So im rather new this whole linux stuff but i took a pc and installed 18.04 on it. after using that for a while i decided that i wanted a change in scenery so i upgraded to 19.10 since that was the version it told me was the latest... this all went fine, no complications at all. later on i was on my normal pc that runs windows and i made an ubuntu vm out of sheer boredom and saw that 20.04 was actually the latest release when i was looking for an iso as the one i had was still 18.04. so when i went back on to 19.10 machine i thought i would be as simple it was upgrading from 18.04, but boy was i wrong. the only error ive really gotten is &quot;This version no longer supported. Please install a supported version.&quot; anyone have any ideas?
Recently I have installed an older version of Ubuntu on my old machine. Whenever I try to install any software, I get an error saying it couldn't be found:  $ sudo apt-get install vlc Reading package lists... Done                Building dependency tree        Reading state information... Done     E: Couldn't find package vlc
How to ask "If you have any problem then ask me" in polite manner How is the width of a slit related to the intensity of light passing through it? Here's a question I got in my final exam this morning. &quot;If in Young's double-slit experiment setup, the ratio of the intensity of the bright spot to the dark spot is 25:9, what is the ratio of the width of the slits?&quot; Here's what I did. Since the ratio of intensity at the bright and dark spots is 25:9, the ratio of amplitudes there must 5:3. Which means the amplitude of one wave is 4 times the other. Now, knowing that the amplitude of light through the wider slit is 4 times the amplitude of light through the narrower slit, how can I determine the ratio of the slits' width? Are all n-ary operators simply compositions of binary operators? Take for example $A \times B \cdot C$ = $(A \times B) \cdot C$ where $A, B, C$ are 3-component real vectors.  We can define a 3-nary operator $\times - \cdot$ that is a composition of the two common binary operators $\times$ and $\cdot$.  The same thing happens with most functions (operators) - the way we calculate them is by doing smaller binary problems and adding together.  Every time I try to come up with an $(n &gt; 2)$-ary operator my mind automatically looks for binary operators.  So, the question is, do there exist operators (of some weird kind in some branch of math) that cannot be decomposed into 2-ary and 1-ary operators?  Thanks. Prevent questions on Hot List from being upvoted by casual visitors (only rep is from association bonus) Sophomore's dream: $\int_0^{1} x^{-x} \; dx = \sum_{n=1}^\infty n^{-n}$ In the solution of the so-called , one of the key steps is to compute $$\int_0^1 x^n (\log x)^n~\mathrm dx$$ using the change of variables $x = \exp\left(-\frac{u}{n+1}\right)$ to obtain the Gamma function.  This substitution to me, looks like it was pulled out of thin air. Can someone help me motivate it? How would I have thought of this substitution? How come  with  set to dragons didn't stop 's effect from being activated? "R cannot be resolved to a variable"? I've allocated an "array" of mystruct of size n like this:  if (NULL == (p = calloc(sizeof(struct mystruct) * n,1))) {  /* handle error */ }   Later on, I only have access to p, and no longer have n. Is there a way to determine the length of the array given just the pointer p?  I figure it must be possible, since free(p) does just that. I know malloc() keeps track of how much memory it has allocated, and that's why it knows the length; perhaps there is a way to query for this information? Something like...  int length = askMallocLibraryHowMuchMemoryWasAlloced(p) / sizeof(mystruct)   I know I should just rework the code so that I know n, but I'd rather not if possible. Any ideas? What is the connection between special and general relativity? What is the connection between  and ? As I understand general relativity does not need the assumption on speed of light constant. It is about the relation between mass and spacetime and gravity. Can general relativity be valid without special relativity? How soon should I "vote to close"? Generating a separate pdf file of tables and figures from a latex file? Is it possible to generate a PDF of figures and tables of a paper from LaTeX itself?  I saw Journals and Conferences asking for a separate file of tables and figures.  In  question, questioner proposed a method that uses \usepackage{endfloat} to push all the figures and tables to the last pages and then use a PDF editor to cut the last pages of PDF. This is a solution but not a good one. LaTeX should be able to do this by its own.  What I have in mind is to compile the LaTeX file and it generates a complete PDF output and beside that a separate file that contains all the figures and tables of former PDF. How to tail multiple files using tail -0f in Linux/AIX I tried tailing two files using the option:  tail -0f file1.log -0f file2.log   In Linux I see an error "tail : can process only one file at a time".  In AIX I see the error as "Invalid options".  This works fine when I use:  tail -f file1 -f file 2   in Linux but not in AIX.  I want to be able to tail multiple files using -0f or -f in AIX/Linux  multitail is not recognized in either of these OS. What is this shell/Bash syntax: someVariable=someValue someCommand bash aliases equivalent for powershell? By default my Windows PowerShell starts in C:\Users\Santosh, my XAMPP installation is in D:\ so the htdocs folder is located at D:\xampp\htdocs. If I have to edit something in htdocs folder then I have to type full cd D:\xampp\htdocs\ (autocompletion is not so kind) then edit that file.  If this PowerShell were a Bash I would do this in .bash_aliases file:  alias htdocs='cd D:\xampp\htdocs'  Is it possible to maintain Bash aliases like file and alias any command in PowerShell? I'm here with weird stuff again.  How can i continue numbering while changing numbering style to Arabic from Roman? For example let's assume I have total of 7 pages and I want to number the first 3 of them as : i,ii,iii; then I change back to Arabic again and continue counting as 4,5,6,7. Need help in the longtable with the figure Can u please help me in this table. The problem in this table that is not move to the next page in a proper way and kindly mention the size of the figure as well as the place of the figure. \begin{longtable}[c]{@{}|c|c|c|c|c|c|c|c|c|@{}} \caption{Bacteria isolates on different media} \label{tab:my-table}\\ \toprule \textbf{Sr.No} &amp;   \textbf{Reference Code} &amp;   \textbf{Sample Location} &amp;   \textbf{Colony Color} &amp;   \textbf{Colony Morphology} &amp;   \textbf{Pigmentation} &amp;   \textbf{Media} &amp;   \textbf{Predicted Name Of Strain} &amp;   \textbf{Figures} \\* \midrule \endhead % 1 &amp;   EMB(P)1 &amp;   Islamabad &amp;   Green sheen &amp;   Circular &amp;   Green Sheen &amp;   \begin{tabular}[c]{@{}c@{}}Eosin methylene\\    \\ blue agar\end{tabular} &amp;   \textit{\textbf{E.coil}} &amp;    \\* \midrule 2 &amp;   MSA(P)1 &amp;   Islamabad &amp;   Yellow &amp;   Punctiform &amp;   Yellow &amp;   Mannitol salt agar &amp;   \textit{\textbf{\begin{tabular}[c]{@{}c@{}}Staphylococcus\\    \\ Epidermidis\end{tabular}}} &amp;    \\* \midrule 3  &amp; MACC(P)1 &amp; Islamabad &amp; Off white       &amp; Circular  &amp; Off white       &amp; MacConkey agar     &amp; \textit{\textbf{Salmonella}}              &amp;  \\* \midrule 4  &amp; MSA(P)2  &amp; Islamabad &amp; White           &amp; Circular  &amp; White           &amp; Mannitol salt agar &amp; \textit{\textbf{Staphylococcus   aureus}} &amp;  \\* \midrule 5 &amp;   B.A(P)1 &amp;   Islamabad &amp;   White &amp;   Smooth &amp;   White &amp;   \begin{tabular}[c]{@{}c@{}}Blood \\    \\ Agar\end{tabular} &amp;   \textit{\textbf{Pseudomonas   aeruginosa}} &amp;    \\* \midrule 6  &amp; B.A(P)2  &amp; Islamabad &amp; White           &amp; Circular  &amp; White           &amp; Blood agar         &amp; \textit{\textbf{Lactobacilli}}            &amp;  \\* \midrule 7  &amp; MACC(P)2 &amp; Islamabad &amp; Pink            &amp; Circular  &amp; Pink            &amp; MacConkey agar     &amp; \textit{\textbf{Klebsiella}}              &amp;  \\* \midrule 8  &amp; MACC(P)3 &amp; Islamabad &amp; Purple          &amp; Irregular &amp; Purple          &amp; MacConkey agar     &amp; \textit{\textbf{pseudomonas}}             &amp;  \\* \midrule 9  &amp; MSA(P)3  &amp; Islamabad &amp; Crystal White   &amp; spherical &amp; Crystal White   &amp; Mannitol salt agar &amp; \textit{\textbf{Salmonella}}              &amp;  \\* \midrule 10 &amp; B.A(P)3  &amp; Islamabad &amp; White           &amp; Puntiform &amp; White           &amp; Blood agar         &amp; \textit{\textbf{Staphylococcus}}          &amp;  \\* \midrule 11 &amp; MACC(P)4 &amp; Islamabad &amp; Orange to amber &amp; Circular  &amp; Orange to amber &amp; MacConkey agar     &amp; \textit{\textbf{Shigella}}                &amp;  \\* \midrule 12 &amp; MSA(P)4  &amp; Islamabad &amp; Yellow          &amp; Circular  &amp; Yellow          &amp; Mannitol salt agar &amp; \textit{\textbf{S. aureus}}               &amp;  \\* \midrule 13 &amp; MACC(P)5 &amp; Islamabad &amp; Pink to purple  &amp; Circular  &amp; Pink to purple  &amp; MacConkey          &amp; \textit{\textbf{Klebisella}}              &amp;  \\* \bottomrule \end{longtable} Can I use my Schengen visa for a completely different purpose and entry point? I am a non-EU national, permanent UK Resident. Recently, my work issued me with a multiple Schengen visa with Norway as the first (main) point of entry. Now I want to go on holidays to Greece - do I need to apply to Schengen visa again, as Greece is not Norway and I am not going there for work? How to interpret the significant interaction of two non-significant main predictors? I have two non-significant main binary variables in my binary logistic regression model, but their interaction is significant. The variables are centered and no multicollinearity is the case (all VIFs about 1.0). The main variables are nonsignificant, but their interaction is. I want to interpret that significant interaction of two non-significant estimates.   It would read something like this: the effect of the variable A is less visible in the level 1 of the variable B (B1) and more visible in the second level of B (B2). Or I can say the same thing about the effect of B being less visible in A1 and more visible in A2...  However, the problem is that neither the effect of A, nor the effect of B are significant! So the above interpretation, although seemingly correct, sounds inconsistent or strange. (How a non-significant effect is supposed to be boosted by the other variable?)...   On a second thought, it seems that it is actually possible. For example, if I exclude cases with B2 from my sample, now the effect of A in the sample would show up as significant (it is B2 cases in the sample that disallow A to appear as significant)... This is getting more clear in my head now, but do you still have something other than the above interpretation in mind? Suppose $n$ is an even positive integer and $H$ is a subgroup of $\mathbb Z/n \mathbb Z$. Prove that either every element of $H$ is... Suppose $n$ is an even positive integer and $H$ is a subgroup of $\mathbb Z/n\mathbb Z$. Prove that either every element of $H$ is even or exactly half of its elements are even. (Gallian, Contemporary Abstract Algebra, Exercise 24, Chapter 3.) Some time ago, we announced that . This has gone well and we're extremely thankful to everyone for their support and feedback. Because it has been successful so far, we're going to be extending the program to the majority of our graduated sites. Well, we've pretty much already done that, but there are quite a few sites that have ads enabled, yet still display nothing. The thing is, we don't really have an abundance of clients offering products that a  would find relevant, but Amazon has stand mixers, a selection of super fine chinois, deliciously sharp cutlery and enough cast iron to fill the Gulf Of Mexico with . Beginning as early as this week (week of 5 February 2018), our ad team is going to be hand selecting affiliate ads to be displayed on select sites. The use of inventory will of course depend on the availability of relevant ads to display which means:  Some sites might see very few, if any ads. Some topics simply don't come remotely close to orbiting anything worth advertising. Furthermore, while graduated, some sites simply don't have enough activity for ads to make sense.  Since these are hand-selected, it could take a while for ads to appear initially.  These would of course yield to inventory from clients if clients had products that were relevant to any given topic.   Nothing changes when it comes to the . If you're used to occasionally seeing a community promotion ad, you'll just notice that you'll also occasionally see an ad for something that is likely to be of interest to someone interested in the topic that your site covers. In fact, to be clear, this is simply a continuation of the announcement we made in November of 2016. We just wanted folks to know that we're going to be continuing the program where there's good potential to show relevant advertisements, even if we don't have clients lined up with a demand for it. Where can I give feedback about a certain ad on [site]? Open a meta post on your per-site meta and let us know. Please remember, the bulk of advertisements are an effort to get something small back from folks that hit the sites through search engines and are extremely unlikely to ever become contributors. Their soufflé stopped falling, and we'll probably never see them again. Maybe we can get a few bucks once they realized that copper ions help egg whites stiffen properly and buy a bowl or a proper bloom whisk. However, you're the experts on these topics and we're very likely going to listen to you. What sites, specifically? Are any sites exempt? If you're a former Stack Exchange 1.0 site and / or subsequently joined the network under a special charter, nothing changes - don't panic :) For the rest, we're just extending what we're currently doing with ads on graduated sites to also include those where there's an opportunity to make sensible use of affiliate ads. If a site has less than 15k (average) daily visits, or fewer than roughly 50k combined total posts - it might not yet be time to invest in selecting ads to be shown there. But, part of this exercise is also seeing what works best. I don't really have feedback, just some suggestions Ads aren't just an opportunity to sell stuff, they're an opportunity to really show people that we understand a given topic. That, of course, makes suggestions from people that do that stuff every day quite valuable. Post on your per-site meta and our community / ad critters will take a look. Questions? Comments? Kvetches? Let us know in an answer or comment below. If anything about the plan changes, we'll update this post to let folks know.