JavaFX Rectangel Array does'nt work
What is a NullPointerException, and how do I fix it?
Get material and color of material on a face of an object in Python I want to iterate over the faces of a mesh and get the diffuse color of the material that is assigned to the face. How can I get the material that is assigned to the face of the object and the diffuse color of that material? How can I bump other users' unanswered questions? I'm looking around for answers to my questions on several Stack Exchange sites and the good boy that I am I don't want to ask duplicate questions.  Often I find that there are other people who asked the same questions, sometimes years earlier, but still don't have an answer. I'd figure I could bump these back to top, but if I don't have enough rep for a edit (or comment), how would I do that?  Or, in that case, I should just post a 'newer' version of the same question? For a prime $p \equiv 1$ or $3$  (mod $8$), show that the equation $x^{2} + 2y^{2} = p$ has a solution.   I'd like to see an elementary proof. My Android device screen got broken and I can't see what I'm doing. That's the only wrong thing with my device, the rest is apparently working OK. Is there any way to send my device screen to my computer? I don't want to work blindly anymore! Can't find wifi drivers for 0bda:f179 Realtek Semiconductor Corp I'm trying to install wifi drivers for a particular mini wifi card i bought. The output of lsusb is:  0bda:f179 Realtek Semiconductor Corp   I've searched everywhere for drivers, but could not find anything. Any help?  Thanks Why does chown report "Operation not permitted" on OS X? I am trying to do the following on my Mac (10.6.7):  sudo chown myusername:wheel ./entries   but Unix/Mac is returning "Operation not permitted". When I ls -lash the culprit file, it looks as follows:  8 -rwxrwxrwx   1 myusername  staff   394B Apr 26 23:26 entries   I've tried sudo and sudo su; nothing works. Any ideas what's up?  I'm trying to chmod files I've copied from my old Ubuntu box. Most of the files have successfully chmod'ed recursively; just this one is stuck and I don't understand why. Consistent, complete, and generalized description of the quantum harmonic oscillator Is it possible to legally visit uninhabited islands in the Pacific for a couple of days/weeks like Robinson Crusoe Can I view the Markdown-source of an unedited question/answer? Once a post has been edited, you can go into the revision list, and click "View Source".  If a post has not been edited (and I don't have the edit privilege) is there any way to see the raw Markdown?  The reason I ask I because of  - it's impossible to see the source markdown, and how it's different from the rendered Markdown.  Not exactly a huge issue, just curious! Unable to upgrade Windows 10 edition from Home to Pro I have a Lenovo laptop which upgraded from Windows 8.1 Home to Windows 10 Home.  I have a (legitimate) Windows 10 Pro key which I ran through the "Change Product Key" wizard.  After a reboot I get an error which states "We couldn't upgrade your edition" and asks me to try again or seek help from my system administrator (me!) or Microsoft.  There is nothing in the event logs except Info entries in the Setup log stating it failed to change the installed state to Pro Edition with a hex error code (I don't have access to the laptop right now, I will update later with the full log details)  Googling the hex error code led me to a Windows 7 KB Article regarding Windows Update failure due to locked files. The article stepped through using MSCONFIG to perform a clean boot which I did, but still got the error.  Any pointers on how to upgrade this laptop? Or will I have to get the sledgehammer out and do a clean install? Failed to mount Windows share: Invalid argument How to change the hostname of a RHEL-based distro? Content replacement from external website "E:Read error - read (5: Input/output error), E:The package lists or status file could not be parsed or opened." So I keep trying to install things on my laptop and whenever I try to use sudo apt-get I get the same errors every  time,  SystemError: E:Read error - read (5: Input/output error), E:The package lists or status file could not be parsed or opened.   Also whenever I try to open software Center through my desktop Icon it will just freeze leaving me to force quit.  If I try to use the command software-center in my terminal I get the longest list in the world which is,   che.open() Traceback (most recent call last):   File "/usr/lib/python2.7/dist-packages/gi/overrides/GLib.py", line 629, in &lt;lambda&gt;     return (lambda data: callback(*data), user_data)   File "/usr/share/software-center/softwarecenter/db/pkginfo_impl/aptcache.py", line 261, in open     self._cache = apt.Cache(progress)   File "/usr/lib/python2.7/dist-packages/apt/cache.py", line 105, in __init__     self.open(progress)   File "/usr/lib/python2.7/dist-packages/apt/cache.py", line 150, in open     self._cache = apt_pkg.Cache(progress) SystemError: E:Read error - read (5: Input/output error), E:The package lists or status file could not be parsed or opened. 2013-10-13 10:13:52,685 - softwarecenter.db.pkginfo_impl.aptcache - INFO - aptcache.open() Traceback (most recent call last):   File "/usr/lib/python2.7/dist-packages/gi/overrides/GLib.py", line 629, in &lt;lambda&gt;     return (lambda data: callback(*data), user_data)   File "/usr/share/software-center/softwarecenter/db/pkginfo_impl/aptcache.py", line 261, in open     self._cache = apt.Cache(progress)   File "/usr/lib/python2.7/dist-packages/apt/cache.py", line 105, in __init__     self.open(progress)   File "/usr/lib/python2.7/dist-packages/apt/cache.py", line 150, in open     self._cache = apt_pkg.Cache(progress) SystemError: E:Read error - read (5: Input/output error), E:The package lists or status file could not be parsed or opened. 2013-10-13 10:13:57,365 - softwarecenter.db.pkginfo_impl.aptcache - INFO - aptcache.open() Traceback (most recent call last):   File "/usr/lib/python2.7/dist-packages/gi/overrides/GLib.py", line 629, in &lt;lambda&gt;     return (lambda data: callback(*data), user_data)   File "/usr/share/software-center/softwarecenter/db/pkginfo_impl/aptcache.py", line 261, in open     self._cache = apt.Cache(progress)   File "/usr/lib/python2.7/dist-packages/apt/cache.py", line 105, in __init__     self.open(progress)   File "/usr/lib/python2.7/dist-packages/apt/cache.py", line 150, in open     self._cache = apt_pkg.Cache(progress) SystemError: E:Read error - read (5: Input/output error), E:The package lists or status file could not be parsed or opened.   That's only about one-tenth of the list which is too long to read. I need help, if anyone has an answer please respond Why are some applications so hard to find in the Ubuntu Software Centre? Some applications don't pop up in the search even when you type in their name. Take for instance Sushi. When you type in "sushi" into the search box, it fails to throw up the application. Only when you type in "gnome-sushi" does it appear. This is despite the fact that the application has "sushi" by itself in the application description. There are other applications which don't spring to mind right now, but I've discovered before. Sort order issue I'm having an issue sorting data in ascending order.   Right now the sort order is: 1.0.0  10.0.0 10.0.1 11.0.0 2.0.0 2.0.1 3.0.0 3.0.1 3.1.0  What I want is: 1.0.0 2.0.0 2.0.1 3.0.0 3.0.1 3.1.0 10.0.0 10.0.1 11.0.0  How can I achieve this? The datatype can't be number or currency because of the 2 decimals, so I used text-field. change color of pgfplot bar plot I want to plot two bar plots next to each other. This works without a problem. However both use the first color defined in a pre or selfdefined colorseries. I tried to modify the color manually in the plot, but the color and fill definitions have no effect:  \documentclass[border=5mm]{standalone} \usepackage{pgfplots, pgfplotstable}  \begin{document}  \pgfplotstableread[header=false, col sep=comma]{  1, first item 5, second item }\datatable  \begin{tikzpicture}   \begin{axis}[             ,xbar     ,bar width=2ex, y=3ex     ,enlarge y limits={abs=0.75}     ,ytick={data} % (\empty,data,{coordinate list})     ,yticklabels from table={\datatable}{1}   ]   \addplot table [     ,red!20!black,fill=red!80!white,     y expr=-\coordindex, % Use negative coordinate index as y coordinate     x index=0 % Use first column as x coordinate   ] {\datatable};   \end{axis} \end{tikzpicture}  \end{document}   The plot is still in the default blue. I have an armature set up, but the bones aren't moving the mesh properly  The mesh and armature:    The vertex group of the bone I am going to move:    As you can see, the circled region doesn't belong to the vertex group. But, when I move the bone look what happens:    That part of the mesh has moved with the bone.. Why? I need help!  I need to prove that for any $2 \le n,k$ positive integers $(n - 1)^2 \mid n^k -1$ if and only if $(n - 1) \mid k$  Thanks! Lazy evaluation in C++ C++ does not have native support for lazy evaluation (as Haskell does).  I'm wondering if it is possible to implement lazy evaluation in C++ in a reasonable manner. If yes, how would you do it?  EDIT: I like Konrad Rudolph's answer.  I'm wondering if it's possible to implement it in a more generic fashion, for example by using a parametrized class lazy that essentially works for T the way matrix_add works for matrix.  Any operation on T would return lazy instead. The only problem is to store the arguments and operation code inside lazy itself. Can anyone see how to improve this?