When running Gnome Software via the terminal, I get the following error message:     (gnome-software:6632): Gs-WARNING **: failed to open plugin   /usr/lib/gs-plugins-9/libgs_plugin_xdg_app_reviews.so:   /usr/lib/gs-plugins-9/libgs_plugin_xdg_app_reviews.so: cannot open   shared object file: No such file or directory   Gnome Software opens fine, just when loading the page for any software, it just get stuck in the loading part, and does not display anything!  I just also installed the packagekit, put the same error persist!    Just in case this is not fixable by just tweaking, and installing, I submitted a bug report:
After plain installation of Ubuntu 16.04 LTS gnome-software doesn't work. It has opened once with GUI, but installation of Unity Tweak Tool didn't finish.  When starting again, GUI doesn't come up. When opening from terminal, a warning appears, but the application GUI doesn't open.  $ gnome-software (gnome-software:7052): Gs-WARNING: failed to open plugin /usr/lib/gs-plugins-9/libgs_plugin_xdg_app_reviews.so: /usr/lib/gs-plugins-9/libgs_plugin_xdg_app_reviews.so: cannot open shared object file: No such file or directory   Does anybody have same experience, and eventually, a solution?    According to the recommendation:  $ dpkg-query -S /usr/lib/gs-plugins-9/libgs_plugin_xdg_app_reviews.so gnome-software: /usr/lib/gs-plugins-9/libgs_plugin_xdg_app_reviews.so   Proposed reinstall of gnome-software did not help.    As workaround, use Synaptic Package manager and command line.
What are 'return' pins? On a VGA connector, there are numerous 'ground' pins. Three of these are Red return, Green return and Blue return; But why does each color component have its own ground pin? I've just been downvoted. How should I react? Determine all functions satisfying $f(x + f(x + y)) + f(xy) = x + f(x + y) +yf(x)$ I read many places that the rule of thumb for swap space is to double the amount of physical RAM. However, 32 GB does seem a LOT. Do I need that much? Do I need it at all with this high amount of physical RAM? How old is Chewbacca? Can you make a non-polar electrolytic capacitor out of two regular electrolytic capacitors? There was some discussion on this question        which I don't see as being conclusively resolved:   "turns out that what might LOOK like two ordinary electrolytics are not, in fact, two ordinary electrolytics." "No, do not do this. It will act as a capacitor also, but once you pass a few volts it will blow out the insulator." 'Kind of like "you can't make a BJT from two diodes"' "it is a process that a tinkerer cannot do"   So is a non-polar (NP) electrolytic cap electrically identical to two electrolytic caps in reverse series, or not?  Does it not survive the same voltages?  What happens to the reverse-biased cap when a large voltage is placed across the combination?  Are there practical limitations other than physical size?  Does it matter which polarity is on the outside?  I don't see what the difference is, but a lot of people seem to think there is one.  Summary:   As posted in one of the comments, there's a sort of electrochemical diode going on:     The film is permeable to free electrons but substantially impermeable to ions, provided the temperature of the cell is not high. When the metal underlying the film is at a negative potential, free electrons are available in this electrode and the current flows through the film of the cell. With the polarity reversed, the electrolyte is subjected to the negative potential, but as there are only ions and no free electrons in the electrolyte the current is blocked. —    Normally a capacitor cannot be reverse-biased for long, or large currents will flow and "destroy the center layer of dielectric material via electrochemical reduction":     An electrolytic can withstand a reverse bias for a short period, but will conduct significant current and not act as a very good capacitor. —    However, when you have two back-to-back, the forward-biased capacitor prevents a prolonged DC current from flowing.  :     For circuit positions when reverse voltage excursions are unavoidable,   two similar capacitors in series connected “back to back” ... will create a   non-polar capacitor function ... This works because almost all the circuit voltage   is dropped across the forward biased capacitor, so that the reverse   biased device sees only a negligible voltage.   :     The oxide dielectric construction that is used in tantalum capacitors   has a basic rectified property which blocks current flow in one   direction and at the same time offers a low resistance path in the   opposite direction. Since I started learning  and  last year, I've read a huge number of articles which insist that design patterns (especially in Java) are workarounds for the missing features in imperative languages. One article I found :     Most people I've met have read     by the Gang of   Four (GoF). Any self respecting programmer   will tell you that the book is   language agnostic and the patterns   apply to software engineering in   general, regardless of which language   you use. This is a noble claim.   Unfortunately it is far removed from   the truth.      Functional languages are extremely   expressive. In a functional language   one does not need design patterns   because the language is likely so high   level, you end up programming in   concepts that eliminate design   patterns all together.   The main features of functional programming (FP) include functions as first-class values, currying, immutable values, etc. It doesn't seem obvious to me that OO design patterns are approximating any of those features.  Additionally, in functional languages which support OOP (such as F# and OCaml), it seems obvious to me that programmers using these languages would use the same design patterns found available to every other OOP language. In fact, right now I use F# and OCaml every day, and there are no striking differences between the patterns I use in these languages vs. the patterns I use when I write in Java.  Is there any truth to the claim that functional programming eliminates the need for OOP design patterns? If so, could you post or link to an example of a typical OOP design pattern and its functional equivalent? I have a package (fcl) in my PPA  in my launchpad PPA and it depends on another package (libccd) which is in another PPA ppa:imnmfotmal/libccd. fcl has both build and run dependency in libccd. So i added libccd as a PPA dependency in launchpad and both are successfully build. but when i am trying to install fcl package after adding the fcl PPA, its throwing an error Reading package lists... Done Building dependency tree        Reading state information... Done Some packages could not be installed. This may mean that you have requested an impossible situation or if you are using the unstable distribution that some required packages have not yet been created or been moved out of Incoming. The following information may help to resolve the situation:  The following packages have unmet dependencies:  fcl : Depends: libccd but it is not installable E: Unable to correct problems, you have held broken packages.  but its successfully getting installed after adding the libccd PPA also. I want fcl to install libccd automatically without adding its PPA. how can i achieve it ?? Output of apt-cache policy fcl fcl:   Installed: (none)   Candidate: 1.0-0ppa5   Version table:      1.0-0ppa5 0         500 http://ppa.launchpad.net/imnmfotmal/fcl/ubuntu/ trusty/main amd64 Packages "Access is denied" JavaScript error when trying to access the document object of a programmatically-created  (IE-only) For example block cipher AES-128, Key size is 128bit and it is used to make a 10 round key which is total 320bit.  Question 1. If i use another Key schedule algorithm in AES, then security decreased or remain same? In other words, if the key schedule algorithm of AES has some relationship with AES encryption itself, then it will be decreased, or it will be same if the new key schedule algorithm is safe enough.  Question 2. Why we expand key? brute force will take O(2^128) time regardless of the key schedule is strong or not. what is the advantage of making key expend? I was curious about this when I was learned about 3DES. Which developed because the former DES has weak key length 56bit so vulnerable to brute force attack, i was wondering why doesn't they just remove key schedule process and use the whole round key as a key. Isle vs. Island I have my bachelors degree in engineering science: computer science, option electrotechnic. I have a good understanding of basic mechanics and dynamics, calculus (differential equations).  The books I'm now having a look at are:       What book do you recommend for studying fluid dynamics on my own and why? A comparison between Grade, Mark, Score and Point Let's suppose a teacher wants to punish a student and wants to decrease his / her achieved points on a test paper; he would say something to the student; I would like to know which one of the following self-made examples may work here:        I have to take two marks of you.   I have to take two grades of you.   I have to take two scores of you.   I have to take two points of you.      For me all the first three mean the same and though the last one is not the same, but works here either. I need to get your feedback. Can others in my party go through TSA PreCheck? If I have  (i.e. I have a KTN from TSA and the "pre-check" logo gets printed on my boarding pass) and a travel companion does not, can they go with me through the PreCheck security lines? This is assuming that the travel companion is booked in the same reservation on the same flights and is also a U.S. citizen and not on any no-fly or otherwise increased scrutiny lists.  I'm guessing the answer is no, but I haven't seen anything from TSA specifically addressing this. I got a bash script to synchronize data between two computers. It works fine but I have to type my password every time the rsync command is called.   #!/bin/bash  sourceIP="192.168.178.128" sourceUser="user1" destinationUser="user2"  function sync() {      rsync --archive --progress -v -e "ssh -l $sourceUser " $sourceIP:/home/$sourceUser/$1/ /home/$destinationUser/$1 }  sync Pictures sync Music sync Videos sync Documents   How to store the password (via prompt) in a variable and pass it to rsync/ssh? Can $n!$ be a perfect square when $n$ is an integer greater than $1$? Can $n!$ be a perfect square when $n$ is an integer greater than $1$?  Clearly, when $n$ is prime, $n!$ is not a perfect square because the exponent of $n$ in $n!$ is $1$.  The same goes when $n-1$ is prime, by considering the exponent of $n-1$. What is the answer for a general value of $n$?  (And is it possible, to prove without Bertrand's postulate. Because Bertrands postulate is quite a strong result.) Prove holomorphism of expression I have to prove that given $\gamma$ contour of $G \subset \mathbb{C}$  and $f$ continuous function on $G$. Then the function $g(z) = \int_{\gamma} \frac{f(w)}{w-z}dw$ is holomorphic on $\mathbb{C} - \bar{G}$ My attempt: I started by using that given any parametrization $\alpha :[a,b] \rightarrow \gamma$ we can rewrite $g(z)$ as: $g(z) = \int_a^b \frac{f(\alpha(t))}{\alpha(t)-z}\alpha'(t)dt$ Now using the fundamental theorem I derivate to see where $g'(z)$ is defined and I get: $g'(z) = \frac{f(\alpha(b))}{\alpha(b)-z}\alpha'(b) - \frac{f(\alpha(a))}{\alpha(a)-z}\alpha'(a) $ Here I get stuck, I fail so see how this links back to $g$ being holomorphic at $\mathbb{C} - \bar{G}$. Any hints on how to proceed? Thanks! How can I draw a dot under a symbol in math mode? Time complexity of nested for-loop I need to calculate the time complexity of the following code:  for (i = 1; i &lt;= n; i++) {   for(j = 1; j &lt;= i; j++)   {    // Some code   } }   Is it O(n^2)? Encouraging people to explain downvotes Note: If you're looking for a simple explanation as to why comments aren't required on downvotes, see .   I used to get "upset" (though that is too strong a term) when I got downvoted without comment. If my answer isn't good enough then I'd like to know why. Not only does it improve the answer for the OP but it improves my knowledge too.  Where the down-vote has been explained I've found it useful &amp; it has improved my answer, or forced me to delete the answer if it was totally wrong.  So is there any way we can encourage people to leave a comment? Perhaps they don't lose rep if they explain their down-vote?  I must admit though that I haven't always explained my down-vote either so you could call me a hypocrite. I've also grown a thicker skin over the months of using SO (it seems to have come with the higher rep score ;-)), so I'm less bothered about this now.