I have a R100 Toshiba external CD-Rom using pci card and usb floppy.  I have tried to install XP to see if it works any different and to do that I have to use recovery disks for the Toshiba to make a X: drive and then use winnt to put files on hard drive and install from there other wise if it tries from the cd I get a blue screen. So is there anyway to do something similar to ubuntu?  I have tried older versions and slow burns of the image.

Error message:  (initramfs) unable to find a live medium containing a live file system   I got this error while trying to install Ubuntu 10.10 from a bootable USB stick on to Asus X64J series laptop. After getting this error the installation fails to start.  I have used the same USB stick on some other laptops and the installation started as usual. Any help will be appreciated.


I have a usb drive with ext4 file system. It is empty. I can't create any files or folders because of the error displayed: "you have no permissions".

I want to mount the device /dev/sda3 to the directory /foo/bar/baz. After mounting the directory should have the uid of user johndoe. So I did:  sudo -u johndoe mkdir /foo/bar/baz stat -c %U /foo/bar/baz johndoe   and added the following line to my /etc/fstab:  /dev/sda3 /foo/bar/baz ext4 noexec,noatime,auto,owner,nodev,nosuid,user 0 1   When I do now sudo -u johndoe mount /dev/sda3 the command stat -c %U /foo/bar/baz results in root rather than johndoe. What is the best way to mount this ext4-filesystem with uid johndoe set?


When describing black body radiation in Physics, one comes across an integral of the form $$I(a)=\int_0^\infty\frac{x^3}{e^{ax}-1}dx \tag1$$ for $a>0$. In our lecture, we were given that this integral evaluates to $$I(a)=\frac{\pi^4}{15a^4}$$ without a derivation of this result. While reviewing my course notes over the Christmas break, I came across this integral and have tried to evaluate it myself, but I have not been successful so far. My first step, of course, was to substitute $u:=ax$, which gives us $$I(a) = \frac{1}{a^4}\int_0^\infty\frac{u^3}{e^u-1}du \tag2$$ but beyond that, I'm stuck. I've tried differentiation under the integral sign on the original integral in $(1)$, which lead to the integral $$\int_0^\infty\frac{\log^4 u}{(u-1)^2}du$$ which I also no have no clue how to tackle. I've also thought about using contour integration, but I'm unsure as to what would be an appropriate contour to consider. I know that the integrand has singularities at $z=2\pi ik$ for $k\in\mathbb{Z},k\neq 0$ but I'm not even sure how one would go about calculating the residues at these singularities due to the peculiar form of the denominator, which is unlike any I have previously encountered.  How would one go about deriving that $$\int_0^\infty\frac{x^3}{e^{ax}-1}dx = \frac{\pi^4}{15a^4}$$ is true?

how to calculate $$\int_0^\infty \frac{x^{3}}{e^{x}-1} \; dx$$   Be $q:= e^{z}-1 , p:= z^{3}$ , then $e^{z} = 1 $ if $z= 2\pi n i $, so the residue at 0 is : $$\frac{p(z_{0})}{q'(z_{0})} = 2\pi i n ^{3}$$  problem is that this is not symmetric, so how does one find the definite integral?


I am new to black hole and general relativity and am just getting introduced to these concepts.  According to my understanding, virtual particle that forms because of quantum fluctuation becomes real particle because of gravitational effects that prolong the life of virtual particle. Is this correct understanding?

I was reading Brian Greene's "Hidden Reality" and came to the part about Hawking Radiation. Quantum jitters that occur near the event horizon of a black hole, which create both positive-energy particles and negative-energy particles, produce the so-called Hawking radiation. However, I do not understand why only the negative-energy particles are being absorbed into the black hole, while the positive-energy particles shoot outward. Shouldn't there be 50/50 chance that each type of particle is being absorbed by the black hole? Also, the book mentions that a negative-energy particle would appear to an observer inside the black hole as positive. Why?


Is $2^n-1$ always a prime for odd values of $n$? $n\not=1$ Taking some odd values of $n$, I observed outcome is coming as a prime number. How to verify it?  Or at-least, is $2^n-1$ always coprime to $n$?

Exactly what the name entails. The function $2^n-1$ I see largely tends to generate primes when $n$ is prime. However, a week ago I heard that this was horribly false. Please show me a disproof.


In Windows 7, lets say I have a "works" directory which containts my work, personal etc information. I want to use a program which always checks the disk and make mirror(s) of this directory. Something like a RAID technology. How can I do that? Thats important, I have now bad sectors....

I want to synchronise two folders in real time under Windows 7.  Basically, I want to monitor a folder and synchronise each change (new files, changed files, deleted files) to another drive. It has to be in real time, so it gets synchronised instantly when a change happens. A one-direction synchronisation is enough.  I tried Microsoft's , but it does only syncing by hand or scheduled (thus not satisfying the "real-time" requirement).  Can this be achieved with Windows 7 itself? If not, are there other methods of doing this?


Excuse me if my question is pretty much about code-style, but for simple cases which of the bellow is better?  CASE 1:  private static int number = 1; public static int Number {     get { return number; }     set { number = value; } }   CASE 2:  public static int Number {     get;     set; }   I think case 2 is better because, when you have many properties in your class they won't consume so much space and the filesize will be reduced.

Note: This was posted when I was starting out C#. With 2014 knowledge, I can truly say that auto-properties are among the best things that ever happened to the C# language.  I am used to create my properties in C# using a private and a public field:  private string title; public string Title {     get { return title;  }     set { title = value;  } }   Now, with  3.0, we got auto-properties:  public string Title { get; set; }   I know this is more a philosophical/subjective questions, but is there any reason to use these auto-properties except from saving five lines of code for each field? My personal gripe is that those properties are hiding stuff from me, and I am not a big fan of black magic.  In fact, the hidden private field does not even show up in the debugger, which is OK given the fact that the get/set functions do nothing. But when I want to actually implement some getter/setter logic, I have to use the private/public pair anyway.  I see the benefit that I save a lot of code (one vs six lines) without losing the ability to change the getter/setter logic later, but then again I can already do that by simply declaring a public field "Public string Title" without the need of the { get; set; } block, thus even saving more code.  So, what am I missing here? Why would anyone actually want to use auto-properties?


I have 2 1080tis. What if I replace one of them on 2080ti? Will I have both cards operational for evee and cycles? like sharing CUDA cores, optix denoising, rtx for evee? thank you!

I have a GTX 1060 6GB in my current build, and I also have a GTX 960 2GB in storage. I was wondering if I got , and got both of my GPUs in one build (not SLI or CrossFire, just in the same system) would I be able to use both GPUs for rendering simultaneously? I don't care if this means having them both render separate tiles in one instance of Blender, or rendering separate frames in two instances. I'm using Cycles for everything I do.


I would like to create a store in drupal commerce_store programmatically, while I am searching for a couple of hours I realize that commerce_store is a entity type. It has bundle named store. Please see image below.....I want to add new store name My Store2 programmatically under Commerce_Store entity type.    Thanks

I created an entity via Entity Construction Kit, Initially I wanted to use rules to create the new entity but the entity is fielded and the fields don't get exposed in rules (as of now, someone is trying to work on a patch for that), but in the interm I wanted to write a simple function that creates a entity, which I assumed would be somewhat like creating a node programmatically, but I've been at this for like 4 hours and I haven't gained an inch, I have entity_create and entity_save but they don't do much and I can't find any documentation on it.  What I'd like to see is how to create an example entity from a bundle made with eck, or through code, that is fielded.  Thanks so much  Edit: The last thing I need to figure out is how to specify the name of the fields that are attached to the entity so I can enter values for those as well.  $values = array('uid' => 1, 'field_receipt_prod_ref' => 1, 'type' => 'receipt');         $new_ent = entity_create('receipt', $values)->save();


My postfix is currently set up to check email content and reject by keywords. However, I can't think of a good way to block this kind of emails:  Return-Path: <gievcyopa@beamtele.com> Delivered-To: xxx Received: from beamtele.com (unknown [183.82.3.184])     by XXX (Postfix) with ESMTP id 3FCAACD1FDD     for XXX; Tue, 15 Dec 2015 13:09:36 +0800 (HKT) From: Jilli M. Gillenwater <gievcyopa@beamtele.com> To: xxx Subject: Do you want to have more lovers? Date: Tue, 15 Dec 2015 10:39:34 +0530 MIME-Version: 1.0 Content-Type: text/html; charset="Windows-1252" Content-Transfer-Encoding: quoted-printable Message-Id: <20151215050936.3FCAACD1FDD@xxx>   Good d̞ay my b̻oy .are you availaḃl͒e? I'm  realֱly h~rny and  want to h00ku֨p  t֧onight! s֯en̗d a  mٌsg so we can  meet!!M͐y  nic̽knͧame is  Jilli88 :PMy account is  here: http://upqepohh.yoursexychick.ru

This is a  about Fighting Spam.   Also related:                    There are so many techniques and so much to know about fighting SPAM. What widely used techniques and technologies are available to Administrator, Domain Owners, and End Users to help keep the junk out of our inboxes?  We're looking for an answer that covers different tech from various angles. The accepted answer should include a variety of technologies (eg SPF/SenderID, DomainKeys/DKIM, Graylisting, DNS RBLs, Reputation Services, Filtering Software [SpamAssassin, etc]); best practices (eg mail on Port 25 should never be allowed to relay, Port 587 should be used; etc), terminology (eg, Open Relay, Backscatter, MSA/MTA/MUA, Spam/Ham), and possibly other techniques.


I am having the same issue as MarkSvalov in . Sadly it seems like it has been removed.    The same thing is happening to the List of tables, but not to the listings (source code).  So what I am using is classicthesis.  I can just download the zip and build it with my TeXstudio and I'll get the exact same behaviour.  As I tried to cope with this issue for an hour now I already tested all the ctf pre and after commands. What I believe is that the word "figure" or "table" gets somehow into the section numbering.  If I take a look at the *.lof or *.lot file the content supports my findings:  \contentsline {figure}{\numberline {1{figure}}{\ignorespaces SomeFigure}{9}{figure.caption.9}   As you can see {1{figure}} doesn't seem right.  I am really happy with TeXstudio, but I'll try another environment to see if it'll still occur.  Do you guys have any idea how I can disable this behaviour?  I read somewhere that people had problems with the automatic language detection of their latex Editor/IDE and some package called bable.  But I couldn't find any settings that would support this idea.  Maybe you guys can help me. Thanks a lot in advance!  Best regards.

As said above, this MWE  \documentclass{book} \usepackage{lipsum} \usepackage{subfig} % this breaks list of figures with overwriting labels  \begin{document}  \mainmatter \lipsum \begin{figure}   \caption[Short caption for list of figures]{Long caption} \end{figure}  \backmatter \listoffigures  \end{document}   when compiled with pdflatex, produces the following problem:    whereas without subfig package everything is fine.  Any clue? Thanks in advance.


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I'd like to show 20 posts on my custom tax template, using this filter:  function customize_customtaxonomy_archive_display ( $query ) {     if ( ( $query->is_main_query()) && ( is_tax() ) ){         $query->set( 'posts_per_page', '20' );         $query->set( 'number_posts', '20' );         $query->set( 'orderby', 'rand' );         return;      } }  //Hook the function  add_action( 'pre_get_posts', 'customize_customtaxonomy_archive_display' );   If I set it to 2, two posts are shown. If I set it to 20, 12 posts are shown. There are never more than 12 posts displayed, although 34 are published.  What could be the issue?


Suppose I have a box on the floor. I lift this box up, being very careful to make sure it rises with a constant upward velocity. (Yes, I will need to accelerate it to start, but assume I do that quickly.) Now, as this box rises with this constant velocity, it gains potential energy, but how? From my understanding, the work done on a body is the integral of its net force over the path it takes. If velocity is constant there is no net force, so there would be no net work done, so somehow this potential energy was created without any work being done ... this makes no sense.  I know this must be wrong since energy is always conserved, but I can't seem to find a flaw in this reasoning.


I want to write an Apex method that takes a country name as input and returns the equivalent two letter country code (ISO A2). Is there a way to write it without explicitly hard coding all countries and code in the method? Can you walk me through how to do this from APEX? To clarify, I am trying to create a custom field on the account level with this return.


I was just talking with a friend about an old Dr Who episode from the late 70s or early 80s where there were some kind of humanoid bat like alien with leathery wings that they used like a cloak to envelop people and dissolve them.  We were talking about it because it was an episode that scared the bejezus out of me when I was a little kid. Does anyone know what episode this was?

Does anyone know the title of a 1980s fantasy film which had creepy black creatures with bat like wings which they wrapped wound their victims and then digested them, and all that was left was a pile of bones and goo.   I thought it might be Dragonslayer but seems a bit unusual for Disney.


I saw this in a bash script, and trying to make sense of it:  exec {STDIN}>&0 exec {STDOUT}>&1 exec {STDERR}>&2   Are the {STDIN}, {STDOUT} etc "magic strings" recognized by exec directive in bash scripts?  Isn't STDOUT already set to &1 (and STDERR set to &2, ...) anyway?   What do these lines do?

That is literal, {fd} isn't a placeholder. I have a script that does this, and does not source in anything, nor does it reference {fd} anywhere else.  Is this valid bash?  exec {fd}</dev/watchdog


public class EqualsTest {  public static void main(String[] args) {      String s1 = "abc";     String s2 = s1;     String s5 = "abc";     String s3 = new String("abc");     String s4 = new String("abc");     System.out.println("== comparison : " + (s1 == s5));     System.out.println("== comparison : " + (s1 == s2));     System.out.println("Using equals method : " + s1.equals(s2));     System.out.println("== comparison : " + s3 == s4);     System.out.println("Using equals method : " + s3.equals(s4)); }   }  Output:        == comparison : true == comparison : true Using equals method : true false Using equals method : true   Can anyone explain how the output of s3==s4 became false in the above, also how is this equals tag operation, i mean its working?

I've been using the == operator in my program to compare all my strings so far. However, I ran into a bug, changed one of them into .equals() instead, and it fixed the bug.  Is == bad? When should it and should it not be used? What's the difference?


I am super new to HTML and CSS and while studying faced with the issue: I have located logo on the left side and hyperlink on the right side. But, unfortunately, I cannot locate hyperlink on the center (based on logo's center):  CSS:   HTML:
           Help & Support

Why won't vertical-align: middle work?  And yet, vertical-align: top does work.   span{   vertical-align: middle; }
      Doesn't work.


The following are primes,  $$P_1 = 2^2 + 3^3$$  $$P_2 = 2^2 + 3^3 +5^5 + 7^7$$  After these two, the only prime of such form I've found is,  $$P_3 = 2^2 + 3^3 + 5^5 + 7^7 + 11^{11} + 13^{13} +\dots+  83^{83} + 89^{89}$$  Is there a prime number with this form after these three? (I've checked prime numbers up to 5500, but I couldn't find any others.)

I found that $2^2+3^3=31$ and $31$ is a prime, also $2^2+3^3+5^5+7^7$ is a prime. After these the only prime I found is $2^2+3^3+5^5+7^7+11^{11}+\cdots+83^{83}+89^{89}$. And I've checked $p(n)$ up to $1009$, but I couldn't find another prime of the form  $$ 2^2+3^3+5^5+7^7+11^{11}+\cdots+p(n-1)^{p(n-1)}+p(n)^{p(n)}. $$ Is there any other prime with that form?


I have cronjobs like so  * * * * * /usr/bin/psql -U usename dbname -c "select usename, now(), pg_terminate_backend(pid) from pg_stat_activity where state like 'idle%' and (now() - query_start) > interval '2 hour';" &> /home/fedora/terminate_backend.log * * * * * /usr/bin/psql -U usename dbname -c "vacuum analyze;" &> /home/fedora/vacuum.log   The second is running and producing the requested, albeit useless, log. The above does not create a log and I have reason to believe that it is not running.   I've tried adding /usr/bin/echo "DUMB" > /home/fedora/dumb.log; in front and still nothing appears.   It looks like so  * * * * * /usr/bin/echo "DUMB" > /home/fedora/dumb.log; /usr/bin/psql -U usename dbname -c "select usename, now(), pg_terminate_backend(pid) from pg_stat_activity where state like 'idle%' and (now() - query_start) > interval '2 hour';" &> /home/fedora/terminate_backend.log   Any help is appreciated. Might it have something to do with env vars? If looked in env and tried adding the host 127.0.0.1, Nothing. And btw, the vacuum one works, so...

This is a  about using cron & crontab.   You have been directed here because the community is fairly sure that the answer to your question can be found below. If your question is not answered below then the answers will help you gather information that will help the community help you. This information should be edited into your original question.  The answer for 'Why is my crontab not working, and how can I troubleshoot it?' can be seen below.  This addresses the cron system with the crontab highlighted.


I am facing the below error Exception Details: Update failed. First exception on row 0 with id *************; first error: TEMPLATE_NOT_FOUND, The record couldn't be saved because it triggered an email alert that failed. Please contact salesforce.com Customer Support.: [] The scenario is that we have a WF Rule on the Invoice object which fires the Email Alert after Registration. The Invoice Template is a VF Page. I researched for it and most of the folks suggest checking the permissions of the fields referenced in the Email template. I do that but still, I am getting the same error. It's the second time I am facing this particular issue. The first time it was resolved by giving permission to a new field added on the Invoice object. But this time it happens suddenly without adding any new field. Please suggest a way to resolve it Thanks.

In a partner community I have a button which users click to accept a request. On the click of this button I perform an update on a record, which then causes it to meet some workflow criteria. At this point a email alert should be fired. Unfortunately the email isn't received and I see the following error being thrown in the logs:        TEMPLATE_NOT_FOUND, The record couldn't be saved because it triggered an email alert that failed. Please contact salesforce.com Customer Support.   In the error it displays the template Id. The template it refers to is a Visualforce template which has previously been pushed across in a change set. This same workflow and email alert are working in a different environment. I have checked security and ensured that all the fields referenced in the template are accessible to the community user. Additionally I have checked that the data in the template is valid. If the email is triggered from the standard sf UI (e.g. I update a field, which causes the wf rule to be valid) the email alert and template work just fine. Can anyone shine a light on a solution for this?   EDIT Interestingly commenting out all the merge fields in the VF template allows the email to fire successfully.


Existing SE sites have a feature that suggests what tags may be appropriate based, perhaps, on comparing keywords with existing tags.  I just had the thought, having had a few times where I wanted to ask SE a question but wasn't sure where to put it, whether it would be possible to make a meta-site where you start typing in your question and, instead of SE suggesting tags, have it suggest links to individual SE sites.  Possibly this could have a default option, if the OP does not select any of the suggested sites, being posted for the interim to an interim.stackexhange.com site, where every post is flagged for moderator attention for migration to an appropriate site with the moderator adding a comment of "I moved your question to _________ because it fits the site for this reason: __________"  Would that kind of thing be possible and/or desirable?

Say if I had a question that I didn't know where to ask, say,     How does myopia work?   I know it goes somewhere around , but if someone (I) didn't know where to ask that, do we just ask on Meta Stack Exchange and hope for a redirect or something?


Question in title really, something I always found strange when I was learning calculus.  I can see that $\int \frac{1}{x} dx$ can't be $\frac{x^0}{0}$ since this is not defined, and then the definite integral $\int_1^t \frac{1}{x} dx$ comes down to $$\lim_{\delta \rightarrow 0} \frac{t^{\delta}-1}{\delta} = \log (t).$$   But this understanding just comes from l'Hopital's rule, and also it still just seems really bizaare that the log function should fit into the set of power functions like this.  Can anyone de-mystify this at all?

Of course, it is easy to see, that the integral (or the antiderivative) of $f(x) = 1/x$ is $\log(|x|)$ and of course for $\alpha\neq - 1$ the antiderivative of $f(x) = x^\alpha$ is $x^{\alpha+1}/(\alpha+1)$.  I was wondering if there is an intuitive (probably geometric) explanation why the case $\alpha=-1$ is so different and why the logarithm appears?  Some answers which I thought of but which are not convincing:   Taking the limit $\alpha=-1$ either from above or below lead to diverging functions. Some speciality of the case $\alpha=-1$ are that both asymptotes are non-integrable. However, the antidrivative is a local thing, and hence, shouldn't care about the behavior at infinity.


I'm a programmer and making graphics is something very difficult for me, but for one project I need to apply a panoramic image to the inner side of a semi sphere.  So I found this tutorial on how to unwrap the sphere  it all went fine up to the part where he uses sphere projection. Look at the time 2:20+. He's got the UV Mapping (Direction, Aling) on the toos shelf. But there is nothing like that in my blender setup (2.73). Just look at my screenshot   Where can I find those options? Or how can I unwrap this semisphere to something like a rectangle like the guy does on the video?

I'm very new to Blender and am having a bit of trouble. After I Shift + A > Mesh > Cylinder, I want to pull up this menu:    How would I do this, please? It doesn't just pop up after I add in the cylinder. Thanks.


I've heard a Canadian friend of mine say, "He needs hit" rather than "he needs to be hit". Is this an Americanism/Canadianism or is it just a quirk of my friend's idiolect? I think I've heard similar things said by other North Americans, so I'm pretty sure that it's current colloquially, but I can't be sure.

I'm from Central Pennsylvania, and apparently, we have a strange language construct in this area. I was recently talking about how "my car needs washed" to a friend from NJ, and she told me that my sentence was grammatically incorrect.   I realize she's right, and I realize my options are "my car needs to be washed" or "my car needs washing". But I'm not clear on the precise rule being invoked.


I want to find anomalies in a time series. Is it possible to find anomalies using moving average?

I am working with a large amount of time series. These time series are basically network measurements coming every 10 minutes, and some of them are periodic (i.e. the bandwidth), while some other aren't (i.e. the amount of routing traffic).  I would like a simple algorithm for doing an online "outlier detection". Basically, I want to keep in memory (or on disk) the whole historical data for each time series, and I want to detect any outlier in a live scenario (each time a new sample is captured). What is the best way to achieve these results?  I'm currently using a moving average in order to remove some noise, but then what next? Simple things like standard deviation, mad, ... against the whole data set doesn't work well (I can't assume the time series are stationary), and I would like something more "accurate", ideally a black box like:  double outlier_detection(double* vector, double value);  where vector is the array of double containing the historical data, and the return value is the anomaly score for the new sample "value" .


How can I create a file with executable permission itself? I want to create a new file with a single command with executable permissions how can I do it?

When creating directories, mkdir -m <mode> <dir> provides for creating one or more directories with the given mode/permissions set (atomically).  Is there an equivalent for creating files, on the command line?  Something akin to:  open("file", O_WRONLY | O_APPEND | O_CREAT, 0777);   Is using touch followed by a chmod my only option here?    Edit: After trying out teppic's suggestion to use install, I ran it through strace to see how close to atomic it was. The answer is, not very:  $ strace install -m 777 /dev/null newfile ... open("newfile", O_WRONLY|O_CREAT|O_EXCL, 0666) = 4 fstat(4, {st_mode=S_IFREG|0666, st_size=0, ...}) = 0 ... fchmod(4, 0600)                         = 0 close(4)                                = 0 ... chmod("newfile", 0777)                  = 0 ...   Still, it's a single shell command and one I didn't know before.


I'm trying to load an existing .qgs project and get a list of the layers inside. I seem to be able to open the project, but I can't get the list of layers. I'm a little confused as to the basic PyQGIS syntax, and the cookbook doesn't cover this specific example.  from qgis.core import * from PyQt4.QtCore import QFileInfo   QgsApplication.setPrefixPath(r"C:\OSGeo4W\apps\qgis-ltr", True) qgs = QgsApplication([], False) qgs.initQgis() # Get the project instance project = QgsProject.instance() # Open the project project.read(QFileInfo(         r'C:\path\to\project\project.qgs')) print project.fileName() # Get the layers in the project layers = QgsMapLayerRegistry.instance().mapLayers()  print layers qgs.exitQgis()   Currently, this just layers returns an empty dict, despite the fact that the project exists and has many layers in it.

I need a list containing the names of all the layers in a QGIS session. I did the task as  layersNames = [] for i in self.iface.mapCanvas().layers():    layersNames.append(str(i.name()))   but this has the problem that only the names for the visible layers are extracted. How can I get a list with the names of all (visible or not) layers using PyQGIS?


How to achieve a rotation animation like this (GIF below)? Where the text rotates on both orange point and its origin point axes, so it stays horizontal along its rotation. Thanks!

I'm new at blender and I'm trying to animate a ferris wheel. But blender is still very difficult for me and I'm stuck. I made the base and the little cars separately but I have no idea how to let them rotate properly.    Anyone who wants to explain me how to do that?  Many thanks!


During the day, usually I'm away from my computer for 3-5 hours. I also sleep 6+ hours every night.  I run Arch Linux x64 on my computer.  Besides the usual things that do not require user intervention (torrenting, backing up data, upgrading the system, etc...), is there anything useful that I can let my computer do while I'm away?  Considering I almost never turn the computer off, it seems like a waste it's sitting there doing nothing. I'm looking for any kind of suggestion, not only machine maintenance.

Just wondering how I can put my idle computer time to some real use  what services like seti@home are out there and worth supporting ?


I was reading Lectures by Feynman (which are soo good at any qualification!) and he talks about how energy of a particular planet in our solar system is constant at all times $ i.e, KE+PE= constant.$ But what if a rogue planet appears all of a sudden and, let's say, kicks out Mars from it's orbit and from the solar system. $(imagine!)$ Now the total energy of Mars is not the same as it was before. Am I missing out on something? (which I believe I do!)

It is said that since work is done by the gravitational potential itself , so at a finite distance the gravitational potential energy of the body is negative. Could someone explain why?


I want to play modded survival with my friends and I have the mods, do they have to download all of those or do I just have to have them?

I'm wondering if I could play Minecraft with my friend. A modded Minecraft, only myself with mods and him without mods.  Is it possible?


As we all know, .  However, on this site, we still have the  tag that refers to the old name of this tab.  This tag should be renamed to .

On the Home page and Questions page, we have a tab for questions that currently have bounties. The tab reads "Featured". I've long wondered why we used "Featured" rather than something like... I don't know... "Bountied". I asked some of my coworkers and the response I got was      Someone typed "Featured" into a text file 10.5 years ago and it stuck, is my guess. ;)   Now, I'm not sure we've had bounties - or at least this tab - since the site first launched but that's being a bit pedantic. There may be a more official answer out there somewhere, but I figured I'd see what your thoughts were about changing it.   To be fair, I'm not sure that "Bounties" or "Bountied" sound particularly great but they do actually say what that tab contains, which "Featured" doesn't. On top of that, we use "Featured on Meta" to indicate questions that moderators or staff have tagged with the  tag, which don't have a bounty associated with them. Using the term in such different ways could be confusing to users.  The thing is, I'd like the option to use "Featured" for something else that's more similar to how it's used in relation to Featured Meta posts, which is why I'm asking this question.  Here's what the tabs look like on the Home page of Meta Stack Exchange:    Should we change this text to read "Bounties" or "Bountied"? or something else? Or should we leave it the way it is?  If something else, what? Promoted? A few ground rules - well, one: It needs to be the same length as "Featured" or shorter.


My approach: Non-square matrices (m-by-n matrices for which m ≠ n) do not have an inverse. However, in some cases such a matrix may have a left inverse or right inverse. If A is m-by-n and the rank of A is equal to n, then A has a left inverse: an n-by-m matrix B such that BA = I. If A has rank m, then it has a right inverse: an n-by-m matrix B such that AB = I.

Let $R$ be a commutative ring with $1 \neq 0$.  It is known that $R^{n} \hookrightarrow R^{m}$ implies $n \leq m$ and $R^{n} \twoheadrightarrow R^{m}$ implies $n \geq m$, and I might use this without mentioning (though I don't think I did). Isomorphisms are $R$-module maps if not mentioned otherwise.  Let $m \geq n$ and consider $R^{n} = R^{n} \times 0 \times \cdots \times 0 \subseteq R^{m}$. We have $\text{Hom}_{R}(R^{n}, R^{m}) \simeq M_{m \times n}(R)$ via $\phi \mapsto M(\phi) = (c_{ij})$ where $\phi(e_{j}) = \sum_{i=1}^{m}c_{ij}e_{i}$. Take any $R$-linearly independent $y_{1}, \cdots, y_{n} \subseteq R^{m}$ and define an $m \times n$ matrix $A = (a_{ij})$ via $y_{j} = b_{1j}e_{1} + \cdots + b_{mj}e_{m}$.  If we understand $e_{j}$ with $1 \leq j \leq n$ as $n \times 1$ column matrix in $R^{n}$ when we multiply an $m \times n$ matrix to it on its left, then $Ae_{j} = y_{j}$ for $1 \leq j \leq n$. Thus, we can understand this matrix as an injection $A : R^{n} \hookrightarrow R^{m}$.  By definition $A$ is an $m \times n$ matrix, but if what I wrote is correct, then $A|_{R^{n}}$ must be an isomorphism $R^{n} \simeq \bigoplus_{j=1}^{n} Ry_{j}$. I am not trying to find an invertible matrix to $A$, but is it okay to think of it as an embedding like how I described?


I want to evaluate $$\int _{\frac{\pi}{6} }^ \frac{\pi}{3} \frac{\sin t+\cos t }{\sqrt{\sin 2t}} dt$$ I  tried to use the properties of the integral to reduce the integral. But I failed. Also I tried using $\sin C+ \sin D$ and $\sin 2t$ trignometric identities. Nothing worked!!  This question has only one answer    But that answer is not satisfactory for me because When a person  see that integral for the first time , how do he know about that particular trick. Is there any elegant way to solve this problem?

Which is the easiest way to evaluate $\int \limits_{0}^{\pi/2} (\sqrt{\tan x} +\sqrt{\cot x})$?   I have reduced this problem to $$   2\int_0^{\pi/2} \sqrt{\tan x} \ dx$$  but now, evaluating this integral is giving me some problems, simply substituting $u=\tan(x)$ and then $\mathrm{d}u=\sec^2(x)\mathrm{d}x \Rightarrow \frac{\mathrm{d}u}{1+u^2}=\mathrm{d}x$ and which in turn gives something a bit ugly, I was wondering which is the most elegant way to evaluate this?


We've seen Yoda deflect Sith lightning, but we haven't seen him defend against a Force choke.  What would happen if Vader or some other powerful Sith lord attempted to apply a Force choke against Yoda?

Like Darth Vader, Asajj Ventress was often seen choking people, many times Jedi like Anakin and Obi-Wan.  Is it possible for Force-users or non-Force-users to counter or defend against a Force choke without distracting the attacker or using ysalamiri?


Today I commented on somebody's answer in a thread in Stack Overflow. Which was lead to an argument mostly started by the other guy. He used very inappropriate language and tone and acted childishly. He downvoted all of my posts and questions that even were not related to the subject of discussion. I sent an email to Stack Overflow team to complain but I don't know if they are going to attend the matter. He has a high ranking in SO and he removed all his nasty comments and my comments to make it look good. What can I do about it? really such people should be able to do anything they want and get away with it.

I just noticed that I lost a bunch of points from my reputation score, and I used the "reputation" tab on my user profile page to try and track down the cause.  During my investigation, I noticed there was an unusual event of type "reversal". In the normal place of a question title, it says "voting corrected".     What does this mean, and what caused it?  Did I do something wrong? Why did I lose all of that reputation? Is the system punishing me for leaving too many good answers?  Is there any way to earn it back?


This was supposed to be a long question but something went wrong and everything I typed was lost. Here goes.   Why is  $k = \dfrac{1}{4\pi\epsilon_0}$ in ?  Is this an experimental fact?  If not, what is the significance of this definition?

I mean to ask why there is $4\pi$ present in force equations governing electricity? Though all objects in universe are not spherical and circular, the constant of proportionality in both equations contain $4\pi$. Why?


I have raster data in a geodatabase and want to open them with QGIS. When I navigate with QGIS to the Geodatabase I get to this window.     Unfortunately, I can't open These atx and GDBTABLX files and I don't recognize which of layers are the files. In ArcGIS the window just Shows the layer names.   Is there a way to recognize the layer name and open the files in QGIS?

Is there a way to open a raster that is stored in ESRI V10.0 Geodatabase in QGIS V2.4?    I can open the vector layer, but there does not seems to be a way to open a raster.


I would expect pressing Ctrl+C without having selected anything to copy the whole line where the cursor is. Unfortunately this is not the case.  Is there a way to change this behaviour?  Of course I am aware of how to select a whole line pressing Home+Shift+End or triple-clicking the line and then copying it to clipboard.  But what I want is just pressing Ctrl+C without having selected anything in the line. Why is this default behaviour not implemented in my favorite editor?

Microsoft OneNote has a handy shortcut (Ctrl+A) that I use all the time to select an entire line.  And if you click it a second time it selects the entire document.  I really would like to use Ctrl+A as shortcut in Notepad++ to select the current line, but its default is to select the entire document.  Is there a way to make it select only the entire current line?


I had applied for a family visit visa to Germany to visit my husband who is a student there. The basis of rejection were  8) the information submitted regarding the justification for the purpose and conditions of the intended stay was not reliable.   your declared travel purpose is not understandable regarding your submitted documents or your information during the interview. the existence of your family relationship is not proved   9) your intention to leave the territory of the member states before the expiry of the visa could not be ascertained.  -you did not submit documents which confirm stable financial background    -the documents you submitted do not allow a positive conclusion as to the existence of a secured background or sufficient family relationship.  also i received comments stating  as per my information:  BE ADVISED THAT YOU MAY APPLY FOR FAMILY REUNION WITH YOUR HUSBAND WHEN IT IS LEGALLY POSSIBLE. IN THAT PROCESS YOUR MARRIAGE DOCUMENTS WILL BE CHECKED. UNTIL THEN IT WILL NOT BE POSSIBLE TO ISSUE A SCHENGEN VISA.  with all this being stated the reason i applied for family visit and not tourism since i felt that applying for a tourism could create a red flag earlier since my husband was already in Germany. I worry that if i apply for a tourist visa now it will get rejected too since somehow they feel i have intentions to stay with my husband and not return whereas the only reason i wish to go is to enjoy my stay for a few days n come back since I am already enrolled a student in my home country. Should i apply for a new application for a tourist visa or sit back ! i fear of getting rejected also it shouldn't look for my desperation. Please help  I am still confused whether i should reply them through remonstrance or apply for a new visa.... Also i have only a few days to go for remonstrance since i received the rejection quite later than the issuance I do not have a lot of time only a week maybe.....  I do not wish to ask the details for rejection instead i wish to know the best practice in reply as to go for a new category or stay stay stick to it

Schengen refusal formulae can be difficult to understand sometimes.  Sometimes an applicant receives a refusal with:       Justification for the purpose and conditions of the intended stay was not reliable.     often accompanied by:       Your intention to leave the territory of the Member States before the expiry of the visa applied for could not be ascertained.   What is meant by this refusal reason?  What are they trying to say?


Get following error while trying to install GIMP 2.8 on Ubuntu 12.04:  The following packages have unmet dependencies:  gimp : Depends: libgimp2.0 (<= 2.6.12-z) but 2.8.6-0precise1~ppa is to be installed         Depends: gimp-data (<= 2.6.12-z) but 2.8.6-0precise1~ppa is to be installed   How do I update those dependencies?

I understand that there is a new version of the GIMP available, although it appears that the only way of doing this is by compiling from source :P  Is there another way of getting it, or if I have to compile can I do that through the terminal or better still; a GUI?


I have been using Ubuntu 16.04 for a couple of years now, and recently did an upgrade to 18.04. This was not a fresh installation, but rather an upgrade as per instructions, from 16.04 to 18.04. Everything went to plan, except that now whenever my computer boots up, it takes an eternity to boot, and briefly flashes up the following error:  failed to connect to lvmetad. Falling back to device scanning Gave up waiting for suspend/resume device /dev/mapper/ubuntu--vg-root: clean, 550775/30154752 files, 23702732/120600576 blocks   If I wait long enough, then the computer boots just fine after this. Looking online I see that LVM is a feature which works a bit like a virtual RAID system, compiling multiple drives into one virtual drive/partition/s etc. I have however never used this.  Is LVM something mandated by Ubuntu 18.04? Do I have to use it? If not, how do I get rid of it?  My computer never had an issue before and always booted very quickly. I only have a single SSD drive in my machine, so LVM would be superfluous to requirements for me.  Thanks for the help guys!  Subsequent research has lead me to believe this is a known bug. I have used the suggestion here (to modify GRUB such that it does not resume)    Furthermore I also used this link to modify /etc/initramfs-tools/conf.d/resume and disable resuming as explained in   Apparently this affects a machine's ability to resume from hibernation too, so not too good a workaround if you wish to retain that feature (which I do not).  With that done the boot time has been reduced by about 20 seconds, however I still get the original message flashing up, which means it's still looking for some virtual volume or swap file that does not exist (I don't use one, who would!).  Hopefully this helps somebody, or at least until the bug is fixed at some point.  FYI - Bug report can be found

After upgrading to ubuntu 16.10 I get this warning in my boot.log file  WARNING: Failed to connect to lvmetad. Falling back to device scanning. Volume group "ubuntu-vg" not found Cannot process volume group ubuntu-vg WARNING: Failed to connect to lvmetad. Falling back to device scanning. Reading all physical volumes.  This may take a while... Found volume group "ubuntu-vg" using metadata type lvm2 WARNING: Failed to connect to lvmetad. Falling back to device scanning. 2 logical volume(s) in volume group "ubuntu-vg" now active /dev/mapper/ubuntu--vg-root: clean, 1180656/30154752 files, 16007858/120604672 blocks   Seems to be an issue that is related to disk encryption. The system startup properly and I do not see any bad behaviour, however do anybody have an idea how to fix


So I want to start collecting old Thinkpads and I think the X61s is a good place to start. With 4gb ram and it's Integrated Intel X3100 will it run smoothly on Ubuntu and play low end games like Undertale? (I know there's a system requirements sheet for Ubuntu and Undertale but I had absolutely no clue what they meant!)

I am a bit financially strapped and received a Gateway GT5056 tower. The tower has an AMD dual core 64-bit processor in it. Will Ubuntu 12.04 run on this machine? I will not have any other application other than LibreOffice installed.


I don't know how long ago this happened, but today I realized that when I open up terminal it no longer says Matthew-MacBook:~matthew$  as it used to. Instead, it appears to have synched up with my roommate's macbook pro. It now displays: $Gabriels-MBP:~matthew$  I've restarted my mac but it doesn't change the name. I've tried the suggestions suggested   posts sudo scutil --set HostName Matthew-Macbook  But no effect! echo "$PS1" returns \h:\W \u\$

For three days straight, I have connected to the public WiFi network at my local library. Each day, I have seen a different prompt in Terminal. Here are some of the prompts I've seen:  zp-pc:~ russell$ mary-pc:~ russell$ normob05:~ russell$   I have check under System Preferences -> Sharing, and my computer name is "Russell's Mac". Also, I set the DHCP Client ID to "RUSSMAC" under System Preferences -> Network -> Advanced -> TCP/IP, but I still see the random host names at the Terminal prompt.  Why is my computer name changing every day?


My husband died.  I have the death certificate.  Also using his iPhone.  Don't have his password.  Would like to obtain it.  How do I do that?

My Auntie died unexpectedly without leaving her icloud information (pretty standard!) I've restored her ipad as I thought it would reset her passcode as I couldn't guess it but now it's asking for Apple ID. I've tried everything but I can't guess her secret info or get into her emails until I go see my grandad and get her phone (he literally lives at the other side of the country.) So now I have this ipad and my cousin has iPod touch which is acting as a paper weight. There must be a way around it as this must be a fairly common thing surely? I don't have her death certificate, there isn't a will and my grandad (next of Kin) is 86 and quite flustered about everything and he's about had enough.   Ive looked online for a bypass but no luck, as it's not reported stolen surely it can't have an anti theft lock?  Thank you


Q1: prove that if a|b and b|a, then a=b or a=-b?

Could someone tell me a simple proof to If a|b and b|a iff a=+-b.


I'm finding this level absolutely impossible. I've been trying for days now to get through it. I can't get past even the first two or three turning platforms.  Is it really this diffucult? It's been such a fun and relaxing game until now – now I really hate this game and i'm just so, so frustrated.  I have seen the answers on "" but it does not quite help enough. Are there any other tips? Any way to cheat it? A way to slow the lava? A way to save the state right at the bottom of the turning platforms? A way to hack my "save state" to say "you finished this level"?!  I'd really just like to hire an expert to get through this level so I can continue with the fun, relaxing exploration that I thought this game was about.  I'm playing on a PC, if that helps.

I'm having a frustrating time on the red lava level in the sewers on Fez. It may be that my platforming skills are not up to par, but are there any suggestions as to how to get through it easier?


I'm trying to convert my python code "new.py" to an exe using pyinstaller. The exe got built successfully but when I try to run it it shows me the following error: $ /Users/name/Desktop/Programming\ Projects/PythonWebscraper/dist/new ; exit; Traceback (most recent call last):   File "new.py", line 37, in <module>   File "openpyxl/reader/excel.py", line 151, in load_workbook   File "openpyxl/reader/excel.py", line 115, in _validate_archive   File "zipfile.py", line 1240, in __init__ FileNotFoundError: [Errno 2] No such file or directory: './PulledData.xlsx' [78053] Failed to execute script new logout Saving session... ...copying shared history... ...saving history...truncating history files... ...completed.  My code is writing to an excel spread sheet and so it's loading up the file './PulledData.xlsx'. I put the excel sheet in the same directory as the exe that I'm tryin to run, yet it still can't find the excel sheet as shown by the logs. (new.exe and PulledData.xlsx are both in the same directory) How do I fix this? Is this something to do with Pyinstaller? I don't want to bundle up the excel sheet as it should be easy to access. The exe (python code) should manipulate the excel sheet called "PulledData" in whatever directory its in, how can I do that?

I have an application that resides in a single .py file.  I've been able to get pyInstaller to bundle it successfully into an EXE for Windows.  The problem is, the application requires a .cfg file that always sits directly beside the application in the same directory.  Normally, I build the path using the following code:  import os config_name = 'myapp.cfg' config_path = os.path.join(sys.path[0], config_name)   However, it seems the sys.path is blank when its called from an EXE generated by pyInstaller.  This same behaviour occurs when you run the python interactive command line and try to fetch sys.path[0].  Is there a more concrete way of getting the path of the currently running application so that I can find files that are relative to it?


Is there a general rule to find the value of infinite sums like $$\sum\limits_{n=1}^{\infty}\frac{n}{r^n}?$$ I know the formula for a sum of a geometric sequence, but this is a geometric sequence multiplied by an arithmetic sequence. How would one calculate this infinite sum?

How can I evaluate $$\sum_{n=1}^\infty\frac{2n}{3^{n+1}}$$? I know the answer thanks to , but I'm more concerned with how I can derive that answer. It cites tests to prove that it is convergent, but my class has never learned these before. So I feel that there must be a simpler method.  In general, how can I evaluate $$\sum_{n=0}^\infty (n+1)x^n?$$


We have a program that is having problem starting up on Windows 10. If the program is NOT run as administrator, it popups a "Access Denied" message right before it starts. If we run the program as an administrator, it does NOT popup any error message and loads normally. However, now the program won't run at STARTUP. So, we need to run our program as administrator and be able to automatically run the program at startup.  Update: Even though my question and the duplicate question maybe the same but the answers provided for both questions did not solve my problem. Task Scheduler only starts my application or program as a background process. Thus, my program doesn't load. However, I do see my process in the task manager under background process. That's all.

I'm currently running a startup script in form of a bat file successfully in Windows 7 (I've inserted a new registry key entry with the bat file path as value in   Computer\HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run).   Now I need to run another bat file at startup, but with elevated rights (as administrator), and without manually confirming a prompt.  How can I achieve this, preferrably without external programs?


Let $1 \le p \le q \le \infty$ and $\Vert x \Vert_p = \big( \sum\limits_{i=1}^\infty \vert x \vert^p \big)^{1/p}$ where $x = (x_1, x_2, \cdots, x_k, \cdots )$. $l^p = \{x: \Vert x \Vert_p < \infty\}$.     Then $\Vert x \Vert_q \le \Vert x \Vert_p$ for $x \in l^p$.    I can show $l^p \subset l^q$, but I am a little struggling to show this. Any help would be appreciated!

I can't seem to work out the inequality $(\sum |x_n|^q)^{1/q} \leq (\sum |x_n|^p)^{1/p}$ for $p \leq q$ (which I'm assuming is the way to go about it).


How do you search for a file of a specific type in OS X Yosemite?  I cannot seem to find any instructions on how to do this.   In the Finder search I enter: kind:zip  But it returns all compressed files.  I only want zip files - so this  does not help me much.  All the solutions either use bash, or I cannot find the options they refer to.

Is there any way to search a specific type of file using Spotlight? I remember there was a special command or something that I had to put in front of the search phrase but I cannot remember it now.   For example, if I want to search only PDFs for a particular phrase in Spotlight, what would I do?


I have written a software in ROR that I want to host it for customers by own. These are some examples:  vanillaforums.com/plans manage.nodebb.org wordpress.com ghost.org/pricing   What I need is a software to automate installation per user and allow them to manage their space (installing plugins, editing source, etc). can  handle this service?

My aim is to implement software as a service using cloud computing. Can we use Juju for implementation of Software as a service? We can deploy MySQL and Wordpress using Juju. But I want to install other applications (e.g matlab etc) on my server and want to give access for those applications to client.


For all $x$ which are real numbers, prove that   $$\lfloor 2x\rfloor = \lfloor x\rfloor + \lfloor x+0.5\rfloor.$$   I know that  Let $\lfloor x\rfloor = n$  $n \leq x < n+1$

I can intuitively see that this is true, but I'm having a very hard time proving it. I'm actually not even quite sure where to begin. I tried using the inequalities that define the floor function, and I'm pretty sure this is the way to go, but I'm failing to make any kind of progress.  I appreciate any help.


How to uninstall many programs in Windows?  Right now I browse to Control Panel\All Control Panel Items\Programs and Features then choose programs one at a time.  Is there any application where I can check a list of programs to uninstall then leave my computer to do them all?

Just been working on a new laptop today (Acer) and it was pre-installed with all sorts of crapware. Mostly games and "backup utilities" and McAfee. I had to manually uninstall about 30 apps via Vista's Programs and Features  So it got me wondering is there any way of mass uninstalling or queuing an app to be uninstalled? Through Vista/XP you need to wait for Install Shield or whatever to close before beginning to uninstall the next app. Took way more time than it should have.  Just another one of those Windows annoyances! Any help appreciated as I often need to do this when I come across a slow machine that's just been clogged with a bunch of useless apps


I'm getting started with iOS development and I need a test device to test my apps. I thought of buying an ipod but then I thought buying an icloud locked iphone 5s might be more convenient (affordable) as it will basically do the same thing as the ipod.  I have a question though. Can I install apps on a device locked to a specific icloud account?

I bought a used iPhone 4.  The previous owner re-set the phone, but did not remove the device from their iCloud.  It is asking me for their iCloud information when I try to set-up the phone.  I don't have contact with the previous owner anymore.  Is there a way to remove the device from their iCloud so I can use a new one?


I am making a dropper mini game on my Minecraft server and I am using a button to give a player the diamond. I need a command block that sees if they have a diamond already so they don't get two diamonds.

I'm building a CTF map of sorts, using command blocks in vanilla 1.8. I've discovered two commands for detecting if an item is in a players inventory:  /clear @a[team=Red] banner 4 0  /testfor @a[team=Red] {Inventory:[{id:"minecraft:banner"}]}  Those work fine, unless you want to perform a command ON the player carrying that item. For example: I want to cause the player who picks up a banner of the opposite team, to automatically equip that banner in their head slot with a command similar to this:  /replaceitem entity @a[???????] slot.armor.head banner 1 4  Can this be done? If not, is there a way to mark a specific player carrying an item using scoreboards?


I'm trying to sculpt side of a mountain but when I try to do it the middle part of mesh is mirroring.   (I draw the left part).  I check normals they are fine  and I didn't use any modifiers apart from multiresolution.  Any ideas how to fix it?

I made my first sculpt model and I used a mirror modifier. But then I applied the mirror modifier, because I got a strange edge on the mirror line in sculpt mode. Now I modeled it, but it still mirrors the model, what in the beginning was good, but sometime I want to do asymmetrical things.  What did I wrong? Many thanks for your help!! Happy modeling :D


I installed a snap package in Ubuntu 18.04 package and I want to edit one of its files using root account. First I switched to root with su, but then when I opened file in nano it tells me:   [ File '/snap/phpstorm/36/bin/phpstorm64.vmoptions' is unwritable ]   Then I tried this:  root@elahe-VPCEA31FX:/home/elahe# sudoedit  /snap/phpstorm/36/bin/phpstorm64.vmoptions   after above command the file opened in nano, but after making changes and saving with Ctrl+O and after exiting with Ctrl+x I got this message:  sudoedit: unable to write to /snap/phpstorm/36/bin/phpstorm64.vmoptions: Read-only file system sudoedit: contents of edit session left in /var/tmp/phpstorm64XXRCQzZi.vmoptions   I even tried to change the permissions of the file with this command:  root@elahe-VPCEA31FX:/home/elahe# chmod 755  /snap/phpstorm/36/bin/phpstorm64.vmoptions   and got this:  chmod: changing permissions of '/snap/phpstorm/36/bin/phpstorm64.vmoptions': Read-only file system   It is really amazing that the root user cannot edit a file! Is this a bug?

I have been trying for a long time to change Blender's icon, but no matter what I do, I am not allowed to edit anything in /snap/blender-tpaw/3/.  Here's what I tried:   Editing the files from nautilus without sudo. Editing the files from nautilus with sudo (sudo nautilus in terminal ). Using terminal commands such as cp or rm without sudo. Using terminal commands with sudo (such as sudo cp <source> /snap/blender-tpaw/3/ or sudo rm /snap/blender-tpaw/3/<filename.ext>) Doing everything above in a root terminal (using sudo -i)   In every case I get the following error:  cannot remove/copy '/snap/blender-tpaw/3/filename.ext': Read-only file system   where filename is the file and .ext is its extension.  This also applies to other snaps' files, not only Blender.  Am I doing something wrong here? Or is it just impossible to change those files? Although I don't think it is impossible because everything here from Ubuntu to Blender is open-source, so they have no reason to block us from modifying those files.  EDIT:  I used Main Menu (alacarte) to change the icon, but I still want to know why I cannot modify any snap file.


My understanding of "measurement in quantum mechanics" was that any interaction causes the probability "fuzziness" to get "resolved" to a particular value for an observable. However, unlike that, a non-observed, non-interacting particle has some probability to be "anywhere" until "interaction" with some other particle.  If an unobserved particle has a probability to be anywhere, then doesn't it sort-of "exist" everywhere? Wouldn't it interact with something, somewhere? Therefore, a non-interacting particle cannot exist by definition unless it is the only particle in the universe. If this conclusion actually correct in quantum mechanics, or my idea of interacting probability distributions just plain wrong?

We've learned that the wave function of a particle collapses when we measure a particle's location. If it is found, it becomes more probable to find it a again in the same area, and if not the probability to finding it in the place that was checked decreases dramatically.  My question is about the definition of measurement. What makes a measurement different from any other interaction between two particles (gravity and EM fields for example)?  In reality, almost every particle interacts with any other particle, so shouldn't there be constant collapse of the wave function all the time? If this happens we're right back in classical mechanics, aren't we?


your friend decides to roll a die repeatedly to analyze whether the probability of a six on each flip is 1/6. He rolls the die 10 times and observes six 7 times. He concludes that the probability of a six for this die is 7/10=0.7. A. Your friend claims that the die is not balanced, since the probability is not 0.166666667. What's wrong with your friend's claim? B. If the probability of rolling a six is 1/6, what would you have to do to ensure that the cumulative proportion of sixes falls very close to 1/6?

Can someone explain me, how the Law of large numbers and the Gambler's Fallacy do not contradict.  The  says, that there is no memory in randomness and any sequence of events has the same probability as any other sequence.  However, the  says, that given enough repetitions a certain event will likely happen.  To my understanding, these two kinda contradict each other because one says that you can not predict any random event but the other one says so (given enough repetitions of course).  For example imagine a series of coin tosses where the coin comes up heads a million times. The Gambler's fallacy says that the chance for the next toss to be tails is still 1/2. However the law of large numbers says, that since enough repetitions of tosses have come up heads, the next toss is more likely to be tails. (Which is definitely wrong?)


I am trying to disable root password login and only allow root login with a ssh key on debian 7.  cat << EOF >> /etc/ssh/sshd_config PasswordAuthentication yes UsePAM no PermitRootLogin without-password AllowUsers root test Port 433 LoginGraceTime 1m ClientAliveInterval 600 ClientAliveCountMax 0 EOF service ssh restart   I run these commands as part of a deployment script and yet still I am able to login as root afterwards using the root's password (and not using a ssh key).   I've read quite a few tutorials and I can't seem to see why this is happening.

I am implementing a basic deploy script and for sshd_config the only change that I need to make is PermitRootLogin yes to PermitRootLogin without-password. I have read through the docs and they make no mention of this but that is not to say it is impossible.  Can I specify a second PermitRootLogin? I.e. echo 'PermitRootLogin without-password' >> /etc/ssh/sshd_config  If so, is this safe?  Updates based on comments:  1) I am aware that I could parse the file and change the variable. My question still remains though.


I want to redirect all traffic from the root of my website to a subfolder on the same domain using .htaccess  Can someone help me out here?

This is a  about Apache's mod_rewrite.   Changing a request URL or redirecting users to a different URL than the one they originally requested is done using mod_rewrite. This includes such things as:   Changing HTTP to HTTPS (or the other way around) Changing a request to a page which no longer exist to a new replacement. Modifying a URL format (such as ?id=3433 to /id/3433 ) Presenting a different page based on the browser, based on the referrer, based on anything possible under the moon and sun. Anything you want to mess around with URL   Everything You Ever Wanted to Know about Mod_Rewrite Rules but Were Afraid to Ask!  How can I become an expert at writing mod_rewrite rules?   What is the fundamental format and structure of mod_rewrite rules? What form/flavor of regular expressions do I need to have a solid grasp of? What are the most common mistakes/pitfalls when writing rewrite rules? What is a good method for testing and verifying mod_rewrite rules? Are there SEO or performance implications of mod_rewrite rules I should be aware of? Are there common situations where mod_rewrite might seem like the right tool for the job but isn't? What are some common examples?   A place to test your rules  The  web site is a great place to play around with your rules and test them. It even shows the debug output so you can see what matched and what did not.


I'm new in ML and I would like some explanation about dummy variables from any experienced data scientist.  I've understood through reading on the web that pre-processing the data is a really important step before even thinking about the model we want to implement. One subject is how we deal with categorical variables and the answer I found  so far on the web was turn it into dummy variables. However, I'm struggling to understand why we do that. What's the reason hidden behind this method? Is that something we do automatically as soon we see a categorical variable in our dataset?   Why do algorithms learn better from  $K-1$ columns made of $1$ and $0$ than from $1$ column made of $K$ features?   Is there something else we can think of doing when we see a categorical variable?

I am not sure why we need to dummy code categorical variables. For instance, if I have a categorical variable with four possible values 0,1,2,3 I can replace it by two dimensions. If the variable had value 0, it would have 0,0 in the two dimension, if it had 3, it would have 1,1 in the two dimension and so on.  I am not sure why we need to do this?


First I know the title isn't the best nor what the site recommends/asks for, but I have no idea how else to put it. I'm using JQuery to edit twitter widgets on my website. I had no problem doing so until this one element. I have checked that I'm searching for the correct element timeline-Widget and what I'm trying to edit is the border-radius  snippet of my code: $('.twitter-block').find('.twitter-timeline').css({"border": "4px solid rgb(255, 225, 241)", "outline" : "8px solid rgb(255, 189, 225)"}); $('.twitter-block').find('.timeline-Widget').css({"border-radius": "0px"});  first line edits twitter-timeline element and it works just fine, but timeline-Widget JQuery just does not find. Sorry, this is my first time working on a website and a first time working with JS and JQuery

I would like to manipulate the HTML inside an iframe using jQuery.  I thought I'd be able to do this by setting the context of the jQuery function to be the document of the iframe, something like:  $(function(){ //document ready     $('some selector', frames['nameOfMyIframe'].document).doStuff() });   However this doesn't seem to work. A bit of inspection shows me that the variables in frames['nameOfMyIframe'] are undefined unless I wait a while for the iframe to load. However, when the iframe loads the variables are not accessible (I get permission denied-type errors).  Does anyone know of a work-around to this?


The sun is a continuous explosion. The reason we cannot hear the sun is because of the vacuum separating us.  If that space was to be filled with air, would the sun be audible?

Theoretically if I were able to build some sort of device that let me sit 1 foot away from the surface of the Sun (or any star for that matter) without being vaporized, would a star produce any sort of audible sound at that distance?   From my understanding, sound waves need a medium to propagate through (air, water, etc).   Does this mean that all stars are completely silent (in the audible spectrum of frequencies at least) as they fuse  hydrogen into helium?   I know stars emit radio, xray, infrared, ultraviolet electromagnetic waves, but how about audible (20 Hz to 20Khz) frequencies?   For some reason it seems like this process would produce some sort of sound.


I'd need a special symbol used in statistics.  What I need is a tilde with something written upon it.  I can get the tilde by using \sim, but I need to add a superscript over it (H_0). If I use \sim^{H_0}, I get a tilde with H_0 over it and on the right, not simply upon it.

I've seen an equals sign with a small exclamation mark on top being used to say "equals because of data that was given in the problem", for example for a boundary condition or initial value in a differential equation.  A rough picture of what I mean:       ! f(x) = 4   How do I typeset this in LaTeX? I've tried $=^!$ (which doesn't produce the desired result) and looked through the "relations" section of the  without success.


Find all $3\times 3$ matrices that commute with  $$A =\left( \begin{array}{cc} a_1 & 0 & 0\\ 0 & a_2 & 0\\ 0 & 0 & a_3\end{array} \right)$$  My progress:  I know that a I need to find a matrix such that $AX = XA$. However I'm getting stuck when:  $$AX =\left( \begin{array}{cc} a_1x_{11} & a_1x_{12} & a_1x_{13}\\ a_2x_{21} & a_2x_{22} & a_2x_{23}\\ a_3x_{31} & a_3x_{32} & a_2x_{33}\end{array} \right)$$  $$XA =\left( \begin{array}{cc} a_1x_{11} & a_2x_{12} & a_3x_{13}\\ a_1x_{21} & a_2x_{22} & a_3x_{23}\\ a_1x_{31} & a_2x_{32} & a_3x_{33}\end{array} \right)$$  The answer has been given as:   $$\left( \begin{array}{cc} b_1 & 0 & 0 \\ 0 & b_2 & 0 \\ 0 & 0 & b_3 \end{array} \right)$$  I don't understand how they're getting that form. Can someone please explain?

Let $A$ be an $n \times n$ matrix and let $\Lambda$ be an $n \times n$ diagonal matrix. Is it always the case that $A\Lambda = \Lambda A$? If not, when is it the case that $A \Lambda = \Lambda A$?  If we restrict the diagonal entries of $\Lambda$ to being the equal (i.e. $\Lambda = \text{drag}(a, a, \dots, a)$), then it is clear that $A\Lambda = AaI = aIA = \Lambda A$. However, I can't seem to come up with an argument for the general case.


When I  question, It says following:     Wait! Some of your past questions have not been well-received, and   you're in danger of being blocked from asking any more.      For help formulating a clear, useful question, see: How do I ask a   good question?      Also, edit your previous questions to improve formatting and clarity.   Here is screen-shot:   So, What should I do? (How long to wait?)

Another "miséricorde":  Consider  (emphasis added):  I think its okay, please dont take any efforts for me. I personally do not feel the system helps ask good questions. I dont know why asking for a software in this case is bad. Basically I needed a command that would give me this data. There is no other way I could have asked the question. I could have changed the question just for the sake of changing. I feel I am better off elsewhere. Thanks for your very very prompt responses. Regards. Bye. – user1744649  We just lost another user due to inadequate guidance on what questions are allowed.  The  by the time they are banned has been proven incorrect. Given that , we need a better way to make sure that users can understand how to ask good questions and what types of questions are allowed. I suggest that we warn newcomers, in a clear but positive tone, when one of their questions has been closed, downvoted (to a score of -2 or lower), or deleted, so that they don't repeat the same mistake.  This is probably best done the next time the user asks a question, and should appear as an "interstitial" page prior to reaching the actual Ask Question form.  The page should not appear to users:  with at least 50 (or perhaps 75 or 100) reputation that have asked a good question since the last downvoted/closed/deleted question that have fixed a bad question and had it reopened/undeleted/upvoted.  The content of the page should be adapted based on the specific problem with the previous question.  I would imagine something similar to the following (example for a question closed as off topic on Super User):  Before you ask another question... One or more of your previous questions have been closed as off topic. The scope of on-topic questions is defined in the , as follows:  What kind of questions can I ask here? Super User is for computer enthusiasts and power users. If you have a question about …  computer hardware, computer software, or personal and home computer networking  and it is not about …  programming and software development, video games or consoles, websites or web services like Facebook, Twitter, and WordPress, electronic devices, media players, cell phones or smart phones, except insofar as they interface with your computer, issues specific to corporate IT support and networks, asking for a shopping or product recommendation,  … then you’re in the right place to ask your question!  Please make sure that the question you are about to ask is on topic as described above. If you need help determining whether your question can be asked on this site, you can ask for advice on  or . You may also want to edit your previous question to address any problems associated with it. To ensure a high standard of content quality and prevent disruption to the community, users who repeatedly post low-quality questions  Continue  The  doesn't address this issue as it is shown only to users with 10 reputation or less (rather than up to 50 and possibly higher) and does not address the specific problem with previous low-quality questions.  The point of this feature request is to provide a easily understood targeted message that actually teaches the user about what happened with the previous question he or she asked.  The EULA is generic and may not have conveyed the intended message clearly if the user still asked a low-quality or off-topic question. For reference,  currently has 143 reputation and the proposed message would probably have been shown after the first closed or deleted question. I know this can be a complex feature to implement, since it needs to be adaptive, but this should help eliminate confusion on what the rules are and minimize the incidence of good-faith users getting post-banned.


Most people know that the speed of light in vacuum is independent of relative motion but I want to know the proof of it.

Is there any theoretical proof for the constant speed of light in all frames of references? I know it is experimentally proven but just curious.


I have a UTF8 workflow: xelatex, using biblatex and biber for the bibliography, and I think I have come across a funny behaviour from biber. It seems to be converting silently to a percent-coding string (no trace in any log) a URL that contains one single non-ASCII character.  See the MWE with output. The URL contains one simple ü, which is being converted to %C3%BC. I would expect and wish the URL to be kept as it is. Can you spot any mistake? As you can see I've tried the biblatex options that affect biber's, but nothing seems to work, I still get the bloody %C3%BC.  Just in case, I manage my .bib file with BibDesk and I've checked it is saved as UTF8 too.  %!TEX TS-program = xelatex %!TEX encoding = UTF-8 Unicode \documentclass{article}  \usepackage{fontspec} \usepackage[backend=biber,bibencoding=utf8,texencoding=utf8,safeinputenc=false]{biblatex}  \usepackage{filecontents}  \begin{filecontents}{bib.bib}  @online{verknupf_expo2016, Author = {{Warburg Institute}}, Title = {Exhibition: \emph{Verknüpfungszwang}}, Url = {http://warburg.sas.ac.uk/exhibition-verknüpfungszwang}, Urldate = {2016-12-12}}  \end{filecontents} \addbibresource{bib.bib} \nocite{*}  \begin{document}  Hello and bla bla bla bla bla bye  \printbibliography \end{document}     I've checked that the .bib file contains the unicode alright, but it has been converted in the .bbl

Is there any way to keep the URLs in the same form they are saved within the .bib files when using biblatex-chicago with Biber? For instance, the entry  @misc{RussianEmpire.1855,  author = {Russian Empire},  year = {1855},  title = {Treaty of Shimoda},  url = {https://ru.wikisource.org/wiki/Симодский_договор_с_Японией_(1855)}, }   results in the following output:    While there certain are benefits to converting the link itself, this sort of output in the footnote makes it both ugly and difficult to re-enter the link when reading a printed copy. How would one proceed about to receive the output along the lines of ""?  Minimal working example:  %!TEX program = xelatex \documentclass{article}  \usepackage{fontspec} \usepackage[russian,british]{babel} \newfontfamily\russianfont[Script=Cyrillic]{CMU Serif}  \usepackage[CJK, Cyrillics]{ucharclasses} \setTransitionsForCyrillics{\russianfont}{} \usepackage{csquotes} \usepackage[labeldate,backend=biber]{biblatex-chicago} \addbibresource{bibliography.bib} \usepackage[unicode,hidelinks]{hyperref}  \begin{filecontents}{bibliography.bib} @misc{RussianEmpire.1855,  author = {Russian Empire},  year = {1855},  title = {Treaty of Shimoda},  url = {https://ru.wikisource.org/wiki/Симодский_договор_с_Японией_(1855)}, } \end{filecontents}  \begin{document}  Cyrillics support test: Тест\\  \cite{RussianEmpire.1855}  \end{document}   Output:


Thanks in advance for the replies. I own a montra trance pro hybrid cycle. The current tyre size is 700 X 35 c. Can someone suggest if I can put slimmer tyres and if yes what size can I put? Regards Jithu

We often get questions on bicycles.stackexchange about fitting wider or narrower tires to bicycles. We have a large number of these with answers suiting the specific bike or style of bicycle in question, but I have been unable to find one that provides a generic answer covering off all things that need to be considered. For most bicycles, the answer is the same regardless of the specific style and sizes of tires in question.   This is intended as a canonical question that we can point closed questions to.


I am building a small app about the human face.  I have an artist that is sketching pencil based illustrations for me. Mostly in black and white (pencil black/grey) with a hint of colour here and there.  What is the best way to digitally capture the sketches/illustrations?  A high resolution scanner I am guessing.  Any suggestions as to the surface he/she should be sketching on?  Apologies for the simple question. Thanks in advance.

I want to color sketches in Photoshop, but when I prepared the sketch (using Levels, Hue, and other modifications) to turn it into workable line art, some details were missing. I think it depends on how you draw your sketch.  What are important steps for drawing a sketch (with pen or pencil) that is to be colored in Photoshop? A step-by-step instruction would be appreciated.  For instance, here it is the sketch    This is after my preparations in Photoshop


This question has asked many times, but this one is slightly different. In my case, I'm not getting any error when running from Eclipse, it successfully runs and is able to connect to MySQL. I have a Maven project in Eclipse, using the MySQL database and MySQL Connector/J for connection. However, after deploying to jar I am getting the error. I am using mvn clean install to deploy I have added dependency in pom.xml like: <dependency>     <groupId>mysql</groupId>     <artifactId>mysql-connector-java</artifactId>     <version>5.1.49</version>     <scope>runtime</scope> </dependency>  I am using following command to run the jar file  java -jar ./target/project.jar but this gives java.lang.ClassNotFoundException: com.mysql.jdbc.Driver What's wrong here?

I want to package my project in a single executable JAR for distribution.  How can I make a Maven project package all dependency JARs into my output JAR?


I have a string array : Arrays.asList("str1", "str2", "str3", "str4");  And I want converti it as string with delimmotors, like this :  "str1,str2,str3,str4"  How I can do it without iterating my list ?

While working in a Java app, I recently needed to assemble a comma-delimited list of values to pass to another web service without knowing how many elements there would be in advance. The best I could come up with off the top of my head was something like this:  public String appendWithDelimiter( String original, String addition, String delimiter ) {     if ( original.equals( "" ) ) {         return addition;     } else {         return original + delimiter + addition;     } }  String parameterString = ""; if ( condition ) parameterString = appendWithDelimiter( parameterString, "elementName", "," ); if ( anotherCondition ) parameterString = appendWithDelimiter( parameterString, "anotherElementName", "," );   I realize this isn't particularly efficient, since there are strings being created all over the place, but I was going for clarity more than optimization.  In Ruby, I can do something like this instead, which feels much more elegant:  parameterArray = []; parameterArray << "elementName" if condition; parameterArray << "anotherElementName" if anotherCondition; parameterString = parameterArray.join(",");   But since Java lacks a join command, I couldn't figure out anything equivalent.  So, what's the best way to do this in Java?


How can we search and replace "xyz" in col3 only?  col1,col2,col3,col4   abc,def,xyz,xyz   xyz,abc,def,xyz

I have a huge file (more than 2 GB) where data is like below.  12,324,32342,E:fsdsf,23432,34534,45345,324  13,3224,342,E:werwefsdsf,23432,34534,45345,324  121,3244,33442,E:,23432,34534,45345,324   Here I need to replace all the occurrences of 4th column wherever it is encountering E: with a blank space "", but wherever it finds a string after E:, that should remain as it is.  The expected output would be:  12,324,32342,E:fsdsf,23432,34534,45345,324  13,3224,342,E:werwefsdsf,23432,34534,45345,324  121,3244,33442,,23432,34534,45345,324


Is there any formula to find out the summation of the series.   $$\sum_{i=1}^{n} \lfloor \frac{n}{i} \rfloor$$ Can someone help me with this.

$$ \sum_{i=1}^N\left\lfloor\frac{N}{i}\right\rfloor $$ Is there a closed form expression to the above sum? (Mathematica doesn't give me anything)


I want to know why the following expression is evaluated to true.  var_dump(('a' == 0)); //bool(true)

What is the difference between == and ===?  How exactly does the loosely == comparison work? How exactly does the strict === comparison work?  What would be some useful examples?


Suppose that , $A$ and $B$ are $n\times n$ positive definite matrices and > $I$ be $n\times n$ identity matrix. Then which of the followings are positive definite ? (i) $A+B$ (ii) $ABA$ (iii) $A^2+I$ (iv) $AB$  I know the definition of positive definite as :  $\color{red}{A_{n\times n}}$ $\color{red}{\text{is positive definite if it's quadratic form}} $ $\color{red}{x^TAx>0}$ Since $A$ and $B$ are positive definite so, $x^TAx>0$ and $x^TBx>0$. Then, $x^T(A+B)x=x^TAx+x^TBx>0.$ So $A+B$ is positive definite. I am confused about the product.. I saw a lot of questions in this site about the product of positive definiteness. But the answer in those questions it is assume that the matrices are symmetric. For example see the answer of  question. I want to know whether the product of any two arbitrary positive definite matrices is positive definite or NOT with a valid proof or counter example....

Let, $A$ & $B$ are $n\times n$ positive definite matrices & $I$ be the $n\times n$ identity matrix. Then which of the followings are positive definite?  (a) $A+B$  (b) $ABA$  (c) $A^{2}+I$  (d) $AB$  I know that, $A^{2}+I$ is positive definite, as if $\lambda$ is an eigen value of $A$ then $(1+\lambda^2)$ is an eigen value of $A^2+I$.  I think (d) is true.Suppose, $\lambda_{1}$ & $\lambda_{2}$ be two eigen values of $A_{2\times 2}$ matrix & $\beta_{1}$, $\beta_{2}$ be two eigen values of $B_{2\times 2}$ matrix.  Now, $det(AB)=det(A)det(B)=\lambda_{1}.\lambda_{2}.\beta_{1}.\beta_{2}.$  As, $\lambda_{1},\lambda_{2},\beta_{1},\beta_{2}$ are all positive so eigen values of $AB$ are all positive, so $AB$ is positive definite.  Similarly, $ABA$ is positive definite.But I am not sure & I have no idea about $A+B$.


Quite probably a silly question, but if I have:  $a^{2} \equiv 1 \pmod n$, is this the same as $a \equiv 1 \pmod n$?

Next is what I have worked out to the moment.   $1$ and $-1$ are roots for all $n$.  $x \in \mathbb{Z}/n\mathbb{Z},\ $ $x^2\equiv1 \Leftrightarrow (x-1)(x+1)\equiv0 \Leftrightarrow \exists k \in \mathbb{Z}/n\mathbb{Z}: k(k+2)\equiv0 $. But how can it be applied to find other roots?


I'm trying to get whenever you hold an item (diamond sword) it will give you particles. I know how to do this but not when something has a custom name.  /scoreboard players set @a HoldSword 1 {SelectedItem:{id:"minecraft:diamond_sword"{display:{Name:"&4FadedSharp's Sword"}}   I don't know what is wrong with this code; can someone please help me?

Often, when making a command block contraption, you need to set an entity's data tag. These tags can sometimes be very long, with many layers of nested curly and square brackets. For example, this is the command to summon a villager with a single custom trade:  /summon Villager ~ ~ ~ {Profession:3,Career:2,Offers:{Recipes:[{buy:{id:minecraft:diamond,Count:6b}},sell:{id:minecraft:diamond_hoe,tag:{ench:[{id:16s,lvl:10s}]}]}}   The single-line command block interface of Minecraft makes it incredibly difficult to find and fix errors, especially when it comes to mismatched brackets. In fact, for illustration purposes, I put an error in the above command.  What techniques can I use to find and fix unbalanced square or curly brackets when writing long and complicated data tags?


Imagine a situation, that I've once read a question (and its answers) on a site. I would need the information again, so I try to find the question as I can (mainly, asking the search bar of the SE, and google queries with "site:X.stackexchange.com").  I can't find the question.  So, I ask intentionally the same, but this time in my formulation. I know that it will be likely closed as dupe, and from the dupe closure, I will find also the original question what I couldn't.  Of course I could also ask it ("Where is the question about...") on the meta, or on the chat. But, creating the dupe, I also make it easier for other readers in the future, to find the original question with regular search.  From the other side, asking questions intentionally for closure doesn't seem a very constructive thing.  So, which is the better option?

I know that according to , leaving existing duplicate questions is good for searchability. But what about intentionally asking a duplicate question with different terms?  made me think of that.


I am new to TeX family and I sincerely thank everyone for reading and replying this question. I know in LaTeX this can be done by "\pagestyle{empty}", but this does not work on original TeX. What is the solution? Thanks again.

I would like to change the page numbering from the default 1, 2, ... to the corresponding symbols in my native language. I have the fonts and typesetting ready and just want to replace the page numberings. How would I go about it ?


I have a Lenovo IdeaPad laptop that came with Windows 10.  It has 4 Gb RAM, which was plenty just a few years ago. But on this machine Windows 10 was pretty slow to start with. Adding a 16Gb flash drive dedicated to ReadyBoost helped matters somewhat.  But now, after half a year of use, it became very slow even with ReadyBoost - so slow even YouTube videos can stutter. I did install Avast which does not detect anything, so I don't think it's malware. It is probably the usual "Windows rot", which I am familiar with since Windows 9x and which requires a fresh reinstall. Yes, half a year is a bit too soon - Windows tended to last over a year until it rotted like that. Perhaps it's those huge updates...  Anyway - HOW can I do that fresh reinstall thing if no installation media came with the device?  An alternative would be installing Windows 7 and I even have some OEM packs, but I'm not sure I can find Windows 7 drivers for everything on the machine, including the touch screen, etc. Also, I wonder if Windows 7 will keep working in "tablet mode" which this thing has.  (Another alternative is Linux and it is seriously being considered but I am asking here so I can look at WIndows options. Also not sure about "tablet mode" on Linux).

If I get a new Win10 computer, filled with bloatware, can I reset the factory installed Windows and create the equivalent of a clean install, getting rid of all the flotsam and jetsam?


I have trouble making the Graph Drawing example on page 363 in the  Manual work.  To this end, I've read the question asked ealier,  but have not had any luck using the code suggested by user @JP-Ellis.  I'm getting the same error on my local install (MikTex 2.9 Fully updated, TexStudio 5.6.2) and on Overleaf.com  Here is my code example:  % !TeX program = lualatex \documentclass[tikz]{standalone} \usepackage{tikz} \usetikzlibrary{arrows} \usetikzlibrary{graphs} \usetikzlibrary{graphdrawing} \usegdlibrary{layered} \title{Tikz Graph Test} \begin{document} \tikz [nodes={text height=.7em,text depth=.2em,draw=black!20,thick,fill=white,font=\footnotesize},>=stealth',rounded corners,semithick] \graph [layered layout,level distance=1cm,sibling sep=0.5em,sibling distance=1cm] {"Femte" -> {"Sjette","Prise"};}; \end{document}    Here is the log from TexStudio () Here is the log from Overleaf ()   The main errors seem to be these:  ./main.tex:10: Undefined control sequence. \sa@placebox ->\newpage \global \pdfpagewidth                                                =\wd \sa@box \global \pdfpageh... l.10 ...tance=1cm] {"Femte" -> {"Sjette","Prise"};};   and this  ! You can't use a prefix with `the character ='. <to be read again> = l.10 ...tance=1cm] {"Femte" -> {"Sjette","Prise"};};

Since I installed TeXLive 2016 I cannot build documents with the standalone document class any more using LuaLaTeX (PDFLaTeX works fine). For example:  \documentclass{standalone} \begin{document} hi \end{document}   Gives me:  ! Undefined control sequence. \sa@placebox ->\newpage \global \pdfpagewidth                                                =\wd \sa@box \global \pdfpageh...  l.4 \end{document}   How to fix that?


During big sales or special deals, Steam changes its background images to those containing their own characters:    Who are these guys? What are their names? How can we be friends?

So with the Steam Summer Sale in full swing, I've finally taken notice of the Steam Mascots.  Judging by the latest background, the black one, at least, has a name: Cyl.  Do the other two have names as well? Are there only these three?   What's their story?


I am quite new to Java but I encountered the following error: Exception in thread "main" java.lang.NullPointerException: Cannot invoke "bussines.Plot$Rectangle.setRectangle(int, int)" because "java.util.ArrayList.get(int).rectangle" is null at bussines.Owner.buyRectangle(Owner.java:24) at construction.Application.run(Application.java:17) at construction.Application.main(Application.java:36) I will insert bellow the relevant code snippet: public class Plot {     Rectangle rectangle;     Square square;          public class Rectangle     {         public int length;         public int width;     }                  public Rectangle()          {             length = 0;             width = 0;         }                  public void setRectangle(int l, int w)          {             length = l;             width = w;         }                  public int getArea()          {             return length * width;         }     }          public class Square     {         public int size;                  public Square()          {             size = 0;         }                  public void setSquare(int s)          {             size = s;         }                  public int getArea()          {             return size * size;         }     } }  public class Owner {          public String name;     public ArrayList<Plot> landPlots;          public Owner(String n)     {         name = n;         landPlots = new ArrayList<Plot>();     }          public void buySquare(int lastUpdate, int size)      {         landPlots.add(new Plot());         landPlots.get(lastUpdate).square.setSquare(size);     }          public void buyRectangle(int lastUpdate, int l, int w)      {         landPlots.add(new Plot());         landPlots.get(0).rectangle.setRectangle(l, w);     } }  public class Application  {     private Owner owner;     private int lastUpdate;          public Application()      {         owner = new Owner("Matei");         lastUpdate = -1;     }          public void run()      {         System.out.println("Buying four plots.");                  owner.buyRectangle(0, 4, 2);         owner.buySquare(1, 5);         owner.buyRectangle(2, 2, 2);         owner.buySquare(3, 4);                  System.out.println("Compute total area.");         System.out.print(owner.getTotalArea());                  System.out.println("Selling two plots.");         owner.sellPlot(0);         owner.sellPlot(1);                  System.out.println("Compute total area.");         System.out.print(owner.getTotalArea());              } }

What are Null Pointer Exceptions (java.lang.NullPointerException) and what causes them?  What methods/tools can be used to determine the cause so that you stop the exception from causing the program to terminate prematurely?


In Delphi (or any Pascal) you can declare sub-range type so if you try assign value from outside allowed range, you would get compiler error.  var     i: 1..8; begin     i := 8; // i := 9 would not work   Can this be done in C#? I can imagine creating custom struct, something like SubrangeType<byte> but I'm looking for something builtin.  EDIT: xanatos's and DavidHeffernan's comments gave me idea for more specific question. Subrange checking in Delphi is available both in run-time and compile-time.  Implementing that on run-time would be possible in C# using custom struct but would it be possible to implement that checking on compile-time in C#?

,  and many other languages support ranges, a way to subtype integers. A range is a signed integer value which ranges from a value (first) to another (last). It's easy to implement a class that does the same in OOP but I think that supporting the feature natively could let the compiler to do additional static checks.  I know that it's impossible to verify statically that a variabile defined in a range is not going to "overflow" runtime, i.e. due to bad input, but I think that something could be done. I think about the  approach (Eiffel) and the Spec# (  ), that give a more general solution.  Is there a simpler solution that checks, at least, static out-of-bound assignment at compile time in C++, C# and Java? Some kind of ?  edit: I understand that "ranges" can be used for different purpose:   iterators enumerators integer subtype   I would focus on the latter, because the formers are easily mappable on C* language . I think about a closed set of values, something like the music volume, i.e. a range that goes from 1 up to 100. I would like to increment or decrement it by a value. I would like to have a compile error in case of static overflow, something like:  volume=rangeInt(0,100); volume=101;  // compile error! volume=getIntFromInput(); // possible runtime exception   Thanks.


What is difference between return and exit statement in C programming when called from anywhere in a C program?

Should I use exit() or just return statements in main()? Personally I favor the return statements because I feel it's like reading any other function and the flow control when I'm reading the code is smooth (in my opinion). And even if I want to refactor the main() function, having return seems like a better choice than exit().  Does exit() do anything special that return doesn't?


Can you please spot the error? I am getting 'null' in the System.debug. However, Account has some value in 'Type' field.    trigger UpdateAccountType on Contact (after insert) {         for(Contact con: Trigger.new){             System.debug('Account Type' + ' ' + con.Account.Type);          }      }

Financial Account is a child of Client in a Master-Detail relationship. The client (John Sandbox) has a Wealth Advisor, 'John Smith', on his client record, however, the system debug that pulls finAcct.client__r.Wealth_Advisor__c shows this field as 'null'.  Does anyone have any idea why I am not getting the value in this field? The goal of this trigger is to make sure that the lookup fields for the Client Team (one of which is 'Wealth Advisor') always match between the client record and the financial account record when they are linked. Thanks!      Boolean UpdateMe;     List <Financial_Account__c> FinAcctsToUpdate = new List<Financial_Account__c>();      //Loop through all Financial Accounts in Trigger.new     for(Financial_Account__c finAcct : newFinAccts){         UpdateMe = false;          System.debug('finAcct WA Lookup: ' + finAcct.Wealth_Advisor_Lookup__c);         System.debug('Client: ' + finAcct.client__c);         System.debug('Acct WA: ' + finAcct.client__r.Wealth_Advisor__c);          if (finAcct.Wealth_Advisor_Lookup__c != finAcct.client__r.Wealth_Advisor__c){             finAcct.Wealth_Advisor_Lookup__c = finAcct.client__r.Wealth_Advisor__c;             UpdateMe = true;         }         if(UpdateMe == true){             FinAcctsToUpdate.add(finAcct);         }         UpdateMe = false;     }      if(FinAcctsToUpdate.size() > 0 ){         update FinAcctsToUpdate;     }


Given a generic class definition BaseClass<T>, is it possible to test this condition?  if (myvar is BaseClass<>)  I would like to know if myvar derives from the generic class, but I do not know (or care) what T might be.  I assume the answer is no... my backup plan is to caveman this via myvar.GetType().ToString().Contains("BaseClass<"), or something.

I have a generic class in my project with derived classes.  public class GenericClass<T> : GenericInterface<T> { }  public class Test : GenericClass<SomeType> { }   Is there any way to find out if a Type object is derived from GenericClass?  t.IsSubclassOf(typeof(GenericClass<>))   does not work.