On attempt to install Signal, I think I made some mistake and now getting some error in Ubuntu 20.04 LTS. How to correct this? Thank you
How can I fix apt error "W: Target Packages ... is configured multiple times"?
I want to write a program for this: In a folder I have n number of files; first read one file and perform some operation then store result in a separate file. Then read 2nd file, perform operation again and save result in new 2nd file. Do the same procedure for n number of files. The program reads all files one by one and stores results of each file separately. Please give examples how I can do it. Can you identifiy this short about teenagers on a raft getting swallowed up by an oil slick? Where do I put item tags on items inside a chest or your inventory? I am being driven crazy by the fact that my media keys aren't working for iTunes. Such a pain! How can I fix this? I've tried the whole Chrome Extensions thing, that being I deleted all my extensions. Still, nothing has fixed this. Thanks to all who reply! I've heard that i can travel to the US any time before my tourist visa expiry.  Is that true?  (please advise) On a quantum scale the smallest unit is the , which is a discrete measure.  There several question that come to mind:   Does that mean that particles can only live in a discrete grid-like structure,  i.e. have to "magically" jump from one pocket to the next? But where are they in between? Does that even give rise to the old paradox that movement as such is impossible (e.g. )? Does the same hold true  for time (i.e. that it is discrete) - with all the ensuing paradoxes? Mathematically does it mean that you have to use difference equations instead of differential equations? (And sums instead of integrals?) From the point of view of the space metric do you have to use a discrete metric (e.g. the ) instead of good old Pythagoras?   Thank you for giving me some answers and/or references where I can turn to.  Update: I just saw this call for papers - it seems to be quite a topic after all: Is Reality Digital or Analog? FQXi Essay Contest, 2011. , , . One can find some pretty amazing papers over there. Non-static variable cannot be referenced from a static context The Problem  Accessing my site over https (the only protocol allowed) I get the content, but none of the CSS, images etc.  Drupal is creating pages in response to https requests that include http links to these resources, but it should be using https.  What I've done  I have copied a site to a dev server. The site loads and basically works fine - I can log in etc. It's just that all the links drupal generates are http. The site I've copied it from also runs over https. The site does not exist on http (it would just get a Forbidden error). I've drush cc all.  So Apache's working - I can access the site. .htaccess is working (clean urls work, for example).  I'm using SNI to access the site because the server has other vhosts too, but I'm only accessing the site using the latest Firefox (and as it's a dev site and I'm the only dev, nobody else will use it).  I've done this dozens of times and am quite stumped! Why does Drupal not notice that the request came over https?  The fix  Turns out that .htaccess has this to say:   /* Base URL (optional).                                                          If Drupal is generating incorrect URLs on your site, which could             be in HTML headers (links to CSS and JS files) or visible links on pages     (such as in menus), uncomment the Base URL statement below (remove the       leading hash sign) and fill in the absolute URL to your Drupal installation.    Sure enough, putting $base_url = 'https://example.com'; fixed it.  But why is this necessary? replacing the default console emulator under Windows XP How can I replace the default program providing console windows under Windows XP?  I know of , and I have a shortcut to start cmd.exe in . But now I want console applications to start in Console2 rather than the default console program, even when I have no control over the program that starts the console application. (I.e. a non-console program starts consoleapp.exe, and I can't change it to start Console2 instead, but I still want the application to be started inside a new instance of Console2.)  (Note that I want to replace the console itself, that is, the window in which console (i.e. text mode) applications run. And I must be able to run arbitrary, unmodified console applications: a substitute for a specific console program such as Cmd won't do me any good.)  EDIT: So what I'm after is a , which           OT: I want to know when Microsoft is going to make a decent CSRSS replacement. Not being able to adjust the width of a "terminal" by resizing the window is a complete joke.         Go download the ISE already. (It's included in Win7/2008R2.)   But as far as I understand this ISE is an , not a general console emulator. Does $\lim_{n\to \infty} \int^{\infty}_{-\infty} f_n(x) dx\, = \int^{\infty}_{-\infty} f(x)\,dx\,$? Is $\mathcal{O}_{\mathbb{Q}(\sqrt{5})} = \mathbb{Z}[\phi]$, where $\phi={1+\sqrt{5}\over 2}$ is the golden ratio?  I know that $5 \equiv 1 \mod 4$, so that then $\mathbb{Z}[\sqrt{5}]$ is not closed as far as integers go. But I'm a little confused cause  $\mathcal{O}_{\mathbb{Q}(\sqrt{-3})} = \mathbb{Z}\left[-\frac{1}{2} + \frac{\sqrt{-3}}{2}\right]$? So how do I know when to use $\frac{1}{2}$ rather than $-\frac{1}{2}$? Which one applies for $\mathcal{O}_{\mathbb{Q}(\sqrt{5})}$? Is there a general formula for finding all subgroups of dihedral groups? PlotLegends disappearing with list of functions Connecting desktop computer to the internet through laptop wifi Due to some home network complications I have had to move my router to a seperate part of the house, therefore the wired network I had set up can no longer work. Before I find the time to go out and buy a Wifi adapter for my desktop PC, I have a laptop that uses a built in Wifi card to connect to my router and this can connect to the internet, and I was wondering if I could somehow access the internet on my desktop PC via my laptop.  I'm hoping for a not-so-complex solution as this will only be set up for a few days, but it is quite vital that my desktop computer gets internet access.  Does anyone have experience in this sort of thing and can help me out? Thanks. How can we prove that any bijection on any set is  a composition of 2 involutions ?  Since involutions are bijections mapping elements of a set to elements of the same set, I find it weird that this applies to any bijection.  Thanks for your help ! How do I avoid the "S to Skip" message on boot? After upgrading my laptop from karmic to lucid, my fat32 partition won't mount automatically. I get the message:  The disk drive for /osshare is not ready yet or not present Continue to wait; or Press S to skip mounting or M for manual recovery   Funny thing is, if I skip, then /osshare/ is mounted once I log in.   I've a similar setup on my desktop, and it works fine. Fstab on desktop:  UUID=4663-6853  /osshare        vfat    utf8,umask=007,gid=46 0       1   /etc/fstab on laptop:  UUID=1234-5678 /osshare vfat utf8,auto,rw,user 0 0 I got a stomach flu or I got the stomach flu or I got stomach flu? What is approximate error of Pythagorean Theorem vs. Haversine Formula in measuring distances on sphere at various scales? Many people when first trying to calculate distances between two longitude / latitude pairs  ask if Pythagorean theorem works as an appropriate distance function.  Most often people answer "no, the Pythagorean theorem only works on a 2D Euclidean plane." Rarely, however, do people mention the effect of scale and location on the sphere on how inaccurate the Pythagorean theorem is.  The basic idea being at very small scales, the surface of a sphere looks very much like a plane. At very large scales, it distances along the surface are more curved and therefore the difference between the incorrect Pythagorean Theorem and the correct Haversine Formula is greater.  Does anyone know a formula or rule of thumb that tells you the difference between the two distance measures based on the scale of the distance you are trying to measure?   I think having this explicitly would help in:   explaining why the Pythagorean Theorem isn't perfect; and in letting people who are looking for more "rough" distances know when Pythagoras actually will serve their purposes. Is denying "Paradoxical Partitioning" equivalent to accepting the Axiom of Choice? In  (to ) it has been noted:     One more point to make about the paradoxical decomposition to more parts than elements [...]   currently we do not know of any model of +$\lnot$ where such decomposition does not exist.    Namely, as far as we know, in all models where choice fails there is some set which can be partitioned into more parts than elements.   (Just for clarification: From the context of the above references the comparison "more parts than" is obviously meant in terms of the  of the suitable  being strictly larger than the cardinality of the suitable initial set itself.)  Now, I find the negation or denial of such "paradoxial partitioning" interesting; i.e. the statement (proposition, "$\lnot$PP"):  "Each partition of each given set has cardinality less than, or at most equal to, the cardinality of the given set."  And I like to further explore how this suggested "proposition $\lnot$PP" (being considered along with ZF, of course) relates to "the standard set theory including Axiom of Choice", . Therefore  My questions:      Are there any models of ZFC known (or could there be any such models, in principle) in which there is some set which can be partitioned into more parts than elements ?  And:  Are there any models of ZF known (or could there be any such models, in principle) in which there is no set which can be partitioned into more parts than elements, and which is not also a model of ZFC ?  (And just for reference: Is there a conventional or concise way of expressing the suggested "proposition $\lnot$PP" in terms of standard notation, such as used in the sources linked above? Has it perhaps been discussed already, by some other name? ...) Are there any organised resources available from where I can begin my quantum computing studies? I am a computer science student and am currently searching for resources from where I can learn about quantum computers, quantum computing models, their working principles, their gates and some simple quantum algorithms.