eventually I have made the decision to get rid of windows and go for ubuntu!! I had been thinking to do so for long time, but I was keeping putting it off. So, I am excited, but I have also started to hit the first issues :).  I now have a problem with skype, and that's why I am writing.  My ubuntu version is the following:  davide@Gis74:~$ lsb_release -a No LSB modules are available. Distributor ID: Ubuntu Description:    Ubuntu 14.04.1 LTS Release:    14.04 Codename:   trusty   I installed skype a couple of weeks ago and it had worked fine until this morning. Since this morning I can no longer connect to it and I have been getting the following notification:  An error occurred, please run Package Manager from the right-click menu or apt-get in a terminal to see what is wrong. The error message was: 'Unknown Error: '' ("The cache has no package named 'skype-bin'")' This usually means that your installed packages have unmet dependencies  I did some research without too much luck. I am posting some of the commands output I seem to understand can be useful to debug the issue:  davide@Gis74:~$ sudo apt-get -f install Reading package lists... Done Building dependency tree        Reading state information... Done 0 to upgrade, 0 to newly install, 0 to remove and 26 not to upgrade.   davide@Gis74:~$ sudo apt-cache policy 'skype*:*' skype:   Installed: 4.2.0.11-0ubuntu0.12.04.2   Candidate: 4.3.0.37-0ubuntu0.12.04.1   Version table:      4.3.0.37-0ubuntu0.12.04.1 0         500 http://archive.canonical.com/ubuntu/ trusty/partner amd64 Packages  *** 4.2.0.11-0ubuntu0.12.04.2 0         100 /var/lib/dpkg/status skype4pidgin:   Installed: (none)   Candidate: (none)   Version table: skype-mid:   Installed: (none)   Candidate: (none)   Version table: pidgin-skype-dbg:   Installed: (none)   Candidate: 20130613+svn660+dfsg-1   Version table:      20130613+svn660+dfsg-1 0         500 http://gb.archive.ubuntu.com/ubuntu/ trusty/multiverse amd64 Packages skype-bin:   Installed: (none)   Candidate: (none)   Version table: skype-common:   Installed: (none)   Candidate: (none)   Version table: empathy-skype:   Installed: (none)   Candidate: 20130613+svn660+dfsg-1   Version table:      20130613+svn660+dfsg-1 0         500 http://gb.archive.ubuntu.com/ubuntu/ trusty/multiverse amd64 Packages pidgin-skype:   Installed: (none)   Candidate: 20130613+svn660+dfsg-1   Version table:      20130613+svn660+dfsg-1 0         500 http://gb.archive.ubuntu.com/ubuntu/ trusty/multiverse amd64 Packages pidgin-skype-common:   Installed: (none)   Candidate: 20130613+svn660+dfsg-1   Version table:      20130613+svn660+dfsg-1 0         500 http://gb.archive.ubuntu.com/ubuntu/ trusty/multiverse amd64 Packages    I was thinking to re-install/upgrade skype but I am not sure how to do it. Can anyone please help?  Many thanks, Davide
First of all, I think this question is not duplicated, because I have tried all other solutions I found here, but nothing solved my problem.  I use Ubuntu 14.04 64 bit.  I have tried until now: sudo apt-get install skype -> It didn't work. The error was:   The following packages have unmet dependencies: skype : Depends: skype-bin E: Unable to correct problems, you have held broken packages.   I have tried sudo dpkg add-architecture &amp;&amp; sudo dpkg -i skype-ubuntu-precise_4.3.0.37-1_i386.deb but it didn't work either. The error was:  dpkg: dependency problems prevent configuration of skype: skype depends on libqt4-dbus (&gt;= 4:4.5.3); however: Package libqt4-dbus is not installed. skype depends on libqt4-network (&gt;= 4:4.8.0); however: Package libqt4-network:i386 is not installed. skype depends on libqt4-xml (&gt;= 4:4.5.3); however: Package libqt4-xml:i386 is not installed. skype depends on libqtcore4 (&gt;= 4:4.7.0~beta1); however: Package libqtcore4:i386 is not installed. skype depends on libqtgui4 (&gt;= 4:4.8.0); however: Package libqtgui4:i386 is not installed. skype depends on libqtwebkit4 (&gt;= 2.2~2011week36); however: skype depends on libstdc++6 (&gt;= 4.2.1); however: Package libstdc++6:i386 is not installed. skype depends on libx11-6; however: Package libx11-6:i386 is not installed. skype depends on libxext6; however: Package libxext6:i386 is not installed. skype depends on libxss1; however: Package libxss1:i386 is not installed. skype depends on libxv1; however: Package libxv1:i386 is not installed. skype depends on dpkg: error processing package skype (--install): dependency problems - leaving unconfigured Processing triggers for hicolor-icon-theme (0.13-1) ... Processing triggers for gnome-menus (3.10.1-0ubuntu2) ... Processing triggers for desktop-file-utils (0.22-1ubuntu1) ... Processing triggers for bamfdaemon (0.5.1+14.04.20140409-0ubuntu1) ... Rebuilding /usr/share/applications/bamf-2.index... Processing triggers for mime-support (3.54ubuntu1) ... Errors were encountered while processing: skype   I have tried to use after sudo apt-get -f install but it didn't solve the issue.  I have tried to install by using Gdebi. The error was:  Cannot install 'libqtwebkit4:i386'   I have tried to install using Ubuntu Software Center. The error was:  Cannot install 'libqtwebkit4:i386'   I have tried changing the server in "Software and Updates". I have tried to use "Main Server" and "Servers for United States". But it couldn't solve my problem.  Anyone has any idea how to solve that?  SOLVED  Well, I formatted my pc and I installed Skype first of all. Probably another installation that I had done before the Skype installation was the problem, i guess.  Thanks people!
I recently installed Lubuntu but I have a problem with Adobe Flash Player. I always see something that looks like this when I open a video:    (source: )    The video is small, grainy, and is green and purple.  I tried to reinstall Flash and to test it in multiple browsers without success. I installed an older version of Flash but no result.  [0300]: Intel Corporation 82865G Integrated Graphics Controller [8086:2572] (rev 02)     Subsystem: Hewlett-Packard Company D530 sff(dc578av) [103c:12bc]     Kernel driver in use: i915 I have been trying to install the latest version of java-8. However, I found out that the  due to changes in the java licence.  How should I update my java to 8.0_201 or 8.0_211 now?  Thanks! Cardinality of the Cartesian Product of Two Equinumerous Infinite Sets Is the cardinality of the Cartesian product of two equinumerous infinite sets the same as the cardinality of any one of the sets? I couldn't find this explicitly stated in any handout or text. This certainly seems to be true from the examples I have seen:  The Cartesian product of two infinitely countable sets is again infinitely countable. The Cartesian product of two sets with cardinality of continuum again has cardinality of continuum. Make font size bigger than max limit of 1296 pt in Adobe Illustrator (2015)? For some reason and for many years there's a limit for font size in Illustrator. It is 1296 points max, so you can't go bigger without converting type to outlines first. Converting to outlines means you will not be able to edit type parameters and text it-self. Don't know how about you, but this makes me sad in non-destructive editing era.  What's your workaround? how to *completely* turn off automatic updates in Windows 10 I have disabled the services &quot;Windows Update&quot; and &quot;Windows Update Medic Service&quot; in using services.mcs. Furthermore, I made changes to the registry, creating a key HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows\WindowsUpdate\AU with a DWORD (32-bit) Value &quot;AUOptions&quot; with value set to 2. I still see frequent queries to ctldl.windowsupdate.com sent to my DNS server. Which services need to be disables to completely shut this down? Evaluating $\int P(\sin x, \cos x) \text{d}x$ Modules over commutative rings I'm trying to get my head around modules, and there's a problem that's bothering me regarding scalar multiplication from the left vs from the right.  In many books/articles I've read, the author may refer to a left $R$-module $M$, and then continue to talk of terms such as $xr$, where $x\in M$, $r\in R$. What is right scalar multiplication in a left module? Does it even make sense to talk about it?  I've been trying to show that over a commutative ring, right scalar multiplication and left scalar multiplication are the same thing, but I've not managed it so far. I've googled it to no avail, and I can't see why the distinction between left and right modules disappears when the base ring is commutative.  Thanks for any replies! Confidence bands for QQ line This question doesn't specifically pertain to R, but I   chose to use R to illustrate it.  Consider the code for producing confidence bands round a (normal) qq-line:  library(car) library(MASS) b0&lt;-lm(deaths~.,data=road) qqPlot(b0$resid,pch=16,line="robust")   I'm looking for an explanation of (or alternative a link to a paper/online document explaining) how these confidence bands are constructed (I have  seen a reference to Fox 2002 in the help files of R  but sadly I don't have this book handy).   My question will be made more precise with an example.  Here's how R computes these particular CI's (I've  shortened/simplified the code used in car::qqPlot)  x&lt;-b0$resid good&lt;-!is.na(x) ord&lt;-order(x[good]) ord.x&lt;-x[good][ord] n&lt;-length(ord.x) P&lt;-ppoints(n) z&lt;-qnorm(P) plot(z,ord.x,type="n") coef&lt;-coef(rlm(ord.x~z)) a&lt;-coef[1] b&lt;-coef[2] abline(a,b,col="red",lwd=2) conf&lt;-0.95 zz&lt;-qnorm(1-(1-conf)/2) SE&lt;-(b/dnorm(z))*sqrt(P*(1-P)/n)     #[WHY?] fit.value&lt;-a+b*z upper&lt;-fit.value+zz*SE lower&lt;-fit.value-zz*SE lines(z,upper,lty=2,lwd=2,col="red") lines(z,lower,lty=2,lwd=2,col="red")   The question is: what is the justification for  the formula used to compute these SE (e.g. the line SE&lt;-(b/dnorm(z))*sqrt(P*(1-P)/n)).   FWIW this formula is very different from the formula of the usual Why Was It 'Essential' That Voldemort Kill Harry Potter? I am working on vector auto-regression (VARs) and impulse response function (IRFs) estimation based on panel data with 33 individuals over 77 quarters.  How should this type of situation be analyzed?  What algorithm's exist for this purpose?  I would prefer to conduct these analyses in R, so if anyone is familiar with R code or a package designed for this purpose that they could suggest, that would be especially helpful. Why does kinetic energy increase quadratically, not linearly, with speed? As  says:     [...] the kinetic energy of a non-rotating object of mass $m$ traveling at a speed $v$ is $\frac{1}{2}mv^2$.   Why does this not increase linearly with speed? Why does it take so much more energy to go from $1\ \mathrm{m/s}$ to $2\ \mathrm{m/s}$ than it does to go from $0\ \mathrm{m/s}$ to $1\ \mathrm{m/s}$?  My intuition is wrong here, please help it out! How do I get a DOI for a dataset? A DOI is a commonly used digital object identifier to refer to an electronic document. How do I secure a DOI for a research dataset, to help share and identify it? Number of automorphisms of a direct product of two cyclic $p$-groups has been edited by .   , see revisions 3 to 4.   Now what he did is totally inexplicable to me, as a matter of fact he destroyed the answer. The new version is neither syntactically valid nor does it make any sense.  Still, the edit got "peer-reviewed" and nodded off.  Is there any way to deal with these kinds of things, other than sighing heavily and rolling back the edit?  Rhetorical side question: Could this be a side-effect of people grinding for reviewer badges? Why do I have two docks in Ubuntu desktop (with GNOME 3) after installing Dash to Dock? What's going on here? I've installed the  on Ubuntu 17.10. Everything was cool, and as I was trying to hone and tweak the look of my desktop, at some point the shortcuts bar (dock?) on the left is duplicated.  (Click image to enlarge) The default, which normally disappears with Dash to Dock, is there underneath the one that usually shows up when I install Dash to Dock. Why? I've tried to go through the options for Dash to Dock, the GNOME Tweak Tool, and the regular Ubuntu settings, but I can't figure it out. Answers no longer sorted by score/votes What is the formula for $\frac{1}{1\cdot 2}+\frac{1}{2\cdot 3}+\frac{1}{3\cdot 4}+\cdots +\frac{1}{n(n+1)}$ How can I find the formula for the following equation?  $$\frac{1}{1\cdot 2}+\frac{1}{2\cdot 3}+\frac{1}{3\cdot 4}+\cdots +\frac{1}{n(n+1)}$$  More importantly, how would you approach finding the formula? I have found that every time, the denominator number seems to go up by $n+2$, but that's about as far as I have been able to get:  $\frac12 + \frac16 + \frac1{12} + \frac1{20} + \frac1{30}...$ the denominator increases by $4,6,8,10,12,\ldots$ etc.  So how should I approach finding the formula? Thanks! Questions like looking for css templates, blog templates, icons ... In general, resources (let's leave the licensing terms aside for now) which you might need when building a project of your own. Where should those questions go?  They're definitely not on-topic on Stack', SuperUser maybe although I doubt it. Webapps? Hmm, probably not.  Is there a place where they would be on-topic on the SE network? Get list of all tables in Oracle? Thermodynamics of supercooled water Now that it's been freezing outside for the last few days, I experimented a bit with supercooling. I've left a bottle of clean water outside for a few hours, and behold, when I shook the bottle, the liquid began to freeze rapidly, as expected.   However, not all of the water froze, only about half of it. This got me thinking.  I reasoned that happens because freezing releases heat, and that heat raises the temperature of the ice and remaning water to 0$^\circ$C, at which point the freezing stops.  To try to quantify this, set   $H_f = 334000 \frac{J}{kg}$, the "freezing heat" (enthalpy of fusion) of ice, $c_i = 2110 \frac{J}{kg\cdot K}$, specific heat of ice, $c_w = 4181 \frac{J}{kg\cdot K}$, specific heat of water, $M$, initial mass of supercooled water, $T_0$, initial temperature of supercooled water, $m$, mass of ice at a given moment, $T$, temperature at a given moment.   We suppose that the energy released by the freezing of a $\textrm dm$ mass of ice is used up by raising the temperature of both the already frozen ice ($m$) and the remaining water ($M-m$):  $$ \textrm dm \cdot H_f = c_i m \cdot\textrm dT + (M-m)c_w \cdot\textrm dT$$  By rearranging we get a linear differential equation for $m(T)$:  $$\frac{\textrm dm}{\textrm dT}+\frac{c_w-c_i}{H_f}m = \frac{c_w}{H_f}M$$  The solution of this equation, using the initial condition that at $T=T_0$, $m=0$:  $$ m = M \frac{c_w}{c_w-c_i}\left[ 1-e^{-\frac{c_w-c_i}{H_f}(T-T_0)} \right]$$  This looks neat, however, plugging in the actual values of the constants, $T = 0^\circ$C and $T_0 = -6^\circ$C, I get that little more than 7% of the water should freeze - as opposed to more than half, as I've observed. What's worse, the formula can be used to calculate the starting temperature required to freeze all the supercooled water: $$T_{all} = \frac{H_f \log\frac{c_w}{c_i}}{c_i-c_w}=-110.26^\circ \textrm C$$ which seems absurd.  Where is the error in the calculation above?  I've made a number of assumptions which may or may not hold:   the constants are really constant. I think this is a good approximation for $c_w$, a not that good but still acceptable approximation for $c_i$, and I suppose it holds to $H_f$ to some extent as well. there is no heat transfer with the environment, i.e. the bottle is a closed system. The process seemed fast enough (a few seconds at most) for this to be a good approximation. the system is in a thermal equilibrium at all times and the heat released by the freezing of the ice is distributed evenly in the emerging ice-water mixture. Now this is where I have doubts. Precisely because of the process happening so fast, this might not be true at all. However, acknowledging the presence of temperature variations makes the problem order of magnitudes harder: one has to solve a system of partial differential equations that take heat transfer, the shape of the bottle and \$deity knows what else into account.