I was upgrading from 13.04 to 13.10 on my laptop when the battery died.  Now when I boot into it, I can get to the login screen.  After I type my password, the screen appears to load but then I am sent back to the login screen with no error message or anything.  Do I have to reinstall?  Is there anyway to easily recover my data?
Last night I was updating my Ubuntu 10.04 to either 11.04 or 12.04 (I'm not entirely sure which one it was, but I think it was 11.04) and I left it overnight to finish. When I came down in the morning, I noticed that the computer hadn't barely begun installing the updates! The update thing said that my computer was on the installation step, but it was still preparing the libc bin (or whatever its called) . It's like the first part of the step installing the upgrades. So, I stupidly restarted the computer, and when it rebooted, I got five options on a purple screen:  Ubuntu, with Linux 3.0.0-28-generic Ubuntu, with Linux 3.0.0-28-generic (recovery mode) Previous Linux versions Memory test (memtest86+) Memory test (memtest86+, serial console 115200)   Long story short, not matter which way I enter Ubuntu to try and reinstall the updates using the root thing (it's like terminal) after I enter sudo apt-get update it basically said it failed to fetch every url link, and it then says:  W: Some index files have failed to download. They have been ignored, or old ones used instead. W: Not using locking for read only lock file /var/lib/dpkg/lock E: dpkg was interrupted, you must manually run 'sudo dpkg --configure -a' to correct the problem.   So, I entered sudo dpkg --configure -a, and it says:  dpkg: error: unable to access dpkg status area: Read-only file system"   I'm left like wtf, and I really just some guidance here. I just got this laptop, and I can not afford a new one if I broke this one.
How did Luke know where to land on Dagobah? Very simply put:  I have a class that consists mostly of static public members, so I can group similar functions together that still have to be called from other classes/functions.  Anyway, I have defined two static unsigned char variables in my class public scope, when I try to modify these values in the same class' constructor, I am getting an "unresolved external symbol" error at compilation.  class test  { public:     static unsigned char X;     static unsigned char Y;      ...      test(); };  test::test()  {     X = 1;     Y = 2; }   I'm new to C++ so go easy on me. Why can't I do this? Apt "Connection failed" Since installing Ubuntu I have been unable to install new packages, it has even failed to update. Below is a dump of connection error I see when I tried to install Wine:  E: Failed to fetch http://archive.ubuntu.com/ubuntu/pool/main/u/unixodbc/odbcinst1debian2_2.3.1-4.1_amd64.deb  Connection failed [IP: 91.189.88.152 80]  E: Failed to fetch http://archive.ubuntu.com/ubuntu/pool/universe/f/fonts-wqy-microhei/ttf-wqy-microhei_0.2.0-beta-2_all.deb  Connection failed [IP: 91.189.88.162 80]  E: Unable to fetch some archives, maybe run apt-get update or try with --fix-missing? I have a sentence:     Please show me the right way so that I can do that rather than take blind action.     Is this sentence grammatically correct?   Can I use instead of to replace rather than? If replaced, the meaning of this sentence is changed?   What is the difference between rather than and instead of? Can you show me some examples to distinguish them? I was wondering. If I have a bilinear symmetric form, it is easy to find its matrix. But, when I have a quadratic form, which is the procedure to do that?  I heard that one possibility is: If $q$ is my quadratic form, then $$f(x,y) = \frac{1}{4}q(x+y) - \frac{1}{4}q(x-y)$$ is the bilinear symmetric form associated, so the method reduces to find the matrix of $f(x,y).$   The point is that seems a little noising... How to find, in practice, the matrix of quadratic form?  Thanks in advance. When in Journey Builder what is the difference between journey data and contact data? I am creating a JB with an engagement split. What is the difference between Contact Data and Journey Data. ie what will I see listed in the two groupings. If I choose the journey data will this only be as up to date as the time that the data entered the Journey? How do I make a 3 dimensional character out of flat picture? I have a cartoon character (a lion) that is part of my business logo that I want to put into Blender and animate it somehow. Is there any way I can take a flat picture (JPEG) and transform it into a 3D image and then animate it in Blender? Can some metadata about deleted posts be included in Data.SE? I like to use  to view usage stats for some of the sites, however deleted posts are not included on Data.SE and I think this skews the numbers quite a bit, particularly on sites with a lot of deletions. Would it be possible to include some limited data about deleted posts in Data.SE to make statistical queries more accurate? You could clear the non-public data fields of deleted posts, such as Posts.Title, Posts.Body, and Posts.OwnerUserId to address privacy concerns explained . You could even leave the PostId set to 0 since I know SE doesn't want to provide users with a way of searching deleted questions. The data I would mostly be interested in is CreationDate, LastActivityDate, PostHistory (date closed, date reopened, date deleted, etc), and the fact there was a deleted question in the first place. Up/Down votes, Score, Tags, and View/Answer/Favorite count would also be preferred. This would make the statistical queries accurate, while still removing the information not meant to be visible to the public. To be honest, I have no idea how to even start this problem. I'm sorry I don't have any work to show, but I'm just at a blank. Help?  Chapter 2: Problem 27:  University B, once boasted $17$ tenured professors of mathematics. Tradition prescribed that at their weekly luncheon meeting, faithfully attended by all $17$, any members who had discovered an error in their published work should make an announcement of this fact, and promptly resign. Such an announcement had never actually been made, because no professor was aware of any errors in her or his work. This is not to say that no errors existed, however. In fact, over the years, in the work of every member of the department at least one error had been found, by some other member of the department. This error had been mentioned to all other members of the department, but the actual author of the error had been kept ignorant of the fact, to forestall any resignations. One fateful year, the department was augmented by a visitor from another university, one Prof. X, who had come with hopes of being offered a permanent position at the end of the academic year. Naturally, he was apprised, by various members of the department, of the published errors which had been discovered. When the hoped-for appointment failed to materialize, Prof. X obtained his revenge at the last luncheon of the year. &quot;I have enjoyed my visit here very much&quot;, he said, &quot;but I feel that there is one thing that I have to tell you. At least one of you has published an incorrect result, which has been discovered by others in the department.&quot; What happened the next year?&quot;   Chapter 2: Problem 28:  After figuring out, or looking up, the answer to Problem 27, consider the following: Each member of the department already knew that Prof.X asserted, so how could his saying it change anything? Is there a correct gender-neutral singular pronoun ("his" vs. "her" vs. "their")? Since I want to protect my ssh connections, I set some global cipher suite options to restrict set of used algorithms. But recently I've encountered a server which doesn't support some of those algorithms. So, I need to selectively enable deprecated algorithms for a specific host record in client (my system) configuration.  I found out that the options override is not working as I expected. Let's take a minimal (not-)working example for the github:  HostKeyAlgorithms ssh-ed25519-cert-v01@openssh.com,ssh-ed25519,ecdsa-sha2-nistp521-cert-v01@openssh.com,ecdsa-sha2-nistp521,ecdsa-sha2-nistp256  Host github     HostKeyAlgorithms ssh-rsa     Hostname        github.com     Port            22     User            git     PubkeyAuthentication yes     IdentityFile    ~/.ssh/some-filename-here   Having that, I receive the following error (HostKeyAlgorithms is not overriden at all):  debug1: /home/username/.ssh/config line 14: Applying options for github &lt;...&gt; debug2: kex_parse_kexinit: ssh-ed25519-cert-v01@openssh.com,ssh-ed25519,ecdsa-sha2-nistp521-cert-v01@openssh.com,ecdsa-sha2-nistp521,ecdsa-sha2-nistp256 &lt;...&gt; Unable to negotiate with 192.30.252.130: no matching host key type found. Their offer: ssh-dss,ssh-rsa   It is similarly not working for the global PubkeyAuthentication no options with an override in a host configuration.  Also, the match doesn't help either:  match host github     HostKeyAlgorithms ssh-rsa   So, is there a way to selectively redefine those options?  NOTE: I'm using the openssh-7.1_p2-r1 on gentoo. How bad for TeX is omitting braces {}, even if the result is the same? Sometimes writing braces and omitting them produces the same result:  \tilde{\psi}  \mathrm{e}^{\mathrm{i} \pi}   vs  \tilde \psi   \mathrm e^{\mathrm i \pi}   Or (taken from Werner's comment below)   \frac{1}{2} vs \frac12   If that's the case, how bad for the quality of my code is omitting them? Of course, if one compiles a pair of formulas, there is no difference. But, since I ignore how TeX works, my point is: if one writes long codes with these habits,   doesn't TeX go somehow crazy because I'm not writing as it expects?   For instance, does it have any effect on how fast are long documents compiled? Any reason to keep them? I've recently been learning about differential equations, and my teacher has been giving some particularly difficult examples out for those of us who finish early. He gave us the following differential equation: $$x=y\frac{dy}{dx}-\left(\frac{dy}{dx}\right)^{2}$$ With the hint "Differentiate with respect to $y$, then let $\frac{dy}{dx}=p$". I've solved it after the lesson and would like someone to check whether or not I've done so correctly.    Following the hint, $$\frac{dx}{dy}=\frac{1}{p}=p+y\frac{dp}{dy}-2p\frac{dp}{dy}$$ Which rearranges to $$p-\frac{1}{p}+y\frac{dp}{dy}=2p\frac{dp}{dy}$$ Multiplying through by $\frac{dy}{dp}$, $$\left(p-\frac{1}{p}\right)\frac{dy}{dp}+y=2p$$ Rearranging into the form $\frac{dy}{dp}+f(p)y=g(p)$, and writing $p-\frac{1}{p}=\frac{p^{2}-1}{p}$ $$\frac{dy}{dp}+\frac{p}{p^{2}-1}y=\frac{2p^{2}}{p^{2}-1}$$ Our integrating factor is $$e^{\int\frac{p}{p^{2}-1}dp}=e^{\frac{1}{2}\ln(p^{2}-1)}=\sqrt{p^{2}-1}$$ So we have $$\sqrt{p^{2}-1}\frac{dy}{dp}+\frac{p}{\sqrt{p^{2}-1}}y=\frac{2p^{2}}{\sqrt{p^{2}-1}}$$ The left hand side is, by design, $\frac{d}{dp}(y\sqrt{p^{2}-1})$, and the right hand side can be integrated as follows: $$\int \frac{2p^{2}}{\sqrt{p^{2}-1}}dp=\int\frac{2(p^{2}-1)+2}{\sqrt{p^{2}-1}}dp=\int 2\sqrt{p^{2}-1}dp+\int \frac{2}{\sqrt{p^{2}-1}} dp$$ These can both be solved using the substitution $p=\cosh(u)$, and gives $$y\sqrt{p^{2}-1}=p\sqrt{p^{2}+1}-\cosh^{-1}(p)+\alpha$$ Where $\alpha$ is an arbitrary constant. Dividing, we finally have $$y=p+\frac{\cosh^{-1}(p)+\alpha}{\sqrt{p^{2}-1}}$$  Here I was stuck for a long time, until I realised that we also have the equation we began with: $x=py-p^{2}$, which we can solve as a quadratic in $p$ to also get $$p=\frac{y\pm \sqrt{y^{2}-4x}}{2} \implies p^{2}=\frac{y^{2}+y^{2}-4x \pm 2y\sqrt{y^{2}-4x}}{4}$$  Thus, $$y=\frac{y\pm \sqrt{y^{2}-4x}}{2}+\frac{\cosh^{-1}\left(\frac{y\pm \sqrt{y^{2}-4x}}{2}\right)+\alpha}{\sqrt{\frac{y^{2}-2x \pm y\sqrt{y^{2}-4x}}{2}-1}}$$  This is as good as I can do - we have a relation between $y$ and $x$ - am I done? Is this the correct answer? Is there an easier way?     Thank you for your time.    Following the suggestion by @Valentin $$\frac{dy}{dp}=1+\frac{\frac{1}{\sqrt{p^{2}-1}}\sqrt{p^{2}-1}-p\frac{\cosh^{-1}(p)+\alpha}{\sqrt{p^{2}-1}}}{p^{2}-1}=1+p\frac{1-\frac{\cosh^{-1}(p)+\alpha}{\sqrt{p^{2}-1}}}{p^{2}-1}$$ Hence, $$dx=\frac{dy}{p}=dp\left(\frac{1}{p}+\frac{1-\frac{\cosh^{-1}(p)+\alpha}{\sqrt{p^{2}-1}}}{p^{2}-1}\right)$$ How To Delete This Red Box on My Screen? I was editing my mesh and I wanted to only see a part of my mesh, so I pressed alt+B to only show a selected area. However, I did ctrl+B and created a red rectangle on my screen (I don't know what it does). Does anybody know how to get it off? Creating a Snapshot of a Windows 7 System Is there a way to create a snapshot of a Windows 7 system?  My goal is to be able to save the current state of my Windows 7 OS, on external storage, and be able to restore it on the same hardware in the future. Much like a snapshot on a virtual machine.   One solution would be to install two hard drives in RAID 1, then take one of them out an store it. Is there an easier solution? sit on the beach vs. sit at the beach Is there any way to know when I will receive my UK visa? I am looking for an adjective/noun for someone who is able to speak/ makes speeches very well and uses words effectively to influence/impress people. I just did my first install of any Linux OS, and I accidentally selected "Desktop GUI" in the install, but I want to build everything myself. Is there any way by which I can remove the GUI environment without re-installing OS? "Economic" vs. "economical"