This is the result of sudo apt update on my system: Ign:1 http://ppa.launchpad.net/webupd8team/atom/ubuntu focal InRelease Hit:2 http://archive.ubuntu.com/ubuntu focal InRelease                          Get:3 http://archive.ubuntu.com/ubuntu focal-updates InRelease [111 kB]         Get:4 http://archive.ubuntu.com/ubuntu focal-backports InRelease [98.3 kB]      Get:5 http://archive.ubuntu.com/ubuntu focal-security InRelease [107 kB]        Err:6 http://ppa.launchpad.net/webupd8team/atom/ubuntu focal Release            Could not connect to ppa.launchpad.net:80 (2001:67c:1560:8008::15). - connect (101: Network is unreachable) Could not connect to ppa.launchpad.net:80 (91.189.95.83), connection timed out [IP: 91.189.95.83 80] Reading package lists... Done                                 E: The repository 'http://ppa.launchpad.net/webupd8team/atom/ubuntu focal Release' does not have a Release file. N: Updating from such a repository can't be done securely, and is therefore disabled by default. N: See apt-secure(8) manpage for repository creation and user configuration details.
When updating, I get the following error message:   W: The repository 'http://ppa.launchpad.net/mc3man/trusty-media/ubuntu xenial Release' does not have a Release file.   Here, I find another statement on this error:   This recommends removing certain PPAs; and, I'm not sure if I should do that since it might mean not getting the updates that I need.    Is this what I should do?
I'd like to map an int value pbs_errno declared as a global in the library libtorque.so using ctypes.  Currently I can load the library like so:  from ctypes import * libtorque = CDLL("libtorque.so")   and have successfully mapped a bunch of the functions. However, for error checking purposes many of them set the pbs_errno variable so I need access to that as well. However if I try to access it I get:  &gt;&gt;&gt; pytorque.libtorque.pbs_errno &lt;_FuncPtr object at 0x9fc690&gt;   Of course, it's not a function pointer and attempting to call it results in a seg fault.  It's declared as int pbs_errno; in the main header and extern int pbs_errno; in the API header files.  Objdump shows the symbol as:  00000000001294f8 g    DO .bss   0000000000000004  Base        pbs_errno Using indefinite articles before adjectives: "Let's have a good breakfast" Let's have breakfast    Let's have a good breakfast      I've learned that indefinite articles aren't used before uncountable nouns, so why is a used before the adjective "good" here?    Is there an exception to the rules or is it wrong? What does the minus sign in Maxwell's third equation imply? If we write out Maxwell's equations with magnetic charges, we get $$ \begin{align} \nabla \cdot \mathbf{E} &amp;= 4 \pi \rho_e \tag{1}\\ \nabla \cdot \mathbf{B} &amp;= 4 \pi \rho_m \tag{2}\\ -\nabla \times \mathbf{E} &amp;= \frac{\partial \mathbf{B}}{\partial t} + 4 \pi \mathbf{J}_m \tag{3}\label{Eq:Faraday}\\ \nabla \times \mathbf{B} &amp;= \frac{\partial \mathbf{E}}{\partial t} + 4 \pi \mathbf{J}_e \tag{4}\label{Eq:Ampere} \end{align} $$ In particular, Faraday's law \eqref{Eq:Faraday} contains a minus sign that Ampere's law \eqref{Eq:Ampere} does not. This always struck me as odd because it's often said the fields are dual to each other (i.e. you can replace E with B and &quot;get the same result&quot;), but that requires a bit of mental recalibration to accommodate that minus. So I'm curious what the origin of that negative is and what it means. Are there any intuitive explanations for how to think about it? Alternative IDE for VB6 and VBA I've been spoiled by Visual studio 2008 and Eclipse and have to do a little maintainence work on a VB6 app.  Does anyone know of an alternative/ updated IDE for VB6?  A rewrite is not an option I'm just fixing a couple of bugs and it's a big codebase. Putting a piece of code in between two html tags in Solaris External hard drive and Recycle Bin behavior When my Seagate external hard drive is plugged in, its $RECYCLE.BIN folder automatically contains all the files contained in the Recycle Bin of the PC. Is it true that actually we don't have any Recycle Bin of external hard drive, rather it is the Recycle Bin of the PC? Why is it so? QGIS corrupting shapefiles? I'm hoping someone out there might be able to help or suggest some tests to try and resolve some very odd QGIS behaviour of late...  Our core GIS team of 4 users has been testing v2.10 prior to roll-out for the remainder of the organization.  In the past couple of weeks we have had some very odd shapefile corruption things happening and are yet to isolate or identify a potential cause...  These have included:   Editing one line (using the scissor tool to split into two records) and having the resulting records attributes completely replaced by attributes from another geometry no-where near the edited row (spatially or in the attribute dbf) Line geometries completely disappear while their attributes get associated with an unrelated geometry  Line geometry get partially deleted and replaced with a vertice in infinity (line visually extends beyond the dataset and no matter how far zoomed out you never see the end)   The above is happening in a polyline layer, that we did discover has some multi-line geometries..? Perhaps this is impacting... but never saw this issue with v2.8 and the same layer. The layer has undergone MANY save-as's in the past week and many verify geometry checks as we thought invalid geometry may have been the cause...  In another separate layer yesterday, to a separate user (me) i created a layer with approx 30 polygons... adding, deleting some and doing some 'avoid intersection' to remove overlaps. Layer looks fine in qgis, saved and also a save-as to a completely new file but when i load into ArcGIS online (and later is ArcMap as a test) some of the overlaps and deleted objects are still there. Close and reopen qgis,  reopen the file and they are definitely not.  The project was created in v2.8 that i was editing in (but had been saved in 2.10).  Does anyone have any ideas/suggestions.  We do still have 2.8 installed as well as 2.10? We have never encountered issues like this when testing other new qgis versions while still running old ones? Should we pass a shared_ptr by reference or by value? Does assigning objects to null in Java impact garbage collection? How to execute several commands after each other with one request to the terminal (without using a file)? Help with this trigonometry problem Prove the given identity.  $$\left(\sin\frac {9\pi}{70}+ \sin\frac {29\pi}{70} - \sin\frac {31\pi}{70}\right) \left(\sin\frac {\pi}{70}-\sin\frac {11\pi}{70} - \sin\frac {19\pi}{70}\right) =\frac {\sqrt {5} -4}{4}$$  Please help, I could not gather enough ideas, even on how to get to the first step. I thought of using the transformation formula (from sum to product) but did not find a fruitful result.   UPDATE 1.:  $\left(-\frac{1 +\sqrt{5}}{8} + \frac{1}{8} \sqrt{14\left(5 - \sqrt{5} \right)}\right)\left(-\frac{ 1+ \sqrt{5}}{8} -\frac{1}{8} \sqrt{14 \left(5 -\sqrt{5} \right)}\right) $,    I noticed that Alexis had got to this point.  Can anyone explain me how did he get here, with calculations. Please help.  Thanks in Advance. How can I abort a running JDBC transaction? Is there a way to prematurely abort a transaction? Say, I have sent a command to the database which runs five minutes and after four, I want to abort it.  Does JDBC define a way to send a "stop whatever you are doing on this connection" signal to the DB? Closure of identity element in a topological group is the intersection of its neighborhood system Consider a topological group $G$. I want to prove that      if $\cal{U}$ is the set of all neighborhoods of $e$ (the identity element), then $\overline{\{e\}}=\cap_{U\in \cal{U}}U$.   What I thought was:  i) If $x\in \overline{\{e\}}$, then every neighborhood $V$ of $x$ intersects $\{e\}$, hence every $V$ is a neighborhood of $e$ as well, i.e. $V\in \cal{U}$.  ii) On the other hand, if $x\in \cap_{U\in \cal{U}}U$, then $x\in U$ for all $U \in \cal{U}$, meaning every $U$ is a neighborhood of $x$ intersecting $\{e\}$.  Now, I think that the missing part is an argument justifying that there is no neighborhood of $e$ that is not a neighborhood of $x$ (part i)), and that there is no neighborhood of $x$ that is not a neighborhood of $e$ (part ii)). My idea for this is to argue that there is a homeomorphism taking $e$ to $x$, therefore the neighborhood system of one cannot have more elements that the neighborhood system of the other.  Is this correct? If not, is there a way I can fix it? Doubt related to a theorem in congruences of Chapter 5 of Apostol Introduction to analytic number theory I am self studying number theory from Introduction to Analytic number theory by Apostol.   I have a doubt in one argument of proof of Theorem 5.14 and I am posting its image.      My doubt is in 2nd line of 2 nd paragraph how Apostol writes - If y is a solution of (5) then ay $\equiv $ at ( mod m) . How does y being a solution of (5) implies that?       Can someone please help I'm working on the question     Let $G$ be the group of invertible real matrices of the form $\left [\begin{array}{c c}a &amp; b\\ &amp; a^2\end{array}\right ]$. Determine the Lie algebra $L$ of $G$, and compute the bracket on $L$.   I'm familiar with how to derive the Lie algebra for a linear group like $U_n$, $SU_n$, etc. but I'm not sure what to do in a more explicit case like this. Increasing Letterspace for words in caps or small caps Some typographers say it's a good habit to increase the letterspace when writing words in caps or small caps. So my question is, how to do it with pdflatex and/or xelatex? And while we're at it, which words would you alter this way? Acronyms like USA, NATO, IBM, GNU, etc.? How about words like PCs, UdSSR, FreeBSD or TV-Station? Two figures side by side How can I put two figures side-by-side? Not two sub-figures, but two actual figures with separate "Fig.: bla bla" captions.  A figure is supposed to spread over the entire text width, but I have two figures which are narrow and long, and I need to save the space in order to withstand the pages limit. When I look in sys.sql_logins, I see a column called is_policy_checked. Can I trust that my password policy has been checked for all of the logins where this column value is 1? Chrome: remove URL from autocomplete which doesn't show up in history? I accidentally visited gist.gihub.com (note the missing t), and now that URL auto completes each time I start typing gist.…. How can I remove this URL?  I've tried removing it from my history, but that doesn't help:     (note the empty search results) Looking for a Simple Argument for "Integral Curve Starting at A Singular Point is Constant" Let $U$ be an open subset of $\mathbf R^n$ and $V:U\to\mathbf R^n$ be a differentiable vector field on $U$. Let $\mathbf p\in U$ be a singular point of $V$, that is, $V(\mathbf p)=\mathbf 0$.     Then the only integral curve which starts at $\mathbf p$ is the constant curve.   I know that one could simply use the theorem of "uniqueness of integral curves" and in fact adapt the same proof for this particular case.  But is anybody aware of a simple argument for this?