Release.gpg                                    Hit http://security.ubuntu.com trusty-security/main Sources                        Hit http://in.archive.ubuntu.com trusty-backports InRelease                        Hit http://extras.ubuntu.com trusty Release                                        Hit http://ppa.launchpad.net trusty/main amd64 Packages                            Hit https://repo.skype.com stable InRelease                                        Hit http://in.archive.ubuntu.com trusty Release.gpg                                Hit http://ppa.launchpad.net trusty/main i386 Packages                             Hit http://security.ubuntu.com trusty-security/restricted Sources                  Hit http://in.archive.ubuntu.com trusty-updates/main Sources                       Hit http://ppa.launchpad.net trusty/main Translation-en                            Hit http://security.ubuntu.com trusty-security/universe Sources                    Hit http://in.archive.ubuntu.com trusty-updates/restricted Sources                 Hit http://security.ubuntu.com trusty-security/multiverse Sources                  Hit https://repo.skype.com stable/main amd64 Packages                              Hit http://in.archive.ubuntu.com trusty-updates/universe Sources                   Hit http://extras.ubuntu.com trusty/main Sources                                   Ign ftp://apt.postgresql.org trusty-pgdg/main Translation-en                       W: Failed to fetch http://dl.google.com/linux/chrome/deb/dists/stable/main/binary-amd64/Packages  403  Forbidden [IP: 172.217.26.206 80]    E: Some index files failed to download. They have been ignored, or old ones used instead.


Prove that $\Vert f(b)-f(a)-f'(a)(b-a) \Vert\leq \sup_{x\in [a,b]} \Vert f''(x)\Vert\Vert b-a\Vert^2$

Let $\Omega$ be an open set in $\Bbb{R}^n$ and $f:\Omega\to \Bbb{R}^m $ be of class $\Bbb{C}^2.$ Let $a,b$ be in $\Omega$ such that $[a,b]\subset \Omega.$ Prove that  \begin{align}\Vert f(b)-f(a)-f'(a)(b-a) \Vert\leq \sup_{x\in [a,b]} \Vert f''(x)\Vert\Vert b-a\Vert^2.\end{align} where $$f'(a)(b-a)=\big<\nabla f(x),(b-a)\big>=\sum^{n}_{k=1}\frac{\partial f_i}{\partial x_k}(a)(b_k-a_k).$$  I  think the idea of Mean Value Theorem for $C'$ functions in $\Bbb{R}^n$ () will help me in showing it but I don't know how to! Please, can anyone show me a proof or reference?


How can I download Ubuntu packages and take them home for installing?

I do not have internet at home but I can go to an internet cafe to download things.  The thing is I have Ubuntu and I don't no how to download Ubuntu-compatible software  from another PC and then get it installed on my PC at home.  What do I need to do?


After rain, we often find shrimp-like creatures in the puddles left on our concrete patio. We have also found them in the cat's water bowl (on the same patio). They are pink in color, and around 3mm long.   The idea of shrimp on land seems absurd, but that's certainly what they look like.  We live in Okinawa, and even long-time local residents don't seem to know what they are. We're on a cliff 10 meters tall, right next to the beach.  My questions: what are they, and how do they magically appear after rain? From eggs that are lying dormant on my patio, waiting for rain??  The alleged duplicate is quite helpful. My question is slightly different because I live beachside in Okinawa, not in central Florida, and my creatures are much smaller. Probably a related species, though one that doesn't seem to be familiar to the locals.


Is it possible to achieve autocomplete to predifined text in gnome-terminal?

I have started learning Ubuntu since 1 year.. During this 1 year period I typed a lot of these below texts in gnome-terminal  sudo -H nautilus /foo1/foo2/foo3/foo4/ sudo -H gedit /foo1/foo2/foo3/foo4/   what i am trying to ask is,  Is there a way I can configure like if I type sn and then press TAB, Autocompletion to sudo -H nautilus type sg TAB, Autocompletion to sudo -H gedit  I am Using Ubuntu 18.04 & 18.10 with gnome-terminal  Edit: I am not looking to type sn /foo1/foo2/foo3/foo4 or sg /foo1/foo2/foo3/foo4. looking for sn TAB or sn TAB TAB to see the text on terminal as sudo -H nautilus


A large (curved) arrow is causing my tikz-cd diagram to have too much space on one side. How can I fix this?

I use tikz-cd to draw commutative diagrams, and recently needed to draw a diagram of the following form (this is a MWE):  \documentclass{standalone} \usepackage{tikz-cd}  \begin{document}  $$ \begin{tikzcd}[column sep=-1cm] &   A \ar[ddd, controls={+(-7,0) and +(-7,0)}, start anchor=west,end anchor=west] & B \\ & C & D\\ E(BIG THING) & & \\ & F(BIG THING HERE, TOO)  &  \end{tikzcd} $$  \end{document}   Sadly, this produces a diagram with strange spacing issues; the output looks like this (never mind the bad anchors of the arrow; I know how to fix that):    Note the large amount of white space on the left side of the diagram (the picture is left-aligned on Stack Exchange). Needless to say, this messes up the way my page looks (the actual diagram I want to draw now does not fit inside the margins because of the space on the left), so I'd like to understand tow things:   Why is this happening? What can I do how to fix it?   Particular emphasis lies on the second point ;-)


What's the thing with empty script tags in HTML?

To include an external JavaScript file in HTML page you would use this:  <script type="text/javascript" src="images/jquery-2.2.2.js"></script>   The body of this tag is empty, yet I have to type the string script twice. Why isn't XML-style implicit closing tag in HTML, like this:  <script type="text/javascript" src="images/jquery-2.2.2.js" />   If it is valid (at least in HTML5), then how to make sure every browser supporting HTML5 (or XHTML5) can pick up on this usage?  EDIT  I'm gonna take this question to HTML WG. Deprecate the src attribute on <script> as it is the source of this entire confusion, with one of the two options:   <link> tag instead of an empty <script> tag:  <link type="text/javascript" href="images/jquery-2.2.2.js" />   Or optionally with a rel attribute:  <link rel="script" type="text/javascript" href="images/jquery-2.2.2.js" />  PHP-style include() in JavaScript itself: (thus force some content into the tag at all times, and allow multiple scripts to be included in one script tag)  <script type="text/javascript">include("images/jquery-2.2.2.js");</script>


A and B are nxn matrices, $A =B^TB$. Prove that if rank(B)=n, A is pos def, and if rank(B)<b, A is pos semi-def.

$A$ and $B$ are $n\times n$ matrices, A = $B^{T}B$. Prove that if $\operatorname{rank}(B)=n$, then  $A$ is positive definite, and if $\operatorname{rank}(B)<n$, $A$ is positive semi-definite.    My current understanding is that if $\operatorname{rank}(B)=n$, then $\operatorname{rank}(B^{T}B)=n$ then $\operatorname{rank}(A)=n$, making $A$ positive definite.   Similarly, if $\operatorname{rank}(B)\le n$, then $\operatorname{rank}(B^{T}B)\le n$ then $\operatorname{rank}(A)\le n$, making $A$ positive semi-definite.  This doesn't feel like a complete proof. Is there anything I am missing?


Finding rows affected by deadlock on page locks

We've got a db that has been pretty much deadlock free for over 6 months, but a day or two ago we had over 60, all on the same two or three pages of the same table (~12,000,000 rows, ~250 bytes per row.)  From the deadlock graph I can see what pages are common in all the deadlocks, and part of the query that was running (always an INSERT vs a SELECT) but I have no idea what rows or data this involves. Is there any way to find out?


Stack Overflow No captcha box is shown in the human verification page

I'm using an approved browsers like Chrome and Safari. But in the human verification page, the Captcha box is not displaying for me.  What should I do?


I apologize for repeating my question, but it was suggested that I ask it on this StackExchange site instead of stackoverflow:  :  I have created a simple .NET 4.5 Entity Framework Winforms application with Visual Studio and would like to open it on OS X.  I have used Wine before to open .exe's in the past and am having difficulty this time around. I have downloaded the most recent version of Wine, as well as OS X.  When I attempt to open the .exe with Wine, nothing happens. No error messages. Nothing.  When I attempt to package the .exe with WineBottler, I get a popup that says "Prefix created successfully"; however, when I attempt to open the newly created file, again, nothing happens.  I am very new to using Wine and have noticed that there are WineTricks you can use, but I am not sure if that is necessary. Again, I used Wine before on a very simple app and it worked just fine without using any WineTricks, but I am not sure whether I should include them for this app.  I have googled for help, but have not found much. Any assistance is greatly appreciated!


A question about the equivalence relation on the localization of a ring.

Let $A$ be a ring and $S$ a multiplicative closed set. Then the localization of $A$ with respect to $S$ is defined as the set $S^{-1}A$ consisting of equivalence classes of pairs $(a, s)$ where to such pairs $(a,s), (b,t)$ are said to be equivalent if there exists some $u$ in $S$ such that  $$u(at-bs)=0$$ Now, in the  about the localization of a ring, it says that the existence of that $u\in S$ is crucial in order to guarantee the transitive property of the equivalence relation.   I've seen the proof that the equivalence relation defined above is indeed an equivalence relation, but I fail to see how crucial the existence of $u$ is. For example, why doesn't it work if we simply say that two pairs $(a,s),(b,t)$ are equivalent iff $at - bs = 0$? I tried to come up with a counterexample for such case, but failed in the attempt.


altering my connect code to protect from SQL injection

I was wondering if someone would be able to help me alter my connect code & queries so that it helps to protect me from SQL injection?   Any advice would be amazing   I have the below code in a dbconfig.php file:  <?php $servername = "localhost"; $username = "root"; $password = "fnjfi8378f3hrn39fb3"; $dbname = "crm4";  // Create connection $conn = new mysqli($servername, $username, $password, $dbname);  // Check connection if ($conn->connect_error) {     die("Connection failed: " . $conn->connect_error); } ?>   and the below on a web page running a query:  <?php                   $sql = "SELECT format(count(id),0) as id3 FROM Orders                  INNER JOIN membership_userrecords ON Orders.id = membership_userrecords.pkValue where Year = 2017 AND membership_userrecords.memberID = '$memberid' AND membership_userrecords.tableName='Orders'   "; $result2 = $conn->query($sql); $row = $result2->fetch_assoc(); echo $row["id3"];   ?>


How do I prove that:   $\lim \limits_{n\to \infty}2^{1/n}=1$  Thank you very much.


Create a blacklist to keep from seeing certain users

Not everyone abides by the rules of Stack Overflow. Sometimes they abuse the system by insulting other users as well as down-voting their questions, among other things. It would be nice if a user could have blacklist, perhaps enabling read-only access to that group of users.  This would not only help the victims of those users, but also Moderators, who constantly have to intervene to resolve petty conflicts, becoming a bigger problem as the community expands.


Best way to extract a subvector from a vector?

Suppose I have a std::vector (let's call it myVec) of size N.  What's the simplest way to construct a new vector consisting of a copy of elements X through Y, where 0 <= X <= Y <= N-1?  For example, myVec [100000] through myVec [100999] in a vector of size 150000.  If this cannot be done efficiently with a vector, is there another STL datatype that I should use instead?


Is it possible to schedule a task only on working days?

Is it possible to schedule a task only for working days (Monday to Friday)?


I am trying to create a script which scrapes a website for phrases which gets saved to a list and then displayed in a randomized manner. Here's the code-  from bs4 import BeautifulSoup import requests import random  url = 'https://www.phrases.org.uk/meanings/phrases-and-sayings-list.html' page = requests.get(url) soup = BeautifulSoup(page.content, 'html.parser')  for phrase in soup.find_all(class_='phrase-list'):     phrase_text = phrase.text     print(phrase_text)   This shows up the entire list of phrases that are scraped. How can I randomly show one phrase from the list of all phrases?


Singular values of the data matrix and eigenvalues of the covariance matrix

I am having some problem in computing SVD and PCA in Matlab. I do not know if I am doing theoretical mistakes or programming mistakes.  Starting with a data matrix $X$, PCA computes the eigenvalues $\lambda_i$ of the covariance matrix $X^TX/(n-1)$.  On the other side SVD of $X$ is given by  $X=U\Sigma V^\top$, and so $$X^T X=V \Sigma^T U^T U\Sigma V^T=V \Sigma^2 V^T,$$ where $\Sigma$ is diagonal matrix of singular values with elements $\sigma_i$.  So we have that $$\lambda_i=\sigma_i^2 /(n-1).$$  Now I try a Matlab example:      load hald;     [u s v] = svd(ingredients);     sigma = cov(ingredients);     [a,b] = eig(sigma);     disp('sigma')     disp(diag(s)')     disp('lambda')     disp(diag(b)')   and here is the output:   sigma   211.3369   77.2356   28.4597   10.2667  lambda     0.2372   12.4054   67.4964  517.7969   The obtained values do not respect the original equation. Where is the mistake?


How to create alias with a command contains ' and "

A few posts ago someone asked how to show memory in percentage. Someone replied with:  free | awk '/^Mem/ { printf("free: %.2f %\n", $4/$2 * 100.0) }'   I was wondering if I can turn this command into an alias in ~/.bashrc. But the syntax of alias is:  alias aliasname='command'   How can I do this? That command contains both ' and ". I tried different ways, but it didn't work. Is this even possible? Am I missing something?


change folder icons in ubuntu-mono-dark theme

I'm running 13.10 with Unity, and I have a "problem":  I'm using Nemo, because I prefer it over Nautilus (for obvious reasons imo), and it works really great.  The drawback of Nemo is, that it is kind of ugly; so I want to change the Icons of the folders. That's not a problem at all, using unity-tweak-tool, to change for example to one of the icon-themes which are delivered by .   The thing is, although this works great, and the Icons change, the problem is, that all of the Icons change, including my applications in the tray, and application icons in the dash. Can I modify the theme in such a way, that only the Icons for the folders change, and nothing else?  So e.g. delete everything in the ~/.icon/<theme-name>/ folder except places and "inherit" everything else from the default ubuntu-mono-dark theme?


What other languages have features and/or libraries similar to Perl's format?

I may be in the minority here, but I very much enjoy .  I especially like being able to wrap a long piece of text within a column ("~~  ^<<<<<<<<<<<<<<<<" type stuff).  Are there any other programming languages that have similar features, or libraries that implement similar features?  I am especially interested in any libraries that implement something similar for Ruby, but I'm also curious about any other options.


I am baffled by a sentence that I came across in a book recently. "Americans are a very practical people". Why do we need the article "a" here?


Here's the description of the badge:     Zero score accepted answers: more than 10 and 25% of total   Is it possible delete my answers with positive points, and then undelete them? What will happen if delete and then undelete an accepted answer - will the "green thick" remain? Has anyone tried to cheat this way?  I won't try this but wondered if it's possible.


How to access shapefile m-values with pyqgis?

How can I access (read/write) m values of a line Shapefile using pyqgis?   I know how to do it with arcpy cursors ( ) but I don't know how to do it with pyqgis.   Is it possible with the QGIS python library?


Which is better, MySQL or MySQLi? And why? Which should I use?  I mean better not just in terms of performance, but any other relevant feature.


What is it called when we follow an acronym with a word already in the acronym?

Example:  PIN Number (PIN=Personal Identification Number), no need to repeat number  RSVP please (RSVP=Answer please in French), no need to say please again  etc.


~/cite : Is the Tie Actully Recommended?

When making citations, I've seen both styles: with the tie/non-breaking space (~\cite{refnm}) and without it (\cite{refnm}). There are a few questions & answers on this topic in the more general sense, recommending reasonable things like a tie before a \ref. However, \cite never seems to be mentioned in these lists...  I happen to be mostly concerned about numeric styles like IEEE, which I think is unlikely to produce bad line breaks if a tie is used, but what about other styles, and is it really recommended?  Interestingly, the  only says the following about references, which I think a few other guides have turned into "should be one the same line" (I'm pretty sure they mean as opposed to super/sub-script).     When they are, they appear on the line, in square   brackets, inside the punctuation. Grammatically, they may be treated as if they were footnote numbers [...]   I did look at , and I thought that \cite deserves a separate question - I think it's pretty different case from \ref. I guess I'm looking for a more stylistic opinion.


When I do the command below:  sudo apt-get upgrade   At the bottom I get an error saying  W: GPG error: http://download.opensuse.org  Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 8873E7BF70F1BBEA   How do I retrieve this key from the opensuse.org server? If I were to look on their website I won't be able to find the key. There are so many nested directories on the , and I don't know where to look to find it. I don't even know what application or what update it's even for.    Update  I have followed the guides in the comments and it doesn't work. I moved my lists file, and created a new one when using apt-get update. I now have 15 PPA files, and 16 security files. After removing some of the other GPG keys, I now have even MORE errors when updating.


A word to describe responses such as "I see" and "Okay"

While conversing, I sometimes find myself, after listening to what my partner has to say, responding with phrases such as "I see" and "Okay" to indicate that I haven't lost interest but I either don't have a point to add, or the other person hasn't finished talking. Is there a word, preferably informal, to describe this kind of response?


Redirect stdout and stderr to a file and also to console in linux

I can redirect stdout and stderr to a file like below  some_command.sh >> file.txt 2>&1   Can someone let me know how can I redirect stdout and stderr to a file and also to console?


things to check prior to moving all FSMO roles to a new domain controller before decommission original old domain controller

need to move a domain controller, the first in the forest that holds all the fsmo roles, to another location in a clients building. it will require turning off this dc, call it dc1 for this question. i want to transfer the fsmo roles to a new domain controller call the new one dc2. dc2 is already on the network and has been promoted and made a domain controller, it's dns settings are set and it is also a global catalog (GC). the work is scheduled to be done after hours and i am also planning on moving the dhcp server to dc2.  i am looking for a best practices checklist of things to verify prior to moving fsmo roles and turning dc1 off? as far as i know there are no issues with replication between the dc's. my biggest worry is if i turn on dc1 after moving it and i have hardware issues or boot issues, i would rather move the fsmo roles to a known good one that is a few months old (dc2) vs still using a 5yr old box (dc1), this is part of my migration strategy too.   thanks for the help.


Can I leave UK without the person that is on my visa?

I’m a minor 17 and I’m from Peru. I have requested a visa for the UK for a short-term study less than 6 months and I didn’t realize that they wrote in there only acc by/ father/. I’ll be entry the country with my father but I will not leave with him. I’ll return alone. If I present at the moment to leave the country a letter consent where both of my parents sign that I’m allowed to leave and entry the country without them. Will they let me leave the UK? Please I’m really worried about it


Remap arrow keys to a new key combination

The Left, Up and Down keys on my keyboard are broken and won't register any key codes. I have tested it using xev.   I would like to make the following keys trigger the key codes associated with the broken keys.  <Win> h -> Left <Win> j -> Down <Win> k -> Up <Win> l -> Right   I have read that this is a job for xkb, but I don't know how to go about it.  Any help is appreciated!


What is the minimum height for garbage disposal drain above the drain stub

Apparently the garbage disposal drain must be above the drain stub, but I can't find a clear answer for how much height difference is actually required.  Let's use this drawing:    The question is how much higher does the disposal drain (#1) have to be relative to the drain stub (#5)?  I've seen answers ranging from "just above it", to 1 inch, to 4 inches, so what's the actual minimum I can get away with?  Also, how do you measure it?  Is the important measurement going from the bottom of #1 to the bottom of #5?  Or from the bottom of #1 to the top of #5?


how to prevent user creating a duplicate node title for a content type?  I already try uniqueness module () but it's only list out the duplicate content title but not return any error message when user save the new content. Any suggestion module or code? :)


How install Ubuntu on Dell 3521 Laptop with new blank disk

I am fixing a Dell 3521 laptop for a friend.    The old hard drive was broken. Put in a Western Digital-blue 320 GB disk.    Using a freeware bootable CD formatted the hard drive and it found zero bad blocks.  It currently has Fat32.  Want to use whatever Ubuntu likes best.  There will be no other OS.  Just Ubuntu on a Dell 3521 Laptop.   What version of Ubuntu should I use? Then make how a bootable Ubuntu install CD.   Thanks.


Prove cancellation law on multiplication without using trichotomy of order

In textbook A Course in Mathematical Analysis by prof D. J. H. Garling, the author proves the cancellation law in multiplication before he moves on to prove the trichotomy of order. I have tried to prove by induction many times but to no avail. Please shed some light!  Below are properties of addition and multiplication that I can use:        Peano's axioms   Definition of Addition: Considering the (successor) mapping $s:\mathbb{N} \to \mathbb{N}$, setting $m_0=m$, and using recursion, there exists a sequence $(m_n)_{n \in \mathbb{N}}$ such that $m_0=m$ and $m_{s(n)}=s(m_n)$. Define $m+n:=m_n$. Thus $m=m+0$ and $s(m)=m+1$. Hence the equation $m_{s(n)}=s(m_n)$ becomes $m+(n+1)=(m+n)+1$.   Definition of Multiplication: Suppose that $n \in \mathbb{N}$. Using recursion, there exists a sequence $(p_m)_{m \in \mathbb{N}}$ such that $p_0=0$ and $p_{m+1}=p_m+n$. Define $m.n:=p_m$.   $m+n=n+m$   $(m+n)+p=m+(n+p)$   $m+n=p+n \implies m=p$   $m+n=0 \implies m=n=0$   $m.n=n.m$   $0.n=0$ and $1.n=n$   $(m.n).p=m.(n.p)$      Now I want to prove the cancellation law on multiplication:     $m.n=p.n \wedge n \neq 0 \implies  m=p$   Here is my take:     Let $U=\{n \in \mathbb{N}^{*} \mid m.n=p.n \implies  m=p, \text{ for all } m,p \in \mathbb{N}\}$ and $V=U \cup \{0\}$.      It's clear that $0 \in V$.      Assume $n \in V$. Then $m.n=p.n \implies  m=p$.      Now we prove $n+1 \in V$ i.e. $m.(n+1)=p.(n+1) \implies  m=p$. To prove this, it is equivalent to prove $m.(n+1)=p.(n+1) \implies m.n=p.n$.   I don't know how to precede to prove $m.(n+1)=p.(n+1) \implies m.n=p.n$  PS: I updated the excerpt from textbook. As you can see, the author proves the cancellation law in multiplication (Theorem 2.1.2) before he proves the trichotomy of order (Theorem 2.1.5).


Prove that if $\alpha$ is an algebraic number and a root of $f(x)$ where $f$ has leading coefficient $a$, then $a\alpha$ is an algebraic integer.

I am currently learning Number Theory and one of the appendices of the book I am currently using introduces algebraic numbers and algebraic integers. One of the exercices is to prove the statement in the title: Prove that if $\alpha$ is an algebraic number and a root of $f(x) \in \mathbb{Z}[x]$ where $f$ has leading coefficient $a$, then $a\alpha$ is an algebraic integer. However, that statement does not make sense to me when looking at the definition of these objects. If $\alpha$ is a root of $f(x)$ then $\alpha$ is an algebraic number, but since $f(x)$ has leading coefficient $a$ then $f(x)$ is not monic sur $\alpha$ is not an algebraic integer. Now, I thought about taking the function $g(x) = \frac{1}{a}f(x)$ so that $g(x)$ is monic, but then $g(x)$ might not be in $\mathbb{Z}[x]$ but we would have $\alpha$ an algebraic integer. However this does not solve the issue of $a\alpha$ being an algebraic integer. I have tried coming up with an example but even with simple ones it does not make sense to me. Take $$f(x) = 2x^2 - 4$$ then $\alpha = \sqrt{2}$ is a solution and $f(x)$ has leading coefficient $a = 2$ so we can apply the statement I am trying to prove and get that $2\sqrt{2}$ is an algebraic number but, even if we forget about the monic part of the definition: $$f(2\sqrt{2}) = 2(2\sqrt{2})^2 - 4 = 16 - 4 = 12 \neq 0$$ So $2\sqrt{2}$ is not a root of $f(x)$ therefore it is not an algebraic number, even less an algebraic integer. What am I doing wrong? Is my understanding of these objects wrong in some way?


Could I play online using one membership on two different consoles?

If I was to buy a PSN online membership card and activate it on my brother's PS4, could I play online on my PS4? (It's two different consoles).


A conjectured vanishing sum involving the Thue–Morse sequence

Let's define $t_n$ by the recurrence $$t_0 = 1, \quad t_n = (-1)^n \, t_{\lfloor n/2\rfloor}.\tag1$$ It is easy to see that $|t_n|=1$, and the signs follow the same pattern as  the : $$1,\,-1,\,-1,\,1,\,-1,\,1,\,1,\,-1,\,-1,\,1,\,1,\,-1,\,1,\,-1,\,-1,\,1,\,...\tag2$$ (see  for an example of a non-recursive formula for $t_n$).  Now, define: $$\mathcal{S}(m, n)=\sum_{k=0}^{2^n-1}t_k\,k^m, \quad \color{gray}{m,\,n\in\mathbb{Z}^+.}\tag3$$ Computing some values of this sum immediately leads to the following conjecture:     $$\text{For all }\, n>m,\,\,\mathcal{S}(m, n)=0.\tag{$\diamond$}$$   (e.g. for $m=2$ and $n=3$ we have $0-1-4+9-16+25+36-49=0$).  How can we prove it? Is it a known result?


How to rollback the view style of file holder as 12.04 in 14.04

I've upgraded the Ubuntu from 12.04 to 14.04. But there are something I want to change.  In 12.04, the view of file holder is as follows:    and we could open the file holder and its sub folders like this:    But in 14.04, the view style is changed into:    When I want to open the sub folder, I should click many times, especially the number of levels of sub folders is large.   So is there any way to back to the view style of file holder like 12.04? Thanks!


My mac encounters lots of internet usage?

My macbook is consuming lots of internet data, but usually my work needs nearly 1 or 2 GB but it consumes 8 to 10 GB of internet data, I don't know which app is using internet in background. I can't find that, tried so many ways.. I am using VPN for my work, in activity monitor its just showing process sslvpnd. Installed wireshark too, but Don't know how to find which app is using lots of data in background, If I find that, If I really don't want I can disable it. If anybody had experience in my issue, kindly help me to resolve that


I know what the  is, but I haven't found a lot of information as to their nature, such as where they came from, what they're capable of, or, most importantly, what they actually are.  Are they deities, or are they the pinnacle of being connected to the Force, or are they the next (or final) step for those who become Force ghosts?  Are they Force itself?  I've oft-heard people refer to the "will of the Force," so that makes me curious if it's actually their will.  ** I feel that it is important to mention that there is a common misconception that Yoda is a Whill.  George Lucas has strongly denied this.  Yoda's race is a mystery to fans, as far as I am aware, as Lucas has not revealed it yet.


Divergent infinite series $n!e^n/n^n$ - simpler proof of divergence?

$$ \sum_{n=1}^\infty \frac{n!e^n}{n^n} $$ Where $e$ is Euler's number.  Recently on calculus class we were covering convergence tests and my group got stuck with this infinite series. Our calculus teacher told us that it diverges but he doesn't see any elementary way or simple test to prove it. He told us something about Euler's Gamma function and said that he knows it diverges because of Stirling's formula but this is not quite our level yet.  I tried to think about it myself but I established only that this  is some kind of an edge case. We could generalize the problem to series of $\frac{n!a^n}{n^n}$. Then, from the ratio test we know that it converges for $a <e$ and diverges for $a>e$. For $a=e$ the test is inconclusive. I've also tried to compare it with various divergent series, but nothing worked...  Does anybody have any idea for a simple solution?


So I’m looking in to automated mobile testing solution and need some suggestions from experience folks who are currently using such tools. So far I’ve evaluated “Silk Mobile” and couple other tools but it seems they all needs to be physically connected to computer via USB. Is there any tool out there which doesn’t requires such USB connection all the times (of course when setting initially is acceptable).


Does blocking of ticket impacts Air fare?

As i discussed with travel agent, he was willing to block an international flight ticket with a low fare for 3-4 days.  Now in such cases where ticket is blocked and then released if person decides not to purchase then does it change air fares on various travel portals?  Take a scenario that a last ticket is remaining for cheapest airfare and somebody blocks it. This implies that the fare is not available anymore but if it is released back then same fare will be available again...right?  This can create a situation where one purchases an expensive ticket and next day, a cheap fare becomes available!!   Is this possible?


In the sentence     He is gone   Is 'is' a a helping verb, as if to say "he has gone". Or is "gone" a complement meaning not present?


When I ran  query, it is giving me this result: Accepted Answers     Scored Answers    Unscored Answers     Percentage Unscored 35                   26                9                    25.7  But when I count from answers tab, I have 42 accepted answers, out of which 27 are scored and 15 unscored. Of course 2 are self-accepted answers. Even then why this much difference? How far am I from the unsung hero badge?


The use of hyphen in consecutive compounds

I am not that punctuation-savy, so I have one question for my research title.  Currently it is      Social crowdfunding:  individual- and project-related determinants of success.    Empirical investigation on Kickstarter   Here I have two questions.   Is it right to say individual- or just individual?  Should there be a period after "Empirical investigation on Kickstarter"?


Is there any way to point the root domain to a CNAME?

Here is the problem: we host our website with an external provider that doesn't give us an IP address, rather, they give us a domain where we point our www CNAME record to. I assume they are using some type of virtual hosting that reads the header for the requested domain and displays that website.  Anyway, a lot of our users complain the website is down when it actually is not because they are typing example.com instead of www.example.com into their browsers.  Is there a way to make this work in our DNS?


I'm trying to get rid of diacritics in my textfile. I converted a pdf to text with a tool, not made by myself. I wasn't able to understand which encoding they use. The text is written in , orthographically familiar with Spanish. I transformed the text into a list of strings. No I'm trying to do the following: # check whether there is a not-ascii character in the item def is_ascii(word):     check = string.ascii_letters + "."     if word not in check:         return False     return True  # if there is a not ascii-character encode the string  def to_ascii(word):     if is_ascii(word) == False:         newWord = word.encode("utf8")         return newWord     return word  What I want to get is a unicode-version of my string. It doesn't work so far and I tried several encodings like latin1, cp1252, iso-8859-1. What I get is  Can anybody tell me what I did wrong? How can I find out the right encoding? Thank you! EDIT: I wrote to the people that developed the converter (pdf-txt) and they said they were using unicode already. So John Machin was right with (1) in his answer. As I wrote in some comment that wasn't clear to me, because in the Eclipse debugger the list itself showed some signs in unicodes, others not. And if I looked at the items seperately they were all decoded in some way, so that I actually saw unicode. Thank you for your help!


Is there any point forcing a post to Community Wiki after 6 owner edits?

Personally I think not. If the concern is spurious bumping then simply stop bumping the post after some arbitrary edit.  This site might be part-Wiki, part-Q&A but I think its clear that people feel a sense of ownership over their questions and answers, which CW diminishes to some respect.  The question is: does this happen enough such that people won't maintain their posts as the facts change? I suspect it does.  Edit: Let me just add that there are plenty of ways of bumping your post without editing it currently, such as:   Retagging the question (assuming you wrote an answer); Editing the question (assuming you wrote an answer); Editing someone else's answer; Adding another answer to the question;  Using a sock puppet to add another answer. Have a sock puppet edit it's own answer. Have a sock puppet edit someone else's answer (provided it has enough rep). Have a sock puppet edit the question/tags (provided it has enough rep, or owns the question).   AFAIK all of these things will bump the question to the front page and none of them involves editing your post. So if someone wanted to constantly bump a question they already can. I haven't seen a problem like this to date, which suggest to me that we don't have a problem with spurious bumping.


How to replace filename whitespace with underscore?

I have a routine need to replace filename whitespace (space, period, hyphen, etc) with underscore.  Normally, it seems faster to brute-force it with rename than to write a script.  Couple of months ago I found a program that does it perfectly and download it.  I should have named it something sensible, put its path in the path variable, and put a link to it on the desktop so I could locate it.  I didn't, and now I cannot find it because I don't remember its name or location.  Can anyone help me with this?


AoOs against the same enemy on his turn?

I have seen this question for D&D 4e:  and I was wondering about attacks of opportunity in Pathfinder/3.5e.  If an enemy goes from one threatened square to another one threatened by the same guy twice, and the threatening creature has combat reflexes and enough dexterity, could he be making more than one AoO against the same enemy for that movement?  As an example, imagine that a Medium size creature (A) with 5ft. reach charges against a Large humanoid with a reach weapon and a non-reach natural attack (e.g. a bite), Dex 20 and Combat Reflexes (B).  B threatens from 20ft to 10ft with his reach weapon and from 10ft to 5ft with the bite. For a total of 4 squares threatened on a straight line.  So, does A provoke three AoOs from B whenever he charges, for leaving 20ft., 15ft. and 10ft. during the same move?  Further, lets say B gets Hold the Line feat, which states:     Benefit      You may make an attack of opportunity against a charging opponent who   enters an area you threaten. Your attack of opportunity happens   immediately before the charge attack is resolved.   Does A now provoke an AoO from B for both entering and leaving these squares, for a total of 6?


Interpretation of a regression where two variables predict a third variable individually but not when entered together

I have a situation where two variables when entered into a regression model independently, both predict a third variable, but when I entered both those variables into the model together, neither one significantly predicts the third variable independently, but overall the model is significant.  In other words.  1st regression - A significantly predicts C  2nd regression - B significantly predcits C  3rd regression (both entered together):   A does not significant predict C               B does not significantly predict C Model overall is significant   What does this mean? Does it just mean they share too much variance (A also significantly predicts B)? How would I interpret this?  thanks


Are finite-dimensional normed spaces injective?

A Banach space $X$ is said to be injective if every linear continuous $T:Y\to X$, with $Y\subseteq Z$ Banach spaces, has a linear continuous extension $T^*:Z\to X$ with the same operator-norm.  My question is: is every finite-dimensional normed space $X$ injective?  All examples I know are infinite-dimensional and besides they're not so simple.   Any hint? Thank you.


What are the steps to establish an academic journal?

We want to establish a journal. Also I want to add the journal to various indexes. What are the main steps /guide to building an academic journal? What should be done to enter the SCI/SCIe/SSCI index. What is the difference between ISBN, ISSN, DOI numbers. I'm not interesting basic steps like deciding topic, name ,reviewers and editors of journal. It would be nice if you mentioned about the application/reference prices.  Note:This question might be broad so I can narrow this topic in the direction of your suggestions/comments


non-singular matrix. Show if $a^TAa \neq -1$

Let $A$ a nonsingular $n\times n$ matrix and $a$ $\in \mathbb{R}^n$.  Show that if $a^TAa \neq -1$, then $(A+aa^T)^{-1}= A^{-1} -\frac{1}{1+a^TAa}A^{-1}aa^TA^{-1}$ I just don't see how I can apply any invertible matrixes properties here.  What approach should I take?


"Inverse Resolution" of a model of a countably categorical theory

Let $T$ be a countably categorical first order theory. Let $M \vDash T$ be arbitrary and countable. Show that there exists $\{M_n : n \in \omega \}$ of countable models of $T$ such that $M_{n+1} \prec M_n$ ($M_{n+1}$ is a proper elementary substructure of $M_n$), and $M = \cap_{n < \omega}M_n$. I don't think it's as simple as doing a bunch of Downwards Lowenheim Skolem. I was thinking of defining a model $B = (N, P_i)_{i \in \omega}$ where each predicate will eventually be interpreted as $M_i$ and say that, for every formula $\phi$, $B$ is a model of $P_{i+1}(a) \implies (\phi(a)^{P_{i+1}} \iff \phi(a)^{P_i})$ where the superscript indicates the relativization of the formula. $B$ will also model other sentences indicating $P_{i+1} \subset P_i$ and the $P_i$ are models, etc. But I'm not sure how to fill the details. I don't think $\cap P_i^B = M$ is necessarily true either. Would appreciate the help.


android.widget.TextView.getText() on a null object reference

i'm new to android and here passing data from one fragment to anther but getting an error  CallFragment callFragment=new CallFragment(); textView=v.findViewById(R.id.editText); text=textView.getText().toString();  Bundle bundle = new Bundle(); bundle.putString("name", text);  callFragment.setArguments(bundle);  FragmentManager fragmentManager=getFragmentManager(); fragmentManager.beginTransaction().replace(R.id.fragment_container,callFragment).commit();


This is a duplicate question, my apologies everyone!  Firstly, I apologize if this is a simple question, I have been searching for a very long time, and either an answer about this does not exist, the answer I am looking for has been buried under answers to questions about how to convert a string to a byte array, or I'm not searching with the right terminology. I have also found a few answers on converting a single hex value into a byte but applying those methods to work with what I want to do doesn't really seem to work very well.  What I am looking for is not how to convert "string" to a byte array, rather, I am trying to convert an already in bytes value from a textbox, into something my application will recognize as a byte array. I'll try to explain better with an example:  textBox.Text = 019F314A I want byte[] bytes to equal { 0x01, 0x9F, 0x31, 0x4A }   Hopefully that makes sense. Thanks to anyone who can offer any assistance!


2000s (or earlier) book/series set in a future where spacefaring people have magic powers granted by elemental symbiotic crystals

I read this book probably close to 20 years ago (and even then I don't think the book was new). It might have even have been a short series.  It's in the future and the descendants of some spacefaring people have ended up on a planet and a small group of them have "magic powers." These powers are granted by symbiotic crystals that are tempered with various elements, e.g. fire/water. Depending on what type of crystal they bind with, it gives them control over the related element. I think this process of binding to the crystals happens in the spaceship that brought the original people to the planet.  I think that the main character binds with a crystal that wasn't tempered by any element and thus can control all of them?


What is most accurate Spatial reference system for calculate Area entire world

I want to know what Spatial reference system is most accurate to calculate area? I want to use it for entire world (-180,+180,-90,+90 area in WGS84 system) I have every thing ok I only need to reproject my layer to an accurate SRS and calculate area,Can you help me to find most accurate Spatial reference system for calculate Area entire world?