Catchphrases and concepts that spread from person to person are known as [memes], which, courtesy the Internet, can now explode across the Earth like a highly contagious virus (hence "going viral"). As with their real-life counterparts, some infectious diseases are global (pandemic), while others are endemic to specific regions. Stack Overflow, and now even more predominantly Meta Stack Exchange, have seen more than their fair share of these pathological social constructs spread through the user base. They are now ingrained units of our collective culture as SOpedians (a term which I hate, by the way). Just as travelers' immune systems can be assaulted by new diseases in new places, new users are increasingly likely to be miffed by an ingrained meme and left sitting scratching their heads. I therefore propose that this space be used to document the memes endemic to Stack Exchange's culture. Each meme should be listed in a separate answer and I hope that we as a community will be able to provide greater context to each one. Please actually explain each meme in a way understandable to those not already in the know. Especially considering that a lot of these memes aren't really understandable to newer users who weren't around in the early years of the network, or are based on system features that no longer exist.  On other Stack Exchange sites          [memes]:


Why does my grep search not find any matches when i loop through the pattern, but does when I write it in manualy?

I am trying to list the number of occurrences of lines that contain a certain word within a file. The words I am looking for are stored in a separate file that I'm looping through with this code: cat swissprot_anims.txt | while read line do     grep "$line" swissprot_list.txt | wc -l done  Where swissprot_anims.txt is the file containing the keywords in this format: BOVINE CHICKEN DROSOPHILA MELANOGASTER HUMAN MOUSE PIG RAT XENOPUS LAEVIS MELANOGASTER  And swissprot_list.txt is the file I'm combing for matches: Acetylcholine (muscarinic) receptors ====================================  ACM1_HUMAN (P11229)   MUSCARINIC ACETYLCHOLINE M1 [CHRM1] - HUMAN ACM1_MOUSE (P12657)   MUSCARINIC ACETYLCHOLINE M1 [CHRM1] - MOUSE ACM1_PIG   (P04761)   MUSCARINIC ACETYLCHOLINE M1 (BRAIN) [CHRM1] - PIG ACM1_RAT   (P08482)   MUSCARINIC ACETYLCHOLINE M1 [CHRM1] - RAT ACM2_BOVIN (P41985)   MUSCARINIC ACETYLCHOLINE M2 [CHRM2] (FRAGMENT) - BOVINE ACM2_CHICK (P30372)   MUSCARINIC ACETYLCHOLINE M2 [CM2] - CHICKEN ACM2_HUMAN (P08172)   MUSCARINIC ACETYLCHOLINE M2 [CHRM2] - HUMAN ACM2_PIG   (P06199)   MUSCARINIC ACETYLCHOLINE M2 (CARDIAC) [CHRM2] - PIG ACM2_RAT   (P10980)   MUSCARINIC ACETYLCHOLINE M2 [CHRM2] - RAT ACM3_BOVIN (P41984)   MUSCARINIC ACETYLCHOLINE M3 [CHRM3] - BOVINE ACM3_HUMAN (P20309)   MUSCARINIC ACETYLCHOLINE M3 [CHRM3] - HUMAN ACM3_PIG   (P11483)   MUSCARINIC ACETYLCHOLINE M3 [CHRM3] - PIG ACM3_RAT   (P08483)   MUSCARINIC ACETYLCHOLINE M3 [CHRM3] - RAT ACM3_CHICK (P49578)   MUSCARINIC ACETYLCHOLINE M3 - CHICKEN ACM4_BOVIN (P41986)   MUSCARINIC ACETYLCHOLINE M4 [CHRM4] (FRAGMENT) - BOVINE ACM4_CHICK (P17200)   MUSCARINIC ACETYLCHOLINE M4 - CHICKEN ACM4_HUMAN (P08173)   MUSCARINIC ACETYLCHOLINE M4 [CHRM4] - HUMAN ACM4_MOUSE (P32211)   MUSCARINIC ACETYLCHOLINE M4 [CHRM4] - MOUSE ACM4_RAT   (P08485)   MUSCARINIC ACETYLCHOLINE M4 [CHRM4] - RAT ACM4_XENLA (P30544)   MUSCARINIC ACETYLCHOLINE M4 - XENOPUS LAEVIS ACM5_HUMAN (P08912)   MUSCARINIC ACETYLCHOLINE M5 [CHRM5] - HUMAN ACM5_RAT   (P08911)   MUSCARINIC ACETYLCHOLINE M5 [CHRM5] - RAT ACM1_DROME (P16395)   MUSCARINIC ACETYLCHOLINE DM1 [ACRC] - DROSOPHILA   But when I run the script it is unable to find matches this way, even though when I replace $line with RAT for example it finds the correct number of matches so the RAT that is read in from the file is somehow not equivalent to the RAT that I put in manually even though the read command should strip the lines of all whitespace (besides the fact that there is no whitespace in my file). What am I doing wrong here?


If I cook chicken breasts in instant pot for a "longer time" would they come out super tender? I'm thinking 12 minutes or so

I would think pressure cooking chicken breasts in the instant pot for longer, and by that I mean 12 minutes or a little more, they would come out super tender. Am I wrong? Would the opposite happen? I may try it as an experiment.


Ball to Ball Collision - Detection and Handling

With the help of the Stack Overflow community I've written a pretty basic-but fun physics simulator.    You click and drag the mouse to launch a ball.  It will bounce around and eventually stop on the "floor".  My next big feature I want to add in is ball to ball collision.  The ball's movement is broken up into a x and y speed vector.  I have gravity (small reduction of the y vector each step), I have friction (small reduction of both vectors each collision with a wall). The balls honestly move around in a surprisingly realistic way.  I guess my question has two parts:   What is the best method to detect ball to ball collision? Do I just have an O(n^2) loop that iterates over each ball and checks every other ball to see if it's radius overlaps? What equations do I use to handle the ball to ball collisions? Physics 101 How does it effect the two balls speed x/y vectors?  What is the resulting direction the two balls head off in?  How do I apply this to each ball?     Handling the collision detection of the "walls" and the resulting vector changes were easy but I see more complications with ball-ball collisions.  With walls I simply had to take the negative of the appropriate x or y vector and off it would go in the correct direction.  With balls I don't think it is that way.  Some quick clarifications: for simplicity I'm ok with a perfectly elastic collision for now, also all my balls have the same mass right now, but I might change that in the future.    Edit: Resources I have found useful  2d Ball physics with vectors:  2d Ball collision detection example:     Success!  I have the ball collision detection and response working great!  Relevant code:  Collision Detection:  for (int i = 0; i < ballCount; i++)   {       for (int j = i + 1; j < ballCount; j++)       {           if (balls[i].colliding(balls[j]))           {             balls[i].resolveCollision(balls[j]);         }     } }   This will check for collisions between every ball but skip redundant checks (if you have to check if ball 1 collides with ball 2 then you don't need to check if ball 2 collides with ball 1.  Also, it skips checking for collisions with itself).  Then, in my ball class I have my colliding() and resolveCollision() methods:  public boolean colliding(Ball ball) {     float xd = position.getX() - ball.position.getX();     float yd = position.getY() - ball.position.getY();      float sumRadius = getRadius() + ball.getRadius();     float sqrRadius = sumRadius * sumRadius;      float distSqr = (xd * xd) + (yd * yd);      if (distSqr <= sqrRadius)     {         return true;     }      return false; }  public void resolveCollision(Ball ball) {     // get the mtd     Vector2d delta = (position.subtract(ball.position));     float d = delta.getLength();     // minimum translation distance to push balls apart after intersecting     Vector2d mtd = delta.multiply(((getRadius() + ball.getRadius())-d)/d);        // resolve intersection --     // inverse mass quantities     float im1 = 1 / getMass();      float im2 = 1 / ball.getMass();      // push-pull them apart based off their mass     position = position.add(mtd.multiply(im1 / (im1 + im2)));     ball.position = ball.position.subtract(mtd.multiply(im2 / (im1 + im2)));      // impact speed     Vector2d v = (this.velocity.subtract(ball.velocity));     float vn = v.dot(mtd.normalize());      // sphere intersecting but moving away from each other already     if (vn > 0.0f) return;      // collision impulse     float i = (-(1.0f + Constants.restitution) * vn) / (im1 + im2);     Vector2d impulse = mtd.normalize().multiply(i);      // change in momentum     this.velocity = this.velocity.add(impulse.multiply(im1));     ball.velocity = ball.velocity.subtract(impulse.multiply(im2));  }   Source Code:     If anyone has some suggestions for how to improve this basic physics simulator let me know!  One thing I have yet to add is angular momentum so the balls will roll more realistically.  Any other suggestions?  Leave a comment!


Adding timestamps to bash history on unix

I've been trying to add timestamps to my bash history on Mac, but it isn't really working. I put the following in both ~/.bash_profile and ~/.bashrc and neither seem to work:  export HISTTIMEFORMAT="%m/%d/%y %T"   I then ran source ~/.bash_profile or source ~/.bashrc, but only the number of the command seems to get printed. Am I missing something?


Need at least 10 Reputation to post an Image, please explain

I am trying to post an  to a question on Stack Overflow. I get this response     You need at least 10 reputation to post an image   What on earth does it mean, what do I need to do to post an image with my answer ?


How to link what user types in AutoCompleteTextView to Firebase Realtime Database?

I just wanna link what the user types in the ACTV, to the name in my Realtime Database, so that i can load the value of that name using Glide, and display the downloadurl value in my app after clicking my button. But right now, nothing is being displayed.  public class Translate extends AppCompatActivity {      private static final String TAG = "Translate";       DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();     DatabaseReference firebaseDatabase = rootRef.child("main");      @Override     protected void onCreate(Bundle savedInstanceState) {         super.onCreate(savedInstanceState);         setContentView(R.layout.activity_translate);          final Button button  = (Button)findViewById(R.id.button3);         final ImageView imageView = findViewById(R.id.imageView1);         final AutoCompleteTextView textView = (AutoCompleteTextView) findViewById(R.id.autoCompleteTextView);          String[] suggest = getResources().getStringArray(R.array.array);         ArrayAdapter<String> adapter = new ArrayAdapter<>(this, R.layout.support_simple_spinner_dropdown_item, suggest);         textView.setAdapter(adapter);           firebaseDatabase.addValueEventListener(new ValueEventListener() {             @Override             public void onDataChange(@NonNull final DataSnapshot dataSnapshot) {                 for (DataSnapshot childSnapshot: dataSnapshot.getChildren()) {                     final String source = textView.getText().toString();                     final String message = childSnapshot.getKey();                               button.setOnClickListener(new View.OnClickListener() {                                 @Override                                 public void onClick(View v) {                                     if(source==message){                                         GlideApp.with(Translate.this).load(firebaseDatabase.child(message)).placeholder(R.drawable.ic_launcher_background).into(imageView);                                     }                                   }                             });                          }                       }                       @Override                     public void onCancelled(@NonNull DatabaseError databaseError) {                         Log.d(TAG, databaseError.getMessage());                     }                 });              }          }   My database is as below :-   I'm trying to link match what the user types in to the database using the if statement if(source==message), but i think that is the wrong way.  Any help is appreciated thank you.


Rational with minimal denominator between two rationals

My question from an easy problem.     $p,q$ are positive integers such that $$ \frac{5}{9}<\frac{p}{q}<\frac{4}{7} $$ find $p,q$ such that $q$ is the smallest number that satisfies this inequality.   Draw the line of $ y<\frac{9}{5}x$ and $y>\frac{7}{4}x$ , we can "observe" that $\frac{9}{16}$ is such number.  However, if the question becomes     $a,b,c,d$ are positive integers such that $$\frac{a}{c}<\frac{b}{d} $$ find $p$,$q$ such that $q$ is the smallest number that satisfies the inequality   $$\frac{a}{c}<\frac{p}{q}<\frac{b}{d}$$   No idea about this.


Recently I've noticed a new trend in user interfaces. Facebook and Twitter do this, and I've come across it on other random, less famous sites. However, to keep things simple, I'll just use Facebook as an example.  When you first log into Facebook, you are presented with a "News Feed" that has a certain amount of posts from your friends. The feed extends down past the bottom of the viewport.  Then, when you scroll down, to see the feeds "below the fold", at some point as you move downward, it loads in more items. Apparently, this is called "infinite scrolling".  On my computer, this often causes my position in the feed to jump while I'm in the action of scrolling, which is really annoying.  What's particularly egregious about this UI concept is that there is footer information at the bottom of the page. I advertise on Facebook, and use the link at the bottom of the page to get to the advertisement management interface.  Because of this incremental load feature I'm describing, I often scroll down to the bottom to get to the link I want, when I reach the bottom of the page, it will suddenly load in new data, pushing the footer down again, and I have to scroll down again.  This whole thing seems completely pointless to me. What's the upside? A Facebook page is near a megabyte of data, so saving the few extra kilobytes of feed data for when the user scrolls down is just not worth it.  What's wrong with a link that just says "show more"?  Since this additional data retrieval thing seems to happen as soon as I start scrolling even a little anyway, why not just load that data in the first place?  To me this minor annoyance reeks of some engineers concept of a "neat trick" that does not have any actual appreciable upside.  Or am I wrong about that? Is there an advantage that I'm not seeing? Am I the only one who thinks it's stupid? Do some people like it?


Convert quaternion to a different coordinate system

OSVR has a right-handed system: x is right, y is up, z is near.  I need to convert orientation data from a sensor in OSVR to a different right-handed system in which x is forward, y is left, and z is up.  I need to calculate the transformation that will convert a quaternion from one system to the other.  I naively tried:  void osvrPoseCallback(const geometry_msgs::PoseStampedConstPtr &msg) { // osvr to ros     geometry_msgs::PoseStamped outputMsg;      outputMsg.header = msg->header;     outputMsg.pose.orientation.x = msg->pose.orientation.y;     outputMsg.pose.orientation.y = msg->pose.orientation.z;     outputMsg.pose.orientation.z = msg->pose.orientation.x;     outputMsg.pose.orientation.w = msg->pose.orientation.w;      osvrPosePub.publish(outputMsg);     ros::spinOnce(); }   But that made things really weird. Facing north pitch is pitch, facing west, pitch is yaw, facing south, pitch is negative pitch...  How can I convert my OSVR quaternion to the a corresponding quaternion in the new coordinate system?


Is it possible to compute $\int_1^{+ \infty} \frac{dx}{x^2(1+e^x)}$?

Essentially, all is in the title: Is it possible to compute the integral $$\int_1^{+ \infty} \frac{dx}{x^2(1+e^x)} \hspace{1cm} ?$$  I suspected some relation with a , but I was not able to find something explicit.


Add vertical space between two tables in a single figure

Similar to  but without the requirement that the tables be the same width:  I have one figure containing two tabular environments:  \begin{figure}     \centering     \begin{tabular}{rlrrrr}         \textbf{sector\_flows} \\         \toprule         a & b & c & d & e & f \\         \midrule         1 & Foo & 1995 & 1 & 1 & 3107 \\         \bottomrule     \end{tabular}     \vspace{12cm}     \begin{tabular}{rlll}         \textbf{sectors} \\         \toprule         g & h & i & j \\         \midrule         1 & Foo & Bar & Baz  \\         \bottomrule     \end{tabular}     \caption{Relational database format for storing input-output flow data}     \label{fig:db_format_for_io} \end{figure}   But the \vspace doesn't put any space between the tables. Instead it puts space between the tables and the caption.  Why doesn't this work, and how can I achieve vertical space between two tables in a single figure?


Is there a way in calculating the total number of reputation points one gained only on his/her answers? Currently the reputation points for questions and answers are combined total.


What is the meaning of Euler's identity?

I know that euler's identity state that $e^{ix} = \cos x + i\sin x$  But e is a real number. What does it even mean to raise a real number to an imaginary power. I mean multiplying it with itself underoot $-1$ times? What does that mean?


Can I enable pixel binning on Canon PowerShot G1X?

On my camera, a Canon PowerShot G1X, I can select picture sizes from S to L.   Now I wondered, if I select a smaller picture size, that would theoretically lead to more sensor surface per pixel, possibly making the camera perform better in low-light or other 'harsh' conditions.   However, when I try this, I can't notice any difference in behaviour. The end result just looks like a resized version of the larger picture, and there are no differences in shutter speed and ISO to get to that result.  So, it looks like the camera just takes a large picture and then downscales it, which was against my expectations (or at least against my hopes).   Pixel Binning  The term that I think I am looking for is  also known as ,  or .   It certainly has advantages over downscaling by software, because it makes more efficient use of the hardware (faster reading, better noise reduction).  I think the answers below don't really answer my question. Neither do the answers of the supposedly 'duplicate' of this question, although the  came closest by at least suggesting that a camera might support this 'hardware-level binning', which allowed me to continue my search.  So far I couldn't find evidence that the Canon G1X supports binning, so I'm afraid it does not. But if someone know if it does (or maybe knows a hack or trick to enable it), please let me know. Previously I had a Canon PowerShot SII, and there was a way to install 3rd party firmware to unlock extra features. Maybe something like that is possible for the G1X as well?


How do you prevent a player from throwing out an item?

I tried the curse of binding, but that only prevented armor from being taken off once put on.  I need this because I have a class system on my server and I don't want players giving each other items.


I would like to know how to prove the following: $2^n \in O(n!)$ I know that I have to show that for a constant C, we have $2^n \leq C*n!$ Right?


Prove that $f(z) = e^z$ maps $\mathbb{C} \setminus B $ onto $\mathbb{C} \setminus \{0\}$.

Prove that $f(z) = e^z$ maps $\mathbb{C} \setminus B $ onto $\mathbb{C} \setminus \{0\}$ where $B$ is a bounded subset of $\mathbb{C}$.  I have no idea how to even attempt this question so I would greatly appreciate some hints.


I had two tabs open within chrome both of them on SO.  I looked at one and it had this:   I went back to the other tab on SO and it showed this:   I thought well where did I lose 15 points and click on my reputation page to see reputation activity (below) and nothing showed up as losing reputation.  Does anyone know why this happened? Was there some global recalc today or something?


How to keep my Debian system with the latest packages?

Most of the "Software" I install on my server needs to be the latest release (Java, Tomcat, MySQL-Cluster). So I never have the luck, that there are pre-built Debian packages (in the distribution) available. Therefore all the software is downloaded from the project-webpage and built from source.  Now my question is, what is the correct way to install them on my Debian system?   My main problem is, when installing them directly from the source, they are not included in the package management (with aptitude). Checkinstall seems to not really be suggested to be used and equiv also has drawbacks. Is the only correct way to handle this by building my own packages with dh_make and dpkg-buildpackage?  What are you doing if you always need the latest version?


When I login as anonymous, (well it sounds weird, but logged in with email only in SO, or as a guest)  What causes me to lose that account? (not being able to post something as the user)   closing down the tab that has the Stack Overflow page?


Why Dumbledore didn't keep Tom's diary to study it?

The remains of the defeated Horcrux was in Dumbledore's possession after Harry's adventure in the Chamber of Secrets,  but it was returned to Lucius Malfoy. Why?


Overwrite a portion of a file w/o modification to the unmodified content

I'd basically like to create an allocated file lets say 1GB with content.  Then hopefully using some command line utility I'd like to overwrite-in-place a portion of the file, lets say the beginning 4 MB ONLY leaving the rest of the file contents in-tact.  I've checked cp, and dd but they don't seem to have anything like this.  Perhaps I am looking in the wrong place and/or not understanding the implications of some of the options.  Yes, I could generate a C program to do this but my preference for portability is to use a command line situation.  Any ideas?


Unable to connect to Dedicated Bedrock Server from the same PC

I have a Dedicated Bedrock Server running on my PC, and I can't connect from the same PC where the server is. If I add it onto the list of servers, it appears as "Locating server" and never finds it.    If I try to connect, I get "Unable to connect to world".    On my friend's PS4, it appears on the Friends tab as a LAN Game on a Dedicated Server.    And also on my sister's laptop.


So I decided to install my copy of Ableton (v9.1) on my computer now that I've upgraded to a machine that isn't ancient. HOWEVER Despite WineHQ reporting that Ableton is platinum-certified, I can't get the dern thing to open.  It crashes out just as the splash screen pops up.  Sometimes I see it, sometimes not.  It tells me that some catastrophic error has occurred, and it needs to close.  I've tried this on two different systems running two different versions of wine  (One runs the up-to-date public distro 1.6.2, while the machine I actually want to install it on is running the 1.7.19)  I don't know what to do.  I'd really just like to get this working, as my friends really like the look and feel of Ableton, and I really don't like LMMS (Linux-y free Audio Software).  Any idea what's going on here? I've found a couple of other people who seem to be having the same problem as me, but no dice on any solutions.  None provided, really.  Specs: Ubuntu 14.04 LTS  8 Gig ram  i7-2670QM CPU @ 2.20GHz × 8  Lots of free space... yadda yadda yadda   Error message:


why is the video sequencer so slow with 4k files 2.79

currently trying to figure out blender's video editing using Mikeycal Meyers video series and it is all seeming to work but no matter what preferences I change the sequencer responds and plays back incredibly slow with a 4k mov file. I've set the memory cache past the amount of ram I have (16) and have tried different clips. Could use some advice.


Can I change the /home folder after ubuntu installation?

I had installed Ubuntu 11.10 on a clear 40gb hd, but now i have a 100gb partition that i want to use as a /home folder, is there a problem to simple use fstab to change the mounting point?  I'm thinking to copy/paste all the archives in actual /home folder to this 100gb partition and then change the mounting point in fstab.  Edit: I will not make this because this 100gb partition is ntfs type, so no donuts for me.


Boarded a flight and flew to the US with no visa, is the airline liable?

I have a Canadian Student Visa. I did not know that I am supposed to get a C-1 visa for a stopover in LAX for 2 hours. I did not need to change airport so I thought that a visa was not required. I booked with Japan Airline with a connection at LAX to Canada. However, I was detained in LA and the officer told me that I would be deported back to the Philippines where I came from.  Luckily, I explained to them my situation and they made me just pay a visa waiver fee of $585.  They also told me that Japan Airlines (the airline that I took) would be penalized for allowing me to board the plane without checking if I had a transit visa.  My question is:  is Japan Airline liable for allowing me to board their plane without checking?


How to assign a SSL Certificate to IIS7 Site from Command Prompt

Can you advise me whether it is possible or not to assign a SSL Certificate to a website in IIS7 using the APPCMD application?  I am familiar with the command to set the HTTPS Binding  appcmd set site /site.name:"A Site" /+bindings.[protocol='https',bindingInformation='*:443:www.mysite.com']   and how to obtain current mappings   %windir%\system32\inetsrv\Appcmd   but can not seem to find any way to map a site to a certificate (say the certificates hash for example)


Confused about Ubuntu and Flavors' LTS support periods

It's widely known that regular Ubuntu LTS releases receive 5+ years of support while Flavors have a shorter, 3 year, support period.  However, I have now read that while the Flavor-specific programs only receive 3 years of support, the core software shared with the regular Ubuntu release will still receive support as long as the vanilla release does (5 years). Is this true?  Would it be safe to use, for example, a Kubuntu 18.04 system until 2023?  What happens if I install a minimal system from the official 18.04 Mini-ISO and just select KDE Plasma as the DE, will that still receive 5 years of updates?  Overall, I'm very confused about these proclaimed update periods.


Why is GetComputerNameEx not fill buffer with data

Given the below code snippet, can anyone tell me why line 17 only prints "Name:"?  #include <Windows.h> #include <stdio.h> #pragma comment(lib, "Ws2_32.lib")  // Caller supplies function with a buffer to copy the name into as // mentioned by nobugz here: https://social.msdn.microsoft.com/Forums/en-US/6547d2bf-2884-4ad2-b600-adaab0fa1031/warning-c4172-returning-address-of-local-variable-or-temporary?forum=Vsexpressvc BOOL getName(int num, LPWSTR buffer) {     DWORD size = sizeof(buffer);     return GetComputerNameEx((COMPUTER_NAME_FORMAT)num, buffer, &size); }  void main(int argc, char ** argv) {     printf("%s\n", "RAT POC RUNNING");      TCHAR buffer[256];     getName((COMPUTER_NAME_FORMAT)1, buffer);     printf("Name: %ws\n", buffer);      TCHAR hostName[MAX_COMPUTERNAME_LENGTH + 1];     DWORD hNsize = sizeof(hostName) / sizeof(hostName[0]);     GetComputerNameEx((COMPUTER_NAME_FORMAT)1, hostName, &hNsize);     printf("Hostname: %ws\n", hostName);      TCHAR domainName[MAX_COMPUTERNAME_LENGTH + 1];     DWORD dNsize = sizeof(domainName) / sizeof(domainName[0]);     GetComputerNameEx((COMPUTER_NAME_FORMAT)2, domainName, &dNsize);     printf("Domain name: %ws\n", domainName);   }   By setting a breakpoint at line 17, I find that the buffer variable contains 256 entries of the value 52428, which I suspect is because I'm doing this in unicode. But I'm not sure why the GetComputerNameEx isn't filling said buffer with the actual name? Line 22, which calls the same GetComputerNameEx returns the correct name.


I am reading these online notes(), and on the bottom of page 2 the following exercise occurs.  Define tensor multiplication of two $R$-algebras $A$ and $B$ as:  $(a_1 \otimes b_1) \cdot (a_2 \otimes b_2) = a_1 a_2 \otimes b_1 b_2$.  Prove this is bilinear.  The first property of a function being bilinear is $(u+w) \cdot v = (u \cdot v) + (w \cdot v)$, so I tested the following:  $(a_1 \otimes b_1 + a_3 \otimes b_3) \cdot (a_2 \otimes b_2) = ???$  Tensor addition is not defined when one of the elements differs, so I am unsure of where to go beyond this.


Why doesn't an extension tube "crop" the picture?

Ever since I've heard of extension tubes I've been curious if they somehow crop the image that appears on the camera sensor.  Based on , the answer is "no" (at least not that I can tell).  Now that I know that, why not?  It seems like they would somehow muck up the image that appears on the sensor, and while they obviously do alter the DOF, it looks like the image still appears on the entire sensor. Obviously my understanding of how the lens forms an image on the sensor has something wrong with it, but what is the actual effect on the light when using an extension tube?


make invisible depending on point of view

suppose I have modelled a room like that:   when I look at it from outside like in screenshot, I want the walls whose normals are not going towards my point of view to go transparent. In other words, I want to see the insides of the room so that the walls at which I am looking from outside, go transparent. see the screenshot for illustration, I have just hidden those faces    when I change my point of view, other faces have to go transparent while others become visible.  I think that must be somewhere on the surface but as always my Google skills are too bad to find out


What's the word for someone who opposes a generally established opinion?

I'm looking for a noun to describe someone who's against something. For example:  He's one of those people who oppose the idea of...  I know you can simply say "He's against the idea of", but I was wondering if there was any noun that I could use in this particular scenario. I thought about simply using the word opponent but isn't it more suitable in perhaps a competitive game context?


Suggestions to make a "uwrap" animation with this ball model

I would like to convert my ball model into a 2d-ish model with an animation. Already tried to find some tutorials or materials presenting ways to do that, without success.    I would like to animate the ball into something like this:    I believe this is a hard thing to do, specially cause I don't have too much experience with Blender (started to model with 3Ds max) or animation, but I would like to try even so. Any ideas or tutorials?


How to show that this group presentation is isomorphic to dihedral group?

The group with the presentation $\langle a, b \mid a^2, b^2, (ab)^4\rangle$ seems like a dihedral group of order 8. But I fail to explain why. Could anyone show me how to prove it?


Appearance of Formal Derivative in Algebra

When studying polynomials, I know it is useful to introduce the concept of a formal derivative. For example, over a field, a polynomial has no repeated roots iff it and its formal derivative are coprime. My question is, should we be surprised to see the formal derivative here?   Is there some way we can make sense of the appearance of the derivative (which to me is an analytic object) in algebra? I suspect it might have something to do with the fact that the derivative is linear and satisfies the product rule, which makes it a useful object to consider. It would also be interesting to hear an explanation which explains this in the context of algebraic geometry.  Thanks!


How to know which elements are in the Quotient Ring $\mathbb{Z}[x]/\langle x, 2\rangle$?

I'm asked to prove that the quotient ring $\mathbb{Z}[x]/\langle x, 2\rangle$ is isomorphic to $\mathbb{Z}_2$.  The first thing that came to my mind was to apply the Theorem of Homomorphism of Rings, but to do so I need to construct a homomorphism $\phi: \mathbb{Z} \to \mathbb{Z}_2$, such that $\mathrm{Ker}\phi = \langle x, 2\rangle$ ($\langle x, 2\rangle$  is an ideal of $\mathbb{Z}[x]$). But     What elements are in $\mathbb{Z}[x]/\langle x, 2\rangle$ in the first   place?   I know that $\langle x, 2\rangle$ of all the polynomials with even constant term, but I can't figure out how the elements of $\mathbb{Z}[x]/\langle x, 2\rangle$ look like.  Any help would be appreciated.


What are the restrictions on picking up locomotives?

If, after drawing one of the five cards from the face up train cards, and after replacing that card, the second card is drawn from the top of the deck and is a locomotive card, is the player allowed to keep that card?     Likewise, if both cards are drawn from the the top of the stack and the second card is a locomotive card, is the player allowed to keep that card?


Ok, so i've got identical problem as in this topic:  But nothing I've tried worked. Also I can't change logo to default one. It's just black screen when booting. Can anyone help?  I want to change my Linux Mint 17 Cinnamon boot image manually. So, I replaced the image located at: /lib/plymouth/themes/mint-logo/logo.png with mine. The logo changes at shutdown but not at boot.


What is the difference between a one-vs-all and a one-vs-one SVM classifier?  Does the one-vs-all mean one classifier to classify all types / categories of the new image and one-vs-one mean each type / category of new image classify with different classifier (each category is handled by special classifier)?  For example, if the new image to be classified into circle, rectangle, triangle, etc.


So, I thought I had a good understanding of this, but just ran a test (in response to a conversation where I disagreed with someone) and found that my understanding is flawed...  In as much detail as possible what exactly happens when I execute a file in my shell? What I mean is, if I type: ./somefile some arguments into my shell and press return (and somefile exists in the cwd, and I have read+execute permissions on somefile) then what happens under the hood?  I thought the answer was:   The shell make a syscall to exec, passing the path to somefile The kernel examines somefile and looks at  of the file to determine if it is a format the processor can handle If the magic number indicates that the file is in a format the processor can execute, then   a new process is created (with an entry in the process table) somefile is read/mapped to memory. A stack is created and execution jumps to the entry point of the code of somefile, with ARGV initialized to an array of the parameters (a char**, ["some","arguments"])  If the magic number is a  then exec() spawns a new process as above, but the executable used is the interpreter referenced by the shebang (e.g. /bin/bash or /bin/perl) and somefile is passed to STDIN If the file doesn't have a valid magic number, then an error like "invalid file (bad magic number): Exec format error" occurs   However someone told me that if the file is plain text, then the shell tries to execute the commands (as if I had typed bash somefile). I didn't believe this, but I just tried it, and it was correct. So I clearly have some misconceptions about what actually happens here, and would like to understand the mechanics.  What exactly happens when I execute a file in my shell? (in as much detail is reasonable...)


I've read both forms in newspapers and online news: elder brother and older brother. What's the difference between them? When should I use which?


Propensity score methods versus GLM for cost comparisons between treatment groups

I'm working with a client that wants cost differences between two treatment groups. They have little background knowledge but have seen in the literature folks doing GLM gamma/log-link, etc. and are suggesting we do the same. However, for their purposes and the ease of the analysis, I want to suggest using IPTW to balance between the groups and compare cost directly using those weights. I need to strengthen my argument and I'd be happy to take suggestions on where to go.


My calculator and google calculated it differently, why? To avoid confusion, where should I put the parenthesis. This can be write in  at least 16 ways with parenthesis, but which one gives the correct value?


Evaluating the indefinite integral $ \int \sqrt{\tan x} ~ \mathrm{d}{x}. $

I have been having extreme difficulties with this integral. I would appreciate any and all help. $$ \int \sqrt{\tan x} ~ \mathrm{d}{x}. $$


Clarification on factors of $c$ in the Lorentz' force

I was told that Lorentz' force is given by   $${\bf F}=  q{\bf v} \times {\bf B}.$$  But I have read that it is given by $${\bf F}=  \frac{q}{c}{\bf v} \times {\bf B}.$$  Why have these two relations different forms if they represent the same force? Thanks for any help!


Book about a one-armed cowboy who travels across time using a torus (sp?)

The elements of the plot that I remember are:   One-Armed cowboy spots something weird while out riding (torus, torroid, ?) He breaks a Yale lock using his one hand He travels through time and picks up a caveman They then pick up some others, including alien(s) in whose language God means means devil/god


In the exercise, W is a standard, one-dimensional Brownian motion and $0 \lt T \lt \infty$. We are asked to show that  $$\lim_{\beta\rightarrow\infty}\sup_{0\le t\le T}|e^{-\beta t}\int_0^t e^{\beta s}dW_s|=0,\ \ a.s.$$ I know that $E|e^{-\beta t}\int_0^t e^{\beta s}dW_s|^2$ can be calculated, and to deal with "sup", I hope to use BDG inequality or Doob's inequality. However, they can only be applied to (sub or super)martingales. So, I try to do some transformation to the integral. Time-change can make it a Brownian motion as $B_{{1\over2\beta}(e^{2t}-1)}$, and local time gives its decomposition as the sum of a martingale and a increasing process. For the martingale part, I could use Doob's inequality. For the other part, I guess that the increasing process cannot increase as fast as exponential function. I think it may be a way to solve the problem, but I cannot get the estimate about local time.  If you have some idea about this exercise itself, or my problem about the estimation of the local time, please share with me. Thank you!


When is Ubuntu Phone/Touch coming to the U.S.?

Does anyone know when it's coming to the U.S.!? The UI looks beautiful and I've been waiting to get it. I feel like we've been waiting forever.   Also did they mention how it will work? Do you have to buy a phone with it already installed on it or will we be able to download and install it on any Android phone like we can download the desktop version of Ubuntu on any Windows PC?


I uploaded my new profile picture in Movies.SE, but in other site it is not shown?

I changed and uploaded a new profile picture of mine in Movies.SE, but the change is not reflected in other Stack Exchange sites, the previous picture is still retained. Do I have to change the picture one at a time for different sites? If so, it would be very problematic. Is there any way I can change the picture everywhere simultaneously?


Installing File Geodatabase (*.gdb) support in QGIS?

I have spent around 2 days to find the way to open GDB (Esri geodatabase) in QGIS (or any other open source software) but still without success.  I have downloaded the newest OSGeo4W installer and tried the setup - express desktop install - all packages, as well as advanced install incl gdal-filegdb.  Can you describe a more detailed procedure, including installation and how to open .gdb in QGIS (OSGeo4W installation)?


load a file and read the information in the file

I am looking to open an excel file via an apex dialog box, then browse the information in my file line by line and display them with visualforce


First, if you are thinking that this question is a joke or troll, I'd like to welcome you to the 21st century when the mankind is discussing legality of gay marriages.  Now, if you look at the sexuality (I'll keep it clean) of all the Avengers minus Captain America:   Iron Man: Well, he is a billionaire playboy who can bring hot female journalists to bed with a snap of a finger (Iron Man movie). Otherwise, he has a girlfriend who is CEO of a multi-billion dollar company. Thor: He has a Nobel prize winning girlfriend who doesn't belong to his species. Hulk: Dr. Banner had a girlfriend, but then the gamma accident happened which could turn him into a green monster upon arousal (The Incredible Hulk movie). It's still unclear whether he can now have sex or not (after he controlled himself with meditation) and his girlfriend is still with him or not, but he isn't a virgin and nobody knows what happened after Age of Ultron. It's possible that Black Widow successfully seduced him after he was found again. Black Widow: Although, she is single and she has been sterilized, it's difficult to believe that she is a virgin and she doesn't have sex regularly because she is seen kissing around. And, she was trying to seduce Dr. Banner (Avengers: Age of Ultron movie). The point is: She is sexually active. Hawkeye: He is married (Avengers: Age of Ultron movie).   Now, look at Captain America:   When Peggy kissed him in Captain America movie, it was their first kiss and then he got iced. Fast forward to 21st century: Although his age is 80+, he is still young. Yet, he doesn't have a girlfriend and he doesn't show any interest in girls. Even when Black Widow kissed him, he didn't try to drag her to bed. Talking about low libido (a medical condition which arises due to stress and other factors), it's impossible because his super soldier serum should keep him healthy in all way. From the functional biology point of view, low libido is actually caused by imbalance of hormones. Stress suppresses rest-and-digest autonomous nervous system and activates fight-or-flight autonomous nervous system (that's why stress, depression etc damage health). In case of Captain America, yes, he got negative emotions after he was defrosted, but his super soldier serum should take care of his biological health. So, one of the other possibilities: He is gay (which has been proved to be a natural condition, not some kind of abnormality).   To prove that he is gay, let's look at his emotional responses: In 21st century, when he met Peggy, he didn't become emotional. But, when he saw Bucky, he became emotional.  I am a straight male and I am creative enough to emulate the situation well. If I had met my first love in such situation, I would have become emotional and it'd actually hurt to know that she is old and I am young. Talking about a dead best friend who is somehow alive and attacking me, my natural response would start with a slang. By no means, Captain America's emotional response looks straight man's response and it looks a gay's response.  Is Captain America really gay? Am I overthinking or producers are really hinting something to throw later? These days it's common in media for awareness. For example, Flash (2014) TV show has a gay police officer.  A more general question: Has sexual orientation of Captain America been disclosed? If he isn't gay, is he straight (there are lots of sexual orientations e.g. Bisexuality)? What about comics?


Reason and timing of specific characters death in s05e10?

At the end of season 5, Mother's Mercy. Jon Snow is killed by a group of Night's Watch "rebels" or group of Night's Watch that didn't agree with Snow's decision of bringing Wildlings in the Black Castle.   What I do not understand is the reason they killed Snow and their timing as well. If they had an issue with wildlings they shouldn't have lifted the door to let them in as we see in Hardhome, I thought that will be the most important scene of season 5 because for a moment it seemed as if Ser Alliser Thorne is not going to permit Wildlings to enter. But we see Wildlings peacefully enter Black Castle. If they had a grudge against Wildlings they shouldn't have let them enter in the first place. But once they have entered, what is the reason to kill Jon Snow, knowing that he is the Lord Commander and an expert swordsman and considering the fact that they are on brink of war with White Walkers, it doesn't make much sense.   It seems as if Jon Snow's murder was not only because of Wildings but because of Ser Alliser Thorne's grudge with Snow as well. If I missed something kindly explain.


When ever I hear the music to indicate the Mysterious Stranger has arrived, I can never find him. It is almost like he is not in the vault.  What is a good way to catch the Mysterious Stranger? Where does he usually show up?


Method to Return a Parsed Decimal Does not Compile

I was wondering the reason why this block of code won't compile.  public decimal? GetDecimalValue(String decimalString) {     return decimalString.IsNullOrWhiteSpace() ? null : decimal.Parse(decimalString); }   ERROR Message: Type of conditional expression cannot be determined because there is no implicit conversion between '<null>' and 'decimal'  However, if I write the ternary statement out, then it works.  public decimal? GetDecimalValueThisOneCompiles(String decimalString) {     if(decimalString.IsNullOrWhiteSpace()) return null;     return decimal.Parse(decimalString); }


To postgenerate fake-module-bpy (For blender Python)... нowever, the language does not matter. So, I use next console command  ]$ ls  | grep -v _init_ | sed -E 's/^([a-zA-Z0-1]+)/import \1/' >> __init__.py   It will written all python files to __init__.py as import (Exclude itself __init__.py)  Can I write/append not the end, but the beginning of the file?


This might already be answered, but I can't find it.   I am getting a bit bored of the traditional purple feel of unity and I would like something new. Where can I find more Unity themes?  I have already tried synaptic, but could not find anything. I would rather avoid people's personal PPA's.


Destroying a user should mark all pending flags against that user's comments as helpful

This appears to be related to the behavior originally suggested in .  It appears to be the same issue raised in , but this post has specific steps to reproduce the issue.  Here's what happened on one site in the network earlier today:   A question was posted much earlier Someone came along, and as an unregistered, new user with no other activity, posted a spam answer to that question at 04:36:54 UTC That same user posted a comment on their own answer with the same spam link at 04:37:31 UTC The answer was deleted as spam via community votes at 07:32:07 UTC A high-rep user saw the comment and raised a custom flag on it as being spammy at 07:32:54 UTC The unregistered user account was destroyed by a moderator at 08:13:10 UTC The comment now shows as "deleted by Anonymous" with a deletion time of 08:13:10 UTC The flag on the comment remains, but the only options are "Edit" and "Decline"; there is no "Delete" action   That there is no "Delete" action possible on the flag is reasonable, since the comment is now deleted. However, the flag is/was legitimate, so to decline the flag would be wrong. There's also nothing to leave while editing out the spammy part of the comment, as the comment consists solely of the same spam URL.  There is also no undelete option on the comment, so it's not possible to undelete the comment and then mark the flag as helpful by re-deleting the comment.  Effectively, this means that while the comment itself is effectively gone, the flag on it is in limbo and there is no good choice for what to do with the flag.  When deleting comments normally, my understanding is that any flags associated with those comments are automatically marked as helpful. However, it appears that the deletion of comments when destroying the user who posted them does not do that.  Therefore, I suggest that whenever comments are deleted as part of the owning user being destroyed, any pending flags against those comments should be marked as helpful at the same time.  It would also be a nice touch if those comments showed as deleted by Community♦, instead of Anonymous, but that's less of a concern in my case.


How to get 4od channel4 working [2015, UK]

used to work with the  installing an ported version of "hal" but it appears to have stopped working (Nov 2015).  I've tried Firefox, Chromium and Chrome, on Ubuntu 14.04.  I've installed hal from  and I've ensured the daemon was running (required sudo) before starting the browser.  Firefox just shows a blank grey space where the player goes; Chrome shows the play buttons but then it just hangs on the endless ubiquitous rotating frustration indicator; Chromium says "flash upgrade required" (I have installed today flashplugin-installed giving me Shockwave Flash v. 11.2 r202)  Obviously the answer would be for public broadcaster Channel 4 to produce a service that was accessible to a wide range of users, but as they've always seemed a little miffed that the internet was invented I don't hold out any hope here so wondering if anyone had found a recent workaround?


the biblatex package doesn't work in Texworks

I have been troubled by the biblatex package for a few days in TexWorks. I follow the instructions from the internet in many ways,but things don't make sense to me.  This is my code   \documentclass{article}  \usepackage[backend=biber]{biblatex} \addbibresource{reference.bib}  \begin{document} It didn't make sense\cite{gbms}  \printbibliography \end{document}   and this is my reference.bib   % This file was created with JabRef 2.10. % Encoding: GBK   @Article{gbms,   Title                    = {{Generalized Born Model Based on a Surface Integral Formulation}},   Author                   = {Avijit Ghosh, Chaya Sendrovic Rapp, and Richard A. Friesner},   Journal                  = {J.Phys.Chem.B},   Year                     = {1998},   Pages                    = {10893-10990},   Volume                   = {102} }   First I use the pdfLaTeX, things work well and give me the pdf without giving the bibliography   Then I use the biber command the console give me this:  INFO - This is Biber 2.2 INFO - Logfile is 'parameters.tex.blg' ERROR - Cannot find control file 'parameters.tex.bcf'! - did you pass the "backend=biber" option to BibLaTeX? INFO - ERRORS: 1   I don't know why it happen?  I also tried the backend=bibtex, the program seems to interrupt and give that ! Undefined control sequence. So, anyone knows this kind of problem?


Concurrent lines proof for a regular 18-gon

Let $X_1 X_2 \dotsb X_{18}$ be a regular 18-gon. Show that $X_1 X_{10}$, $X_2 X_{13}$, and $X_3 X_{15}$ are concurrent.   What would be the best way to prove this? I am actually struggling understanding 'concurrent' as I am not sure how they are concurrent in a regular 18-gon


Do I have a couple of questions or a few?

I know what the dictionary definitions are for few and couple.  Not looking for reciting the definition or etymology.  I would like someone to tell me in common usage is it appropriate to call 3 of something a couple or to call 2 of something a few?  This comes from my workplace.  I work in a very global setting.  In emails and on conference calls often people will say "a few" when they are talking about two things.  Or "a couple" when they are talking about three things and sometimes more.  Are there any regional/social/demographic based differences?    For instance my grandma often uses the terms interchangeably and might go back and forth with the two words about the exact same topic. What is the cutoff point for couple and a few?


Does the potential energy of a single object exist?

I know that potential energy exists for a system of objects. But why? Is there no potential energy for a single object system? I assume that there is.  Consider the earth-object system. Suppose an external force lifts the object above the earth. Then the work done by it gets stored in the earth-object system as potential energy.Right?  Now, my question is that is the potential energy always zero for a single object system.   MY REASONING  If we consider the object only as the system and lift it above the Earth, we are doing positive work on it and filling it with energy and the gravitational field of the Earth is doing negative work on it and draining it of energy. Thus whenever the object is moving it has kinetic energy which is fine. But when it is not moving,i.e. when its weight is equal to the force applied by us, the net work done is zero and so the object should not have any kinetic energy. Does it have potential energy?


Can we add 'asked', 'answered', 'edited' text to each question featured on the front page?

When I'm looking down the front page on , I often wish I could tell at a glance what happened to the question to bump it there. Sometimes it is obvious from looking at the number of answers, other times you have to follow a link to find out if it has been edited or if an answer has been added or updated.  I'm guessing this is just as applicable on other SE sites - this is the kind of thing I'm suggesting:    A couple of suggestions from the comments that might be good:   To reduce clutter the word 'ago' could be removed at the same time. The new text could be visible only to established users - ie users who are likely to be reviewing/editing and would benefit from seeing at a glance what kind of change has occurred.


Let $$ P = \frac{1}{\sqrt{2}} + \frac{1}{\sqrt{3}}+  \frac{1}{\sqrt{4}}  ... +\frac{1}{\sqrt{10000}}$$ what is the value of the floor function of P?  My try:  I tried assuming these 2 bounds   $$ P_x = 1 + 1 + 1 + \frac{1}{2}+...\frac{1}{99 }$$ where it is repeated until the next square number (eg. there are 3 1's at the beginning of the sequence corresponding to the $\frac{1}{\sqrt{2}},\frac{1}{\sqrt{3}},\frac{1}{\sqrt{4}}$ where $\frac{1}{\sqrt{4}}$ is the next square number  and   $$ P_y = \frac{1}{2} + \frac{1}{2} +\frac{1}{2} + \frac{1}{3} + \frac{1}{3} ... \frac{1}{100}$$ withe the same counting process as $P_x$  then we know that  $$P_x>P>P_y$$  $$99*2 + (\frac{1}{1} + \frac{1}{3} + \frac{1}{4} ... \frac{1}{99}) > P >99*2 -(\frac{1}{2} + \frac{1}{3} + \frac{1}{4} ... \frac{1}{100}) $$  but as you can see, the floor function of P can be either 197 or 198, how would I answer this?


Understading a quicksort python implementation

I found this code online.  def quick_sort(items): """ Implementation of quick sort """ if len(items) > 1:     pivot_index = len(items) / 2     smaller_items = []     larger_items = []     for i, val in enumerate(items):         if i != pivot_index:             if val < items[pivot_index]:                 smaller_items.append(val)             else:                 larger_items.append(val)      quick_sort(smaller_items)     quick_sort(larger_items)     items[:] = smaller_items + [items[pivot_index]] + larger_items   The one line that gives me trouble is the last one. I believe it's basic concatenation, however, when I change "items[:]" to "items", the algorithm fails. What is special about the [:] at the end of the list?   If anyone one can help, I would really appreciate. Thank you in advance!


PHP export of accent characters to XML fails

I am working with exporting accented characters from a mySQL database to XML, but I am getting really wonky results.  For the basics - the mySQL table is set up as latin-1 encoding.  Not ideal.  However, all input is run through HTML entities, which seems to be working great; I can read data back all day long, and it looks correct on the screen.  Here is a sample item.    On the screen, it looks like this:   me hace reír  Note the accented "i" character (with acute accent).  In the database, it is stored like this:  me hace re&iacute;r  The "i" with the acute is properly replaced with the HTML entity, which allows for proper display on screen.  If I wrap that inside of a textarea, it still reads correctly - no acute HTML entity, just he correct accented "i" character.  My XML file has a proper UTF-8 header on it:  <?xml version="1.0" encoding="UTF-8" standalone="yes"?  But when I read the data from the DB and export it to the XML...  $xml.="<dedicatedBecause>".($dedicatedbecause)."</dedicatedBecause>"."\n";  With "$dedicatedbecause" holding a totally unprocessed piece of data from the DB, I get the following in my XML file:  me hace reÃ-r  In other words, a DIFFERENT accent character plus a dash.  In other cases, I get other nonsense characters (copyright symbol, various other accents, etc, etc).    I have a huge function for massaging data to UTF-8, but it doesn't seem to matter.  If I turn it off, I get the same result.  What gives?  What am I missing here?    Thanks for your help!


How to format a string as a telephone number in C#

I have a string "1112224444' it is a telephone number. I want to format as 111-222-4444 before I store it in a file. It is on a datarecord and I would prefer to be able to do this without assigning a new variable.  I was thinking:  String.Format("{0:###-###-####}", i["MyPhone"].ToString() );   but that does not seem to do the trick.  ** UPDATE **  Ok. I went with this solution  Convert.ToInt64(i["Customer Phone"]).ToString("###-###-#### ####")   Now its gets messed up when the extension is less than 4 digits. It will fill in the numbers from the right. so  1112224444 333  becomes  11-221-244 3334   Any ideas?


How would I go about evaluating $\int_{0}^{\infty}e^{{-u}^{2}}\cos(ux)du$?

So I had this question as extra credit on my exam and no one was able to solve it.  I tried to do integration by parts but that just keep on expanding with no solution in sight.  I have also tried to take the derivative of the integral but that didn't seem to help either.  How would I integrate $\int_{0}^{\infty}e^{{-u}^{2}}\cos(ux)du$?


Routes out of Seattle-Tacoma airport (SEA) served by Boeing 747

I’m looking for routes served by a Boeing 747 out of Seattle. I know Lufthansa has a Seattle to Frankfurt but haven’t been able to find any other ones. Trying to fly on the Queen of the Skies before they all get decommissioned like United and Delta have done. Thanks in advance!


Jquery change checkbox checked / uncheked

I need to uncheck / check the below checkbox using jquery.  Please tell how to change the below checked attribute to unchecked attribute using jquery.  <input name="op1" type="checkbox" checked  id="chkEmailNotification" />


Is there a way to have respondents attach a file to a form response?

I need to have a form with the normal questions, in addition to having respondents attach or download a file. Is this possible?


Password Hacking How to get into admin account?

I need some help getting into my dad's admin account on my laptop.  I need to know the password because my dad forgot it.  I need to be able to do this without Command Prompt, because my dad blocked it.  Any methods that don't require admin permisson would be helpful.  Thanks :)


Examining the metric tensor used to explain expansion, I see no reason why the expansion should not occur everywhere, i.e. between molecules, between the planets, between the stars in a galaxy, etc. Yet apparently, only the galaxies are "locked into" the space portion of space-time, and only the proper distance between the galaxies is subject to red-shift analysis.  I have often thought that maybe the black hole seemingly at the center of each galaxy somehow locks a galaxy into the space portion of space-time and the use of the idea of "expanding space" doesn't apply to the space portion of space-time uniformly.  I apologize for any misuse of words here, e.g., "proper distance."


Can a PHP script be expected to have more performace (i.e. processing more code in less time) by passing variable by reference?

In C++ passing variables from functions to the function caller can always have better performance when returning a variable by const & (constant reference).  class A {     private:     std::string name;     public:     inline const std::string& getName() { return this->name; } const }   I am wondering if returning variables from a function in PHP as a reference can have better performance then just returning a variable like normal.  In C++ I understand that when you return a variable without const ref it copies the data into the variable that you are setting it to. So you will have two locations in memory with the same data.  But when you pass around references, you are just passing the address in memory to the same data.  Is this how it works in PHP? Or does PHP do optimization regardless?  Will the following function run faster if it is written like so? Returning a reference?  public function &getDatabaseConnection() { return $this->databaseConnection; }   Or does it not make much of a difference?


How can we show that $\frac{x}{1-x} = \sum \frac{x^{2^n}}{1-x^{2^{n+1}}}$   I've been stuck on this question. I've tried using the geometric series but to no avail.


How the time slows down? In thought experiment of special theory of relativity in which two mirrors are used how the time gets slow for moving person?

If experiment is observed from stationery frame of reference then light travels more distance than frame of reference of mirrors so to keep speed constant time for stationery frame of reference should be increased which maybe means that same event is happening slower in stationery frame because completion of same event is taking more time when viewed from that frame because distance covered has increased. Then why we say that in moving frame time passes slowly?


Determine if some application is currently using microphone

Is it possible to determine if some application is currently using microphone (i.e. is actively listening)?  Do operating systems (Windows in my case, but I'm curious about other OS-es as well) provide APIs for such feature?  I'm trying to test if apps are spying on users and data from such feature could serve as circumstantial evidence.


Can you protect People with the Death Note by writing their name in it?

A person whose name is written in a death note is immune to all other death notes. Are they immune to a bullet to the head or eating an arsenic cream pie, too? If so, would they have a sort of "luck shield" that stops any potential causes of death from making it impossible to fulfill the death note entry, or would they just survive it?


How to install VirtualBox Guest Additions in a Debian virtual machine

I have been struggling to install VirtualBox Guest Additions in a Debian Virtual Machine (Debian 7, Debian 8 and Debian 9).


Cardinality of the union of all repeated Cartesian products of N with itself

Here is a silly question, but I am a silly person.  Consider the: Natural Numbers. Natural Numbers X Natural Numbers. Natural Numbers X Natural Numbers X Natural Numbers ...  Now take the union of all of these sets. In other words, this is the set of all sequences of natural numbers/tuples of any size, of natural numbers.  The cardinality is certainly at least that of the power set of the naturals, or the cardinality of the reals, because this is essentially like the power set except now, order matters/repetition is allowed.  But does having order matter, and allowing repetitions, increase cardinality of an infinite set? Will this set have a cardinality aleph-one, or will it be higher? I suspect it is the same, but maybe this does push the cardinality up in the same way that taking a power set would?  Thank you.


Can we get people to fill in tag wikis when they create a new tag?

Orphaned Tag Wikis are sad. They hang around, shambling, and groaning and wait... that's zombies. Or maybe teenagers.  What does happen in many cases is they can be ambiguous, get misused, and on some larger sites end up needing many man hours of cleanup.   On the other hand, people who create a tag ought to know what it's for. We can change them later. If its a new user, it also ensures the user's put some thought into it, and lets people review it better. Making them write at least an excerpt, that's peer reviewed. In short, can we make sure that the need and goal of any new tag is clearly stated when its created?


Path Environment Variable Windows 10. Echo %Path% on command prompt shows only %Path%

My variable value in path is as follows  C:\ProgramData\Oracle\Java\javapath;%SystemRoot%\system32;%SystemRoot%;%SystemRoot%\System32\Wbem;%SYSTEMROOT%\System32\WindowsPowerShell\v1.0\;C:\Program Files (x86)\Skype\Phone\;C:\Program Files\Intel\WiFi\bin\;C:\Program Files\Common Files\Intel\WirelessCommon\;%PYTHON_HOME%\;%PYTHON_HOME%\Scripts;C:\SQLite   When I type echo %Path% on command prompt, I get below output  PS C:\Users\Arun> echo %Path% %Path%   Why is this?


I have a module that create custom PDF with multiple selected nodes and I use the below function to create the link to styled images:  $file = File::load($img_id); $imagesPath[] = ImageStyle::load('550x300')->buildUrl($file->uri->value);   Unfortunately, the image itself is not created, only the link, which is ok if I display it on a simple webpage because Drupal will create it on the fly when needed but on a PDF it cause errors because the image it not found before the PDF could be displayed.  Is there a programmatically way to create this image ?  Thanks.


Why are eigenvalues of nilpotent matrices equal to zero?

If $A$ is a $ \displaystyle  10 \times 10 $ matrix such that $A^{3} = 0$ but $A^{2}  \neq 0$ (so A is nilpotent) then I know that $A$ is not invertible, but why does at least one eigenvalue of $A$ have to be equal to zero? How would one show that all eigenvalues of $A$ are equal to zero?


I can't find .local in home file Inside local file:  Inside home file:


How do I design a circuit for a bi-color led to display power?

I'm trying to create a simple circuit that will turn a  green when the power is on and red when it is off. I figure the simplest way to do this would be using a SPDT switch, but the switch in the circuit I'm designing is a 40 amp relay, and I found a SPST one for about a buck while the SPDT one was almost 4. For future reference, and also to cut the cost of designing my current circuit I'm trying to come up with some way to wire it up and basically make a "normally on" switch for the red and "normally off for the green.  The closest I've come is finding this circuit which would work except for the fact that the bicolor led shares a cathode.     Is there any way to change up the circuit, or is there something else I can try which would free up the cathode to make it so I can independently switch on the two LEDs?


Object not appearing the render, but is appearing in viewport render

Sorry in advance if this is a duplicate, but I have read anything I can find with "Object missing in render".  I am doing the updated blender 2.8 doughnut tutorial.   My Icing for my Doughnut is missing in action.   My icing appears just fine in the viewport, including in render mode.    However if I do an actual render:   It does not seem to be disabled, these are the setting I have already checked and they all seem to make sence.


How can Window Managers shutdown the computer?

When logged in to a virtual shell as an unprivileged user and try to shutdown, reboot, init 0 or init 6 don't work. But if you're running a desktop environment, you can easily select its shutdown functionality. Why is that?


Black screen on boot after update to 14.04

I have a Dell Latitude D410 that I bought used with Ubuntu installed on it. It worked fine for several months.  I updated to 12.04. I wanted to read Nook books on it, so i tried to find the software to do so.  I may have downloaded Wine onto the machine,  but I don't remember.  I discovered i could read my Nook books at the Barnes and Noble web site,  so I did that a bit.  The next day, when I started it, all I got was a black screen.  Right clicking would produce a small box that allowed me to open a terminal window or a web browser,  but nothing else.  I decided to update to 14.04,  which I think I did successfully, but now it's even worse.  I can't even get the box to open a terminal window.  Imma try installing 14.10 from a DVD, since I can get to the bios and change the boot order. I welcome any suggestions.


I always thought that $force$ is $mass * acceleration$. Well, that's what I learnt at school a while back. Now, I have been enlightened that force is in fact the rate of change of momentum.   What makes this interesting to me, is that this takes into account a change in mass with respect to time as also playing a role in the force. A nice example of this is that of a rocket taking off. But clearly, this was not an example that Newton had in mind.   So my question: What did Newton have in mind of something where the mass changes with time?  I appreciate that my question is similar to say:  but I didn't read anywhere there about the concept of change of mass with time.


Convergence of $a_n$ given $a_{\lfloor{x^n}\rfloor}$ converges to $0$

Sequence $a_n$ has a property that for every real $x > 1$, sequence $a_{\lfloor{x^n}\rfloor}$ converges to $0$. Does that mean that $a_n$ converges to $0$? I have tried to find a counterexample, but failed at it, so I think it might be true, but I don't know how to prove it.


How can I auto adjust an align to appear in the entire page?

For example   \documentclass[14pt,twoside]{extreport} \renewcommand{\baselinestretch}{1.5}  \usepackage[utf8]{inputenc} \usepackage{graphicx} \usepackage[a4paper,width=150mm,top=25mm,bottom=25mm,bindingoffset=6mm]{geometry} \usepackage{fancyhdr} \pagestyle{fancy} \fancyhead{} \fancyhead{} \fancyhead[RO,LE]{\small\leftmark } \usepackage{amsfonts} \usepackage{graphicx} \usepackage{amsthm} \usepackage{amsmath} \usepackage[english]{babel}  \begin{document} First, we compute the following products: \begin{align*} R_2R_5&=a_2 a_5 t^2+\left(a_5 b_2+a_2 b_5\right) t+b_2 b_5,\\ R_2 R_3 R_5&=a_2 a_3 a_5 t^3+\left(a_3 a_5 b_2+a_2 a_5 b_3+a_2 a_3 b_5\right) t^2+\left(a_5 b_2 b_3+a_2 b_5 b_3+a_3 b_2 b_5\right) t\\ &+b_2 b_3 b_5,\\ R_4 R_6&=a_4 a_6 t^2+\left(a_6 b_4+a_4 b_6\right) t+b_4 b_6,\\ R_3 R_4 R_6&=a_3 a_4 a_6 t^3+\left(a_4 a_6 b_3+a_3 a_6 b_4+a_3 a_4 b_6\right) t^2+\left(a_6 b_3 b_4+a_3 b_6 b_4+a_4 b_3 b_6\right) t\\ &+b_3 b_4 b_6, \end{align*} By replacement, ordering by powers of t and identifying, we obtain a system whose solutions describe the number of straight lines situated on the "reliability" hypersurface. We write the system ordering by the coefficients of the powers of degree from zero to five,relative to t: \begin{align*} b_7&=b_2 b_5+ b_2 b_3 b_5 - b_2 b_3 b_6 b_5 + b_3 b_6 b_5 - b_2 b_4 b_6 b_5 + b_2 b_3 b_4 b_6 b_5 - b_3 b_4 b_6 b_5 + b_3 b_4 b_6 + b_4 b_6, \end{align*} Starting from the last equation, at least one of the numbers $a_i$; $i = 2,\ldots , 6$ must be zero (number of cases: $C_1^5 + C_2^5 + C_3^5 + C_4^5 = 30)$. So the straight-lines are parallel to some hyperplane of coordinates. The first equation shows that at t = 0, point $(b_2,\ldots, b_7)$ is on the "reliability" hypersurface. This remark requires the following procedure: we choose arbitrarily $b_2, \ldots ,b_6$, and compute $b_7$. We replace the values $(b_2,\ldots, b_7)$ in the remaining equations. If the new system, in unknown $(a_2,\ldots, a_7)$ , it has a solution with at least a nonzero component, then there exists one straight line passing through the point $(b_2,\ldots, b_7)$  and lying on the "reliability" hypersurface. Explicitly, after solving the algebraic system, we have the following cases:     \end{document}   The result is this   How can I adjust the equation within the limits of the text?  thanks for the help


Interpreting the residuals vs. fitted values plot

Residuals vs. Fitted Values plot    Can someone tell me which OLS assumptions might be violated according to the figure and why? Moreover, what are the consequences for the point estimators and the standard errors?


Show reference label when it is undefined

When a reference is undefined, LaTeX shows simply [??] which doesn't give much information. I would like it to show the label instead. This is useful when more collaborators work on the same preprint and the references are yet to be done.  I'm using neither biblatex nor natbib. I do use bibtex but it is irrelevant for this question.  MWE:  \documentclass{article}  \begin{document}  This: \cite{undef} should look like: [{\bfseries ?? undef}]  \end{document}


Marked as duplicate but no currently-visible link to duplicate

is marked as an exact duplicate, but there's no non-deleted content indicating what it is a duplicate of.   contains a link to the duplicate, as do past , but nothing immediately visible to normal users.  As the question has a net score of 52, and 22 favorites, and one answer has 132 net votes, I suggest deleting this post is not the optimal solution.


Future usage of "will" and "be going to"

I need some clarification about the future using "will" and "be going to".  Please, describe which variant sounds as a plan, that I planned in advance and it will definitely happen.   I'm going to move in America to permanent residence. I'll go to London in September.    As I understand, 1) is sounds like a plan for the future, that may be happen, but it's not clear yet. And the point 2) sounds like that will happen definitely.  Am I right? Thanks.


No, actually I didn't, but that was a close call and I'm really curious how would one go about that one.  On my third or fourth visit to the Nether, I still didn't realize the risk, and didn't place marks that would help me get back to the origin (currently I like to use flint and iron to create big flaming arrows towards the exit, visible from afar.) I wandered past one hill, and then I couldn't locate the place I came from. I wisened up and started placing marks in form of torches, towers of netherrack with glowstones on top etc. The bunch of wood I had in my stash has proven invaluable as I ran out of steaks, and had to craft a bowl and start making mushroom soup. I realized the fastest way back would be to simply die, but since I had no clue where I was, that would mean losing my quite precious equipment, which cost me a lot of time and effort to gather and enchant, for that trip specifically. I also knew I had traveled rather far from the portal before starting placing marks, so the chances of finding it again by going in any random direction were rather slim.  By sheer luck I found one of the caverns I had explored before, and found my way back, but that was really a close call and I'd prefer to know any hints what to do in Nether if you're already lost (no Obsidian to build a new portal, not willing to die and forgot the direction to the exit.)


The Sequence Lemma and the Axiom of Countable Choice

Consider the following lemma (sometimes called Sequence Lemma)  Let $X$ be a topological space, $A\subseteq X$ any subset and $x\in X$. If there is a sequence of points in $A$ converging to $x$, then $x\in\bar A$; the converse holds if $X$ is first-countable.  A proof of the converse exhibits an enumeration of a neighborhood basis of $x$, which exits due to $X$ being first-countable, and constructs a sequence of points $(x_n)_n$ such that $x_n\in A\cap (U_1\cap\dots\cap U_n)$. These finite intersections are non-empty since $x\in\bar A$ and thus consequently $A\cap U\ne\emptyset$ for all neighborhoods $U\subseteq X$ of $x$ (in fact, as $x$ is a limit point of $A$ there is some point $y\in A$ different from $x$ in every $U$; but this does not seem relevant here). The proof is easily completed by the definition of a neighborhood basis and the construction of $(x_n)_n$ (see  for example). However, we have to somehow (non-trivially?) choose the elements of the sequence $(x_n)_n$. I am aware of the Axiom of Countable Choice which should suffice here instead of, say, the full Axiom of Choice. Defining $S_i=A\cap(U_1\cap\dots\cap U_i)$ for $i\in\Bbb N$ and letting $S=\bigcup_{i\in\Bbb N} S_i$ should do the trick (unless I am fundamentally misunderstanding something). I am not sure if we actually need choice since the sets $S_i$ form a chain and this might allow a neat way of chosing "trivially".  Is the Axiom of Countable Choice needed here, does a weaker choice principle suffice, or is there maybe no need for any kind of choice at all?  Thanks in advance!


I trying to replace the value in the arraylist of edge under the updateEdge() method.  At If statement, the value of the edge.a.name and edge.b.name matches my source and dest value but somehow it doesn't enter the IF condition.  What I found out is this, edge.a = Node@55f96302 and a.name = Node@55f96302.  What I know this when I print out the node address, both does not match.  private ArrayList<Node> nodes = new ArrayList<Node>(); private ArrayList<Edge> edges = new ArrayList<Edge>();  //add new node public void addNode(String nodeName) {     Node node = new Node(nodeName);     nodes.add(node);             }  //add edge public void addEdge(String source, String dest, String weight) {     Node a, b;     a = new Node(source);            b = new Node(dest);          Double w = Double.parseDouble(weight);      Edge edge = new Edge(a, b, w);     edges.add(edge); }  //Check index of the node public int indexOfNode(String name) {     for (int i = 0; i < nodes.size(); i++)     {         if(nodes.get(i).name.equals(name))         {                            return i;         }     }                 return -1; } //update edge public void updateEdge(String source, String dest, String weight) {        Node a, b;     a = nodes.get(indexOfNode(source));     b = nodes.get(indexOfNode(dest));       Double w = Double.parseDouble(weight);        for(int i = 0; i < edges.size(); i++)     {         Edge edge = edges.get(i);          if(edge.a.name == a.name && edge.b.name == b.name)         {             edge.weight = w;         }     }        }


What is the geometric interpretation of the transpose?

I can follow the definition of the transpose algebraically, i.e. as a reflection of a matrix across its diagonal, or in terms of dual spaces, but I lack any sort of geometric understanding of the transpose, or even symmetric matrices.  For example, if I have a linear transformation, say on the plane, my intuition is to visualize it as some linear distortion of the plane via scaling and rotation. I do not know how this distortion compares to the distortion that results from applying the transpose, or what one can say if the linear transformation is symmetric. Geometrically, why might we expect orthogonal matrices to be combinations of rotations and reflections?


Is it possible to query multiple sites in one data SE query?

I was curious about finding users that have higher reputation on SE sites other than stackoverflow. I'm kind of fuzzy on what I want to do, but my hypothesis is that ... people who are involved in SE but not very involved in SO are rare. So anyway, I went to  and immediately realized that I need to limit my query to a single site. Question(s): a) Is it possible to query multiple sites in some way that I've overlooked? b) If not, is this feature planned? c) If not, then out of interest, what is missing for it to be implemented? thanks!


Run command once and filter output in multiple files

Is there anyway to redirect filtered output to multiple files by running mycommand.sh only once?  Example output should be similar to this:  mycommand.sh | grep --line-buffered -B 1 A >> file1 ; my command.sh | grep --line-buffered -A 1 B >> file2   Or maybe with egrep somehow...


I want to remove / hide "sharepoint suite bar ribbon and header" ? It is the yellow part in my hardcopy. Is there a way to do it ? Best Regards, Pierre


How can I prove continuity of this function: $f(x, y)=\frac{xy}{x^2+y^2}$ for $(x, y)\neq (0,0)$?

I have to prove that the function $f:\Bbb{R}\times\Bbb{R}\to\Bbb{R}$ defined as follows: $$f(x, y)=\frac{xy}{x^2+y^2}\text{for } (x, y)\neq (0,0)$$ $$f(x, y)=0\text{ for }(x, y)=(0,0)$$when taken as a function of $x$, is continuous.   My method:  Take any $\epsilon>0$. I have to prove that there exists a $\delta$ such that $\left|\frac{(x+\delta)y}{(x+\delta)^2+y^2}-\frac{xy}{x^2+y^2}\right|<\epsilon$. I'm getting a quadratic inequality in $\delta$.   My question is, what if the situation was more complicated? I got easily get a very messy expression for $\delta$. What should we do then? How should we prove continuity?  Thanks in advance!


“User memory limit exceeded” using Random Forest classification algorithm in Google Earth Engine

I have see this conversation  I have exactly the same problem with Random forest classifier and I would like know if it was resolved ? if so, which means did you find to resolve it ?


How to edit next line after pattern using sed?

Using sed, how do I search for a line ending with foo and then edit the next line if it starts with #bar?  Or put another way, I want to remove a comment # from the next line if it starts with #bar and the previous line ends in foo.  For example:  This is a line ending in foo #bar is commented out There are many lines ending in foo #bar commented out again   I tried:  sed -i 's/^foo\n#bar/foo\nbar/' infile


What do angle have to do with waves? Why do we use trigonometric functions to model waves?

I've just learned SHM and I'm not able to understand why "phi" (initial phase) is an angle. Why are angles used in SHM?


Intuition behind the sigma algebra generated by a series of random variables?

I am reading David Williams' "Probability with Martingales" and in this book he supposes that you are given the following information about some 'outcome' $\omega \in \Omega$: $$X_n(\omega) \ \text{s.t.} \ n\in \mathbb{N}$$ for a series of random variables $X_n:\Omega \rightarrow \mathbb{R}$. He then says, based on this information, $\sigma(X_n : n \in \mathbb{N})$ consists of 'events' $F$ such that for each point $\omega$, you can tell whether the event $F$ has occurred or not (that $\omega \in F$).  However, no matter how hard I try to wrap my head around this vague idea, I can't seem to understand it. I don't understand how the 'information' provided helps to understand whether some event has occurred or not and what this means in terms of a sigma algebra generated by random variables (which also confuses me). Is there any easier way to understand what a sigma algebra generated by these functions actually is?


How do I force Firefox to remember a password?

There are a couple of sites that I use (off the top of my head, the  and ) for which Firefox will not offer to remember my password. Any ideas on how to force Firefox to recognize the username/password fields for these pages?  EDIT: My primary laptop is Windows, but I believe I've seen the same behavior for these sites on my MacBook as well. Also, these sites are not in my Exceptions list.


Flash drives do not have the memory they're meant to have

Whenever you buy a flash-drive, it always says it has 4GB, but when you plug it into a PC it says it has 3.72 GB, why is that?  I don't really care too much for the 200MB, but with my 512GB pen-drive, I lose 12GB of space and this is quite a lot. Does anyone know why this happens?


TypeError: super() takes at least 1 argument [Python 3]

In the following codes, I kept on getting the same error although I rechecked it for more than 15 minutes. For your info, I ran it on sublime text and the error:      TypeError: super() takes at least 1 argument (0 given)     The code is as shown below:  class Car(): """A simple attempt to represent a car."""      def __init__(self, make, model, year):         self.make = make         self.model = model         self.year = year         self.odometer_reading = 0      def get_descriptive_name(self):         long_name = str(self.year) + ' ' + self.make + ' ' + self.model         return long_name.title()      def read_odometer(self):         print("This car has " + str(self.odometer_reading) + " miles on it.")      def update_odometer(self, mileage):         if mileage >= self.odometer_reading:             self.odometer_reading = mileage         else:             print("You can't roll back an odometer!")      def increment_odometer(self, miles):         self.odometer_reading += miles  class ElectricCar(Car):     """Represent aspects of a car, specific to electric vehicles."""      def __init__(self, make, model, year):         """Initialize attributes of the parent class."""         super().__init__(make, model, year)  my_tesla = ElectricCar('tesla', 'model s', 2016) print(my_tesla.get_descriptive_name())


If I want to produce a batch of circuit boards which consist of various electronic components. But I found there is a shortage of a certain component whose part number is xxxx. Can I say there is a shortage of 44 pcs xxxx, or I should say there are 44 pcs shortage of xxxx.


Why is the work done on a charge calculated from infinity?

Why is the work done on a charge calculated from infinity to a point? Why not from one particular point to other?


Programmatically encrypting a config-file in .NET

Could somebody please do a rundown of how to programmatically encrypt a config-file in .NET, preferably in C#.  What I would like to do is do some kind of check on an application's startup to see if a section is unprotected, and if it is, then encrypt it. This for both settings and connection-strings.  Also if anyone could list the types of encryption-providers and what is the difference between them.  I don't know if the code for doing this in a normal WinForms-application is transparent to doing this in ASP.NET.


"Don't comment on your downvote." <- Just the opposite!

If you add a comment explaining why you downvoted - and I mean a long-ish comment which goes into a bit of depth to explain the issue you have with the answer - your comment gets rejected, and a dialog box pops up saying:     Don't comment on your downvote. If you think this post can be improved, please offer specific guidance.   That's just wrong, since:   Downvotes without comments are antagonistic and somewhat hurtful (for posts written in good faith). You might well be offering specific guidance in the downvote comments. It's much better for the downvoter to leave a sub-optimal comment with some feedback then to be discouraged by this message and not provide any feedback.   Instead, the comment should be accepted (except perhaps for a very brief "-1 wrong"-style comments), and the message could say something like:     When commenting on a downvote, try to explain how this post can be improved, and offer specific guidance.   The comment should remain in edit mode to encourage it to be edited, but canceling the edit would leave the comment as-is (again, except for the case of problematic/very brief comments).  Notes:   This question focuses on the specific scenario of a meaningful comment being rejected, and on the rejection message. This is distinct from how to encourage meaningful/positive criticism in general. If it's the "-1" indication that is super-bothersome to people, then either this should be removed from the comment (with the rest of it left), or it should be made very clear that is the reason the comment can't be accepted i.e. "don't explicitly mention the downvote in downvote comments" rather than "don't comment on downvotes".


What are the rules for China's visa-free transit programs?

Assuming one wants to travel through China, what are the rules for visa-free access? To be more specific:   How does the 24-hour visa free transit work? How does the 72-hour version work? What does a person ineligible for either of these programs have to do to transit China? Do the programs apply to flights only or do they also work for transit on land? Would a visitor save much hassle by using visa free transit instead of just getting a visa?      NB: this is intended as a canonical question on transiting China


My intended goal is to create a script that when run, will check the state of a setting, then change it to the opposite state. The setting in question is regarding the manual or disabled state of proxy settings in Ubuntu's settings.  I can manually obtain the state of this setting with the command:  gsettings get org.gnome.system.proxy mode   This will return auto, manual, or none. I don't use the first state, so let's ignore that from here on. Now, once the state is returned, my goal with the script is to then run either one of the following commands:  gsettings set org.gnome.system.proxy mode 'manual' gsettings set org.gnome.system.proxy mode 'none'   The command it runs will be the state not currently set. To that end, I have attempted the following in a script:  if [ 'gsettings get org.gnome.system.proxy mode' = 'none' ] then gsettings set org.gnome.system.proxy mode 'manual' notify-send "Manual" else if [ 'gsettings get org.gnome.system.proxy mode' = 'manual' ] then gsettings set org.gnome.system.proxy mode 'none' notify-send "Disabled" fi fi   This is saved in a file with chmod +x applied. When run from the terminal, nothing happens. I just get a new line to await a new command.  Where have I gone wrong?  In addition, is it possible to get this to work on a single line, like so:  sh -c "if [ $(gsettings get org.gnome.system.proxy mode) = \"'none'\" ];then gsettings set org.gnome.system.proxy mode 'manual' && notify-send \"Manual\";elif [ $(gsettings get org.gnome.system.proxy mode) = \"'manual'\" ];then gsettings set org.gnome.system.proxy mode 'none' && notify-send \"Disabled\";fi"   Again, same (lack of) results.


is there a way to lock my pc completely for a specific time?

I use a HP Pavilion ab253cl laptop running windows 10 home. I am kind of addicted to the laptop and couldn't make productive use of my time. most of the time, i kill my time doiong random stuff on laptop. Is there a way by which i can lock this laptop for a certain time, so that even i couldn't unlock it until the time lapses?? I tried searching for a solution, but couldn't find any. Please help me. thanks in advance.


In the proof of the the lemma   suppose $G$ is a finite abelian $p$-group, and let $C$ a cyclic subgroup of maximal order, then $G=C\oplus H$ for some subgroup $H$  at ,   They say that since $H\cap(C+K)= K$, we have $H\cap C=\{e\}$. But how do they have that  $H\cap(C+K)= K$? Can someone prove that please is because I don't see why is that true with the arguments presented in that proof. thanks a lot in advance :)   I am sorry for this but my doubt was in the part that I pst here and in the other question the answer was to other thing :)


How often should I use the battery on my MacBook (which I exclusively use as desktop)?

Since getting my mb-pro 3 years ago, I've only used it as a desktop. A few times, the battery has kicked-in for a few hours while the power was out. Someday, I might want to task it as a laptop. For the sake of the battery :       Should I be unplugging my mb from the wall just to use the battery?   For how long should I run on battery?   How often should I do this?


Did any Nanites ever show up in any Star Trek stories after Evolution?

In , Wesley is working on an experiment with , tiny molecular machines he has programmed to work together and evolve.  Spoiler:      The nanites get loose and wreak havoc on the ship's computer systems.   Do any kind of nanites ever show up in any other Star Trek stories? (e.g. - tv shows, movies, games, or books) I prefer answers that are canon, not fanfic stories.  Wesley mentions nanites in an offhand comment in , but I am not asking for a simple mention of them, but where nanites actually participate in the plot of the story.  Edit to add: I am asking about nanites made by the Federation or Starfleet, not by the Borg. I know Borg nanites show up in a few episodes. I am asking because I think nanites would be interesting plot devices, but I can't think of where they show up besides in stories about the Borg.  Edit to add:  focuses specifically on Wesley's nanites, not on other nanites. It does not ask if any Federation-made nanites show up in other episodes. It is kind of like asking what specifically happened to Data's cat, Spot, rather than asking if other episodes have cats. :-)


Show that the numbers 1, 2, 3, ..., 16 can be arranged in a line so that the sum of any of two neighbors is a square.

Ex.: 8, 1, 15, 10, 6, 3, 13, 12, 4, 5, 11, 14, 2, 7, 9, 16 The sums are: 9, 16, 25, 16, ... In fact I want to know for which numbers N the numbers 1, 2, 3, ..., N has this property. Maybe the sum not being a square but a cube or k-th power, or maybe arranging in a circle... Is there any sequence of N's on oeis or something?


Do I need a visa to go to Canada from America if I have a Green Card?

I am planning to drive to Niagara Falls to see it from the Canadian side. I have heard good things about seeing it from the other side. So, I want to stay in Toronto for a day, see Niagara Falls and come back.  I have a green card, and, my wife is a citizen from US.  I have read this link, , and this doesn't talk about person with a green card. So, could you advise if I can go to the Canadian side or give me links on this one?  I am on an Indian passport.  EDIT: My experience: We went there at around 7:30 in the morning to avoid the long queue. The border security official asked us to give us our passports, I have given my green card as well with the passport, she asked the purpose of our visit and how many days we were planning to stay. The whole process took around 10 minutes, 7-8 minutes for waiting and 2-3 minutes with the official.


I have the following assembly line which I want to understand:  TEST DL,DL JE SHORT 6C250EDF   So, in DL we have the character 'C'. Actually, the value 43 which is ANSCII code for 43. I know that TEST is like AND, but in TEST we don´t store the result.  But ollydbg says that the jump is not taken. How that can be? 43 AND 43 is equal, right ? so, why not jump?  my second question would be: How can i translate that in C code ?


Where to signal my wish: a desktop topbar taking away the menubar of the application windows?

Is there an alive Ubuntu wish list?  The main reason why I use Unity desktop is the top bar which is able to take away the menu bars of the application window.  It was published, that in the future Unity will be dropped and Gnome desktop will be the default instead.  My wish if this desktop could have a Unity like top bar.  Can I configure a gnome desktop this way right now, or it needs an amount of programming, and a better knowledge of the gnome system?  There is no kind of bugs mentioned in this question.


Error message id: cannot find name for group ID after logging in

BACKGROUND  Trevor logs into his account on ssh://foobar.university.edu as one of the developers on the box, and he gets the message:   id: cannot find name for group ID 131   Trevor then checks this out using    vim /etc/group   PROBLEM  Trevor discovers that there is no 131 anywhere in the /etc/group file.  Trevor then runs id ...   > id trevor  uid=4460(trevor) gid=131 groups=48(foobar),51(doobar),131   To discover his primary group apparently does not have a name attached to it.  QUESTIONS   What likely happened to cause this circumstance on the foobar.university.edu box ? Suppose trevor wants to fix this (e.g., by just creating a "trevor" group that maps to GID 131) what is the best way to do this without potentially breaking anything else on the server ?


Exercise:  For which $p\in [1,\infty]$ is $L^p([0,1])$ strictly convex?  Solution: For strict convexity we have two equivalent definition:    If $x\neq 0\neq y$ and $\Vert x+y\Vert=\Vert x\Vert+\Vert y\Vert$ then $x=\lambda y$ for some $\lambda$. If $x\neq y$ with $\Vert y\Vert=\Vert x\Vert=1$ then $\Vert\frac{x+y}{2}\Vert<1$   So I found that $L^p([0,1])$ is strictly convex for $p=2$: \begin{equation} \int_0^1(\frac{f(t)+g(t)}{2})^2dt=0.5\int_0^1(f(t)^2+g(t)^2+2f(t)g(t))dt\leq \frac{\Vert f\Vert^2_2+\Vert g\Vert^2_2}{2}<1 \end{equation}  Question: Are there other $p$ for which $L^p([0,1])$ is strictly convex?


I want to set a environment variable when a specific response header has a value.  But when I make this it doesn't set the variable.  Header add X-foo "bar" <If "resp('X-foo') == 'bar'">     Header add X-test-foobar "foobarnew" </If>   It doesn't set the header X-test-foobar.  Maybe I don't have correctly understand how does it should work. I'm not really fluent in apache programming... I think that programming is not sequential in apache environment but I don't know how to set an env variable with the content of the response header.  Thanks for any help,  ZS


Why are so many hats named after numbers? What do the numbers mean?

The names for Winter Bash hats are often puns or refer to something. This year, several of the hats are named as some number, which is a little more opaque. Why are numbers so popular this year?  What do they refer to for each hat? Here are the number-named hats for reference: Secret hats: 180°   Presumably a 180-degree turn / U-turn   8,243,721   6   Regular hats: 011 collect 11 hats   Presumably the "11" is for collecting 11 hats, but why the leading "0"?   925 earn a silver badge   24 earn a gold badge   Presumably 24-carat (pure) gold


Why do films from before 1917 seem to run faster than normal?

Why do the scenes in the films of year 1917 and before seem to run faster than the normal speed? Does it have to do something with the equipment of that era or that the actors used to act like that?


Flight ticket reimbursement after Travel Warning

I've got a round-trip flight with Royal Air Maroc from Strasbourg, France (SXB) to Ouagadougou, Burkina Faso (OUA) on Monday, Nov 10. Return is on Dec 1. The recent turmoils in Ouagadougou have led the US Department of State for Travels to issue a , which is why I'd like to refrain from the trip.  Any chance I can get a reimbursement for my tickets? In Germany (where I live), an official travel warning can help you get a refund when you book a trip with a tour operator/travel agency, but in this case I booked the flight directly with a non-German airline, so German law surely doesn't apply here.  EDIT: Sorry for failing to state this earlier, but I had already called the airline as suggested in the answers. They had told me it's not possible to get a refund with my standard fare. However, I understand that sometimes you really have to bargain to get a refund, so I wanted to learn about similar experiences and possibly about some hard (legal) facts that I could bring forward.


Can I use a Decanter of Endless Water to harm a Vampire?

The Decanter of Endless Water, DMG pg. 161, can fire a 30 foot long, 1 foot wide stream of water that can knock a target prone. On top of that, it keeps streaming until the end of my next turn (important).  A Vampire, MM pg. 297, takes 20 acid damage if it ends its turn in running water.  If I somehow manage to get this going on a vampire that we've prevented from moving, would this count as running water?


Why draw diagrams using LaTeX when there are open source tools like OpenOffice?

I was looking at recent questions here and was surprized that people were drawing diagrams in LaTeX, when it can be done in SmartDraw, OpenOffice or other programs. Is there any benefit to using LaTeX for diagrams (at least for normal diagrams like a layered architecture)?