How does depth and width in neural networks affect the performance of the network?   For example,  introduced very deep residual networks and claimed “We obtain [compelling accuracy] via a simple but essential concept— going deeper.”  On the other hand  argues that wide residual networks “are far superior over their commonly used thin and very deep counterparts.”  Can someone summarise the current (theoretical) understanding in deep learning about the effects of width and depth in deep neural networks?

I haven't seen the question stated precisely in these terms, and this is why I make a new question.  What I am interested in knowing is not the definition of a neural network, but understanding the actual difference with a deep neural network.  For more context: I know what a neural network is and how backpropagation works. I know that a DNN must have multiple hidden layers. However, 10 years ago in class I learned that having several layers or one layer (not counting the input and output layers) was equivalent in terms of the functions a neural network is able to represent (see Cybenko's ), and that having more layers made it more complex to analyse without gain in performance. Obviously, that is not the case anymore.  I suppose, maybe wrongly, that the differences are in terms of training algorithm and properties rather than structure, and therefore I would really appreciate if the answer could underline the reasons that made the move to DNN possible (e.g. mathematical proof or randomly playing with networks?) and desirable (e.g. speed of convergence?)


Two balls, with masses $m_1$ and $m_2$ are falling from the heigh $h$. All the collisions are perfectly elastic. Do not consider the size of the balls. $m_1 < m_2$ and lighter ball is on the top.    What heights $h_1$ and $h_2$ will the balls jump to?     And so I have many equation like: $V(-m_1+m_2)=m_1v_1+m_2v_2$, $(m_1+m_2)gh=m_1gh_1+m_2gh_2$ and $\frac12 V^2(m_1+m_2)= \frac12 m_1 v_1^2 + \frac12 m_2 v_2^2$ (Where $V$ is velocity of both balls right before collision. I consider lighter ball is falling down the same velocity as heavier ball is flying up, so I put opposite sign in the equation of momentum. $v_1$ is a velocity of lighter ball after collision and $v_2$ velocity of heavier ball). But I have no idea how to get $h_1$ and $h_2$ independent of each other.  Please don't describe me "you have to do this and this" and "think about what happen when...". I need to see the progress. I need to see these equations and what's happening.

Two balls, first with the mass $m_1$ and the second with the mass $m_2$ are falling from the heigh $h$. Suppose all the collisions are perfectly elastic and do not consider the size of the balls. $m_1 < m_2$ and ball with the mass $m_1$ is on the top.    What height $h_1$ will the ball with the mass $m_1$ jump to and what height $h_2$ will the ball with the mass $m_1$ jump to?     I think equations as $(m_1+m_2)gh=m_1gh_1+m_2gh_2$ and $(m_1+m_2)v=m_1v_1+m_2v_2$, where $v$ is the velocity of both balls falling, are correct, but I have no idea how to get $h_1$ and $h_2$ independent of each other.  It seems to me, like here is some common operation or relation, that I just don't know, that I have never seen or don't remember... Please don't describe me "you have to do this and this" and "think about what happen when...". I need to see the progress. I need to see these equations and what's happening.


I am using Roman Numerals for the contents page however this is clashing with the section title as shown in the image. Is it possible to increase the spacing between these two?  Many thanks in advance.

There is a problem with the alignment of the numbering of the ToC: When we use   \renewcommand{\thesection}{\Roman{section}}   the numbers encroach on the titles. When the command is commented out, the numbers are all aligned [from the first number on the left] but the titles do not begin at the same position.  What I want is to use \Roman{section} but with the numbers being displaced after V (or 9 in arabic) so that the first letters of the  titles are all aligned !  An illustration:  %\RequirePackage{fix-cm} \documentclass[a4paper, 11pt, twoside]{article}  \renewcommand{\thesection}{\Roman{section}}  \begin{document}   \tableofcontents \normalfont %\cleardoublepage  \section{QWERTY} \section{QWERTY} \section{QWERTY} \section{QWERTY} \section{QWERTY} \section{QWERTY} \section{QWERTY} \section{QWERTY} \section{QWERTY} \section{QWERTY} \section{QWERTY} \section{QWERTY} \section{QWERTY} \section{QWERTY} \section{QWERTY} \section{QWERTY} \section{QWERTY} \section{QWERTY} \section{QWERTY} \section{QWERTY} \section{QWERTY} \section{QWERTY} \section{QWERTY} \section{QWERTY} \section{QWERTY} \section{QWERTY} \section{QWERTY} \section{QWERTY} \section{QWERTY} \section{QWERTY} \section{QWERTY} \section{QWERTY} \section{QWERTY} \section{QWERTY} \section{QWERTY} \section{QWERTY} \section{QWERTY} \section{QWERTY} \section{QWERTY} \section{QWERTY} \section{QWERTY} \section{QWERTY} \section{QWERTY} \section{QWERTY} \section{QWERTY} \section{QWERTY} \section{QWERTY} \section{QWERTY} \section{QWERTY} \section{QWERTY} \section{QWERTY} \section{QWERTY} \section{QWERTY} \section{QWERTY}  \end{document}


I have some strange titles when I get comment notifications for my nomination on [SO] there stands something like "6|rekire" in the title. I guess that comes from the 6 in the URL   I'm pretty sure that this does not happen often however this is a small bug :-)  Edit: The "dublicated" question  is about links in the web. I'm talking about the app. So that question is related, but not a dublicate at all.

In the responses tab in my profile, responses to comments on nomination posts include a working link in the page source, but because there's no title the links are empty and useless.    When listed in the inbox such posts do have a title, though in this case the link is to the post and not directly to the comment. (Actually, the links in responses end up being redirected and also go to the post and not to the comment, but they try to go to the comment.)  In Supercollider:    In Global Profile:


Show that if $A$, $B$, and $A + B$ are invertible matrices with the same size, then $$A(A^{-1} + B^{-1})B(A + B)^{-1} = I$$ What does the result in part $1$ tell you about the matrix $A^{-1} + B^{-1}$?   Ok I never came across any identities that would allow me to cancel these values out in the book so far... So I have no idea how I'm supposed to "show" that they are equal... So how do I solve/show this?  Note: for those who say this is a duplicate, read both questions again, this question asks how to solve the first part, the other question asks and only answers how to solve the second part. the first part isn,t explained in the other question, only the second part.

Show that if $A$, $B$, and $A + B$ are invertible matrices with the same size, then   $A(A^{-1}+B^{-1})B(A+B)^{-1}=I$      What does the result in the first part tell you about the matrix $(A^{-1}+B^{-1})$?   I get the first part. Help me with the second part.


I am trying to fetch the RecordType.Name in a list, but my list doesn't has the value displayed. Please find below the block of code and the list 'clist' where I need the RecordType.Name This is in a test class. Id RecordTypeIdCase = Schema.SObjectType.case.getRecordTypeInfosByName().get('Core eG@r Case RecType').getRecordTypeId(); case cs = new case (Type='Warranty Support',EmailContactDealer__c='test@gmail.com', Origin='RENAULT SITE', AccountId=Acc.Id, ContactId=Acc.PersoncontactId, Status='New', Description='Trigger test clas', CountryCase__c='Argentina',RecordTypeid = RecordTypeIdCase); insert cs; List<RecordType> RTList = [SELECT Id, Name,DeveloperName FROM RecordType WHERE Id = :RecordTypeIdCase];             System.debug('$&$&$& RecordType RT:' + RTList);             System.debug('$&$&$& Case ID:' + cs.Id);             System.debug('$&$&$& Case RTID:' + cs.RecordTypeid);             System.debug('$&$&$& Case RT:' + cs.RecordType.DeveloperName);              List<Case> cList = [SELECT Id,Type,RecordTypeid,RecordType.Name FROM Case WHERE Type = 'Warranty Support' AND RecordType.Name = 'Core eG@r Case RecType']; System.assertEquals(cList.size(), 1);

This is a canonical question and answer developed by the community to help address common questions. If you've been directed here, or your question has been closed as a duplicate, please look through the resources here and use them to shape more specific questions. To browse all canonical questions and answers, navigate to the  tag. This question and answer is owned by the community! If you can improve it and make it more useful, you're welcome to edit it. I am building a trigger, a unit test, or other Apex code. I'm working with sObject records, and trying to access related record information. For example, I might have a structure like this: Account a = new Account(Name = 'Test'); insert a;  Opportunity o = new Opportunity(Name = 'Donation', AccountId = a.Id); insert o;  System.assertEquals(o.Account.Name, 'Test', 'Correct Account associated'); // Assertion fails!  Or, in a trigger, I might be aiming for something like this: trigger ContactTrigger on Contact (after insert) {     for (Contact c : Trigger.new) {         if (c.Account.Name == 'Test') {             // Take some action here         }      } }  Why doesn't this work? Why am I getting null values, or NullPointerExceptions?


Right now the interaction is that when you click the small "i" icon next to a questions, additional text displays for clarification. (Shown in the example "Carrying anything that makes it heavier?")  My questions are: - Is it better to use "i" or "?" for this icon?   Is it ok to have the help content appear inline like this or is it better to have it in a tooltip box? I like it this way because it doesn't cover the existing content and it doesn't have to be closed out to continue. In material design how would you do this type of tooltip? The only documentation I can find  and it's not quite the same scenario.

We're debating inside our team on whether to use a question mark icon, or an "i" icon for prompting a tooltip that reveals more info.  Which do you say conveys the message better? Or, how do they differ in the message they convey?


so i installed ubuntu 14.04 on a windows 8 pre-installed hp laptop.  the problem is when i boot the computer it takes me straight to windows and NO grub is shown.  i tried following this:  and used boot-repair which threw this error    i am completely lost with this eufi stuff, can someone help me with an easy solution to have grub working on this laptop where i can choose Ubuntu or windows 8?  PS: i cant seem to get this working on my hp. i disabled fast startup and secure boot and ran bcdedit /set {bootmgr} path \EFI\ubuntu\grubx64.efi and still no Grub :(  the solution that this question was marked as duplicate is not working for me

Ok, so I'm such a newbie to Ubuntu and I bought a Windows 8 pre-installed laptop last month.  I updated to Windows 8.1 and then I thought about installing Ubuntu as a dual boot so I could mess around and learn more about it.   So I followed a Youtube tutorial (  ) and I got my stuff working fine.   The first few times I booted I got the GRUB menu instead of my default HP Boot OS Manager, and I was able to select my OS.   So I went to sleep and the next day I turned on my computer and the GRUB menu did not show up. I tried several times and it didn't automatically show up.  In order for me to see the GRUB menu I had to turn on my PC and on start had to press ESC to pause startup and press F9 to get boot options. Then from there I had to pick from OS Boot, Ubuntu, Ubuntu (Yes there were two Ubuntus available) and a default EFI file thingy.   When I click the first Ubuntu I get the GRUB Menu (I was too scared to try the second in case I screwed my laptop up) and I can safely load Ubuntu from there and use it (although I do have to increase my brightness every time I load Ubuntu because it somehow reduces my brightness to complete darkness on boot)  So my problem here is why isn't my GRUB showing on boot, after it worked on the first day?   My laptop is a HP TouchSmart j-078CA.  EDIT 1: FYI I just switched to Ubuntu LiveCD to check my Installation and found out that one of my partition is flagged as msftres. Here is a screenshot of my GParted on a LiveCD:


I am going to Poland (Delhi-Frankfurt-Warsaw) with Polish National Visa. Do I need Transit visa for layover in Frankfurt?

I found many related questions on this site but I am still not sure about the rules. How can I decide if I need a visa to transit? Schengen members as of May 2021 are as follows:  Austria Belgium Czech Republic Denmark (excluding Greenland and the Faroe Islands - but an open border with the Schengen Area is maintained) Estonia Finland France (excluding overseas departments and collectivities) Germany Greece Hungary Iceland Italy Latvia Liechtenstein Lithuania Luxembourg Malta Netherlands (excluding Aruba, Curaçao, Sint Maarten and the Caribbean Netherlands) Norway (excluding Svalbard) Poland Portugal Slovakia Slovenia Spain (except Ceuta and Melilla) Sweden Switzerland


I notice a lot of questions tagged VMware should be migrated to ServerFault, but the option is not available as you can see in the picture below.  Is there a way to pick what options show up here?

Currently, there is a 40% (updated Nov 9, 2012) rejection rate on migrations from Stack Overflow to Server Fault.  Here are some samples of rejected questions from the last few days:   .     The first example is from 2009 and already had an accepted answer (in addition to being bad and off-topic on SF). There was no reason to migrate it. The second two, while seemingly on-topic for SF based on the title, are borderline unintelligible in regards to the content. They contained no details, no relevant information, and amount to "Halp! Halp! Itz broked!"  I realize that there is a much larger number of users on Stack Overflow that are capable of voting to migrate and as a result, it takes 4/5 votes to migrate, while every other site is 3/5. This, unfortunately, does not appear to be an effective solution.  Questions should not be migrated based on their title, they should be judged on their content and topicality on the target site. This, obviously, is not happening as there is a 40% rejection rate on Server Fault.  What can we do to further educate Stack Overflow users about what is and is not on-topic elsewhere? Should SO have a higher reputation threshold than the other sites for vote-to-migrate privs? Should a migration require 5/5 votes instead of the current 4/5?


whenever i try to access my drive this appears and i can't access my drive. I am using 15.04 alongside windows 8.1    Error mounting /dev/sda2 at /media/sharif/EEE: Command-line `mount -t "ntfs" -o "uhelper=udisks2,nodev,nosuid,uid=1000,gid=1000" "/dev/sda2" "/media/sharif/EEE"' exited with non-zero exit status 14: The disk contains an unclean file system (0, 0). Metadata kept in Windows cache, refused to mount. Failed to mount '/dev/sda2': Operation not permitted The NTFS partition is in an unsafe state. Please resume and shutdown Windows fully (no hibernation or fast restarting), or mount the volume read-only with the 'ro' mount option.

Whenever I boot Ubuntu, I get a message that it cannot mount my windows partition, and I can choose to either wait, skip or manually mount.  When I try to enter my Windows partition through Nautilus I get a message saying that this partition is hibernated and that I need to enter the file system and properly close it, something I have done with no problem so I don't know why this happens.    Here's my partition table, if any more data is needed please let me know.     Device Boot      Start         End      Blocks   Id  System /dev/sda1            2048    20000767     9999360   83  Linux /dev/sda2        20002814   478001151   228999169    5  Extended /dev/sda3   *   478001152   622532607    72265728    7  HPFS/NTFS/exFAT /dev/sda4       622532608   625141759     1304576   82  Linux swap / Solaris /dev/sda5        20002816   478001151   228999168   83  Linux


I am creating a chrome extension that exposes extra APIs to websites. Before these APIs can be used by websites, I want to show a warning if the website was served over HTTP and not HTTPS. This is because these APIs reduce the web sandbox and could be more dangerous if the JavaScript source from the website is not verified to have come from the correct party.  Is there a reliable method I can use to check if a website was served over HTTPS? Maybe a chrome extension API (for example inside a content script)?  Checking location.protocol seems to be potentially inaccurate in case of problems with the certificate:

Is it possible to detect, on the client side, whether the user is using an encrypted page or not?  Put another way -- I want to know if the URL of the current page starts with http or https.


I would like to clear find history in WinSCP as shown in the following picture:  Hope you can help in this Thanks in advance

I would like to know how to clear recent created file names that appearing in the dialogue box when creating a new file:  I tried a lot without success


I have a little problem. I'm reading files from directory and it works, but it read two extra files on the beginning ...what is it?  for example, there is a list of files: "A348", "A348A", "A348B" and this is what i get: ".", "..", "A348", "A348A", "A348B"  ???  DIR *dir; struct dirent *dp; char * file_name; while ((dp=readdir(dir)) != NULL) {          file_name = dp->d_name;             }

Whenever I list the contents of a directory with a function like readdir, the returned file names also include "." and "..". I have the suspicion that these are just normal links in the file system and therefore indistinguishable from actual files, but I always have to filter them out because they are not actual objects in the directory I am listing. Is there a good reason for functions like readdir to include them? Do some operating systems or file systems contain more or different virtual file names? Is there a better way to filter them out other than by doing string comparison with "." and ".."?  Update: thank you all for answering. I suppose I always thought that things like ./ and ../ were mere conventions that could be handled by searching and replacing. I find it a bit surprising, though probably more efficient and transparent, to have them be part of the file system itself.  One question remains, though: since . and .. are arbitrary names for these links, are there file systems that use different ones?


So recently I noticed that, around the windows, and the right click menu of all applications, there are these weird colored stripes. They disappear after I restart Ubuntu or Unity, but then appear again shortly after.    My laptop used NVIDIA GeForce 960M, and for those who knows, I just started CUDA programming a few weeks ago.  These are the installed packages related to nvidia:  quan@quantran:~$ sudo apt list --installed | grep nvidia  WARNING: apt does not have a stable CLI interface. Use with caution in scripts.  nvidia-367/xenial,now 375.39-0ubuntu0~gpu16.04.2 amd64 [installed] nvidia-367-dev/xenial,now 375.39-0ubuntu0~gpu16.04.2 amd64 [installed,automatic] nvidia-375/xenial,now 375.39-0ubuntu0~gpu16.04.2 amd64 [installed,automatic] nvidia-375-dev/xenial,now 375.39-0ubuntu0~gpu16.04.2 amd64 [installed,automatic] nvidia-cuda-dev/xenial,now 7.5.18-0ubuntu1 amd64 [installed,automatic] nvidia-cuda-doc/xenial,xenial,now 7.5.18-0ubuntu1 all [installed,automatic] nvidia-cuda-gdb/xenial,now 7.5.18-0ubuntu1 amd64 [installed,automatic] nvidia-cuda-toolkit/xenial,now 7.5.18-0ubuntu1 amd64 [installed] nvidia-modprobe/unknown,now 367.48-0ubuntu1 amd64 [installed,automatic] nvidia-opencl-dev/xenial,now 7.5.18-0ubuntu1 amd64 [installed,automatic] nvidia-opencl-icd-367/xenial,now 375.39-0ubuntu0~gpu16.04.2 amd64 [installed,automatic] nvidia-opencl-icd-375/xenial,now 375.39-0ubuntu0~gpu16.04.2 amd64 [installed,automatic] nvidia-prime/xenial,now 0.8.2 amd64 [installed,automatic] nvidia-profiler/xenial,now 7.5.18-0ubuntu1 amd64 [installed,automatic] nvidia-settings/xenial,now 378.09-0ubuntu0~gpu16.04.1 amd64 [installed,automatic] nvidia-visual-profiler/xenial,now 7.5.18-0ubuntu1 amd64 [installed,automatic]   Result of lspci:  quan@quantran:~$ lspci 00:00.0 Host bridge: Intel Corporation Xeon E3-1200 v3/4th Gen Core Processor DRAM Controller (rev 06) 00:01.0 PCI bridge: Intel Corporation Xeon E3-1200 v3/4th Gen Core Processor PCI Express x16 Controller (rev 06) 00:02.0 VGA compatible controller: Intel Corporation 4th Gen Core Processor Integrated Graphics Controller (rev 06) 00:03.0 Audio device: Intel Corporation Xeon E3-1200 v3/4th Gen Core Processor HD Audio Controller (rev 06) 00:14.0 USB controller: Intel Corporation 8 Series/C220 Series Chipset Family USB xHCI (rev 05) 00:16.0 Communication controller: Intel Corporation 8 Series/C220 Series Chipset Family MEI Controller #1 (rev 04) 00:1a.0 USB controller: Intel Corporation 8 Series/C220 Series Chipset Family USB EHCI #2 (rev 05) 00:1b.0 Audio device: Intel Corporation 8 Series/C220 Series Chipset High Definition Audio Controller (rev 05) 00:1c.0 PCI bridge: Intel Corporation 8 Series/C220 Series Chipset Family PCI Express Root Port #1 (rev d5) 00:1c.1 PCI bridge: Intel Corporation 8 Series/C220 Series Chipset Family PCI Express Root Port #2 (rev d5) 00:1c.2 PCI bridge: Intel Corporation 8 Series/C220 Series Chipset Family PCI Express Root Port #3 (rev d5) 00:1c.3 PCI bridge: Intel Corporation 8 Series/C220 Series Chipset Family PCI Express Root Port #4 (rev d5) 00:1d.0 USB controller: Intel Corporation 8 Series/C220 Series Chipset Family USB EHCI #1 (rev 05) 00:1f.0 ISA bridge: Intel Corporation HM86 Express LPC Controller (rev 05) 00:1f.2 SATA controller: Intel Corporation 8 Series/C220 Series Chipset Family 6-port SATA Controller 1 [AHCI mode] (rev 05) 00:1f.3 SMBus: Intel Corporation 8 Series/C220 Series Chipset Family SMBus Controller (rev 05) 01:00.0 3D controller: NVIDIA Corporation GM107M [GeForce GTX 960M] (rev a2) 04:00.0 Network controller: Intel Corporation Wireless 7260 (rev bb) 05:00.0 Unassigned class [ff00]: Realtek Semiconductor Co., Ltd. Device 5287 (rev 01) 05:00.1 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller (rev 12)   Thanks everyone in advance!

Everyday I check for updates on Ubuntu 16.04 LTS. I updated to 4.4.0-65-generic today and now on everything I'm getting thick rainbow coloured lines around every dialog box in every program. My setup is pretty standard. Skylake i5-6500, Nvidia 950gtx. Does anyone know how to fix it?


I want to install oracle 11g Release 2 Enterprise Edition on Ubuntu 18.04. How do I install that? the question is not about express edition since the installation is different than entreprise edition so it's not a duplicate question.

I need a Step By Step guide for Installing Oracle Database Express Edition version 11g Release R2 on Ubuntu Desktop 12.04.1 LTS 64 bit Edition


Back in AD&D, a spell scroll was created by basically casting a spell onto a specially prepared scroll. The next person to read said scroll was able to cast the spell exactly as the original creator.  I don't think that's how it works in 5e. In fact, I thought I'd read somewhere that only a member of a spell casting class that's able to use the spell inscribed on a spell scroll is able to use that scroll. But I can't for the life of me find where this is written!!  So, who is able to cast a spell from a spell scroll?

I'm confused about who can use scrolls in 5e. In the DMG, p139 under Magic Item Categories: Scrolls, it states that:     Any creature that can understand a written language can read the   arcane script on a scroll and attempt to activate it.   This implies that anyone can try to cast a spell using a scroll. However, on p.200 in the Spell Scroll entry it states that:     If the spell is on your class's spell list, you can use an action to read the scroll and cast its spell without having to provide any of the spell's components. Otherwise, the scroll is unintelligible.   Then there is the bit about a DC 10 + scroll spell level ability check if the spell is higher than a spell slot that you can cast.     If the spell is on your class's spell list but of a higher level than you can normally cast, you must make an ability check using your spellcasting ability to determine whether you cast it successfully. The DC equals 10 + spell's level. On a failed check, the spell disappears from the scroll with no other effect.    So, which is it? Can anyone who can read a language use a scroll (like a fighter) if they make an arcana check, or just a PC with that specific spell in their spell list (only spell casters)?


I have a catalog I am experimenting with that has some spectroscopic red shift data available (in the range from 0.5-1) as well as total Ks (K -short band) flux data available, how would I go about obtaining distance measures from Earth in parsecs or some other conventional units. Mainly I would need to know the method/formula for converting these values. Thanks!

I am looking for a exact derivation of a relation between redshift $z$ and distance $d$.  What I know is the definition $$z=\frac{\lambda_{\text{observed}}}{\lambda_{\text{unshifted}}}-1=\sqrt{\frac{1+\frac{v}{c}}{1-\frac{v}{c}}}-1$$ and that the Hubble constant $H$ as a function of $z$ is: $$H^2=H_0^2\left(\Omega_m\left(1+z\right)^3+\Omega_{\Lambda}\right)$$  How can I use this to derive the distance?


I would like to find a formula for $$f(x) = \prod_{n=0}^{\infty} (1 + x^n)$$ $$g(x) = \prod_{n=0}^{\infty} (1 - x^n)$$ In particular, $f(1/4)$ appears as the normalization factor for the CORDIC, the coefficients of $f(x)$ gives, coefficient gives the number of partitions of n into distinct parts; number of partitions of n into odd parts.. I only know that that these functions can be expressed in terms of q-Pochhammer symbol. Are there closed forms for $f(x)$ and $g(x)$ in terms of common functions. In particular, can $f(1/4)$ be expressed in a closed form? Are there general any solutions for the finite products that could have some advantage compared to this definition?

I am trying to find a simplified formula for the following products: $(a^0+1)\cdot(a^1+1)\cdot(a^2+1)\cdot...\cdot(a^n+1)$ but it seems quite difficult to figure out. Just wondering if anyone know how to do this.


I quoted a few pages of a book, pages 20-23， I use JabRef reference manager，How can I display the referenced page？

I have a little problem. I am using the abntex2 package in my document, and I am using bibtex to make the bibliography. When I use, for instance, \cite{reis}, that gives me the name of the author and the year his article was published. In this case, (REIS, 2013.) However, I need the page in which the citation was found to be between those parenthesis as well. Is there any way I could keep using the \cite{} command and have the page appear in the document as well?


Prove or find a counterexample: The product of any three consecutive natural numbers is divisible by 6.  Answer  Let n=1,             Since xeN is arbitrary p(N) holds for all xeN.  (n).(n+1).(n+2),  (1).(1+1).(1+2)= 6  Thus,6|6

I'm new to number theory and was wondering if someone could help me with this proof.  Prove: The product of any three consecutive integers is divisible by $6$.   So far I have $\cfrac{x(x+1)(x+2)}{6}$; How would I go about proving this? Should I replace $x$ with $k$ and then $k$ with $k+1$ and see if the statement is true?


I'm using the Schedule timer    But, when working with the listview I received the error below:  Cross-thread operation not valid: Control 'lsViewIm' accessed from a thread other than the thread it was created on.  Here's my code: This is for my button to execute the timer:  delegate void TickHandler(string Profile); private void btnStart_Click(object sender, EventArgs e) {     Configuration config = ConfigurationManager.OpenExeConfiguration(Application.ExecutablePath);        if(ConfigurationManager.AppSettings.AllKeys.Contains("Stock-Enable"))     {         if (config.AppSettings.Settings["Stock-Enable"].Value.ToString() == "Y")         {             main.oWriteText(lsViewIm, "Reading... " + DateTime.Now.ToString(), Color.Black, false, "logs");               IScheduledItem Item = GetSchedStock();             _AlarmTimer.Stop();             _AlarmTimer.ClearJobs();             _AlarmTimer.AddJob(Item, new TickHandler(updateStocks), "Woo1");             _AlarmTimer.Start();         }     } }  private ScheduleTimer _AlarmTimer = new ScheduleTimer(); private IScheduledItem GetSchedStock() {     return new ScheduledTime("ByMinute", "1");  }   This code will show details to ListView:  public void oWriteText(ListView lsView, string txt, Color? oColor = null, Boolean isStored = false, string oFile = "logs") {     ListViewItem addItem = lsView.Items.Add(txt);     lsView.EnsureVisible(lsView.Items.Count - 1);     addItem.SubItems[0].ForeColor = oColor ?? Color.Black;     lsView.Refresh();  }   And this is my method, and will put here the rest of the code here.  public void updateStocks(string Profile) {     oWriteText(lsViewIm, DateTime.Now.ToString(), Color.Black, false, "logs");     return; }

I have a scenario. (Windows Forms, C#, .NET)   There is a main form which hosts some user control. The user control does some heavy data operation, such that if I directly call the UserControl_Load method the UI become nonresponsive for the duration for load method execution. To overcome this I load data on different thread (trying to change existing code as little as I can)   I used a background worker thread which will be loading the data and when done will notify the application that it has done its work.   Now came a real problem. All the UI (main form and its child usercontrols) was created on the primary main thread. In the LOAD method of the usercontrol I'm fetching data based on the values of some control (like textbox) on userControl.    The pseudocode would look like this:  CODE 1  UserContrl1_LoadDataMethod() {     if (textbox1.text == "MyName") // This gives exception     {         //Load data corresponding to "MyName".         //Populate a globale variable List<string> which will be binded to grid at some later stage.     } }   The Exception it gave was     Cross-thread operation not valid: Control accessed from a thread other than the thread it was created on.   To know more about this I did some googling and a suggestion came up like using the following code  CODE 2  UserContrl1_LoadDataMethod() {     if (InvokeRequired) // Line #1     {         this.Invoke(new MethodInvoker(UserContrl1_LoadDataMethod));         return;     }      if (textbox1.text == "MyName") // Now it wont give an exception     {     //Load data correspondin to "MyName"         //Populate a globale variable List<string> which will be binded to grid at some later stage     } }   BUT BUT BUT... it seems I'm back to square one. The Application again  become nonresponsive. It seems to be due to the execution of line #1 if condition. The loading task is again done by the parent thread and not the third that I spawned.  I don't know whether I perceived this right or wrong. I'm new to threading.  How do I resolve this and also what is the effect of execution of Line#1 if block?  The situation is this: I want to load data into a global variable based on the value of a control. I don't want to change the value of a control from the child thread. I'm not going to do it ever from a child thread.   So only accessing the value so that the corresponding data can be fetched from the database.


Writing backticks within backticks works differently in posts and in comments. For example:  Use `` `backticks` `` instead of bold text for code-like terms.   In posts, this is rendered as the text "backticks" surrounded by backticks in <code>.  In comments, this is rendered as 2 backticks in normal style, followed by the text "backticks" in <code>, follewed by 2 backticks in normal style.  It would be better if markdown behaved consistently everywhere.  Please don't jump quickly to mark this as duplicate. The similar posts I found are about escaping backticks using backslash, but this case is not using backslash at all.

In comments, mini-Markdown sometimes has a different syntax for backticks within backticks: when the code starts and/or ends with a backtick, one needs escaping. In those cases, could mini-Markdown also support adding one space to the delimiters, just like Markdown does?  Markdown:   Use any unique number of backticks in the delimiter to allow for (other sequences of) backticks in the code itself: ```code with `embedded```` backticks``` yields code with `embedded```` backticks. Add one additional space to the delimiters above if the code fragment starts and/or ends with backticks, : `` `code with `embedded```` backticks` `` and Perl's `` $` `` yield `code with `embedded```` backticks` and Perl's $`.   Mini-Markdown (for comments):    as in Markdown†. The Markdown extra-space . Instead, this  single opening and closing backticks, and escaping of all embedded backticks: `\`code with \`embedded\`\`\`\` backticks\`` and `$\``.   I realize that the current escaping should always be supported to preserve the existing comments. But maybe mini-Markdown could also support the extra space.  † One could also escape, like `code with \`embedded\`\` backticks`, which however does not work in Markdown. Until today, I thought this escaping was required in comments. But today I realized that Markdown and mini-Markdown behave almost the same.


I am working on a wpf application which performs few operations. I was working on C++ application few days before and now their is a requirement to implement the same in my wpf app.  In my c++ code I had written the following:  m_texti2cRead->clear();  unsigned char buffer[512]; int address = m_texteditAddress->getText().getHexValue32(); m_msp430->SetAddress(address); if(m_msp430->ReadBytes(m_dataSize, buffer) == 1 ) {    //Display    String output = String::toHexString(buffer, m_dataSize);    m_texti2cRead->setText(output); }   I implemented the same in my Wpf App as follows:  ReadMessage = string.Empty; Byte[] buffer = new Byte[512]; int address; int m_DataSize = 1;  string strValue = AddressMessage; if (strValue.StartsWith("0x")) {      strValue = strValue.Remove(0, 2);      address = Convert.ToInt32(strValue);      mComm.setAddress(address); }            if (mComm.ReadBytes(m_datasize, ref buffer) == 1) {     // Here I don know how to perform ToHexString Operation of (buffer and m_DataSize) }   How can I do the same in my wpf app??? Please help!!!

How do I convert a byte[] to a string? Every time I attempt it, I get      System.Byte[]    instead of the value.  Also, how do I get the value in Hex instead of a decimal?


I don't know how it got uninstalled since I had it before, but when I try to install it again I get the following error:  oierlauzi@akerbeltz:~$ sudo apt-get install unity-control-center Reading package lists... Done Building dependency tree        Reading state information... Done    Some packages could not be installed. This may mean that you have requested an     impossible situation or if you are using the unstable distribution that some       required packages have not yet been created or been moved out of Incoming.  The following information may help to resolve the situation: The following packages have unmet dependencies:   unity-control-center : Depends: libcheese-gtk23 (>= 3.4.0) but it is not going to be installed                         Depends: libcheese7 (>= 3.0.1) but it is not going to be installed E: Unable to correct problems, you have held broken packages.   I have read several answers but none have solved my issue. I also could not solve it by using aptitude.

I'm getting the following error message when attempting to install libglew-dev,  Reading package lists... Done Building dependency tree        Reading state information... Done Some packages could not be installed. This may mean that you have requested an impossible situation or if you are using the unstable distribution that some required packages have not yet been created or been moved out of Incoming. The following information may help to resolve the situation:  The following packages have unmet dependencies:  libcheese-gtk23 : Depends: libclutter-gtk-1.0-0 (>= 0.91.8) but it is not going to be installed                    Depends: libcogl15 (>= 1.15.8) but it is not going to be installed  libcheese7 : Depends: libclutter-gst-2.0-0 (>= 0.10.0) but it is not going to be installed               Depends: gstreamer1.0-clutter but it is not going to be installed  libclutter-1.0-0 : Depends: libcogl-pango15 (>= 1.15.8) but it is not going to be installed                     Depends: libcogl15 (>= 1.15.8) but it is not going to be installed E: Error, pkgProblemResolver::Resolve generated breaks, this may be caused by held packages.   All those packages are however apparently already installed.  I have tried all possible solutions in  post, without any luck. I have not added any PPAs. The version of ubuntu is 14.04.2.  I have looked at similar posts, and tried the following:  Running  dpkg --get-selections | grep hold   prints nothing.  sudo apt-get -oDebug::pkgProblemResolver=true install -f   Gives me nothing of interest, 0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.


I am beginner for Ubuntu 13.04 OS. I have downloaded Vuze torrent software from Vuze wesite as a VuzeInstaller.tar.bz2 file and saved it in my Download folder. I have extracted the folder and extracted folder name is Vuze.  How can I install Vuze software from the Download folder?

I have downloaded tar.gz files. But I don't know how to install it. How do I install this kind of file?


Let $\pi$ denote a prime element in $\Bbb{Z}[i]$ such that $\pi\not\in \Bbb{Z},i\Bbb{Z}$. Prove that $N(\pi)=2$ or $N(\pi)=p$, where $p$ is a prime number $\equiv 1\pmod4$. Give a complete classification of the prime elements of $\Bbb{Z}[i]$ using the prime numbers in $\Bbb{Z}$.   This exact question has been asked  but I do not understand the answers given, so I will ask it again in hope of further explanation.  Here's everything I know that will probably help me with the problem:   We know that $\pi=a+bi$ where $a,b\in \Bbb{Z}\setminus \{ 0\}$. Fermat's Two Square theorem: A prime number $p\equiv 1 \mod4$ satisfies $p=a^2+b^2$ where $a\neq b$ and $a,b\in \Bbb{N}\setminus    \{0\}$. $\pi$ is irreducible in $\Bbb{Z}[i]$ If $\pi=xy$ then $\pi \mid x$ or $\pi \mid y$ If $N(\pi)=2$ then $a=\pm 1, b=\pm 1$. If $N(\pi)=p$ where prime $p\equiv 1\pmod 4$ then we know $p=a+bi$ for some $a,b\in \Bbb{Z}\setminus \{0\}$ by Fermat's theorem.   I can't figure out where to start. I was thinking of starting with this:  Let $x,y\in \Bbb{Z}[i]$ such that $x=x_1+x_2 i$ and $y=y_1+y_2i$. Then $\pi\mid x$ or $\pi\mid y$. Suppose $\pi\mid x$.....   Can I have a hint on how to begin this?

Let $\pi$ denote a prime element in $\mathbb Z[i], \pi \notin \mathbb Z, i \mathbb Z$. Prove that $N(\pi)=2$ or $N(\pi)=p$, $p \equiv 1 \pmod 4, p$ is a prime.   I know that $\pi$ is prime in $\mathbb Z[i]$ implies it is irreducible. Also if $\pi$ has a prime norm, that is $N(\pi) = p$ then $\pi$ is irreducible.  For any $z \in \mathbb Z[i]$ we have $N(z) = a^2 + b^2$. Since $\pi \notin \mathbb Z, i \mathbb Z$ both $a$ and $b$ must be non-zero in the case of $\pi$. By Fermat's Two Square theorem every prime number $\equiv 1 \pmod 4$ can be written as a unique sum of two squares. I have some idea I should utilize this theorem here, but no success so far.  However I've come to a dead end. I don't know how to go on from here. Could someone help me out ?  Thanks.


$\lim \limits_{x \to 0}$  $f(x)$ DNE , and $\lim \limits_{x \to 0}$ $[f(x) + g(x)] = 42$

This is a true/false question.     If the limits $$\lim_ {x\to a}\ f(x)\quad \text{ and }\quad  \lim_ {x\to a}\ g(x)$$ don't exist, limits $$\lim_ {x\to a}\ (f(x)+g(x))\quad \text{ and }\quad \lim_ {x\to a}\ (f(x)g(x))$$ don't exist also.   My idea is, that, because $$\lim_ {x\to a}\ (f(x)+g(x))=\lim_ {x\to a}\ f(x)+\lim_ {x\to a} g(x)$$ then the limits doesn't exist, correct?


I have seen pictures that must of been taken with a slow shutter speed, the car was in focus but the background had motion blur, how can this happen?

Some shots I see online I don't understand how the tracking is done.      The car is coming at the camera while the motion blur is also towards the camera, so if you move your camera in the direction of the motion you will also blur the car. I guess these photos are a complete photoshop job?


I'm trying to prove the following:  A critical point of  $f \in\mathfrak {F} (M)$ is a point $p \in M $ in which $ df_ {p} = 0.$ Then:  a) at such a point there is a Hessian function $H: T_ {p} (M) \times T_ {p} (M)\rightarrow\mathbb{R}$ such that $H (X_ { p}, Y_ {p}) = X_ {p} (Yf) = Y_ {p} (Xf)$ for all $X, Y \in \mathfrak {X} (M).$  b) $H$ is symmetric, Bilinear and satisfies $H (\partial_ {i} | _ {p}, \partial_ {j} | _ {p}) = (\partial ^ {2 } / \partial x ^ {i} \partial x ^ {j}) (p)$ relative to a coordinate system.  Here $M$ is the differentiable manifold, $\mathfrak {F} (M)$ is the set of all differentiable functions of $M$ in $\mathbb {R}$, $\mathfrak {F} (M)$ corresponds to the set of all vector fields in $M$ and $T_ {p} (M)$ is the set of all vectors tangent to $M$ in $p.$  Assuming part a), the properties of symmetry, bilinearity and equality with the partial derivatives are followed by the definition of vector field and derivation.  The part where I'm stuck is a). How do I prove the existence of such a mapping? My idea is that if $p$ is a critical point, it should be possible, by means of charts of the variety $M$ and of $\mathbb {R}$ 'bring the Hessian matrix' from such a point in $\mathbb {R}$  but I can't get this.  Any help is appreciated in advance.

In Milnor's Morse Theory, the Hessian of a smooth function $f : M \to \mathbb R$ defined on a manifold $M$ at a critical point $p$ is the bilinear functional on $T_p M$ defined as follows:  $$f_{**}(v, w) = \tilde v_p(\tilde w(f))$$  where $\tilde v, \tilde w$ are vector fields that extend $v$ and $w$. It is written that $\tilde w(f)$ denotes the directional derivative of $f$ in the direction $\tilde w$ and that $\tilde v_p$ is, of course, $v$. I am assuming that this means $\tilde w(f) = T_p(f)(w)$, but   I do not know what it means to write $v(T_p(f)(w))$ it is claimed that $f_{**}$ is symmetric because $$\tilde v_p(\tilde w(f)) - \tilde w_p(\tilde v(f)) = [v, w]_p(f) = 0$$ since $p$ is critical. If I am not mistaken, the argument used here is that since $p$ is critical, any directional derivative of $f$ at $p$ (e.g. $[v, w]_p(f)$) is zero, but wouldn't that also mean that $\tilde w(f) = \tilde v(f) = 0$?   Hopefully, I am only mixing up notations. I would appreciate any comment.


Let $u \in \mathbb{R}^m$ and $v \in \mathbb{R}^n$ and $u,v \neq 0$. Since $u$ is an $m\times1$ matrix and $v^T$ is a $1\times n$ matrix, the product $uv^{T}$  is a $m\times n$ matrix. Then:     $$\text{rank} (uv^{T}) =1$$   Just to illustrate: pick a random vector $u$ in $\mathbb{R}^4$, and $v$ in $\mathbb{R}^5$, for example: $u= (1, 2, 3, 4),$ and $v= (1, 2, 3, 4, 5)$. The rank of the matrix $m\times n$ is $1$ which can be checked by row-reducing. Chosing arbitrary vectors $u,v \neq 0$, the rank of the product matrix mxn of $uv^{T}$ is always $1$.  Why is this?   Any help would be greatly appreciated.

If $u$ $∈ \mathbb R^{m \times 1}$ and $v ∈ \mathbb R^{n \times 1}$ how do you show that the $(m \times  n)$ matrix $uv^T$ has rank $1$? Would providing an example be sufficient to prove it?


Which is more correct to say:   Five and four are eight Five and four is eight   My Logic teacher has sent this to us to figure out.  What is written above is all the information we were given.  I know that in terms of math neither is correct.    I have tried to disregard that the words are numbers and think about in in a different way.  I do not know the rules for the correct use of are and is in the English language.  If you can help that would be great.

I am having trouble with the following sentence:      "The complexity and diversity of the new platforms is worrying us."   If "complexity" and "diversity" constitute two subjects, then the verb should presumably be "are"; however, the sentence feels more natural with "is". Is this correct? Is there a linguistic term for this occurrence?    The following questions address the general topic of compound subjects, but not specific cases like this:             And the following question seems to have somewhat inconclusive answers:         So this question is not really a duplicate of these three.


I would like to ask a question for computing a hashvalue for a empty file. I need to compute a hash_value when the file f is first created and is empty. Then, at the end I will update the hash_value again. My code is not working for windows os. Can you tell me how to handle this? Thanks.               objectFile = File(fullFilePath);             fileInputStream = FileInputStream(objectFile);             data = IOUtils.toString(fileInputStream, 'UTF-8');              persistent digest;                          if isempty(digest)                 digest = MessageDigest.getInstance('SHA-256');             end              hash = digest.digest(java.lang.String(data).getBytes('UTF-8'));   Error Message      digest.digest(java.lang.String(data).getBytes('UTF-8'))     Java exception occurred:     java.lang.NullPointerException          at java.security.MessageDigest.update(Unknown Source)          at java.security.MessageDigest.digest(Unknown Source)

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?


I am travelling to Usa for a conference and my nationality is Bangladeshi. I have B1/B2 visa for USA.  Recently i also got an invitation from italy. But because of my travel date to usa is nearby i cannot apply for italian visa or Schengen visa from Bangladesh. Cause for visa application they will take my passport. So my question is, can I apply for italy visa from New York, usa. I don’t have any permanent residence id or something only the valid visa. Is it possible to apply?

I'm a citizen of country A who would like to apply for a Schengen visa at a consulate in country B. When is this possible?


I tried using the same trick as $\lim\limits_{n\to\infty}\frac{n!}{n^n}$, where you compare the terms one to one.  $(\frac{1}{n})(\frac{2}{n})(\frac{3}{n})...(\frac{n}{n})\cdot e^n$ = $(\frac{e}{n})(\frac{2e}{n})(\frac{3e}{n})\cdots(\frac{ne}{n})$  I can't really figure out what to do after this.  Some of the terms are less than one and some are greater than one.  It would be great if someone could lead me in the right direction of what to do here.

As seen in  question, the series $\sum\limits_{n=1}^{\infty} \dfrac{n!e^n}{n^n}$ diverges. (One way to see this is by noting that the terms of the sum are greater than $1$ and, therefore, don't converge to zero.)  However, more is true: not only are the terms greater than $1$, they blow up to $+\infty$! To see this, one can apply Stirling's approximation and get $\dfrac{n!e^n}{n^n} \sim \sqrt{2\pi n}$.  My question is: is there an elementary proof for $\lim_{n \to\infty}\dfrac{n!e^n}{n^n} = +\infty$?  The reason I'm asking this is that I'm taking a Calculus course and I was assigned the exercise of proving the divergence of the series above and I would feel more satisfied if I could prove that its terms go to $+\infty$ (as opposed to merely proving the terms are greater than $1$.) Obviously, things like Stirling's approximation are outside the scope of the course, so I can't really use them.  (To be clear, you can use anything one learns in $4$ semesters of standard Calculus courses. I hope this restriction is not too obscure.)


Since Microsoft has started rolling out Chromium Edge for everyone having the versions v1803 and above via software updates, so, is there any way to uninstall the Legacy Edge in the lower versions of Windows 10. I am running on v1709 and have installed the new Edge by running the setup file. But the Legacy Edge remained as it has been. Now I have two Edge(s) in my PC and hence trying to figure out to uninstall the Legacy Edge. The last time I tried doing it some months ago didn't  go through well and had to keep the old one. So far, I haven't been able to figure out how this is to be done. Can anyone tell me if this is even possible at all?

Is there any possibility to completely disable the new Edge browser? The old IE could be disabled in Settings → Default Programs, but in Windows 10, the checkbox is missing for Edge.  Is there any way to get rid of Edge, or at least to disable all entry-points?


Lets say I want to power a laptop using an external power supply. Lets say I have a 20 volt supply and the laptop runs at 12 volts. Can i use a simple voltage divider with the appropriate resistors (resistance, wattage) to drop the voltage down to 12 volts and run the laptop ? Or is there a better way of doing this ?

When would you use a voltage regulator vs a resistor voltage divider?  Are there any uses for which a resistor divider is particularly bad?


@Override     protected void onCreate(Bundle savedInstanceState) {         super.onCreate(savedInstanceState);         setContentView(R.layout.activity_story);          Intent intent = getIntent();         String name = intent.getStringExtra("name");          if (name == "d")         {             name = "Spike";         }          TextView heading = (TextView) findViewById(R.id.storyTextView);         heading.setText("And our story begins with " + name);

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'm required to install some software on my work laptop. It's running Windows 10 Enterprise. It failed, telling me that I need to have the .NET Framework 3.5 installed. I've tried, unsuccessfully, to install .NET 3.5 both by going to Microsoft's website and also by going through Turn Windows Features on and off. Neither worked. I've looked here on Superuser, but couldn't find anything the discussed error 0x800F0954. Found other errors, but not 0x800F0954, so I don't believe this is a duplicate. Given this, then how to I resolve this problem? Here's a picture of the error:

When I try to install .net 3.5 I get the follwing message:     The following feature couldn't be installed:      .NET Framework 3.5   (includes .NET 2.0 and 3.0)      Error code: 0x800F081F   I tried with a standalone package and through Windows Features.  Update: Internet connection is fine.


In my 1 TB hard-disk very strange problem occurs. When I backup my Linux Data into another hard disk during copy process because of interrupted power supply or may be connection cable problem hard disk automatically unmount but that same time copying process was working. After that I reconnect HDD I face a problem in that problem  1. my all previous data is OK. But a folder in which I coping my data is corrupt. and unable to open.. 2. All previous folder data also non accessible but folder proper shows data size. Other info. HDD file system is NTFS. HDD only works with linux and when I connect to Windows HDD unable to detect.  Here is screen-shot of problem.

About two weeks ago I had a problem with my PC that my brother wrote a question about at .  I still haven't solved the problem, so my PC is unusable now.  Now I think that it would be simpler to re-install both Win7 & Ubuntu than repair them, but there're some data on their partitions. I want to recover this data.  These partitions are not mountable for some reason. I don't know why.  sudo fdisk -l about the problematic partitions:     Device    Boot      Start         End      Blocks   Id  System /dev/sda1            2048     147912703    73955328   83 Linux /dev/sdb2            206848   174079999    86936576    7  HPFS/NTFS/exFAT   And in GParted:      And the error of the mount command:  Failed to mount '/dev/sdb2': Invalid argument The device '/dev/sdb2' doesn't seem to have a valid NTFS. Maybe the wrong device is used? Or the whole disk instead of a partition (e.g. /dev/sda, not /dev/sda1)? Or the other way around?   And the exact same message for /dev/sda1  How can I recover my data from those HDDs?  EDIT     I have tried to specify the type of the drive:  $ sudo mount -t ext4 /dev/sda1 /olddisk mount: wrong fs type, bad option, bad superblock on /dev/sda1,        missing codepage or helper program, or other error        In some cases useful info is found in syslog - try        dmesg | tail  or so $ sudo mount -t ntfs /dev/sdb2 /olddisk NTFS signature is missing. Failed to mount '/dev/sdb2': Invalid argument The device '/dev/sdb2' doesn't seem to have a valid NTFS. Maybe the wrong device is used? Or the whole disk instead of a partition (e.g. /dev/sda, not /dev/sda1)? Or the other way around?   EDIT     sudo ntfsfix /dev/sdb2 returns:  Mounting volume... NTFS signature is missing. FAILED Attempting to correct errors... NTFS signature is missing. FAILED Failed to startup volume: Invalid argument NTFS signature is missing. Trying the alternate boot sector Unrecoverable error Volume is corrupt. You should run chkdsk.


In order to bypass firewall/GPO constraint, I want to use Ubuntu as springboard to rdp to a Windows box on the same LAN remotely. I can xrdp to ubuntu via sesman-Xvnc module. I can run remmina from the vnc session. But in the remmina Windows session, keyboard doesn't work at all. Only mouse works. Keyboard works with other apps in vnc session. Also, if I use remmina at local Ubuntu console, keyboard works.  Any suggestions?

Unlike rdesktop, when I press ALT + F4 in remmina, it doesn't react in the Windows system, but instead closes the remmina window.  Any thoughts?


This question is from . I thought of using a bottom up approach, calculating the possible subsets from the leaves, and then making my way up. I'm not to sure why it isn't working. The question  is:  Sales have slumped at the Zionoi noodle factory and the management may need to terminate the contracts of some employees. Every employee has one immediate boss. The seniormost person in the company is the president, who has no boss. For legal reasons, if an employee’s contract is not terminated, then his or her boss’s contract cannot be terminated either. For how many different sets of employees can the management legally terminate contracts? Note that one possibility that has to be counted explicitly is that no employees’ contracts are terminated (that is, the set of employees whose contract is terminated is the empty set).  For example, suppose there are four employees, organised as follows. Each arrow points from an employee to his or her boss.    Here, there are $7$ different ways to terminate contracts for a set of employees, as follows:  $\Bigg[\{1, 2, 3, 4\}, \{\}, \{4\}, \{2\}, \{3, 4\}, \{2, 4\}, \{2, 3, 4\}\Bigg]$  In each of the following cases, compute the number of different sets of employees whose contracts can be legally terminated by the management.

Greetings Community! The above problem you see is a combinatorics problem I could not solve. :( This problem is from ZIO $2010$, P$1$.     Here is what I did: Observe that every graph can be divided into "sub-groups" which may help in solving. We first remove the empty set. Then the singleton set. Consider the bigger but smaller than the sub-parts example:    The singleton sets are $\{4,5,6\}$ which are at the least position in the graph.   The dual sets are $\{2,4\}, \{3,5\}, \{3,6\}$, the bottom - two portions in the graph. The triplet sets are $\{2,4,5\}, \{4,5,6\}$ which we may manually count but for the bigger graphs in the sub-part, this may prove to be difficult and this is where I am stuck.   Any help would be appreciated. Thanks.


Let $m$ be a number all of whose digits are either $6$ or $0$. Prove that '$m$' cannot be a perfect square.

I proceeded using infinite descent. Let $ N =a_na_{n-1}a_{n-2}\ldots\ldots a_2a_1a_0$ be the decimal representation of the number. Then either $N$ ends in an even number of zeroes  or $a_0=6$  Now all squares are $\equiv 0 \text{ or } 1 \bmod 4 $. But  if $N$ ends in $06\text{ or }66 $, then $N\equiv 2 \bmod 4 $. Thus $ N $ does not end in $6$.  If $N$ ends in an even number of zeroes then, then $ N=10^{2n}\cdot N'$.  Applying the same argument to $ N'$ we commence an infinite descent.  Is the proof correct ? Any shorter proofs ?


Once upon a time, Mi Yodeya had a community ad which looked like this:    This was a really neat ad, and was heavily upvoted and put into the rotation year after year...until however long ago it's been now that non-imgur pictures are banned.   Can this be reversed? If the community wants these kinds of ads which aren't stills, why shouldn't they be able to have it? SE has the final say on if ads can go on rotation, and the fact that they have vetoed ads in the past indicates that they do regularly monitor what community ads are on rotation, so if it's one of increased moderation, at least from my completely uninformed and superficial perspective as a user it doesn't seem like there's any loss there.

, , and . This ad has been used more or less widely around the network. For those who don't know, it's an ad hosted by Kyle Cronin that shows the current number of bounties and their sum. Here's an example: (this is the SFF one, because codegolf.se doesn't have any bounties at the moment)  This is what the image currently looks like for SFF, . Looks like this for no bounties:  (the two in this post are static and won't change, and are hosted on imgur, just examples of what it looks like) But most of this is beside the point, it's just some background info. From the ads post:  Image requirements  The image that you create must be 300 x 250 pixels, or double that if high DPI. Must be hosted through our standard image uploader (imgur)   This is not hosted on imgur. Normally, the system blocks you from submitting it, but you can submit any imgur link and then ninja-edit (i.e. those edits that don't show in the rev history) into the auto-updating version. What's the official stance? Is this ad allowed? I'd assume that the imgur-only part is mostly for 1. to keep the ads up, because imgur doesn't go down often (as another image hosting site might) and 2. to prevent malicious websites changing the image to a nsfw one/clickbaity/spam ad. Can we continue to use this ad?


Im sure this is a repeated question, however I have no idea how to phrase it. What does pythons[1:3] yield?  pythons = [’Graham’, ’Eric’, ’Terry’, ’John’, ’Michael’, ’Terry’]   I know now the answer is Eric and Terry, but why?

I need a good explanation (references are a plus) on Python's slice notation.   To me, this notation needs a bit of picking up.   It looks extremely powerful, but I haven't quite got my head around it.


Let $K$ be a field, and let $K\subset E\subset K(a)$ be an extension, where $a$ is transcendental element over $K$. How can I show that $K(a)/E$ is finite ?

Let $X$ be transcendental over a field $F$, and let $E$ be a subfield of $F(X)$ properly containing $F$. Prove that $X$ is algebraic over $E$.   Could we maybe use also the following??   Let $f(x) \in E \Rightarrow f(x) \in F(X) \Rightarrow f(x)=\frac{h(X)}{g(X)}$, where $g(X) \neq 0, h,g \in F[x]$.   Or doesn't this help ??


I would like to center both vertically and horizontally the text "apple". I tried every solution already proposed (an inner div, vertical-align, margin:auto...) I just don't get it.    I think that the problem is located below.  #distance {  height:20%;   text-align: center;  vertical-align: middle;  font-size: 2em; }   Thanks.

I want to center a div vertically with CSS. I don't want tables or JavaScript, but only pure CSS. I found some solutions, but all of them are missing Internet Explorer 6 support.
Div to be aligned vertically
   How can I center a div vertically in all major browsers, including Internet Explorer 6?


What is better (more secure) way to handle SQL injections ?  $var = filter_var($_POST['var'], FILTER_SANITIZE_STRING);   or  mysqli_real_escape_string($link, $_POST['var']);

If user input is inserted without modification into an SQL query, then the application becomes vulnerable to , like in the following example:  $unsafe_variable = $_POST['user_input'];   mysql_query("INSERT INTO `table` (`column`) VALUES ('$unsafe_variable')");   That's because the user can input something like value'); DROP TABLE table;--, and the query becomes:  INSERT INTO `table` (`column`) VALUES('value'); DROP TABLE table;--')   What can be done to prevent this from happening?


I have the distinct perception that there is an idiom similar to such a meaning. I just can't remember it. An example to clarify:  John writes a program to solve something. Bob writes another program (probably unaware of John's) to do the same thing although he could have just used John's program. Bob has [idiom]

In Polish, and I believe in a number of other European languages, there is an idiomatic expression which translates to "to force a door which is already open". It is used to describe a situation when much effort is spent on solving a problem which has already been solved, or did not exist in the first place. For example, if someone was doing research to answer a question which has already been answered, one would be said to be "forcing an open door". The same would apply to a person who is arguing a point that everyone already agrees with.  As far as I am aware, this phrase does not carry similar meaning in English. (Or does it?). Hence, I would like to know if there is an idiom with similar meaning? If not, is there a succinct way to describe such situations?


I'd like to install Ubuntu on my computer. I have a 500GB HDD with the following partitions: (at least what the Ubuntu installer shows):  / - Windows 7 (loader) - 100GB  - 400GB   I'd like to install Ubuntu to the 100GB partition as on the 400GB I have Windows. But I have problems with the following:   Whether I can set a swap particion without messing up my Windows. Which file system to set to the partition.   Please tell me what and how to do it in the installer.

I have a formatted 55GB partition as NTFS, the other part of the hard disk has Windows 7.  Is NTFS the right format for Ubuntu? If not how should I format it and with what format?  Once I finish preparing the partition, how do I install Ubuntu on that partition? I'm not sure how to set up dual-boot Ubuntu and Windows.


I am using the following command to retrieve the number of files which names contains sv or json in a given directory in a remote server: nbs_files=`ssh -q -i ${sshkey} ${user}@${server} "find ${path}/ -maxdepth 1 -mindepth 1 -type f -name '*sv*' -o -name '*.json' -exec basename {} \; | wc -l"`   This command returns only the number of .json files, whereas files with sv in their names exist in the ${path}. When I remove the -o -name '*.json' part, the command works well, and returns the number of files containing the 'sv' in their names. Does anyone know how can I modify the command in order to retrieve the files containing sv in their names and the files with the extension .json as well?

When I'm using  find . -type f -name "*.htm*" -o -name "*.js*" -o -name "*.txt"  it finds all the types of file. But when I add -exec at the end:  find . -type f -name "*.htm*" -o -name "*.js*" -o -name "*.txt" -exec sh -c 'echo "$0"' {} \;  it seems it only prints .txt files. What am I doing wrong?  Note: using MINGW (Git Bash)


I want to run google-chrome --app=URL in my .sh file in the moment when I log in to the my account. I don't want to see a terminal window.

How can I run scripts automatically when Ubuntu starts up so I don't have to run them manually after startup?


Top gives me an output like:  %Cpu(s):  4.7 us,  1.3 sy,  0.0 ni, 93.9 id,  0.1 wa,  0.0 hi,  0.0 si,  0.0 st   if my CPU has spent 4.7% of its time on user processes, how much of time history has it considered before coming up with such a result?

When I run the top command, the third line is;  Cpu(s):  0.3%us,  0.3%sy,  0.0%ni, 99.2%id,  0.1%wa,  0.0%hi,  0.0%si,  0.1%st  From where does top command get this data? Does it get from /proc?, if yes, what is the exact location?


Is there any way to check out only modified files through subversion commands because I want only modified files to be in my working copy Jenkins to build only modified files?

Is it possible to checkout only those files from a SVN repository that were modified in a revision or range of revisions, without checking out any files that were not modified?


I have an update query below written in Microsoft Access and I would like to convert that to Oracle SQL Developer 17.2.0.188. There is also an image in the attachment showing the query expression.   The query said: "update the Products.UnitsInStock to UnitsInStock-Quantity if the ShippedDate is not null and This_Order_Was_Shipped = "YES"  UPDATE Products INNER JOIN (            Orders INNER JOIN [Order Details] ON Orders.OrderID = [Order Details].OrderID        ) ON Products.ProductID = [Order Details].ProductID SET    Products.UnitsInStock = [UnitsInStock] -[Quantity] WHERE  (            ((Orders.ShippedDate) IS NOT NULL)            AND ((Orders.This_Order_Was_Shipped) = "YES")        );

Software Name: Oracle SQL Developer Version 17.2.0.188  I have three tables: orders, order_details, and products.  I wanted to run a query to update units_in_stock in the products table based on quantity in order_details, where the associated orders row has been marked as shipped, and has a shipping date.  Here's what I tried:  UPDATE Products SET (Products.Unit_In_Stock = Products.Unit_In_Stock - Order_Details.Quantity) INNER JOIN (     Orders INNER JOIN Order_Details ON Orders.Order_ID = Order_Details.Order_ID     ) ON Products.Product_ID = Order_Details.Product_ID WHERE (         ((Orders.Shipped_Date) IS NOT NULL)         AND ((Orders.This_Order_Was_Shipped) = "YES")         );   When I run this, I get:  Error at Command Line : 1 Column : 45   Line 1, Column 45 is the equal sign in the very first statement that said  Products.Unit_In_Stock = Products.Unit_In_Stock - Order_Details.Quantity   Can you help me get this working?


I am trying to prove the following statement, but I have been stuck for a while and I am looking for an hint about how to prove it: "Suppose $B\subset\mathbb{R}$ and $f:B\to\mathbb{R}$ is an increasing function. Prove that $f$ is continuous at every element of $B$ except for a countable subset of $B$." What I have tried to do: Since I wasn't able to tackle the original statement I tried by assuming that $B$ is also a Borel set so as to exploit in some way the fact that $f$ must then be a Borel measurable function. Then if $D:=\{x\in B: f\text{ is not continuous at }x\}$ and $C$ is a Borel set we have that $f^{-1}(C)$ is a Borel set and $f^{-1}(C)=(f^{-1}(C)\cap D)\cup (f^{-1}(C)\cap B\setminus D)$ and at this point I tried to go on by contradiction, assuming that $D$ is uncountable and tried to show that $(f^{-1}(C)\cap D)\cup (f^{-1}(C)\cap B\setminus D)$ is not a Borel set but I haven't succeeded so I would greatly appreciate any hint or comment or explanation that could nudge me towards a more fruitful approach, thanks.  EDIT (Proof): Let $D:=\{x\in B:f\text{ is not continuous at }x\}$: since $f$ is monotone (increasing)  so if $d\in D$ then $I_d:=(\lim\limits_{x \to d^-,\ x\in B\\}f(x),\lim\limits_{x \to d^+,\ x\in B}f(x))=(\sup_{x<d,\ x\in B}f(x),\inf_{x>d,\ x\in B} f(x))$ is a non-empty interval in $\mathbb{R}$ hence there must be a rational number $q_d$ in it which we can choose and since $I_d\cap I_{d'}=\emptyset$ for $d\neq d'$* this rational number is also unique so we can define an injective function $g:D\to\mathbb{Q}, g(d):=q_d$. Thus $\#(D)\leq \#(\mathbb{Q})=\#(\mathbb{N})$ ie the set of points at which $f$ is discontinuous is (at most) countable, as desired. $\square$  (*) Suppose $I_d\cap I_{d'}\neq\emptyset$ for some $d\neq d'$ (we can suppose wlog that $d<d'$): then there must be $y\in I_d\cap I_{d'}$ so $\sup_{x<d,\ x\in B}f(x)<y<\inf_{x>d,\ x\in B}f(x)$ and $\sup_{x<d',\ x\in B}f(x)<y<\inf_{x>d',\ x\in B}f(x)$ which implies (since $d\leq d'\Rightarrow \inf_{x>d,\ x\in B}f(x)\leq \sup_{x<d', x\in B}f(x)$) that $y<y$, contradiction.

I would like to prove the following:       Let $g$ be a monotone increasing function on $[0,1]$. Then the set of points where $g$ is not continuous is at most countable.     My attempt:    Let $g(x^-)~,g(x^+)$ denote the left and right hand limits of $g$ respectively. Let $A$ be the set of points where $g$ is not continuous. Then for any $x\in A$, there is a rational, say, $f(x)$ such that $g(x^-)\lt f(x)\lt g(x^+)$. For $x_1\lt x_2$, we have that $g(x_1^+)\leq g(x_2^-)$. Thus $f(x_1)\neq f(x_2)$ if $x_1\neq x_2$. This shows an injection between $A$ and a subset of the rationals. Since the rationals are countable, $A$ is countable, being a subset of a countable set.    Is my work okay? Are there better/cleaner ways of approaching it?


I'm downloading Fortnite and was wondering if I can turn off my PC while it's downloading. What would happen if I turned off my PC?

I am downloading Fortnite; I want to exit the launcher, but I dont want to lose the progress on my download. If I exit the launcher, will the download fail? Currently, it is paused. Is it possible for me to shutdown my PC and then resume the download later?


At the start of GoF, the portkey has a time that it is due to leave, and the implication is that it will leave at that time whether there are people touching it or not.   Towards the end of the book however, the portkey is activated by touch and presumably wouldn't have left until it was touched.   Is this a contradiction or are there different spells for this?

In Harry Potter and The Goblet of Fire, when Mr. Weasley and Mr. Diggory are leading a group to the Quidditch World Cup, Mr. Weasly explains:     I believe there’s a handy wood they’re using as the Apparition point. For those who don’t want to Apparate, or can’t, we use Portkeys. They’re objects that are used to transport wizards from one spot to another at a prearranged time. You can do large groups at a time if you need to.   However, this happens at the end of Chapter 31, The Third Task:      “On three, right?” said Harry. “One — two — three —”He and Cedric both grasped a handle.Instantly, Harry felt a jerk somewhere behind his navel. His feet had left the ground. He could not unclench the hand holding the Triwizard Cup; it was pulling him onward in a howl of wind and swirling color, Cedric at his side.   So, how come the Triwizard Cup didn't transport the holder at a prearranged time, but at the first touch?  The canonical answer might be "you just put a charm so it will transport the first holder instantaneously", but if it was so easy/simple, many wizards would have done it to get to the World Cup before they were supposed to (or after! if they didn't want to wait for so many days...).


Since sorcerers are inherently magical (or maybe more accurately, inherently contain magic), would the  spell reveal an aura around the sorcerer?  If so, would this also be the case with a warlock? I would assume wizards to be a definite no, since their magic is more of a harnessing of magic than any personal ability.    I believe this is unrelated to any possible aura attributed to prepared spells. To quote my below comment:     To my mind a prepared spell is just that, the preparation of materials and maybe a quick study of somatics/verbal. This wouldn't make the spellcaster any more or less magical. This is why I specifically reference the Sorcerer

Inspired by a recent question about discerning divine and arcane spellcasters, of like to hear the case for and against detecting spellcasters of either style with .  I think you can detect whether someone has prepared spells, based on this language:     For the duration, you sense the presence of magic within 30 feet of you. If you sense magic in this way, you can use your action to see a faint aura around any visible creature or object in the area that bears magic, and you learn its school of magic, if any. (emphasis mine)   Preparing spells is described as having the spell "fixed in mind" (). I'd argue that qualifies as bearing magic, and opens the door to using detect magic to identify spellcasters with currently prepared spells. What do you think?


I am trying to find a regex which supports a pattern like below:  String starts with // String has a delimiter after //; (suppose ; is the delimiter) String has \n after demiliter (//;\n) Finally String contains any number of digits with that delimiter (//;\n2;3;4;5)  Could you help? I tried ^//\\D+\\n.*$ but it doesn't work. Thanks in advance!

I don't really understand regular expressions.  Can you explain them to me in an easy-to-follow manner?  If there are any online tools or books, could you also link to them?


I am writing a program to implement "quiz" in Java 8  import java.util.Scanner; import java.util.*;  class Question {     String question;     int no;     HashMap<Integer, String> options;     String correctanswer;      public static void q_no() {         System.out.println("enter a question no");         int num;         Scanner no = new Scanner(System.in);         num = no.nextInt();     }      public static void set_question(){         System.out.println("enter aquestion");         Scanner f = new Scanner(System.in);         String question = f.nextLine();      }   Here in setting options, I am getting errors in the while loop while implementing the program.      public void set_options() {         System.out.println("enter options");         int count = 1;         String q;         Scanner str = new Scanner(System.in);         while (count < 5) {             System.out.print("set option" + count);             q = str.nextLine();             options.put(count, q);             count++;         }     }      public void set_correctanswer() {         System.out.println("enter correct answer");         Scanner d = new Scanner(System.in);         String ans = d.nextLine();     }      public static void marks() {      }            }   Here you would write your questions to an ArrayList and display them in a second question.  class Quiz {     ArrayList<Question> list = new ArrayList<>();     public ArrayList<Question> adding(Question q){         list.add(q);         return list;     }     public void show() {         int g = list.size();         int count = 0;         while (count < g) {             list.get(count);         }     } }   In menu, if you choose 1 you get add questions or type 2 you could get a list of questions. I am still working on printing questions.  class Menu {     public static void main(String[] args) {         System.out.println("enter 1 for adding questions");         Scanner input = new Scanner(System.in);         int g;         g = input.nextInt();         if (g == 1) {             System.out.println("how many questions do you add");             int number;             Scanner b = new Scanner(System.in);             Quiz programming = new Quiz();             number = b.nextInt();             int count = 0;             while (count < number) {                 Question q1 = new Question();                 q1.q_no();                 q1.set_question();                 q1.set_options();                 q1.set_correctanswer();                 programming.adding(q1);             }          } else if(g == 2){             Quiz programming = new Quiz();             programming.show();         }      } }

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?


I am trying to remove the letter x if it is present as the first or last character of any given string. Why does my code not check strings with length 0 even though I have accounted for it in my code?  I have already tried using an if statement to check if the length is 0 and, if so, to return the original string. I have also tried returning an empty string with the same value.  public String withoutX(String str) {   if (((str.charAt(0)=='x') || str.charAt(str.length()-1) == 'x') && str.length()>=2){     if (str.charAt(0)=='x'){         str = str.substring(1,str.length());     } if (str.charAt(str.length()-1) == 'x'){         str = str.substring(0,str.length()-1);     }   } if (str.length()==1 && str == "x"){       return "";   } if (str.length()==0){       return str;     // the above if statement (length = 0) does not work   } else{       return str;   } }   The expected result is for it to return the string without the letter x. This has been achieved for all strings, except an empty one, where it says that the index is out of range.

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?


How can one compute the following limit $$ \lim_{n\rightarrow+\infty}n^{2}\left(  \ln\left(  1+\frac{1}{n}\right) -\frac{1}{n+1}\right) \quad ? $$ I wrote   $$ \lim_{n\rightarrow+\infty}n^{2}\left(  \ln\left(  1+\frac{1}{n}\right) -\frac{1}{n+1}\right)  =\lim_{x\rightarrow0}\frac{\ln\left(  1+x\right) -x}{x^{2}}\overset{l^{\prime}H}{=}\lim_{x\rightarrow0}\frac{\dfrac{1}{1+x}% -1}{2x}\overset{l^{\prime}H}{=}\lim_{x\rightarrow0}\frac{-1}{2\left( 1+x\right)  ^{2}}=-\frac{1}{2}. $$ But how can be a limit of a positive sequence be negative?

I need help solving this problem. I tried L'hospital and rearranging but nothing worked. $$ \lim_\limits{x→∞} x^2\left(\ln\left(1 + \frac{1}{x}\right)- \frac{1}{x+1}\right) $$


This is a very basic sum of 5 floats. It's very obvious that the result is 1, so why does python shows me 0.9999999 when i print the result? sum([.25,.35,.3,.1,0]) # gives 0.999999(9)

Consider the following code:   0.1 + 0.2 == 0.3  ->  false   0.1 + 0.2         ->  0.30000000000000004   Why do these inaccuracies happen?


I answered one of my questions (see ) and accepted it but it randomly appears first or second (out of two answers).

What does it mean to accept an answer? How do I accept an answer, and what are the rules? Can I accept my own self-answer? What are the reputation benefits? Which answer should I accept? Should I upvote the accepted answer? What should I do if none of the answers are suitable?      For more information, see "" in the .


I have got a text box in WinForms which is just for entering phone numbers. how can I do it by just masking it. I have used if instruction but i want to use the mask. actually my biggest problem was that I didn't know even where is the mask text box.

I have a windows forms app with a textbox control that I want to only accept integer values. In the past I've done this kind of validation by overloading the KeyPress event and just removing characters which didn't fit the specification. I've looked at the MaskedTextBox control but I'd like a more general solution that could work with perhaps a regular expression, or depend on the values of other controls.  Ideally this would behave such that pressing a non numeric character would either produce no result or immediately provide the user with feedback about the invalid character.


After forcing strict firewall rules (deny everything) and creating following exceptions with ufw: To                         Action      From --                         ------      ---- OpenSSH                    ALLOW       Anywhere 22/tcp                     LIMIT       Anywhere 21/tcp                     ALLOW       Anywhere 990/tcp                    ALLOW       Anywhere 20/tcp                     ALLOW       Anywhere 989/tcp                    ALLOW       Anywhere OpenSSH (v6)               ALLOW       Anywhere (v6) 22/tcp (v6)                LIMIT       Anywhere (v6) 21/tcp (v6)                ALLOW       Anywhere (v6) 990/tcp (v6)               ALLOW       Anywhere (v6) 20/tcp (v6)                ALLOW       Anywhere (v6) 989/tcp (v6)               ALLOW       Anywhere (v6)  I'm still not able to log-in via ftp client such as FileZilla. Using ufw disable allows connection without problems. I bet there is some port I missed. There is vsftpd server running on the linux machine. Connection is done via explicit FTP over TLS. The log of the client when ufw is enabled is: Status: Connecting to xx.xx.... Status: Connection established, waiting for welcome message... Status: Initializing TLS... Status: Verifying certificate... Status: TLS connection established. Status: Server does not support non-ASCII characters. Status: Logged in Status: Retrieving directory listing... Command:    PWD Response:   257 "/" is the current directory Command:    TYPE I Response:   200 Switching to Binary mode. Command:    PASV Response:   227 Entering Passive Mode (85,255,3,229,40,216). Command:    LIST Error:  Connection timed out after 20 seconds of inactivity Error:  Failed to retrieve directory listing

I am trying to set up a local FTP server in my house. Whenever I connect to the account on the computer that hosts the server, everything works, but when I try connecting on another computer, the directory listing fails even though the account connection is successful. I have allowed port 21 TCP and UDP through the host's firewall and have added FileZilla Server to the list of programs allowed to communicate. How can I solve this?


This is what happened:   My desktop background changed 3 times at different times.   The change picture (every x time) option is disabled and I have always had it in that way.   When I selected a picture to be open, two more pictures were opened too.   I perfectly remember that I only choose one picture to be open. As a matter of fact, this event had never happened to me in my life. Also, think about this, what a "coincidence" that the same day that pictures are opened without requesting is the same day that my desktop background changes too.      There must be a reason because things don't happen just like that.   NOTES.   All the time when this happened, my mac didn't have connection to internet. Every once in a while I see a message on the upper RHS (in the corner of the screen) telling me that I should update something related to the system but I always click on later and then the message vanishes. User Allan said that , then what could possibly have happened?   Please tell me.  I think there must be a reason because things don't happen just like that.

Today when I turned on my macbook I could see that the Desktop Background has been changed to Yosemite picture. Then right after clicking on Change Desktop background... the background changed to the one I had, which was a green background with a dog in the center, except for the dog picture, it was only the green background. After this I clicked again on Change Desktop background... and it changed again to the Yosemite picture. Finally I went to finder file to see where the picture of the dog was, and when I clicked to see it, it was opened but at the same time 2 more pictures were opened. After all this, I clicked again on Change Desktop background... but nothing happened. The Yosemite background didn't change this time. All the time when this happened, my mac didn't have connection to internet. Why? Is my mac hacked? Does it have a virus? What do I do? Notes.  Every once in a while I see a message on the upper RHS (in the corner of the screen) telling me that I should update something related to the system but I always click on later and then the message vanishes.  Update More details of the situation above. 3 pictures were opened by itself at the same time. I did not chose to open 2 of them, had I chose them then they weren't be displayed in the way they did because there is a standard way when one open several pictures at once. There 3 pictures displayed like  if I were selected 1, then the other and then the other within milliseconds. That above plus the change of desktop background, it's 10000% strange. I know that is stupid to think that I am hacked but have I another option than to this so? So, how can I know if someone,  from another part in the world, is in my macbook? Footnote. Related question of mine


I can't possibly fathom this not being a duplicate, but I looked...  Two straight-forward questions that are extremely similar to each other (hence included in one post).  If they need to be separated that's fine.  1. What is allowed in a profile picture?  2. What is allowed in a profile description?  Maybe easier to answer in the form of what isn't allowed.  The ideal answer would be something referencing a living document.  An answer that doesn't get obsoleted over time and can be referred later, if needed.

Like always I hang around in Stack Overflow's chatrooms. Today, someone posted a link to his new "reloaded" user profile.  Along the lines I read in Arabic "god is a pig". So I asked him to remove it:     Me: I have a lot of respect towards you because of your knowledge but what you wrote there in Arabic is offensive. Could you remove it please?   OP: if it were in English, would it be equally offensive?   I will write it in Dutch because you ask it so kindly.   Me: yeah, I mean what's your goal? You're just seeding hatred   OP: It is an experiment.   After that, the user changed it to Dutch.  My question is: are such statements acceptable by Stack Exchange's standards? If not, should I flag one of his posts like stated ? If yes, could you state why?  My answers to possible questions:   This happened on SO, why don't you post it on MSO?   This happened on SO but I think it's applicable to all SE sites.  Why didn't you link the user or the chat conversation?   I want the user to remain anonymous unless he or she chooses to reveal him/her self. I will give the user a link to this question  Why do you care?   I find it offensive, not only to my religion but to any religion that believes in god. I posted this question to know what you guys and girls think about this. I live by the rules, so if it's acceptable by SE then so be it and I won't bother you again.  If you don't like it then move on.   I know that this is not a mosque/church/temple and that swearing  to a certain degree. But I don't see the point in insulting god, a religion or a race in a public profile. More over, it's not even built on arguments.


I am using a Acer Aspire One ZG5 netbook (1 gb ram) and it is currently running Microsoft Windows XP. I installed Ubuntu 14.04 LTS but it is not working properly and it takes a long time to open apps and browser. Please suggest me which version of Ubuntu will be best suitable for this  netbook.

For a given hardware configuration, how do I find out if Ubuntu will run on it? What considerations should I take into account when choosing an Ubuntu version and  such as:    with a lighter desktop than the usual Gnome and Unity  with the even lighter LXDE desktop   Obviously Ubuntu does not run on some processor architectures. So how do I go about choosing the right version and derivate. How can I find out the minmal system requirements?


So today I tried to run my old php website and it didn't work but I knew I installed php so I tried installing it again but couldn't.  It gave me this error:  hyperx@Hyperx:~$ sudo apt-get install php5 Reading package lists... Done Building dependency tree Reading state information... Done Package php5 is not available, but is referred to by another package. This may mean that the package is missing, has been obsoleted, or is only available from another source  E: Package 'php5' has no installation candidate hyperx@Hyperx:~$   Nor is mysql running. How could I fix that or install it?

What does the above Error mean? What is an installation candidate?  I was trying to do  sudo apt-get install munin-memcached     and I get this message:  Reading package lists... Done Building dependency tree        Reading state information... Done Package munin-memcached is not available, but is referred to by another package. This may mean that the package is missing, has been obsoleted, or is only available from another source E: Package munin-memcached has no installation candidate   I googled for the problem and someone said to do a apt-get upgrade but it still did not solve my problem.


Let $L$ be a Lie algebra and $\mathrm{Rad}(L)$ its unique maximal solvable ideal.     Problem: Show that if $B$ is a maximal solvable subalgebra of $L$ (i.e. a Borel subalgebra) then $\mathrm{Rad}(L)\subseteq B$.   I am not sure why. We know that $\mathrm{Rad}(L)$ is a solvable subalgebra, so it is contained in at least one maximal solvable subalgebra. But why all of them?

Let $L$ be a Lie algebra and let $B$ be a Borel subalgebra (a maximal solvable subalgebra) of $L$. I want to understand why $\operatorname{Rad} L \subseteq B$.   In his proof, Humphreys (Introduction to Lie Algebras and Representation Theory - pag 83) says that, since $B$ is a solvable subalgebra and $\operatorname{Rad}L$ is a solvable ideal of $L$, then $B+\operatorname{Rad}L$ is a solvable subalgebra.  Why should it be true? I know in general that the sum of two solvable ideal is a solvable ideal, but I don't know how to apply this in my situation. Thanks.


I have come with a problem with programming language. //php $a = (int) (10.20 * 100); echo $a;  // expected output: 1020 // output: 1019  # python int(10.20 * 100) # expected output: 1020 # output: 1019

Consider the following code:   0.1 + 0.2 == 0.3  ->  false   0.1 + 0.2         ->  0.30000000000000004   Why do these inaccuracies happen?


I rebooted my Amazon EC2 Linux Instance today, though Amazon's AWS website.  Now if I go to my website Safari says it can't find the server, AWS says my IP has stayed the same.  What is wrong here?  My website is  and my IP is 54.213.219.247  Thanks for your effort!

This is a  about Connection Refused    We see a lot of questions to the effect      When I try to connect to a system I get a message      Connection refused      Why is this ?


How can I extrude edges inwards and keep same distance for all exuded edges?  When I try to extrude (see pic 1) and press "s" all extruded edges have different offset from original (see pic 2) and I need extruded edges to have same offset distance from original. How can I do so?

I'm quite new to Blender, so forgive me if this is a dumb question. I don't even know hot to describe it properly, so:      Basically I want to extrude a rectangle and then scale it along two axis, but without keeping the proportions; I want to reduce them of the same quantity, so that I get something similar to the frame of a picture.


Can I use my 27" 2010 imac with mini display as a monitor with my new PC that has an HDMI and USB-C inputs? I bought a mini display to HDMI cable off Amazon and it did not work.

Recently (less than one year ago) i bought an iMac 21,5". Now i would like to use it as secondary monitor for my laptop. (My laptop runs Windows 7).  Is it possible? (I found conflicting opinions on the web, even on the Apple forum).  What type of cable do I need? (I will appreciate also a link to the product on some online store: amazon, ebay etc.)  Thank you in advance.  UPDATE:  I tried air display... i'm not satisfied at all...  typical scenario: browser window on the main Windows laptop, dev tools/firebug on the secondary iMac screen. The mouse goes fast between the 2 screens (GOOD), but when i changed the selected tab nothing happens. I had to drag the dev tools window to the main screen to get an update of the selected tab.  My test is ended here.  I'm still waiting for other answers.   I will prefer an answer that suggest me what kind of cable i've to buy, and where i can find it on the web.


i have the following python script:  import sys   text = "" while 1:     while 1:        c = sys.stdin.read(1)        text = text + c        if c == '\n':            break      print("Input: %s" % text)     print (text)     print ( text == 'Exit')     print(text)     if(text is "Exit"):         print('you have exited')         break     text = ''   The intent is to keep on printing words which user inputs, till the word he inputs is 'Exit'. But when i enter the word 'Exit' it doesn't break out of the outer while loop. Any idea why?

Given the following code (that doesn't work):  while True:     #snip: print out current state     while True:         ok = get_input("Is this ok? (y/n)")         if ok.lower() == "y": break 2 #this doesn't work :(         if ok.lower() == "n": break     #do more processing with menus and stuff   Is there a way to make this work? Or do I have do one check to break out of the input loop, then another, more limited, check in the outside loop to break out all together if the user is satisfied?


Friend suggested to type :(){ :|: & };: and pres enter on my Ubuntu machine's terminal and I did, it gave me output as number and system hanged forever. Could anyone help me understand why did this happen?

I was reading Ubuntu Forum's warning about malicious commands and found this interesting gem:  :(){ :|:& };: WARNING: The above code will crash your machine unless you have strict proc limits in place (which you probably don't) prompting a hard restart. Consider this code similar to running sudo rm -rf /.  But what does that mean? Even with my programming experience I've never seen a command that cryptic that's not assembly language.


I know complex numbers but what is the meaning of "complex" in "Complex Number"? Does "complex" mean "complicated here? Are complex numbers used in easy real world problems? Give me examples please.

I've always enjoyed solving problems in the complex numbers during my undergrad. However, I've always wondered where are they used and for what? In my domain (computer science) I've rarely seen it be used/applied and hence am curious.  So what practical applications of complex numbers exist and what are the ways in which complex  transformation helps address the problem that wasn't immediately addressable?  Way back in undergrad when I asked my professor this he mentioned that "the folks in mechanical and aerospace engineering use it a lot" but for what? (Don't other domains use it too?). I'm well aware of its use in Fourier analysis but that's the farthest I got to a 'real world application'. I'm sure that's not it.  PS: I'm not looking for the ability to make one problem easier to solve, but a bigger picture where the result of the complex analysis is used for something meaningful in the real world. A naive analogy is deciding the height of tower based on trigonometry. That's going from paper to the real world. Similarly, what is it that is analyzed in the complex world and the result is used in the real world without imaginaries clouding the problem?  The question:  is nice but covers a more mathematical perspective on interim results that make solving a problem easier. It covers different ground IMHO.


the mac book pro create many cron process.I deleted all cron tasks and it still not work and created many cron process.How to stop? if I ignore this problem,it would create thousands of processes and make my PC stuck.

EDIT: I solved this, so see below for my own answer. While the bounty asks for a fix to the problem, I'd like to award it to someone who can explain why a cron process that ran for 6 years over multiple MacOS versions suddenly became a problem in Catalina.  First note, this is not a duplicate of  because I don't have active crontabs on my computer. Cron processes spawn, but they never finish, so they just keep piling up. I'm running MacOS Catalina 10.15.1  Cron jobs are spawning every couple of minutes and never dying. The oldest cron process always has a parent process "launchd", and I've searched for populated crontabs and can't find any. If I let this go on long enough, eventually I run into a scenario where I have hundreds of running cron processes and everything on my computer grinds to a halt, and I can't even open new apps (I get cryptic messages like ".app cannot be opened" when I try to open an app). My only solution at this point has been to keep activity monitor open and periodically killing off all active cron processes.  I've been able to create a new user account that seems to be immune from this issue. However, as soon as I logged into my apple ID on that account to set up iCloud drive, the problem started with that account, too. I logged out of my Apple ID and attempted uninstall iCloud drive, but the problem persisted. Clean installs of Catalina don't clear up the problem, I've reset SMC and PRAM multiple times, and repairing permissions (via this ). I've also ensured that cron has full disk access (via this ). I'm at a dead end with trying to troubleshoot this problem.  I'm not sure it's related, but my "system.log" file seems to get spammed the following few lines:  <redacted> AMPDeviceDiscoveryAgent[2132]: Entered:_AMMuxedDeviceDisconnected, mux-device:63 <redacted> AMPDeviceDiscoveryAgent[2132]: Entered:__thr_AMMuxedDeviceDisconnected, mux-device:63 <redacted> AMPDeviceDiscoveryAgent[2132]: tid:9a27 - Mux ID not found in mapping dictionary   ANY help is appreciated.


String lines = "a,b,c"; List<String> letters = Arrays.asList(lines.split(","));  if (letters.get(0) == "a") {     //process     }  Tried to debug it and it seems like the conditional at the if statement doesn't get True, even if the first letter is exactly just "a" What did I do wrong?

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?