Number of possible keys in a Play fair cipher
How many keys does the Playfair Cipher have?
I tried to use sudo cd name_of_dir but am getting the error message:   sudo: cd: command not found   Is there any other way to enter a directory owned by another user which has 700 permission? 2D graphics - why use spritesheets? I have seen many examples of how to render sprites from a spritesheet but I havent grasped why it is the most common way of dealing with sprites in 2d games.  I have started out with 2d sprite rendering in the few demo applications I've made by dealing with each animation frame for any given sprite type as its own texture - and this collection of textures is stored in a dictionary. This seems to work for me, and suits my workflow pretty well, as I tend to make my animations as gif/mng files and then extract the frames to individual pngs.  Is there a noticeable performance advantage to rendering from a single sheet rather than from individual textures? With modern hardware that is capable of drawing millions of polygons to the screen a hundred times a second, does it even matter for my 2d games which just deal with a few dozen 50x100px rectangles?  The implementation details of loading a texture into graphics memory and displaying it in XNA seems pretty abstracted. All I know is that textures are bound to the graphics device when they are loaded, then during the game loop, the textures get rendered in batches. So it's not clear to me whether my choice affects performance.  I suspect that there are some very good reasons most 2d game developers seem to be using them, I just don't understand why. Why can't I associate files with Excel after upgrading to 2010? Let $f$ be defined on $\mathbb{R}$ by $f(x) = e^{-1/x^2}$ for $x$ not equal to $0$. and $f(0)= 0$. Prove that $f^{(n)}(0)=0$ for all $n = 1, 2,3$ ...  Do I need to use Taylor expansion from calculus class?  Any hint would be appreciated. How do you "OR" criteria together when using a criteria query with hibernate? Notification that ‘someone might be watching what you browse’ I got a notification on my iPhone. The notification reads     Someone might be watching what you browse. Follow 3 steps to encrypt your web traffic and change your IP address.   What does this mean? Can I safely use my camera with a external power supply? Firefox running with rare arguments I got this output from ps aux|grep firefox command:  $ ps aux|grep firefox auraham   5443 17.3 11.0 2600628 426484 ?      Sl   18:10   0:54 /usr/lib/firefox/firefox auraham   5496 24.0 17.9 2558108 691700 ?      Sl   18:10   1:15 /usr/lib/firefox/firefox -contentproc -childID 1 -isForBrowser -intPrefs 5:50|6:-1|18:0|28:1000|33:20|34:10|43:128|44:10000|49:0|51:400|52:1|53:0|54:0|59:0|60:120|61:120|91:2|92:1|106:5000|117:0|119:0|130:10000|155:24|156:32768|158:0|159:0|167:5|171:1048576|172:100|173:5000|175:600|176:4|177:1|186:2|200:60000| -boolPrefs 1:0|2:0|4:0|26:1|27:1|30:0|35:1|36:0|37:0|38:0|41:1|42:1|45:0|46:0|47:0|48:0|50:0|55:1|56:1|57:0|58:1|62:1|63:1|64:0|65:1|66:1|67:0|68:1|71:0|72:0|75:1|76:1|80:1|81:1|82:1|83:0|85:0|86:0|87:1|88:0|93:1|94:0|100:0|105:0|108:1|109:0|111:1|112:1|114:1|118:0|120:0|122:0|124:1|125:1|131:0|132:0|133:1|135:0|146:0|153:0|154:0|157:1|160:0|162:1|164:1|165:0|170:0|174:1|179:0|180:0|181:0|182:1|183:0|184:0|185:1|188:1|192:0|193:0|194:1|195:1|196:0|197:1|198:1|199:1|201:0|202:0|204:0|212:1|213:1|214:0|215:0|216:0| -stringPrefs 3:7;release|134:3;1.0|151:332;  ¼½¾ǃː??։֊׃״؉؊٪۔܁܂܃܄ᅟᅠ᜵           ???‐’․‧??????? ‹›⁁⁄⁒ ⅓⅔⅕⅖⅗⅘⅙⅚?⅜⅝⅞⅟∕∶⎮╱⧶⧸⫻⫽⿰⿱⿲⿳⿴⿵⿶⿷⿸⿹⿺⿻　。〔〕〳゠ㅤ㈝㈞㎮㎯㏆㏟꞉︔︕︿﹝﹞?．／｡ﾠ???￼�|152:8;moderate| -greomni /usr/lib/firefox/omni.ja -appomni /usr/lib/firefox/browser/omni.ja -appdir /usr/lib/firefox/browser 5443 true tab auraham   5694  0.0  0.0  15444  1092 pts/2    S+   18:15   0:00 grep --color=auto firefox   According to , this error occurs after firefox crashes. However, every time I run Firefox again, that large line of arguments appears too.  I already try these things:   Run Firefox with addons disabled Reinstall Firefox (sudo apt-get purge firefox; sudo apt-get install firefox)   However, it did not work.  Is it possible to remove such a line of arguments? Why can't I tame my ocelot? I'm trying to make a cat house for my zoo on Minecraft. I have some untamed ocelots and I also want a few tamed ocelots. Fish only puts them in breeding mode. n tasks assigned to n computers, what is the EX value of a computer getting 5 or more tasks? Getting key with maximum value in dictionary? I have a dictionary: keys are strings, values are integers.  Example:   stats = {'a':1000, 'b':3000, 'c': 100}   I'd like to get 'b' as an answer, since it's the key with a higher value.  I did the following, using an intermediate list with reversed key-value tuples:  inverse = [(value, key) for key, value in stats.items()] print max(inverse)[1]   Is that one the better (or even more elegant) approach? How to change the default fonts in Windows 10 I have read the entries for other OS versions.    Changing the MS Shell Dlg (2) entries in FontSubstitues registry key doesn't seem to work (in Windows 10), or it works in two minor places.  I don't have access to a Windows 95/98/etc. machine, the "earliest" I have is Windows 8.1, so I can't use the Plus directory trick either (directory doesn't exist). For the WindowMetrics registry entry, I seem to have all the *Font keys to be set to the font I want, but that doesn't seem to be doing the trick (on Windows 10). For Windows 8/8.1, there was a program called Windows 8 Font Changer, which worked like a charm, but doesn't seem to on Windows 10 (though it was probably that program run that changed the fonts in the WindowMetrics).   Thanks.   Update: One more method that came out that is perhaps still not the solution: Winaero Tweaker (winaero.com), as it has some issues, the biggest two of which seem to be:   If you have changed the size of text etc. from: "Settings –> Display –> Advanced display settings –> Advanced sizing of text and other items –> set a custom scaling level (not recommended)", the changes do not stick upon a logoff-login or restart. You need to have changed it, if at all, only through "Settings –> Display –> Change the size of text, etc." (which goes up to only a certain percentage, depending on the maximum resolution of your device – 125% on a tablet of mine, which I was able to set to 175% or even 200% with the other, older method that is now apparently listed as not recommended).  Even though it lists a number of items to change the font and size of, not everything gets changed. A typical example of this is the right click menu on the desktop, which still shows the View, Sort By, etc. items in the default font, however much it has a clear 'Change menu font' item. How do I read / convert an InputStream into a String in Java? How to remove or hide the GRUB boot menu? Recently I decided to use only Ubuntu and there is no Windows in my laptop. When I turn on my laptop the GRUB menu is showing but I don't need to choose OS anymore.   How can I remove or hide this? And after removing this how could I access to recovery mode? Drag and drop not working inside Nautilus on Ubuntu 17.10 I'm having a strange problem on Ubuntu 17.10: when I try to drag and drop something inside Nautilus it simply doesn't work, it doesn't even select the item, it seems like it's ignoring the action... Also, I cannot select things inside nautilus by drawing rectangles with the mouse.  All of these actions work only on the Desktop. Here is a demo:    I'm using the Xorg session with nVidia proprietary drivers. I also noticed that Nautilus seems to hang when I try to copy, paste or cut a file...  EDIT 1: I solved the problem for the slow copy/paste by disabling the clipboard sync plugin of KDEConnect. I also discovered that if I open Nautilus as root, I can drag and drop or select whatever I want... Quick question about curly braces not showing up Ii am writing a short code, so I doubt anything else in the code is causing the problem. This is the problematic line of code:  \[ M_R := \max {|f(z)|: |z - z_0| = R }\le M\]   It doesn't show the curly braces. I've tried using \left{ and \right} but to no avail.  What should I do?  Thank you Invalid SSL certificate when pushing to Git server Look and you shall find (a correlation) Display each sub-directory size in a list format using one line command in Bash? I want to get a list of the directories and their sizes in a list format like how you get when you do a ls -l.  The thing is that is there a one line command that can do this? I see others have long commands just to output this. That's just too long.  What command can do this or combination of commands that can be easily typed? du -h gives it, but it displays all of the sub-folders which is not what I want. just the current directories folders. How to re-enable the systray (indicator panel) after latest updates