Same memory usage of matrices with different size
How to compute the size of the allocated memory for a general type
I never had this problem until today. When I watch a youtube video everything is fine, until I make the video fullscreen. It actually continues to play perfectly when fullscreen, but when I then exit fullscreen my sidebar and topbar are gone, and the screen is just frozen. Also my cursor is gone. It does seem to respond to ALT-F4, but it takes about 15 seconds to even close the window, and after that everything is unusable (basically frozen). What's strange though, when I re-enter fullscreen after exiting (and unity being frozen) the video plays perfectly still.   For now my workaround is opening tty1 and executing pkill -u username which logs off the user. I have looked at /var/log/syslog but it seems to be empty.  Is this freezing a common problem, if not, how can I make steps to fix this?    EDIT with specs:  I'm on a simple Samsung laptop with:  Ubuntu 14.10 64-bit,  Intel® Core™ i5-3210M,  Intel® Ivybridge Mobile (So integrated intel hd graphics 4000),  8GB ram. I don't think i've ever changed my video drivers, but it's reported as i915.  Ubuntu is up to date, and my browser is Chrome 40.0.2214.91 (64-bit). (Will test out now with firefox, but already posting this because my pc might freeze again)     EDIT 2: It doesn't freeze on Firefox. Will try reinstalling chrome now... EDIT 3: Reinstalling chrome didn't help. Will try chrome 32-bit too now... Why is Excel truncating my 16-digit numbers? If I type in a 16 digit number (format: number, no decimals) it changes the number on me. Example: 1234567812345678 changes the view to 1234567812345670.    If I type it in as a general format it changes the numbers above so it displays 1.23457E+15 but if you click on the cell, the display shows the last digit as a 0 instead of an 8 once again.   I opened the file on a different computer and same issue now with it.  I have changed the auto correction and auto formatting all to no avail.  Help! Clustering on the output of t-SNE I've got an application where it'd be handy to cluster a noisy dataset before looking for subgroup effects within the clusters.  I first looked at PCA, but it takes ~30 components to get to 90% of the variability, so clustering on just a couple of PC's will throw away a lot of information.    I then tried t-SNE (for the first time), which gives me an odd shape in two dimensions that is very amenable to clustering via k-means.  What's more, running a random forest on the data with the cluster assignment as the outcome shows that the clusters have a fairly sensible interpretation given the context of the problem, in terms of the variables that make up the raw data.  But if I'm going to report on these clusters, how do I describe them?  K-means clusters on principal components reveal individuals who are nearby to one another in terms of the derived variables that comprise X% of the variance in the dataset.  What equivalent statement can be made about t-SNE clusters?  Perhaps something to the effect of:     t-SNE reveals approximate contiguity in an underlying high-dimensional manifold, so clusters on the low-dimensional representation of the high-dimensional space maximize the "likelihood" that contiguous individuals will not be in the same cluster   Can anyone propose a better blurb than that? Why is "what can I ask about here" not the first entry in the help center? On a lot of sites, the first section of the Help Center looks like this:    When I go to a site's help center it's almost always to find out what's on-topic there, because I'm considering asking or migrating a question.  Leading with what not to ask seems odd to me, and I suspect that to someone not already familiar with SE it could be a little off-putting.  It's not always like this, though; here on MSE we get this, which I've seen on some other sites too:    That ordering makes a lot more sense to me.  It's also consistent with the tour.  (Maybe "how do I ask a good question?" should also be "above the fold", in the top five somewhere.)  Why the difference?  Can we either make the order consistent across the network and more logical, or give users or moderators the ability to change the order on their sites? When you hit up a site, such as cnn.com, does the TCP/IP packet contain the MAC address of your network card?  Could cnn.com theoretically record my MAC address? sum of the residue at all poles of the rational function p/q is 0. We are given two polynomials p, q with deg(q)>1+deg(p). Show that the sum of the residue at all poles of the rational function p/q is 0.   How do I go about solving this? Number of solutions of $x_1+2x_2+\cdots+kx_k=n$? "Dare speak" vs. "dare to speak" vs "dares to speak" Which is the most appropriate improvement in the following     I am surprised that he dares speak in such a tone to his father.     a) he dares to speak b) he dare to speak c) he dare speak    I think the answer should be 'c' but the book says 'a'. I'm trying to change sign text color in Java Edition on Windows 10. According to , this is done using the § symbol:  To enter &quot;§&quot; on Windows with most US/UK English keyboards type ALT + NUMPAD_2 NUMPAD_1  This works for me inside Notepad or this browser. However, when I enter this sequence in the sign input dialog, nothing happens. What could be causing this? How to unmap TAB and do not make Ctrl-I invalid in VIM Normed vector spaces over finite fields Normed vector spaces are typically defined over the reals or complex numbers.  Is there any "standard," well-behaved construction that generalizes this to a vector space over a finite field, such as $\Bbb F_2$?  I'm looking for something kind of like the class of $\ell_p$ norms, except designed with finite fields in mind.  Ideally, something that has deep fundamental properties making it well-behaved in the same way that the Euclidean norm is. I want to know if I can pass an argument with an alias command.  for example:  alias d="dmesg|grep -iw usb|tail -5"    Now d will print the last 5 lines. If I want to use d to print a different number of lines, I have to make change in the alias command declaration of d again.  Is there any way I can modify the declaration of an alias so that I don't have to retype the declaration to change the number of lines. Like incorporating passing the number of lines as an argument while declaring alias for d? Or is there some other method to solve this? How to install the Pantheon desktop environment? Bash auto_completion with Xubuntu and xrdp from windows I'm using Xubuntu and connecting over RemoteDesktop with Windows 7.  Everything works fine, but the auto_completion in my bash doesn't work. I checked the .bashrc file in my home directory and also the /etc/bash.bashrc.  I uncommend the lines below in my local bashrc configuration and also in bash.bashrc, but nothing changes.  if ! shopt -oq posix; then   if [ -f /usr/share/bash-completion/bash_completion ]; then     . /usr/share/bash-completion/bash_completion   elif [ -f /etc/bash_completion ]; then     . /etc/bash_completion   fi fi How to install mods for the new Minecraft launcher What is the difference between can and could in 'Can/could you please explain this to me?' Can you please explain this to me?          Could you please explain this to me?   I am unable to figure out which to use which situation. I did google, and some posts say they are both the same, even if the second one is more formal. Other posts say could is the past tense of can, but in the above example, I don't think could is used as past tense of can.  What is correct way to use these words? How to change the name of document elements like "Figure", "Contents", "Bibliography", "Appendix", etc.? How to get client date and time in ASP.NET? I would like to get a USB token to secure my keys. My use case is protection of 3 GnuPG keys that I will be using 10 times per day at least. I plan to create a new key ring from scratch. Because ECC seems more future-oriented than RSA, this is what I chose to use. I'm wondering which USB token to choose as well as which curve.  On  it is said that many people think curves recommended by the NIST or defined by Brainpool have a doubtful origin; therefore, they recommend the non-standardized Bernstein’s Curve 25519. On  one poster says that    He is not aware of any profound criticism of Brainpool curves, and Bernstein’s Curve 25519 is hard to protect against side-channel attacks when implemented in embedded devices.   As a result, I'm a bit lost as to which key/curve to choose. load a file and read the information I want to open an Excel file through an Apex dialog box, then browse the information in my file line and display it with visualforce. I show you my code  public class ImportExcel {       public String fileName{get; set;}     public Blob contentFile{get;set;}     public String[] csvFileLines{get;set;}     public List&lt;String&gt; acclist{get;set;}     public String[] data{get;set;}     public ImportExcel(){         csvFileLines = new String[]{};         acclist = New List&lt;String&gt;();      } public void readFile(){         try         {             fileName=contentFile.toString();         }catch(Exception e){         ApexPages.Message myMsg = new ApexPages.Message(ApexPages.Severity.FATAL,'Please upload a valid CSV document');         ApexPages.addMessage(myMsg);              return ;          }         csvFileLines=fileName.split('\n');          system.debug(csvFileLines);         for(Integer i=0;i&lt;csvFileLines.size();i++){             data=csvFileLines[i].split(',');             acclist.add(data[i]);         }     } }   Once I execute my code, it puts me this error:     13:52:13:012 VARIABLE_ASSIGNMENT   [15]|e|"common.apex.runtime.impl.ExecutionException: BLOB is not a   valid UTF-8 string"|0x4e4728