I have a dual boot Ubuntu 18.04 and Windows10. Since 3 month, I use this configuration without any bug, but this morning, when I launch ubuntu from grub, no graphic interface appear just a terminal which ask me to type my login and my password. After this, I can use the terminal like all of the terminal and acceeded to my file but I haven't graphic interface. Does someone have a solution?
How to switch between virtual console and GUI in Ubuntu? I wanted to see what key functions would allow me to switch between the two.
Suppose $f$ and $g$ are continuously differentiable functions such that $f(x) = g'(x)$ and $g(x) = f'(x)$ and that any product of $f, f', g$ and $g'$ is commutative for all $x ∈ R$. Show that $ f^2 − g^2 = C $ for some real constant C  I have actually no clue how to solve this, and would be really greatfull for all the help i can get Combinatorial proof of summation of $\sum\limits_{k = 0}^n {n \choose k}^2= {2n \choose n}$ I was hoping to find a more "mathematical" proof, instead of proving logically $\displaystyle \sum_{k = 0}^n {n \choose k}^2= {2n \choose n}$.  I already know the logical Proof:  $${n \choose k}^2 = {n \choose k}{ n \choose n-k}$$  Hence summation can be expressed as:  $$\binom{n}{0}\binom{n}{n} + \binom{n}{1}\binom{n}{n-1} + \cdots + \binom{n}{n}\binom{n}{0}$$  One can think of it as choosing $n$ people from a group of $2n$  (imagine dividing a group of $2n$ into $2$ groups of $n$ people each. I can get $k$ people from group $1$ and another $n-k$ people from group $2$. We do this from $k = 0$ to $n$. Everybody who is using Lightroom probably has seen this. After importing RAW files, Lightroom shows a preview, but contrast and color of the preview change after a few short seconds to a slightly different view.  For some users the change is small, for others the change is huge. Colors are different (read: wrong), contrast is off.  Rumor says this is happening only (more?) for Nikon users.  What is Lightroom doing here?  I'd guess that for the first preview, LR is showing the JPG preview file, which is embedded in the RAW file. Then after a moment, LR renders the RAW file itself to show it's own interpretation.  But why is this interpretation so different from the embedded JPG? Do these leaves signify anything? I would like to make a debian system where you can only open one GUI program at boot, no other graphical interface, no minimize, or any X apart from that program, is there a way to do it on debian if possible, or any other custom distro? I just want to boot open the program and allow the user to only see and use that program. Minimize the sum of distances between two point and a circle Let's $A$,$B$ and $O$ be random point in a plane, such that they are not colinear. Let's $c$ be a circle centered on $O$, such that points $A$ and $B$ are outside of it. Find a point $X$ that lies on the circle $c$ and the sum $AX + BX$ is minimal.  First I tried to minimize the function:  $$f(x,y) = \sqrt{(A.x - x)^2 + (A.y - y)^2} + \sqrt{(B.x - x)^2 + (B.y - y)^2}$$ with  constraint $$g(x,y) = x^2 + y^2 - r^2 = 0$$  By moving $O$ to $(0,0)$ and do the same with $A$,$B$ so the relative distance will not change.  But these works when we know the coordinates of $A$,$B$ and the radius of the circle. Yet this isn't the right way because the problem is to construct that point.  Later I tried to approach using geometry.  The smallest distance from the point $A$ to the circle is the intersection of the circle $c$ and the ray $OA$, this is the same for $B$. Then we construct circles centered on $A$ and $B$ that are tangent to $c$. If the two circle intersect we'll get a common point for the both $A$ and $B$ and the distance will be minimal. Using computer I find the point X should be somewhere around the intercetion of the circle $c$ and the ray from $O$ to the new point.   Sometimes the optimal point differs just a bit and also this method fails when the two circles do not intersect each other How to reverse name and first name? With biblatex and verbose-trad2 style, I would like to reverse the order of the last name and the first name for inline references.  The default behavior is:     John DOE, Title, place : publisher, year   for inline references (in my case, in a footnote with footcite command) and:     DOE, John, Title, place : publisher, year   in the bibliography at the end of the document.  I would like to have both inline and final references in the following format (similar to the bibiography style).      DOE, John, Title, place : publisher, year   P-S : There are some close questions (like ) but only about the final bibliography (and no inline references). \DeclareNameAlias{sortname}{last-first} works only for the ending references (not inline ones). What issues / pitfalls must be considered when overriding equals and hashCode? Is it possible to show our custom message in QGIS Status bar using python? I flagged a post today, typed out a fairly thorough explanation, clicked the button... and got told that I'd already flagged this post (for something else, which I'd forgotten about) so this flag wasn't allowed.  (This happens if the first flag is still active.)  The dialogue with my explanation was gone at this point, so if I wanted to communicate with the moderators about that, I was going to have to start over.  (In case you're wondering how this could happen, one flag was related to the post itself and one was related to the user -- there being no way to flag a user directly, you have to hang it off of a post.  But I've also seen this with cases where the first flag hangs around unhandled for a week or two and I've forgotten about it.)  Since the system is going to detect that I've already flagged a post and reject a second flag, can it do that after I click the "flag" link instead of waiting until the end of the process?  (Or gray out the link so I can't click it in the first place?)  2015-12-18: someone suggested to me in chat today that this had been implemented, so I tested again.  The behavior has not changed: I flagged a post using "other", then flagged it again (also "other") before the first flag was handled, and the flag was rejected only after I'd typed the message.  (I did this on a site where I'm a moderator so I could then clean up after myself.) Combining Multiple Lists A particular big Delta I would like to insert the below mathematical symbol, it looks like a big Delta but different. Is there command to obtain a similar shape? With the following AppleScript code within a "Run AppleScript" action in a Service:  tell application "System Events"     set theSBounds to {{572, 64}, {332, 515}}     set position of window "Google Hangouts - myemailaddress@gmail.com" of application process "Google Chrome" to item 1 of theSBounds     set size of window "Google Hangouts - myemailaddress@gmail.com" of application process "Google Chrome" to item 2 of theSBounds end tell   the Service will only work if the application from which that Service has been called has been added to the list of applications under "Allow the apps below to control your computer." This list is found at System Preferences → Security &amp; Privacy → Accessibility.  Is it possible to modify the AppleScript code somehow so that adding every application on one's computer to the list is not necessary? Or, so that, one only needs to add one item to the list, as opposed to every application on one's computer?  I thought that something like this might work:  do shell script "osascript -e 'tell application \"System Events\"' -e 'set theSBounds to {{572, 64}, {332, 515}}' -e 'set position of window \"Google Hangouts - myemailaddress@gmail.com\" of application process \"Google Chrome\" to item 1 of theSBounds' -e 'set size of window \"Google Hangouts - myemailaddress@gmail.com\" of application process \"Google Chrome\" to item 2 of theSBounds' -e 'end tell'" with administrator privileges   but this code also requires that the application from which the Service is run is added to the Accessibility list.  Note: I only want to run this AppleScript as a Service, and not in an Automator-created Application, because the code receives selected text as its input (system-wide). How to programmatically click a button in WPF? on the premise that it "wasn't getting any attention" and now it has gotten a bunch of helpful answers which all help me in some ways making it impossible for me to decide which one to award the bounty to.  Shouldn't there be an option to award the bounty equally among selected answerers, especially in this case where was getting no answers whatsoever before the bounty, or am I overthinking it and should award it to the first answer? I wanted to remove and reinstall the software-center package.  I removed it, but now I can't reinstall.  I tried these commands without success:  sudo apt-get update sudo apt-get install software-center   How can I reinstall software-center?    When I performed the install command this is what I got:  $ sudo apt-get install software-center Reading package lists... Done Building dependency tree        Reading state information... Done Package software-center is not available, but is referred to by another package. This may mean that the package is missing, has been obsoleted, or is only available from another source  E: Package 'software-center' has no installation candidate How to include third party Python libraries in Google App Engine? How do you make an image emission without washing out the image? For each positive integer $n$, let $x_n=1/(n+1)+1/(n+2)+\cdots+1/(2n)$. Prove that the sequence $(x_n)$ converges.   This is what I have so far..  Let $\epsilon &gt; 0$ be given to us. We must show that there exists an $N \in \mathbb{N}$  such that $n\ge N \implies \left|\frac{1}{2n} - 1\right| &lt; \epsilon$. Choose $N$ to be any positive integer which is larger than $\frac{1}{\epsilon}$. (So $N&gt;\frac{1}{\epsilon}$.) Then $n\ge N \implies \left|\frac{1}{2n} - 1\right| = |\frac{1-2n}{2n}|$ Why must we "avoid discussions in comments"? I've just started getting these messages:     Please avoid extended discussions in comments. Would you like to automatically move this discussion to chat?   Why should one avoid doing this? I think it adds to the site...  (Tagged  in more ways than one!)