Failed to install pidgin-whatsapp in Ubuntu 14.10 (Error - Failed to fetch PPA)
How can I add a PPA from a previous release?
Which tube size to prefer if several options apply? I have 40-622 (a.k.a. 28x1.5") tires, and  offers  two different sizes of tubes - their models "17" and "19" - as applicable for that tire size.  Ok, either one would surely fit well. But apart from weight difference (150 vs. 220 grams), is there any reason to prefer one over another? Is it better to have as small &amp; light tube as possible? Or perhaps a bit larger and heavier one would be more durable, as it wouldn't be stretched as much? Err on which side? Any Set with Associativity, Left Identity, Left Inverse is a Group solving diophantine equations using congruences So, a question in Elementary Number Theory by David M. Burton:     Problems 4.4      2(a) Using congruences, solve the diophantine equation 4x + 51y = 9       Hint: $4x \equiv 9(mod \ 51) $ gives $ x = 15 +51t$, whereas $ \ 51y \equiv 9 (mod \ 4)$ gives $y = 3+4s $. Find the relation between $s$ and $t$ From this hint, I substitute $ x = 15 +51t$ and $y = 3+4s$ in the given equation $4x + 51y = 9$ to get the relation $s = -t-1$ and using which I can get the solutions $ x = 15 + 51t, \ y =-1-4t$ But we know that the solutions of $ax \equiv b (mod \ n)$ is equivatent to the solutions of the diophantine equation $ax -ny = b$, so, solutions of $4x \equiv 9(mod \ 51) $ is equivalent to solutions of the equation $4x-51y=9$ whereas, solutions of $51y \equiv 9(mod \ 4) $ is equivalent to solutions of the equation $-4x+51y=9$ Now, my question is: as, the above equations $4x-51y=9$ and $-4x+51y=9$ are different, then what is the point of substituting $ x = 15 +51t$ (solution of $4x-51y=9$) and $y = 3+4s $ (solution of $-4x+51y=9$) in the given equation $4x+51y=9$ to find a relation between $t$ and $s$ ? Isn't it absurd as $ x = 15 +51t$ and $y = 3+4s $ are solutions of two different equations? Can anyone please explain this? PS: I did it like this $4x \equiv 9(mod \ 51) $ gives $ x = 15 +51t$ and by substituting it in $4x+51y=9$ we get $y=-1-4t$ Let's assume a very simplified situation. There is only one seller asking for 10$ and there is only one buyer bidding 20$. At what price would the transaction go?   Some answers say it won't, because the ask price has to match the bid price. () Other answers say, that the time ordering is important. () Which answer is correct? What is the final price in the presented situation? No icons for automounted volumes on GNOME / Nautilius desktop on Ubuntu 19.04 Up to Ubuntu 18.04, using default GNOME/Nautilius desktop, when I inserted a (data file) USB stick it would automount and put a USB icon onto the desktop.  I find this very useful, especially for quick eject via context menu.  Now at 19.04, on USB insertion I do see a "banner" appear for a few seconds, but I no longer get any desktop icon .  I run under VirtualBox on Windows, but that has not changed and I do not think is at issue.  Ubuntu does still automount the stick at /media/&lt;username&gt;.  I found .  I checked in dconf-editor and both keys, including org.gnome.desktop.media-handling.automount-open, are set. Lightning:input type="date": how to change the date fomat - Summer'18 "World's Hardest Easy Geometry Problem" How can I remove snaps without losing GUI? I want to know how to check how many snaps programs/apps I'm running. Also, how to replace them (if possible) without losing GUI? Why are you not able to declare a class as static in Java? Do small title edits constitute trivial edits? How to use stars and bars for solving number of integral solutions to an equality? After the top bar changes in the , when a non logged-in user click the Sign Up button, instead of navigating to the corresponding page it displays the openid related code in the screen.  Screenshots for reference: Best method for short time-series What is an ultra-wide lens? What is the point at which a lens is considered "ultra-wide angle" vs just wide angle? Runtime error : ERROR 000358: Invalid expression using SelectLayerByAttribute in ArcPy? I cannot for the life of me persuade SelectLayerByAttribute to work (I need to automate this for a complex script).  Working in ArcMap's python console on already loaded shapefile, the format below:  import arcpy from arcpy import env arcpy.env.workspace = r"C:/Users/.../working" arcpy.SelectLayerByAttribute_management("layer", "NEW_SELECTION", " 'ATTRIBUTE' = 'Criterion' ")   results in error:     Runtime error : ERROR 000358:   Invalid expression Failed to execute (SelectLayerByAttribute).   An alternative method:  import arcgisscripting import arcpy gp = arcgisscripting.create(9.3) gp.workspace = "C://...//working" sFile = "C://...//working//shapefile.shp" lyr = "layer" gp.makefeatureLayer_management(sFile, lyr) gp.toolbox = "management" gp.SelectLayerByAttribute("layer", "NEW_SELECTION", " 'ATTRIBUTE' = 'Criterion' ")   .. selects everything, including features that don't meet the criterion!  Does anyone have any idea what's going wrong?  I've read some pages on , but found no solution that works here. The working directory is correct. The attribute field and criterion are correctly specified (case sensitive etc), etc. Its very confusing. Electrical potential energy stored in vacumm for a single point charge? I have come to know the electrostatic potential energy in vacuum is given by $${\frac{1}{2}} \epsilon_0\int d^3x {E^2} $$ and this energy  is due to the mutual electrostatic coulomb potential energy. So only a single point charge in space also contributes to some electrostatic potential energy according to $${\frac{1}{2}} \epsilon_0 \int d^3x {E^2} $$  as due to a single point charge also we have an electric field at every point in space. Now I am not getting it physically, why should there be any Coulomb energy in this case as there is no other charge to provide the electrostatic coulomb potential energy? I would like to get all descendant text nodes of an element, as a jQuery collection. What is the best way to do that? What is the easiest way to match non-ASCII characters in a regex? I would like to match all words individually in an input string, but the language may not be English, so I will need to match things like ü, ö, ß, and ñ. Also, this is in Javascript/jQuery, so any solution will need to apply to that. Use Data From Class Without A New Init What is a "static" function in C? The question was about plain  functions, not  static methods, as clarified in comments.  I understand what a static variable is, but what is a static function?  And why is it that if I declare a function, let's say void print_matrix, in let's say a.c (WITHOUT a.h) and include "a.c" -  I get "print_matrix@@....) already defined in a.obj", BUT if I declare it as static void print_matrix then it compiles?  UPDATE Just to clear things up - I know that including .c is bad, as many of you pointed out. I just do it to temporarily clear space in main.c until I have a better idea of how to group all those functions into proper .h and .c files. Just a temporary, quick solution.