I want to play Fallout 4 and I found out I need 64bit system in order to play it, but I have 32bit system and I'm capable of upgrading.   Can I reinstall Windows without losing pictures and that stuff if I put them in D:\files or something like that?   I don't want to buy more storage just to save my files.   I also don't want to use Google drive or similar because I have a lot of pictures on my PC.

Possible Duplicate:          I'm getting a new PC soon and thinking that I'll start with Win 7/32 bit then upgrade later (if needed) to 64 bit and add RAM (beyond 4 GB).  Is this fairly easy to do?


HTML template   <div class="DataCollection">      //content..................................  </div>   CSS  .DataCollection{     height: 100vh;     width:100%;     padding: 15px;     position: absolute;     overflow: auto !important;     -webkit-overflow-scrolling: touch; }   how can i do this?

I am in process of implementing a native old HTML table (<table> ... </table>) in a Lightning Aura Component which will be rendered in native Salesforce Mobile App (historically known as Salesforce1). I cannot use  here as it is not supported in the app and that I also know this is not the best UX but there is a history to this why it all ended up this way. As the table itself has quite a few rows and columns thus I need both a vertical and horizontal scroll.  While I am able to get vertical scroll working using  but the horizontal scroll does not work consistently. Note that ui:scrollerWrapper does not support horizontal scroll as documented but the interesting fact here is that it actually works on Android devices and that on iOS it's hyper-sensitive. There's a  related to this behavior on horizontal scroll but doesn't seem to have been documented correctly as the issue refers using ui:scrollerWrapper whereas the docs mention that horizontal isn't supported at all.  Additionally, I am not able to use  as that's not compatible with Salesforce Mobile App either.  My current code looks as below:  Component  <ui:scrollerWrapper class="scrollerSize">     <table>      <!-- all stuff goes here -->     </table> </ui:scrollerWrapper>   CSS  .THIS .scrollerSize {     height: 100%;     width : 100%;     overflow : scroll;     border-radius: 1px; }   My question to the Community here is:     Has anyone been able to successfully implement a horizontal scroll in a HTML table on Salesforce Mobile App (as well as vertical scroll)? Either using standard available components or any other library that I can use?


How to find $gcd(5^{100}-1, 5^{120}-1)$? The problem is numbers are really big ($5^{100}$ is 70 digits).  None of the numbers is prime. I ran Euclid's algorithm on Python and found the answer in less than a second, however it seems that there is no on-paper approach to this problem, is it?


Let $\Bbb Q^+$ be the set of positive rational numbers. Find all solutions $f:\Bbb Q^+ \to \Bbb R$ of the functional equation $$ f(xy)=f(x)f(y), \quad x, y\in \Bbb Q. $$  Is $f(x)=x^a$ the only solution? If not, is it true if we assume that $f$ is continuous?

Let  $f(xy) =f(x)f(y)$ for all $x,y\geq 0$. Show that $f(x) = x^p$ for some $p$.    I am not very experienced with proof. If we let $g(x)=\log (f(x))$ then this is the same as  $g(xy) = g(x) + g(y)$   I looked up the hint and it says let $g(x) = \log f(a^x) $   The wikipedia page for functional equations only states the form of the solutions without proof.  Attempt  Using the hint (which was like pulling a rabbit out of the hat)  Restricting the codomain $f:(0,+\infty)\rightarrow (0,+\infty)$ so that we can define the real function $g(x) =  \log f(a^x)$ and we have $$g(x+y) = g(x)+ g(y)$$   i.e $g(x) = xg(1)$ as $g(x)$ is continuous (assuming $f$ is).  Letting $\log_a f(a) = p$ we get $f(a^x) =a^p $. I do not have a rigorous argument but I think I can conclude that $f(x) = x^p$ (please fill any holes or unspecified assumptions) Different solutions are invited


Why can't  be  $(\mathbb{Z}_5,+) $  isomorphic  to $U(R)$  for  some  rings $R$  where $U(R)$  is  the  unity  groups  of  $R$  ? Is important  that $(\mathbb{Z}_5,+)$ is  cyclic?

Let $R$ be a ring with unity. How can I prove that group of invertible elements of $R$ is never of order $5$?   My teacher told me and my colleagues that problem is very hard to solve. I would be glad if someone can provide me even a small hint because, at this point, I have no clue how to attack the problem.


I was solving past exam papers and stuck on the following problem:  Let $p$ be a prime number .Suppose $G$ be the group of all $2 \times 2$ matrix over $\Bbb Z_p$,with determinant $1$ under matrix multiplication. Then order of $G$ is which of the following :  $p(p-1)(p+1)$  $p^2(p-1)$  $p^3$  $p^2(p-1)+p$    Can someone explain it? Thanks and regards to all.

Let $\mathbb{F}_3$ be the field with three elements. Let $n\geq 1$. How many elements do the following groups have?   $\text{GL}_n(\mathbb{F}_3)$ $\text{SL}_n(\mathbb{F}_3)$   Here GL is the , the group of invertible n×n matrices, and SL is the , the group of n×n matrices with determinant 1.


I am new to SQL Server, can someone help me what is the significance of @ notation followed by name of variable? Like @OrderId ?

I was browsing through the questions and noticed this:  SELECT prodid, issue FROM Sales  WHERE custid = @custid  AND datesold = SELECT MAX(datesold)               FROM Sales s               WHERE s.prodid = Sales.prodid                   AND s.issue = Sales.issue                   AND s.custid = @custid   I was wondering what the "@" does in front of custID?  Is it just a way of referencing the custID from the table being selected?


I captured this picture from the movie A Beautiful Mind.  I see this is a problem solving for the dimension of a quotient space, so I guess $W$ is assumed to be a subspace of $V$, and let's also assume $V$ is a vector space over $\mathbb{Q}$.  I cannot figure out what $X$ is here. Also, how do I solve this?

I was watching the said movie the other night, and I started thinking about the equation posed by Nash in the movie.  More specifically, the one he said would take some students a lifetime to solve (obviously, an exaggeration).  Nonetheless, one can't say it's a simple problem.  Anyway, here it is  $$V = \{F:\mathbb{R^3}/X\rightarrow \mathbb{R^3} \text{ so } \hspace{1mm}\nabla \times F=0\}$$ $$W = \{F = \nabla g\}$$ $$\dim(V/W) = \; 8$$  I haven't actually attempted a solution myself to be honest, but I thought it would be an interesting question to pose. I have done a quick search on this site and Google, but there were surprisingly few results.   In any case, I was curious if anyone knew the answer aside from the trivial.


I currently finished my undergraduate studies and I plan to apply to PhD programs in the near future. In the mean time I will be starting a masters to get additional research experience and take some advanced courses in my field of interest. I plan to go into Condensed Matter Physics (CMP) and I plan to take masters courses in CMP and get research experience in CMP. During my undergrad I was a Physics and Mathematics major who had taken some classes in Engineering to get some "hands on" and "practical" experiences. I did well in these classes and learned a lot. During my time as an undergrad I also have taken some grad courses in physics; all but one were CMP-related or CMP pre-requisites and I did well in these as well. Although I did well in my Physics, Mathematics, and CMP-related classes, I originally wanted to go into a different area of Physics and so my last graduate class was in this non-CMP area. I found out during that semester that this area was not that interesting to me after all and that CMP was something I really enjoyed. This class was also stressing me out and was going to affect my performance in the other CMP-related classes I was taking. As a result, I decided to take this class as Pass/No-Credit (Covid Pass/No-Credit); this lowered my anxiety and I was able to do well in my other classes. In the end I performed well in my graduating class and received some honors and accolades from the university. During that semester it seemed to me that this was the right thing to do. Looking back now, I am wondering: will grad admissions frown upon the Pass/No-Credit in this non-CMP graduate course? Will they think I slacked off, or will my other classes counter this? Or should I not sweat it and move on?

I plan on doing a PhD in computational linguistics, which I intend to start in about 3 years. I have one more year of undergraduate study, and 5/6 of the courses remaining are for my minor in Applied Linguistics.  I plan on taking 2/6 of those classes as credit/no-credit (CR/NC) because I'm also working two jobs, and worst-case scenario I'll fall behind in these classes, but not so far behind that I wouldn't pass with 75% (and still receive credit).   that:     Admissions committees do not place as much weight on courses outside the major as courses in the major. If you are a physics major, for instance, a C in a US History course is not going to be as problematic as a C in electricity and magnetism.   These CR/NC courses are not in my majors (Computer Science and French), so I don't think that they would raise flags to admissions committees, but I also don't want admissions to think "oh he seriously slacked off his last year of undergrad!"  Do admissions committees care about CR/NC courses in undergrad?


The Dungeon Master's Guide classifies an immovable rod as a rod rather than a wondrous item. Does this imply that it is a valid spellcasting focus? If not, what purpose does this classification serve?

Reading the PHB chapter 5 equipment pg. 151. It describes an arcane focus as such:     Arcane Focus. An arcane focus is a special item — an orb, a crystal, a rod, a specially constructed staff, a wand like length of wood, or some similar item — designed to channel the power of arcane spells. A sorcerer, warlock, or wizard can use such an item as a spellcasting focus, as described in chapter 10.   Now I have been coming up with a dwarven war mage character concept, and was curious to know would it be allowed to have an arcane focus as warhammer?


We are using the classical machine-to-machine approach to connect to our DevHub to create scratch org, but in pre-release we need to connect to sandbox environments, which we would like to refresh nightly. Although the key associated to the connect app we use to sign the jwt is  not changed during sandbox refresh, the consumer id is changed every time we refresh the sandbox How can we get access to the sandbox after we have refreshed it, in CI/CD? If we have access to production, is there a way we can use it to get login access to sandbox?

I'm trying to connect to a sandbox using the sfdx cli and the JWT flow through force:auth:jwt:grant. According to , we can use the same connected app information from Production to connect to our Scratch Org.  Is it something that should work for sandbox too ? I'm getting a "Failed: Not approved" error.  Connected app in sandbox comes from the refresh but has a different consumer key. The Permission set is set correctly on my user.  Is there a way to connect to a recently refreshed sandbox using the JWT flow (without manually changing something like the consumer key) ?


Wrote text in an rtl language (from the  you can see it is done with good reason). I then tried to make bold one letter within the word, while making the entire word in italics -> example.  As you can see, it's actually not connected to the orientation of the language.

There are tons of questions I could maybe post this as an answer to, but before choosing the best one, I'll just post this as an announcement question that can be linked elsewhere. The short story From now on, intra-word emphasis is possible in our Markdown version. That means you can now write  The "V" is for Model**View**Controller. That's un*fricking*believable.  and it renders like this:  The "V" is for ModelViewController. That's unfrickingbelievable.  This only works for asterisks, not for underscores. It works in posts and comments. The reasons There are two big reasons for this. For one thing, this is more or less the behavior of , which we eventually . "More or less" because CommonMark's emphasis behavior is still in flux, and supports a few things that we don't support yet, but at least with this change we're closer. The other reason is languages that don't even have the concept of "words separated by spaces". See  and  for two examples. This change allow posts in those languages to emphasize words without having to resort to HTML tags. To use an example from the first linked post,  **北京**和**上海**是直辖市。   now renders like this:  北京和上海是直辖市。  Possible issues In the 99% cases, this should only make things better; I've only found very few posts where this change causes unintended bolding/italicizing. And even in those cases, note that the rendered versions of questions and answers are not re-rendered until a post is edited, so this will not affect anything in posts retroactively. Unlike posts, comments are rendered , so this immediately applies to all comments. In most cases this doesn't change anything or actually fixes things. Should you discover a rare case where this breaks an important comment badly, we can always edit it to fix. There's one side effect that I'd like to mention: If you find a great quicksort implementation on GitHub that has a bug that causes a crash when sorting Windows versions, and the author doesn't want to fix it, you may be inclined to say  f**k this s**t   (i.e., "fork this sort"). With intraword emphasis, this would however look like this:  fk this st  So you would have to escape the asterisks (one of them would actually be enough). I'm not worried about this case too much, since if you must put censor-worthy words into a post, you might as well have to jump through a little hoop. Some details This being Meta, there are probably lots of people interested in a more detailed description of the new behavior (don't feel bad if you're not one of them; just skip this section). Here are the major rules regarding intraword-emphasis:  As mentioned, it only applies to asterisks, not underscores. Underscores  this restriction was in place at all; asterisks are much less of a problem.  If a single or double asterisk is supposed to be interpreted as intra-word emphasis, it cannot have punctuation on one side; it actually must be inside a word. An example of an edge case this solves is  It's a web*-based solution. *see Wikipedia for a definition of "web"  where the asterisks after "web" could cause unintended italicizing if there was a second asterisk in the same paragraph somewhere.  For italics, the "inside a word" part of rule 2 is even a bit stricter. For bolding, any word or digit character is allowed; for italics, digits don't work either. That's because the asterisk is often used as a multiplication symbol, so  The game worked in 320200 and 640480 resolution.  wouldn't look right without this restriction.  A minor addition that I made that's only tangentially related to intra-word emphasis is that a sequence of more than three underscores or more than three asterisks will no longer take part in any emphasis. This shouldn't really cause any problems, but fixes some (e.g. the underline in the second blockquote in , while not really visible, is a weird combination of bold and italic underscore characters; after this change, it would just be (more) underscore characters). This behavior also matches CommonMark.


I cannot count how many times I missed my meetings appointment because I Was so deep into my programming work. I wonder if anyone has a quick/easy solution where it will halt my entire monitor red (or something like that) x minutes prior to the meetings. I think I tried to write a VBA that will be bright and grand so I won't missed it but I failed to have it working.   my issues with the default outlook reminder is that it can easily goes to the background unnoticed. I need it to be more "in your face" alert if possible  I used both outlook 2010 and outlook 2013.  both have exactly the same reminder behaviour.  Any tips from the pros?  Thank you

I'm just starting to use Windows 7 and I want to know how to make my Outlook reminders pop up and show themselves prominently.  They keep opening discreetly, as just another window in the Outlook stack on the taskbar.  As a result, I keep overlooking them because they pop up behind everything else.  How do I make them less easy to overlook?  (Clearly, one usually doesn't want obnoxious apps that push themselves to the forefront.  But there are a few places where such behavior is desirable, and Outlook calendar reminders are one of them.)


"It was almost midnight when i reached home" .  in this sentence " home" funtion as  noun or adverb.  kindly clarify

In this sentence:     Ben and Jen went home.    Is home both an adverb and a noun?


By definition, $i^2=-1$, right?  But one can then clearly deduce that $(-i)^2=-1$.  The only difference I see is that one is $-1$ times the second.  So what allows us to differentiate between $i$ and $-i$?  Can they be used synonymous?  That is, does nothing happen if all of a sudden we were to switch $i$ and $-i$ in math, so long as we are consistent?

Suppose now we are trying to explain to students who do not know complex numbers, how do we distinguish $i$ and $-i$ to them? They will object that they both squared to $-1$ and thus they are indistinguishable. Is there a way of explaining this in an elementary way without go into introductory things in complex analysis?


I just replaced my motherboard, and now my Windows hard drive (secondary) seems not to be detected. I'm running Ubuntu 16.04 on my main hard drive and Windows 10 on my 2nd.

I installed Windows 7, which ate Ubuntu's boot file. When starting up the computer, it now goes straight to Windows, without giving me the option of booting Ubuntu.   How can I get Ubuntu back?


I got my laptop two days ago, a Dell G5-5587, at it came with Linux Ubuntu 16.04. It's my first time with this OS.   My problem came when I tried to change the Linux dash to a dock with GNOME. I installed the gnome tweek tool and the Firefox extension to enable the "Dash to Dock" extension, but when I go into  it shows   Unable to locate GNOME Shell settings or version. Make sure it is installed and running.   Also when I go into the preference menu of the GNOME shell integration firefox extension it displays  GDBus.Error:org.freedesktop.DBus.Error.UnknownMethod: No such interface 'org.gnome.Shell.Extensions' on object at path /org/gnome/Shell   Moreover, I also removed the Unity tweek tool and packages. I would be incredibly grateful if somebody could help me with this!

Today I saw an article about extensions for GNOME Shell, so it got me thinking a couple of questions that may apply to many users in Unity:   Will the GNOME Shell extensions be compatible with Unity? Can I install them directly to Unity from the  website? In case 2 is NO, is there a similar idea for Unity in the works?


In Chapter Thirty-Six of Deathly Hallows we have the following passage:  The house-elves of Hogwarts swarmed into the entrance hall, screaming and waving carving knives and cleavers, and at their head, the locket of Regulus Black bouncing on his chest, was Kreacher, his bullfrog's voice audible even above this din: "Fight! Fight! Fight for my Master, defender of house-elves! Fight the Dark Lord, in the name of brave Regulus! Fight!" They were hacking and stabbing at the ankles and shins of Death Eaters, their tiny faces alive with malice, and everywhere Harry looked Death Eaters were folding under sheer weight of numbers, overcome by spells, dragging arrows from wounds, stabbed in the leg by elves, or else simply attempting to escape, but swallowed by the oncoming horde.  It is well established that house-elves are capable of combative magic. For example, in Chapter Twenty-Three of Deathly Hallows Dobby is able to easily disarm Narcissa:  “Dobby!” she screamed and even Bellatrix froze. “You! You dropped the chandelier – ?” The tiny elf trotted into the room, his shaking finger pointing at his old mistress. “You must not hurt Harry Potter,” he squeaked. “Kill him, Cissy!” shrieked Bellatrix, but there was another loud crack, and Narcissa’s wand too flew into the air and landed on the other side of the room.  And in Chapter Eighteen of Chamber of Secrets he was able to throw Lucius backward:  But Dobby shouted, "You shall not harm Harry Potter!" There was a loud bang, and Mr. Malfoy was thrown backward.  Why, then, did the elves at Hogwarts resort to crude Muggle tactics when they could have been disarming Death Eaters, throwing them around, and who knows what else?

The house-elves can do some pretty good magic, so why at the Battle of Hogwarts do they chose to use knifes and cleavers? I assume they use magic to get out the kitchen      The centaurs Bane, Ronan and Magorian burst into the Hall with a great clatter of hooves, as behind Harry the door that led to the kitchens was blasted off its hinges1. The house-elves of Hogwarts swarmed into the Entrance Hall, screaming and waving carving knives and cleavers, and at their head, the locket of Regulus Black bouncing on his chest, was Kreacher, his bullfrog’s voice audible even above this din: ‘Fight! Fight! Fight for my master, defender of house-elves!2   Why the reliance on basic weapons?    1. Not sure why they don't apparate at this point  2. This is my favourite part of all of the Harry Potter series


I am currently writing a Java Application, that needs to filter the name of the Program whichs UI is front. Sorry for my bad english. So let's say the Java App is running in Background and I open Windows -> Games -> Minesweeper then i want the App to only tell me "Active: Minesweeper". Without any additional information. Just the name "Minesweeper"  I already tried using JavaNativeAccess but I'm still unfamiliar with it.  Thanks you all in advance

Does any one know how do I get the current open windows or process of a local machine using Java?    What I'm trying to do is: list the current open task, windows or process open, like in  Windows Taskmanager, but using a multi-platform approach - using only Java if it's possible.


Assume $f$ is Riemann integrable on $[0,1]$ and continuous at $x = 0$. Show that $\lim\limits_{t \to 0^+} \int^1_0 tx^{t−1}f(x)dx=f(0)$.   Hints are welcome.

Suppose $f$ is Riemann integrable on $[0,1]$ and continuous at 0. Show that $$\lim\limits_{a \to 0^+} \int^1_0 ax^{a−1}f(x)dx=f(0).$$   Can anyone share some insight on this one? I have no idea where to begin. Maybe a substitution?


I really need some help regarding rendering a night scene. When i tick the denoising option. My render become ugly where there is a black dirt on the image. As in the image below.   And if i untick the denoising option. There will be a lot of noise in the scene.   How should i really render this kind of scene. Hope anyone can help me. And sorry for my bad english.

I know that this question is a bit old or maybe overdone, but I'm running the latest edition of Blender and when I use the Cycles engine I get really fuzzy results and I can't find a simple, non-compromising solution to the quality.  I don't know exactly what I'm doing wrong here, but I'm sure others share my frustration.  Leaving everything in default settings, I started a new project and switched to the Cycles render.  I duplicated the cube and set colors for two Diffuse BSDF shaders, then went ahead and made walls and a floor all sharing the same diffuse shader.  I made two windows to emit blue light.  The screenshot has gaps between the walls because of the setup:  I'm aware that it's considered very incomplete and many have come to terms with some amount of noise, but is this normal?  Furthermore, with default settings or not, I can't change the amount of noise produced.  Supposedly, using "progressively refine" in the rendering tab should make it refine itself indefinitely, however Cycles only counts to 10 refines and then stops, creating a render which is a pixel-perfect match of the ordinary rendering method when it's completed.  I understand that there are tricks that can be used to reduce noise, but at the cost of extra processing time and usually small quality conflicts, like blurring.  My question essentially boils down to is this Cycles' current limit?


I am a PhD student in computer science and have submitted a paper to a conference which details my proposed architecture. However in the month or so since this paper has been submitted my architecture has undergone changes (relatively major), how is this normally dealt with?  If the paper is accepted do I present the work as it was at the time of submission or do I openly state that changes have been made and present the updated version of the architecture?

My paper is accepted in one of the Taylor and Francis journals and Today I figured out that I made a mistake in one row of one of my tables ( the minimum of one of variables in statistic analysis table is 0 in the paper but the actual value is 1). In fact, it does not affect the other parts of paper and the verification part.   Editor will provide the proofread of my paper in a week.  My question is, Will the editor give me a chance to edit the paper again? or he will change the grammatical problems his self?  And if I ask the editor to correct that row of paper, will he give the paper to reviewers again? I am worried that if I ask him to correct that mistake, he ask the reviewers to review my paper again. I need my paper to be published soon.


Let $A$ be nonempty, compact. Then, $\sup A$ and $\inf A$ exist are elements of $A$.  Pf. By Heine-Borel, $A$ is closed and bounded. By the completeness axiom, a bounded set of the reals has a sup and inf, so we have existence.  I'm not sure how to show they're actually elements in $A$. I know I can choose $x_n\in A$ with $x_{n_k}\rightarrow x$ where $x\in A$ by compactness, but I'm not sure how to guarantee that $x=\sup A$ or $x=\inf A$.

Prove if nonempty $K \subset \mathbb{R}$ is compact, then both sup $K$ and inf $K$ exist and are elements of $K$.   I manage to prove the existence of sup $K$ by using the Axiom of Completeness. But I failed to prove that $\sup K \in K$. Can anyone guide me ?


I need help jogging my memory about a low budget science fiction film (or perhaps TV series) from the late 1970s or early 1980s.  The first scene of the movie depicts the characters on a disabled luxury cruise ship stranded in space. That's all I remember. I don't think it's Battlestar Galactica or Buck Rogers.

I need help identyfying this movie I once saw late night on TNT, late 90s or early 2000s.  I don't have very clear recollection about it. The movie was very strange. It all took place in a single room of a spaceship or an escape pod that had lost power. A woman and a man, or several men, were stuck in a ship or a spacepod that was somehow damaged or didn't have power.   The movie was entirely made of the dialogs between the woman and the man (or men). They would talk about what was happening outside, how to contact help, about their lives. During their conversation details about the world around them emerge. In this movie people have colonized the solar system but not moved outside it, and there is some sort of a war.  Other things I remember are that it was dark in that room. I think they used only a lightbulb or even direct starlight and sunlight (if they were far away from the sun), because there was no power. Also it was getting colder, becaus the ship's heating system was not functioning, and so it was losing its heat. The people would constantly complain about how cold it's getting. I think that the woman was the captain of the ship. She would sometimes go to the control cabin and try to do something to help their situation, either restore power or contact someone so they can be rescued.  What impressed me about it was how they managed to make it realistic. Because the actors would talk and act like it was all real, it made it somehow feel very realistic to me as well.  That's about it as far as I remember. Hope someone has watched this movie and can tell me what it is.  Update  I want to add a few more details about the movie. While I watched it in the late 90s/early 2000s the movie looked much older. It looked like a vintage B-Movie made in the style of the 70s or 80s. In particular the decor looked more like Alien 1 or Cosmos 1999.   I just watched the firefly episode and it can't be it. It has too much action, and the atmosphere is not dark enough.


I just stumbled across the problem and have no idea how to solve it: "Considering the Time-Independent Schrodinger Equation for a stationary state $\psi$ with energy $E$, that is $$\psi '' = \frac{2m}{\hbar ^2 }(V(x)-E)\psi,$$ prove that $E$ must exceed the minimum value of the potential, by noting that $E=\left\langle H \right\rangle $" My attempt: We assume firstly that $E<\min(V(x))$, and thus $V(x)-E>0$ for all $x$. Thus if define $\frac{2m}{\hbar ^2 }(V(x)-E) = A(x)>0$, as all the terms in the function are positive, we get: $$\psi '' = A(x)\psi$$ Since $A(x)>0$, we know that $\psi ''$ and $\psi$ have the same sign. I don't know where to go from here. Haven't even used the fact that $E=\left\langle H \right\rangle $. Any help would be appreciated!

Suppose we have a particle of mass $m$ that is in an eigenstate $|\psi\rangle$ of the Hamiltonian $\hat{H}=\hat{T}+\hat{V}$, where $\hat{T}$ is the kinetic energy operator and $\hat{V}=V(\hat{r})$ is the potential energy operator. If the potential has lower bound $V_0$, then is it necessary for the energy eigenvalue $E$ of $|\psi\rangle$ to be greater than $V_0$? Classically this is true, since we regard negative kinetic energy as physically unrealizable/meaningless. However, I don't know if I can necessarily say the same in the quantum case. For example, what I'm tempted to do is write  $$\langle\psi | \hat{T}|\psi \rangle = \langle\psi | E-\hat{V}|\psi\rangle$$  and say "If $E<V_0$, then the RHS is necessarily negative, implying the LHS is as well, which we will regard as physically meaningless. If $E=V_0$, then $|\psi\rangle$ is trivial.", but I'm not sure if that's right.   Confused by that, I then wanted to show that, if $E< V_0$, then a non-trivial $|\psi\rangle$ is non-normalizable. However, I'm not entirely sure how to do this.


Okay so this is a pretty famous statement made to anyone who is introduced to the magnetic effects of electric current a.k.a. electromagnetism:  The relative strength of the magnetic field is shown by the degree of closeness of the field lines.  But it never made sense to me so I dropped the idea of studying e.m. deeply and just overviewed it superficially and somehow managed to pass the exam and moved to the next class. It's not until recently that I realised that we have the same chapter again in highschool graduation so I thought I'd better ask. Yeah so we were told that field lines arise from north pole of a magnet and are closed curves going "into" the south pole (and run parallel to each other inside the magnet?) Then there's that statement. Out teacher drew small equal-area boxes showing that the one's "near" the poles contain in themselves more field lines than the ones farther apart(ring a bell?). But isn't it like every point in space has a field line passing through it? I mean there is exactly just as much "space" (or 2 dimensionally, area) in the other box as is in the first one. There can't be regions having no magnetic field in-between those lines? Isn't it kinda wrong?

When we're dealing with problems in electrostatics (especially when we use Gauss' law) we often refer to the density of electric , which is inversely proportional to the radius in the case of a single point charge (all field lines are directed radially).   My question may sound dumb, despite the fact that this concept is quite intuitive, but if you think about it there is actually an infinite amount of field lines which we can draw everywhere (one through every point), so speaking of an area where field lines are more "dense" or "sparse" doesn't make much sense to me.  With this in mind, why can we still use such a concept? Why does it really work?


I have the code below which creates a button and registers an event on it.When a button is clicked it writes a data into .csv file.The getFullName() etc methods return JTexField.getText(). When ALL of JTextFields I mean every single JTextFields are filled with user input then writeDataIntoFile() is called otherwise it returns a message "Empty fields left". The problem is If I fill only getFullName() - reference of JTextField, writeDataIntoFile() is getting called. Any suggestions how to fix this?           JButton registBtn = new JButton("register");         add(registBtn);          registBtn.addActionListener(new ActionListener() {          @Override         public void actionPerformed(ActionEvent evt) {                 try {                      if (getFullName() != ("") && getRegNum() != ("") &&  //It doesnt matter if i use .equils()                         getItemName() != ("") && getNote() != (""))                     {                            writeDataIntoFile();            }                     else                            {                             JOptionPane.showMessageDialog(null, "Empty fields left.Please fill");                           }                 } catch (IOException ex) {                     System.out.Println("E), ex);                 }                }         });

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 have two big datasets of different species. One shp is point which shows the location of species, and the other file is in polygon of same places and has got attribute table of public and free holds. I wanted to see how many percentage of the first one (point shp) is in free hold and how many is in public hold?

I am trying to create a grid road map with an index table for street look up.  I am using this tutorial by ESRI:   I am at the step whereby I am supposed to spatially join a point file (centroid point for each label) to a grid (which has the grid ID):      The next step is to use the Spatial Join tool (one to many is the join   option) and join the annotation to each grid cell they fall within.    However, you will likely not want to work directly with the annotation   because the spatial join options for “contains” or “within” will not   include any annotation that overlaps more than one grid cell. Further,   the “intersects” option will create duplicate entries in the same   circumstances. To get around that convert the annotation to point   features using the Feature to Point tool (Important note: I had to   delete the Element field; the type is blob, the field isn’t needed,   but if it’s there, the tool won’t run).   It seems to be telling me to spatially join the points to the grid in order to match up each label point with its grid ID value. However, whenever I spatially join, the output table is empty.   Any advice? I simply need to find a way to extract the grid ID of where the points falls within the grid.     I've included a photo of the spatial join parameters. After the process runs, it simply spits out a new shapefile with no features and an empty attribute table.


How can I make sed not append a newline character to an input stream that was missing one? If I can't, what's the quickest way to remove a newline character from a variable?  A code sample was requested in the comments, so here you go. Imagine a .csv file that has no newline at the end. Pipe it into a script.   Then inside that script:  function foobarize() {     sed \     -e "s|foo|bar|g" \     $1 }  INPUT=`tee` printf "$INPUT" | foobarize   If the input has no newline at the end, foobarize will add a newline to it 100% of the time.

I am running the following 2 sed commands. The first one adds newline characters where I want them, the second also adds newline characters where I want them, BUT also adds an extra one at the end of the file where there wasn't one before.  sed -e 's|\<LIST_G_STATEMENT>|&\ |g' ${XMLDIR}/statement_tmp_1.xml > ${XMLDIR}/statement_tmp_2.xml  sed -e 's|\</LIST_G_STATEMENT>|&\ |g' ${XMLDIR}/statement_tmp_2.xml > ${XMLDIR}/statement_tmp_3.xml   Using od -c on all 3 of the files gives the following output.  statement_tmp_1.xml (no \n at end of file)  1314700    T   A   T   E   M   E   N   T   >   <   /   L   I   S   T   _ 1314720    G   _   S   T   A   T   E   M   E   N   T   >   <   /   G   _ 1314740    S   E   T   U   P   >   <   /   L   I   S   T   _   G   _   S 1314760    E   T   U   P   >   <   /   A   R   X   S   G   P   O   > 1314777   statement_tmp_2.xml (no \n at end of file)  1314700    S   T   A   T   E   M   E   N   T   >   <   /   L   I   S   T 1314720    _   G   _   S   T   A   T   E   M   E   N   T   >   <   /   G 1314740    _   S   E   T   U   P   >   <   /   L   I   S   T   _   G   _ 1314760    S   E   T   U   P   >   <   /   A   R   X   S   G   P   O   > 1315000   statement_tmp_3.xml (\n at end of file - where did it come from?)  1314700    S   T   A   T   E   M   E   N   T   >   <   /   L   I   S   T 1314720    _   G   _   S   T   A   T   E   M   E   N   T   >  \n   <   / 1314740    G   _   S   E   T   U   P   >   <   /   L   I   S   T   _   G 1314760    _   S   E   T   U   P   >   <   /   A   R   X   S   G   P   O 1315000    >  \n 1315002   I am running AIX 5.3  Basically, I either want it to stop adding the extra \n, or find a way of removing it.


This is a meta question and personally, I think the answer should be on the footer of EVERY PAGE.  What is the process I ought to follow if I feel a question is of a dubious or unethical nature?  I did a few quick searches and found nothing obvious.  Considering the content of this family of web sites; it might be good to sometimes to nominate questions some vetting and perhaps ask for the use-case or application.  Like what if I asked, "how to programmatically coordinate multiple helicopter drones to converge on the New York Twin Towers in 1998?"    I'd like to imagine that kind of question gets bumped to some kind of "use case review" meta-management role to just ask the errant quester:   "Why did you ask?" or  "What will you use it for?"   I'm naive perhaps, not yet dumb.

How should we treat questions that are, or have seeds of, evil or malicious purposes and actions, such as writing spambots and malware?    Should they be answered like regular "everybody keeps their pants on" questions? Or should there be some other type of response to this bad behaviour lot?


This question  states that you require 10 reputation to be able to post an answer.  According to the site header bar, I currently have 101 reputation on the site (1 + 100 for association bonus).  Does the 10 reputation required not include the association bonus?  edit: My attempt to ask the question was via the API to test that posting answers would work.  I have not tested doing so directly from the website.

I tried to post an answer in the   I got this:    ...but I am able to  in the formatting sandbox    ...and I have more than 10 rep on MSE:    One needs 10 reputation to post an answer in a protected post, but I have more than 10, and I am allowed to post comments, which is a 50 rep privilege.  Then why am I not allowed to post an answer in the formatting sandbox?


Can anyone let me know the difference between SHA1 and SHA1HMAC algo?

On a  it became apparent that there's a significant difference between an HMAC of input data and a hash of input data.   What exactly is the difference between an HMAC and a hash of a span of input data?


How many integer solutions of $x_1$ + $x_2$ + $x_3$ + $x_4$ = 28 are there with  (a) 0 ≤ $x_i$ ≤ 12?  (b) −10 ≤ $x_i$ ≤ 20?  (c) 0 ≤ $x_i$, $x_1$ ≤ 6, $x_2$ ≤ 10, $x_3$ ≤ 15, $x_4$ ≤ 21?  I have tried.  a) To count the compliment value, so (31 choose 3) -  (15 choose 3)  b) Not quite sure where to begin  c) (31 choose 3)-(24 choose 3)-(18 choose 3)- (13 choose 3)- (9 choose 3)

How many integer solutions of $x_1 + x_2 + x_3 + x_4 = 28$ are there with:  (a) $0 ≤ x_i ≤ 12$?  (b) $−10 ≤ x_i ≤ 20$?  (c) $0 ≤ x_i, x_1 ≤ 6, x_2 ≤ 10, x_3 ≤ 15, x_4 ≤ 21$?  \ \  My attempts (I was really only able to solve part (a) but I would appreciate if you could check my work for this one as well):  (a) First I took the total number of integer solutions with no restrictions: There would be ${28+3\choose 3}$ = ${31\choose 3}$ total solutions with no restrictions.   Then I used the inclusion exclusion principle and knew I would have to subtract [P(A) + P(B) + P(C) + P(D)] where A --> $x_1$ is greater than or equal to 13, ..., D--> $x_4$ is greater than or equal to 13. The probabilities of all these cases would equal ${15+3\choose 3}$ = ${18\choose 3}$ because once we assign 13 to one of the $x_i$ there would be $28 - 13 = 15$ remaining to distribute among the $x_i$ values. We would also need to choose which of the $x_i$ to give the 13 to so we would multiply the ${18\choose 3}$ by ${4\choose 1}$ = ${4\choose 1}{18\choose 3}$  We would then have to add back, since we "oversubtracted", the case in which there is an intersection between two of the $x_i$ or in other words two of the $x_i$ receive 13 or more. P$(A\bigcap B)$ = $28-2(13) = 2$ remaining to distribute among the $x_i$ values. So we would also have to choose which of the $x_i$ to give the 13 to so we would have ${4\choose 2}$ ways to choose them. So there would be ${4\choose 2}{2+3\choose 3}$ = ${4\choose 2}{5\choose 3}$ solutions in this case.   Thus the number of solutions would be: ${31\choose 3} - {4\choose 1}{18\choose 3} + {4\choose 2}{5\choose 3}$.  I'm not sure if this is correct and I'm really stuck on b and c so I would appreciate any help or feedback. Thank you!


Example: a Druid and his party decide to go get rid of an orc tribe. The weather is currently clear, with no precipitation. If the party succeeds in clearing the orc tribe, the Druid will use control weather to make it rain heavily. If they don't, he'll not change the weather.  Is it possible to tell if a given event will succeed by using this trick?

If Druidcraft can predict a location's weather for the next 24 hours, would it note weird weather caused by Control Weather, such as a sudden storm at midday on an otherwise clear and cloudless day? Or would only naturally occurring weather be predicted?  I predict the matter will come up at our next game session (my friends like to exploit loopholes, but in good fun) so I'm hoping to be prepared for the inevitable. I read the answer to "", but my question is more specific than that question answers.


Prove that: $$\sum _{k=0}^{n}{{(-1)}^{k}\binom n k}=0$$  I tried with induction and failed.  A solution explain would be greatly appreciated.

Show that $$\sum_{k=0}^n(-1)^k\binom nk=0$$ So for odd $n$ we have an even number of terms. So $\binom nk=\binom n{n-k}$ which have opposite signs. Thus the sum is 0.  For even $n$ we have that $$\sum_{k=0}^n(-1)^k\binom nk= \binom n0+\sum_{k=1}^{n-1}(-1)^k\binom nk+\binom nn$$ Now $$\sum_{k=1}^{n-1}(-1)^k\binom nk= \sum_{k=1}^{n-1}(-1)^k\left[\binom{n-1}k+\binom{n-1}{k-1}\right]$$ What would that sum be in the square brackets?


For example say I am using a WHERE clause and I would like to see the iteration happen without changing it to an iterated loop.  In Visual Studio 2012 or higher for checking lambda function iterations.

I have a Linq to objects statement   var confirm = from l in lines.Lines   where (l.LineNumber == startline.LineNumber) || (l.LineNumber == endline.LineNumber)   select l;   The confirm object is returning an 'Object Null or Not A Reference' at at System.Linq.Enumerable.WhereListIterator`1.MoveNext()  If the result of the query was empty, it would just return an empty enumerator. I know for a fact that there are no null objects in the statement. Is it possible to step through the LINQ statement to see where it is falling over?  EDIT When I said I know for a fact that there are no null objects it turns out I was lying :[, but the question remains, though I am asuming the answer will be 'you can't really'  LINQPad is a good idea, I used it to teach myself LINQ, but I may start looking at it again as a debug / slash and burn style tool


I have tried to update my Ubuntu version and after updating, my boot screen is displaying a kernel panic message and I'm unable to access my login screen.    I was upgrading my ubuntu from 19.10 to 20.04, please let me know the kernal names and steps to access ubuntu again.


I am a junior computer science major at Western Kentucky University. I want to make use of Stack Exchange and sites like it to let my future employers know that I know what I'm doing. Unfortunately I have realized that there is an almost vertical learning curve when starting out on this site.  Here are my reasons:   I have owned a Stack Overflow account for months now and I can't build my reputation above 13 There are so many people answering the easier questions that I know before I have the chance The questions that go through the general feed of 'new questions' or 'hot questions' are way over my head. When I do answer a question I have yet to get any credit for my contribution due to the negligence of the inquisitor to accept an answer.   What I'm suggesting is that there be a site for more basic questions. Maybe a Learning/Tutoring site where people who are asking more basic questions can have them answered by people who are closer to their level of knowledge.  This site would also give new Stack Overflow members a chance to get some reputation and learn how to tread water before having to jump into the ocean.  Ultimately I would like this site to do what I believe is the point of these Stack exchange sites. Make it easy to learn and share knowledge.  Does anyone have any advice or is there anybody who can make this happen?

SO has helped me so much in times of need. It is crazy - sometimes I am having a huge issue with a program I'm working on at school or work, and I post it on SO and the answers come quickly and easily. Lots of time it's a typo, while others it's a deep misunderstanding of mine. I wonder how I can fit in here at Stack Overflow. How I can contribute. In fact, I feel such a “beginner”, I don't even know where to look half the time. But I see there is now a place for /Programmers/ which leads me to wonder if there can be a site for beginners - and strictly beginners. Beginners post in Stack Overflow, and only beginners can post answers. Meaning, you must ask a question in the beginners forum in order to answer one. Or something, I'm not sure, I just want a place to connect with others who are just starting out how to learn about programming, and want to get the chance to answer other beginner questions so I can learn more (you learn 40% of what you do and 90% of what you teach). What do you all think about this?


I am trying to show that $R=\Bbb Z[x,y,z,w]/(xw-zy)$ is not a UFD.    Let $I=(xw-zy)$.  Let $X=x+I$, $Y=y+I$, $Z=z+I$, and $W=w+I$. My guess is that $X$ is irreducible and therefore $(X)$ is a prime ideal. Now, $XW=ZY$, so that $ZY\in(X)$. I want to show that $Z,Y\notin(X)$ and conclude that $R$ is not a UFD.  However, I cannot confirm my guess because I don't even know how $R$ looks like and how to find an argument to show $X$ is irreducible. I think it suffices to prove that $X$ is irreducible. If it is so, the argument can be applied to $Y$, $Z$, and $W$. Therefore, $Z,Y\notin(X)$.  Any help?

I want to show that $k[x,y,z,w]/(xy-zw)$, the coordinate ring of $V(xy-zw)\subset\mathbb{A}^4$, is not a unique factorization domain.    Morally, all we need to do is find some nonzero element that can be written in two distinct ways as a product of irreducible elements, but nothing is coming to mind immediately. Thoughts?


I know of bc:  $> var="304" $> echo "obase=2; $var" | bc 100110000   Could it be done in shell (no external call)?  This question:  Asks how to convert FROM binary, not TO a binary number.  The answers there deal either with binary byte (as opposed to binary number, i.e.: a base-2 number) using xxd, or some other external tool. So, no, this question is not a duplicate of that.

I have a context where I need to convert binary to hexadecimal and decimal and viceversa in a shell script. Can someone suggest me a tool for this?


I can't play any video at Dailymotion in Chromium web browser in Ubuntu 16.04. The warning says Whoops! Looks like we can't play this video in this browser. Also the videos from Facebook and Twitter are not being played -- there it says "couldn't load plug-in" / "The media could not be played". I have tried many solutions available on the web, but nothing is working.   Results of running sudo apt-get update and sudo apt-get install adobe-flashplugin    :~$ sudo apt-get update   Err:11 ppa.launchpad.net/skunk/pepper-flash/ubuntu xenial/main i386 Packages 404 Not Found  E: Failed to fetch ppa.launchpad.net/skunk/pepper-flash/ubuntu/dists/xenial/main/… 404 Not Found  E: Some index files failed to download. They have been ignored, or old ones used instead.   :~$ sudo apt-get install adobe-flashplugin  Reading package lists... Done  Building dependency tree  Reading state information... Done  adobe-flashplugin is already the newest version (1:20170411.1-0ubuntu0.16.10.1).  0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded. 1 not fully installed or removed.  After this operation, 0 B of additional disk space will be used.  Do you want to continue? [Y/n] y  Setting up runit (2.1.2-3ubuntu1) ...  start: Unable to connect to Upstart:  Failed to connect to socket /com/ubuntu/upstart: Connection refused   dpkg: error processing package runit (--configure):     subprocess installed post-installation script returned error exit status 1  Errors were encountered while processing: runit  E: Sub-process /usr/bin/dpkg returned an error code (1)

PPA seems to be constantly offline. Whenever I use sudo apt-get update, this error is shown:  W: Failed to fetch http://ppa.launchpad.net/ 404  Not Found   How do I fix these errors?


Given input as:  #start   random string 1 #end  #start   random string 2 #end   I can write a regex as   (#start[\s\S]*?#end)   Now thing gets a bit complex with this given data:    #start     random string 1     #start       random string 2     #end   #end    #start     random string 3   #end   and i want to get 03 matches, which are:  #start   random string 1 #end  #start   random string 2 #end  #start   random string 3 #end   Will this even be possible with regex? Cause i tried most of the regex rules, but i think i missed something cause it doesn't work as I want.  Can someone show me which rules can I used to achieve this goal?  Thank you.

Is it possible to write a regular expression that matches a nested pattern that occurs an unknown number of times? For example, can a regular expression match an opening and closing brace when there are an unknown number of open/close braces nested within the outer braces?  For example:  public MyMethod() {   if (test)   {     // More { }   }    // More { } } // End   Should match:  {   if (test)   {     // More { }   }    // More { } }


While trying exercises of Section 1.4 I am unable to prove this question (Question no. 26 ) to be a topology.   Statement ->     While proving that countable Union of U belongs to T, I am unable to prove that cl(C) =C, for that C for which Countable Union of U = X- C.    Similarly , I am unable to prove that cl(C') = C' for that C' for which finite intersection of U = X - C'.   Rest of steps are clear to me.  I think (b) part could be used but I am unable to get an equality.   Any help would be really appreciated.

Proof:- From (c) $X\in \mathscr T$. $X\subset cl(X)[\because by (a)]$ and also we have $cl(X)\subset X$. Hence $cl(X)=X$ and $\emptyset \in \mathscr T$.   Let $\{U_i\}_{i=1}^n$ be a collection of open sets in $\mathscr T$. For each $i$ there exists $C_i$:$cl(C_i)=C_i$ and $U_i=X\setminus C_i$ then $\bigcap_{i=1}^{n}U_i=X\setminus \bigcup_{i=1}^n C_i$. We have $cl(C_i)=C_i,i=1,2,3,..,n$. By (d), we have $\bigcap_{i=1}^{n}U_i \in \mathscr T$. How do I prove arbitrary union axiom? If there is an axiom $\bigcap_{\alpha \in \Lambda}cl(A_\alpha)=cl(\bigcap_{\alpha \in \Lambda}A_\alpha)$. I could prove. Can you please help me?


I'm student and I wonder there're a way to specific a type for Generic type? Example, I has a IEntity interface as the code below    public interface IEntity<T> where T : // What I should input here? {     public T Id { get; set; } }   If I only want T is int, string, and Guid, what should I do? I tried do this:   public interface IEntity<T> where T : int, string, Guid // Compile Error:  //'int' is not a valid constraint. A type used as a constraint must be an interface, a non-sealed class or a type parameter. //'string' is not a valid constraint. A type used as a constraint must be an interface, a non-sealed class or a type parameter. //'Guid' is not a valid constraint. A type used as a constraint must be an interface, a non-sealed class or a type parameter. {     public T Id { get; set; } }   I can make T as IComparable for int, string and Guid, but some data type such as float also be delivered from IComparable too. I just want 3 type: int, string and Guid, is there able to do that?

I have built myself a generic collection class which is defined like this.   public class StatisticItemHits<T>{...}   This class can be used with int and string values only. However this  public class StatisticItemHits<T> where T : string, int {...}   won't compile. What am I doing wrong?


I asked  over 10 years ago, about C#, and got a good answer there. Now I'm trying to do the same thing in Java.  Say I have an abstract class Animal. I want a static method create() in that class, that will return a value of the type of whatever the subclass is. I managed this in C# using the following structure:  public class Animal<T> where T : Animal<T>, new() {     public static T Create()     {         var t = new T();         // do generic stuff on the new T instance         return t;     } }  public class Dog : Animal<Dog> {  }  //usage: var dog = Dog.Create();   This worked a charm in C#. But now I'm trying to replicate this structure in Java, and hitting a wall. One big wall is that it seems that . So this would seem to be a bit of a showstopper. But I'm an optimistic kind of guy, and maybe some Java expert out there has come up with a totally out of the box pattern for achieving more or less what I'm trying to do here?

Is it possible to create an instance of a generic type in Java? I'm thinking based on what I've seen that the answer is no (due to type erasure), but I'd be interested if anyone can see something I'm missing:  class SomeContainer<E> {     E createContents()     {         return what???     } }   EDIT: It turns out that  could be used to resolve my issue, but it requires a lot of reflection-based code, as some of the answers below have indicated.  I'll leave this open for a little while to see if anyone comes up with anything dramatically different than Ian Robertson's .


I found out that making a server doesn't work for me , and I've seen servers which support multiple versions at once, so players can connect using a wide range of Minecraft versions. How do i do that on my own server?  (I'm looking specifically for help with 1.8 to 1.12.2)

I've seen multiple servers where you can connect from any (recent) major version. (Example, 1.9, 1.8 OR 1.7) And they all seem to be able to do it. Alas, a simple google search did not fix the problem. Any ideas? Thanks guys.  (PS: The Minecraft server is running on the latest Spigot for 1.10 as of 6/27/16)


When I try to install missing plugins on terminal, the following output appears:       arif@arif-HP-Pavilion-15-Notebook-PC:~$ sudo apt-get purge ubuntu-restricted-extras [sudo] password for arif:  Reading package lists... Done Building dependency tree        Reading state information... Done E: Unable to locate package ubuntu-restricted-extras arif@arif-HP-Pavilion-15-Notebook-PC:~$ sudo apt-get install ubuntu-restricted-extras Reading package lists... Done Building dependency tree        Reading state information... Done E: Unable to locate package ubuntu-restricted-extras arif@arif-HP-Pavilion-15-Notebook-PC:~$

When I try to install any package through the command line, I get an error.   $ sudo apt-get install <package> Reading package lists... Done Building dependency tree        Reading state information... Done E: Unable to locate package <package>   Can anyone help me on this?


My "hat" is shown twice in my answer, once in my sig, and again above. MacOS 10.14.6; Safari Version 14.0.2 (14610.3.7.1.10)

It seems like there is a bug that is causing a duplicate hat to appear when I expand info, like pressing "(more)" on a suggested edit. This bug does not seem to be specific to the suggested edits review queue though, as others have reported seeing this bug in other places, like code snippet expansion. Steps to repro:  Put on a hat. Navigate to one of your own suggested edits. (You can just also open the Suggested Edits review queue and go to a random suggestion, but there is no guarantee any of those users will be wearing a hat.) Click the "(more)" button to expand the top box.  What should happen: Hat should shift down with the rest of the content. What happens: All the content shifts down, but a duplicate hat remains in the initial place. Before expansion:  After expansion with duplicate hat:


I have an Ubuntu 14.04 installed on my computer with XFCE as Desktop environment. When i'm inserting usb flash formatted in NTFS system mounts it with default permissions on files are setted in 600, and I want to change this behaviour to mount with default permissions 660 instead. How can I do it?

I would like all FAT volumes to be mounted with the option uni_xlate enabled.  How can I configure mount or udisks2 to use that option while mounting the volume?


I have made a program inside of which, there is a specific method that makes sure that all of the objects in an array that point to null point to a blank space. For some reason, whenever I run the code, it gives me a java.lang.NullPointerException.  I understand what a NullPointerException is, which is why I added the if statement, so that it wouldn't give the error, but it still does  Code:  public class TextGraphics {     public static void main(String[] args) {          displaySize size = new displaySize(5,5);         displaySize.output(5,3,size,"H");         displaySize.run(size);     }  }  class displaySize {     public static int indent;     public static int sizeX = 0;     public static int sizeY = 0;      public displaySize() {      }      public displaySize(int screenX, int screenY) {          sizeX = screenX;         sizeY = screenY;         indent = sizeX;     }      public static void output(int x, int y, displaySize size, String print) {         rarray(size)[x + y * size.sizeX] = print;      }      public static String[] rarray(displaySize size) {         String [] display;         return display = new String[sizeX * sizeY];     }      public static void run(displaySize size) {         int next = 0;         for (int i = 0; i < sizeY; i++) {             for (int b = 0; b < indent; b++) {                 next++;                 if(rarray(size)[next].equals(null) )                 {                     System.out.print( rarray(size)[next] + " ");                     rarray(size)[next] = " ";                 }                 System.out.print( rarray(size)[next] + " ");              } System.out.println("/n");         }      }  }

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?


For odd primes $p,q$ with $p\equiv q\pmod{4a}$, then how can we show that $a$ is a quadratic residue $\mod p$ if and only if it is a quadratic residue $\mod q$ using legendre/jacobi symbols?

This problem also had me prove that $(\frac pq) = (\frac aq)$, but I've already managed to do that. I've tried messing around with the Law of Quadratic Reciprocity but can't get anything. I've also tried using the first identity by proving that $(\frac pq) = (\frac ap)$, but again I've got nothing.


I need to write the code in C#.  I get the following string containing xml elements.   **"\n                        <iqn:CDFID xmlns:iqn=\"ns:iqn:cwm:1.0\">Clearance Type</iqn:CDFID>\n                        <iqn:CDFName xmlns:iqn=\"ns:iqn:cwm:1.0\">Clearance Type</iqn:CDFName>\n                        <iqn:CDFValue xmlns:iqn=\"ns:iqn:cwm:1.0\">THE ACTUAL VALUE</iqn:CDFValue>\n                     "**   The elements are  CDFID CDFName CDFValue  The above 3 elements could be in any order inside the string. How do I identify the CDFValue xml element and extract the value "THE ACTUAL VALUE" out.   How can I treat the string in an xml manner and get the value of the desired element out.

Is there a simple method of parsing XML files in C#? If so, what?


Does anyone have any hints for proving the following via mathematical induction?   Obviously the base case is easy enough... I'm getting stuck on how these exponents may be manipulated to show $S_k\Rightarrow S_{k+1}$.  Here is the proposition:   Prove that $(1+2+3+\cdots+n)^2=1^3+2^3+3^3+\cdots+n^3$ for every $n\in\mathbb{N}$.

I know that $$1^3+2^3+3^3+\cdots+n^3=\left(\frac{n(n+1)}{2}\right)^2$$  What I would like to know is whether there is a simple proof (that obviously does not use the above info) as to why the sum of the first $n$ cubes always a perfect square.


In the link below, this circuit I found is what I needed. Only the length of the pulse and the delay are not what I want.  When I want just 0.5sec before pin 3 is up and the pulse duration I want is also 0.5sec, can someone tell me how big my resistors and capacitors must be? Or can someone tell me how I can calculate this?  My source power is 16 Volts I have already found 555 timers that can operate with 16 Volts, so thats not the problem.  When someone has another idea with two 555-timers, or something else that does the same, it's also OK.  Thanks

I have built numerous 555 circuits over the years. I recently had to built a Monostable 555 cct. as per this site :    The cct. is used in a motor vehicle. When the remote control is pushed to open the doors, it sends positive 12V to this Monostable cct. to initiate it and a 3 Amp Power Transistor pulses the siren momentarily to indicatse "unlocking" by audible means.   The issue I have is that Rt and Ct used to time the output pulse is not short enough. I replaced these components to the smallest values I could get, but the output is still "too long". Teh siren makes a "chooow" sound instead of "chow". Sounmds too unprofessional or after-market.  Any ideas to get a short pulse (nearly a few micro seconds) out of this old 555 cct. ?


Why does matter in orbital motion around a central body tend to form an , as opposed to some other configuration like a sphere? I know this has something to do with angular momentum making a disk the most stable configuration.

Most images you see of the solar system are 2D and all planets orbit in the same plane. In a 3D view, are really all planets orbiting in similar planes? Is there a reason for this? I'd expect that the orbits distributed all around the sun, in 3D. Has an object made by man (a probe) ever left the Solar System?


Let $P(n)$ be the property: $2^n > n^3$. Let's use mathematical induction to prove that $P(n)$ is true for $n\geq10$.  Basis: $P(10): 2^{10} > 10^3 \Leftrightarrow 1024 > 1000$ which is true.  Hypothesis: $P(k): 2^k > k^3$  Inductive step: we have to prove $P(k) \Rightarrow P(k+1)$:  $2^{k+1} = 2\cdot 2^k > 2\cdot k^3 = k^3 + k^3$  Everything is clear up to here, but then it goes on like this:  $k^3 + k^3 \geq k^3 + 7\cdot k^2$  Question here: How to prove that $k^3 > 7\cdot k^2$ ? I know it's because $n\geq 10$, but how to prove it? Besides empirically - which shows it's true.  Then the proof goes on:  $k^3 + k^3 \geq k^3 + 3\cdot k^2 + 3\cdot k + 1$  Question here: I suppose it's the same "technique" like above, isn't it? If not, how to prove that:  $k^3 \geq 3\cdot k^2 + 3\cdot k + 1$ ?

Problem  For what natural numbers is $n^3 < 2^n$?  Attempt @ Solution   For $n=1$, $1 < 2$ Suppose $n^3 < 2^n$ for some $n = k \ge 1$ It looks like the inequality is true for $n = 0$, $n = 1$ and $n\ge10$ But, how can I prove this through induction?


Which is correct: "To believe this is committing a fallacy" or "To believe this is to commit a fallacy"?  Context: "When a conditional expression and its consequent are both true, one cannot automatically infer its antecedent. To believe the contrary is  committing/to commit a fallacy known as affirming the consequent".  Edit: I changed "incurring/to incur" to "committing/to commit", but I'm still hearing proposals...

Some verbs are followed by ing, e.g. I enjoy swimming. We can't say I enjoy to swim. Likewise, some verbs are followed by to, e.g. I decided to make a plan.   Which particular verbs are followed by ing and to? Can you please provide a list for that?  Moreover, which verbs can be followed by both without having the meaning changed?


The example code is ok.  if ($xxx != false) {     echo 'xxxxxxxxxxx'; } else {     echo 'aaaaaaaaaaa'; }  // result: xxxxxxxxxxx   if ($xxx !== 0) {     echo 'xxxxxxxxxxx'; } else {     echo 'aaaaaaaaaaa'; }  // result: aaaaaaaaaaa   But this one confuses me   if ($xxx != 0) {     echo 'xxxxxxxxxxx'; } else {     echo 'aaaaaaaaaaa'; } // result: aaaaaaaaaaa   $xxx is string, why this code returns me false? I have read the document  but still don't understand about it.

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


I know this question may sound naïve but why can't we write $\int e^{x^2} dx$ as $\int e^{2x} dx$? The former does not have an antiderivative, while the latter has.  In light of this question, what are sufficient conditions for a function NOT to have an antiderivative. That is, do we need careful examination of a function to say it does not have an antiderivative or is there any way that once you see the function, you can right away say it does not have an antiderivative?

In the past, I've come across statements  along the lines of "function $f(x)$ has no closed form integral", which I assume means that there is no combination of the operations:  addition/subtraction multiplication/division raising to powers and roots trigonometric functions exponential functions logarithmic functions  which when differentiated gives the function $f(x)$. I've heard this said about the function $f(x) = x^x$, for example. What sort of techniques are used to prove statements like this? What is this branch of mathematics called?  Merged with "" by : Sometimes we are told that some functions like $\dfrac{\sin(x)}{x}$ don't have an indefinite integral, or that it can't be expressed in term of other simple functions. I wonder how we can prove that kind of assertion?


How big is instance of following class after constructor is called? I guess this can be written generally as size = nx + c, where x = 4 in x86, and x = 8 in x64. n = ? c = ? Is there some method in .NET which can return this number?   {     byte[][] a;     int[] b;     List<Node> c;     public Node()     {         a = new byte[3][];         b = new int[3];         c = new List<Node>(0);     } }

I need to know how much bytes my object consumes in memory (in C#). for example how much my Hashtable, or SortedList, or List<String>.


Is there any way to define a new value that is a counter + a constant?  e.g.  \foreach\k in {0,1,...,7} {    \def\m    % ???? I want to make m=k+4    \draw[->] (box\k) -- (box\m); }

In LaTeX2e,how can I sum two values and assign them to other variable?  I want to compute something like:   var=\textwidth - 1cm    And if both were constants:   var=1+1


I couldn't find debug symbol in the official repo:  $ apt-cache search openmpi gromacs-openmpi - Molecular dynamics sim, binaries for OpenMPI parallelization libblacs-openmpi1 - Basic Linear Algebra Comm. Subprograms - Shared libs. for OpenMPI libhdf5-openmpi-10 - Hierarchical Data Format 5 (HDF5) - runtime files - OpenMPI version libhdf5-openmpi-10-dbg - Hierarchical Data Format 5 (HDF5) - OpenMPI Debug package libhdf5-openmpi-dev - Hierarchical Data Format 5 (HDF5) - development files - OpenMPI version libmeep-lam4-8 - library for using parallel (OpenMPI) version of meep libmeep-lam4-dev - development library for using parallel (OpenMPI) version of meep libmeep-mpi-default-dev - development library for using parallel (OpenMPI) version of meep libmeep-mpi-default8 - library for using parallel (OpenMPI) version of meep libmeep-mpich2-8 - library for using parallel (OpenMPI) version of meep libmeep-mpich2-dev - development library for using parallel (OpenMPI) version of meep libmeep-openmpi-dev - development library for using parallel (OpenMPI) version of meep libmeep-openmpi8 - library for using parallel (OpenMPI) version of meep libopenmpi-dev - high performance message passing library -- header files libopenmpi1.10 - high performance message passing library -- shared library libscalapack-openmpi1 - Scalable Linear Algebra Package - Shared libs. for OpenMPI libtachyon-openmpi-0 - Parallel/Multiprocessor Ray Tracing Library - runtime - OpenMPI flavour libtachyon-openmpi-0-dbg - Parallel/Multiprocessor Ray Tracing Library - debug package - OpenMPI flavour libtachyon-openmpi-0-dev - Parallel/Multiprocessor Ray Tracing Library - development - OpenMPI flavour libtachyon-serial-0 - Parallel/Multiprocessor Ray Tracing Library - runtime - serial flavour likwid - toolsuite for performance oriented programmers meep-lam4 - software package for FDTD simulation, parallel (OpenMPI) version meep-mpi-default - software package for FDTD simulation, parallel (OpenMPI) version meep-mpich2 - software package for FDTD simulation, parallel (OpenMPI) version meep-openmpi - software package for FDTD simulation, parallel (OpenMPI) version mpqc-openmpi - Massively Parallel Quantum Chemistry Program (OpenMPI transitional package) netpipe-openmpi - Network performance tool using OpenMPI openmpi-bin - high performance message passing library -- binaries openmpi-common - high performance message passing library -- common files openmpi-doc - high performance message passing library -- man pages relion-bin+mpi - parallel toolkit for 3D reconstructions in cryo-electron microscopy yorick-full - full installation of the Yorick interpreter and add-ons yorick-mpy-openmpi - Message Passing Yorick (OpenMPI build) zalign - parallel local alignment of biological sequences   Do I have to manually install debug symbol from source? I found some related package . It looks like they are from the official repo. But why are they not displayed in apt-cache?

I try to watch how programs work by running them by the 'Qt Creator' debugger. For better orientation I'd like to see also the system (core) utilities fully in the call stack window as I am used from the MS Visual Studio 6.0, not only to see their assembly code. For the utilities, the 'Qt Creator' debugger displays only that their debug symbols are not available. (Sometimes, the system generates bug reports for its developers; the bug report dialog has requested installing such symbols only for a particular program.) How can I get the core debug symbols? (Without translating the whole Ubuntu version. I use the 'Update Manager' to install updates regularly. My /sys/kernel/debug/x86 directory contains only one empty file. I have not found it in the 'Ubuntu software center' nor do I see if some of the packages at the  is what I seek.) Thanks!


I was playing mine craft on a friends account. I liked it so much I bought my own account. But now I want to transfer all the cool stuff I made from the random world on their account to my account.   How do I do this?

I want to copy/modify/delete a Minecraft world. Where can I find my saves folder?


I'm familiarizing myself with disk partitioning, in the effort to get comfortable un/mounting.  I'm working on my understanding of my filesystem hierarchy.  My os runs through an LVM.  So via my root, df   Filesystem                  1K-blocks     Used Available Use% Mounted on udev                          2959116        0   2959116   0% /dev tmpfs                          597496     1892    595604   1% /run /dev/mapper/ubuntu--vg-root 953054756 11539200 893033252   2% / tmpfs                         2987460    86160   2901300   3% /dev/shm tmpfs                            5120        4      5116   1% /run/lock tmpfs                         2987460        0   2987460   0% /sys/fs/cgroup /dev/sda2                      721392   156200    512728  24% /boot /dev/sda1                      523248     4736    518512   1% /boot/efi tmpfs                          597492       16    597476   1% /run/user/121 tmpfs                          597492     2740    594752   1% /run/user/1000enter   I'm perplexed why doesn't /dev/sda3 (under which /dev/mapper/ubuntu--vg-root is) pop up?   running fdisk -l and I get:  Disk /dev/sda: 931.5 GiB, 1000204886016 bytes, 1953525168 sectors Units: sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 4096 bytes I/O size (minimum/optimal): 4096 bytes / 4096 bytes Disklabel type: gpt Disk identifier: B4C74C49-9F61-4047-8B95-02FDFB5EF348  Device       Start        End    Sectors   Size Type /dev/sda1     2048    1050623    1048576   512M EFI System /dev/sda2  1050624    2549759    1499136   732M Linux filesystem /dev/sda3  2549760 1953523711 1950973952 930.3G Linux filesystem   And I notice in myunits I only have 1 sector which is very different from online examples and books I've consulted.    Finally, using lsblk prints:  NAME                    MAJ:MIN RM   SIZE RO TYPE  MOUNTPOINT sda                       8:0    0 931.5G  0 disk   ├─sda1                    8:1    0   512M  0 part  /boot/efi ├─sda2                    8:2    0   732M  0 part  /boot └─sda3                    8:3    0 930.3G  0 part     └─sda3_crypt          253:0    0 930.3G  0 crypt      ├─ubuntu--vg-root   253:1    0 924.4G  0 lvm   /     └─ubuntu--vg-swap_1 253:2    0   5.9G  0 lvm   [SWAP] sr0                      11:0    1  1024M  0 rom `   So this backs the idea that my os is part of sda3, not sda2  is there a quick command that I could utilize to find out what partition /some/directory is?

I have a lot of filesystems:   / on a PCI-E SSD swap on a SATA SSD /media/ned is a RAID5 array /tmp lives on RAM Parts of /home/oli are symlinked and bind-mounted in from ned I also have /media/jeff/ which is RAID1 that I store backups and bind-mount ~/.wine in off.   It's actually a lot more complicated than that. There are all sorts of extra symlinks that I need to untangle in the long run but for now I just need a nice way of taking a path and finding out where it physically lives.


I have a script that needs a tunnel to a remote server. Something like this:  ssh -fNL 8080:localhost:80 my_server   How can I close the tunnel after my local script ends?   The above example is just one of the combinations I tried. I have seen how to make a blocking ssh call, executing a remote command and a self closing the tunnel with 'sleep', but I just want a way to provide the tunnel only during the execution of my script.  My last approach was forking ssh into the background and let it get killed when the script dies, but with the above command the ssh process is still alive after ending the script. Also I am exploring how to obtain the PID to manually kill the background ssh.

I'm trying to spawn an SSH from my bash profile script that runs in the background for connection sharing (via its control socket). The problem I'm running into is a reliable way to ensure the SSH doesn't stay running once the TTY is closed (or more directly; once the parent bash shell has exited).    I know the shell can run commands (to terminate SSH) when it exits gracefully, but I'm trying to handle all possible scenarios where the shell doesn't get a chance to shut things down.  Is there a clever way I can do this?  The best idea I've had is   ssh -o PermitLocalCommand=yes -o LocalCommand='cat >/dev/null; kill $PPID' $HOST &   But this won't work because I need the command to only background once it has successfully started. Alternatively, I can't use -fN instead of the shell's & because the SSH -f only backgrounds after the LocalCommand has completed.  Also I'm trying to avoid running any command on the remote host. Otherwise I could probably do something like ssh -fN $HOST 'cat >/dev/null'


I make an animation with ffmpeg video format (1280x1115) I did see this problem today. "Height not divisible by 2"  and i find a solution. But i don't want to resize or scale my animation. If i don't use ffmpeg format my sounds are disappear on video with avi format. How can i fix it? Is there a any solution fro it?

I can't seem to figure out what this is talking about. I've tried to change my settings, but nothing works.  This is what it says.    These are my settings. I can't find anything that is 1171x658.


Trying to compare strings using:  !(stringvector[i]).compare(vector[j][k])    only works for some entries of  vector[j][k]    -- namely ones that are a case sensitive string match.   How do I get case-insensitive matching from this functionality?  Here is a bit of code I was working on  #include <iostream> #include <vector> #include <string>  using namespace std; //poor form   vector<string> stringvector = {"Yo", "YO", "babbybabby"}; vector<string> vec1 = {"yo", "Yo" , "these"}; vector<string> vec2 = {"these", "checked" , "too" , "Yo", "babbybabby"}; vector<vector<string>> vvs = {vec1, vec2};  for (int v = 0; v < vvs.size(); v++) //first index of vector {     for(int s = 0; s < vvs[v].size(); s++) //second index of vector         {              for(int w = 0; w < stringvector.size(); w++)             {                 if (stringvector[w] == vvs[v][s])                 {cout << "******FOUND******";}             }      } }   This doesn't print out FOUND for the case-insensitive matches.  Stringvector[w] == vvs[v][s] does not make case-insensitive comparison, is there a way to add this functionality easily?  --Prof D

What is the best way of doing case-insensitive string comparison in C++ without transforming a string to all uppercase or all lowercase?  Please indicate whether the methods are Unicode-friendly and how portable they are.


What is the exact shape of the main component of the Mandelbrot set? I’m referring to the heart-shaped area centered at at the origin. Is there a simple way to express this shape in Cartesian or polar coordinates?

In a  to a previous answer it has been mentioned that the boundary of the Mandelbrot set contains the cardioid $$ c = e^{it} \, \frac{2 - e^{it}}{4} $$ but how can we prove this?


I have a valid US visa on my old passport which is still valid for next 3 months. I have applied and acquired a new passport with same first name (Ambreen) and Surname (Alwani, that is my maiden name) as that of my old passport but previously my father name was written on my old passport and now on my new passport (after marriage) father name is replaced by my husband's name.   So do I have to apply for new US visa again because of change in my father to husband name while my name and surname remains same i-e Ambreen Alwani.  Please suggest what should I do?

I had my US visa about 7 month age, and I had to renew my passport for certain circumstances, so there was a mismatch in the name between both the visa and the new passport, you see they had to put my grand grandfather's name which was not on the old passport nor the visa, the name on old passport and visa is: Abdelrahman Samy Ali Mohammed and the new passport is: Abdelrahman Samy Ali Ibrahim Mohammed. My grand grandfather's name is Ibrahim, so the question is that gonna cause me any troubles concerning my entry to the US? is there any document should I consider taking it while i'm traveling?  Thanks,,


Using only trig identities, how would you approach the following question?     Determine the value of    $$ \prod_{i=1}^{89} \tan i^° = \tan 1^° \cdot \tan 2^° \cdots \tan 89^° $$

How can I find the following product using elementary trigonometry?     $$ \tan 1^\circ \cdot \tan 2^\circ \cdot \tan 3^\circ \cdots \tan 89^\circ.$$   I have tried using a substitution, but nothing has worked.


Let $a$, $b$ and $c$ be the sides of a triangle. Prove that $$a^\text{2}(b+c-a) + b^\text{2}(c+a-b) + c^\text{2}(a+b-c) \leqslant 3abc$$   SOURCE: BANGLADESH MATH OLYMPIAD (Preparatory Question.)  I am very new and novice at this problem. I did a little try but couldn't succeed because I was unable to substitute the left term of the inequality into formula. I know a formula that   $a^\text{3} + b^\text{3} + c^\text{3} - 3abc$ = $(a+b+c)(a^\text{2} + b^\text{2} + c^\text{2} - ab -bc - ca)$. But how to use this formula in that case isn't known to me. And how to show the relation of the both side and when they will become equal?  A small help will be enough for me. Thanks in advance.

Suppose that $a,b,c$ are the lengths of the sides of a triangle. Prove that $$a^2(b+c-a)+b^2(a+c-b)+c^2(a+b-c) \leq 3abc.$$   Attempt  It's hard to do much simplification here so we are going to have to use that $a > b+c, b>a+b, c>a+c.$ Using that fact we obtain that $$b^2(c-b)+c^2(b-c) > a^2(b+c-a)+b^2(a+c-b)+c^2(a+b-c).$$ Then should I use AM-GM to finish it or what inequality?


$$\lim_{x \to 0} \frac{1}{x} \ln(1 + x) = 1 $$ Limit is of type $+\infty \cdot 1$, so must be $+\infty$, but answer is natural exponential to the power $1/2$.

$$\lim_{x\to 0} \frac{\ln(1+x)}x$$  The process I  want to take to solving this is by using the definition of the limit, but I am getting confused. ( without l'hopitals rule)   $$\lim_{h \to 0} \frac{f(x+h) - f(x)}h$$  $$\lim_{h \to 0} \frac{\frac{\ln (1+x+h)}{x+h} - \frac{\ln(1+x)}x}h$$  $$\lim_{h \to 0} \frac{x\ln(1+x+h) - (x+h)\ln (1+x)}{hx(x+h))}$$  At this point I get confused because I know the answer is $1$, but I am not getting this answer through simplification of my formula.


so i want to know how to make a variable not exceed its number limit.  for example:  int x;   the size of x is four bytes  and since it is signed it starts from  (−2,147,483,648) to (2,147,483,647)  so if the input is larger than 2,147,483,647 it would not register and i want to prevent the program from letting a number larger than its number limit from being inputted  here is a code that will run into that problem:  int x[3]; x[0] = 12; x[1] = 642; x[2] = 800000000; for (int z = 0;z < 3;z++) {          x[z] = x[z] * 3;   }   so how will i go about preventing x[z] from multiplying its self by 3 if the result is bigger than the number limit of the variable type?

I was writing a program in C++ to find all solutions of ab = c, where a, b and c together use all the digits 0-9 exactly once. The program looped over values of a and b, and it ran a digit-counting routine each time on a, b and ab to check if the digits condition was satisfied.  However, spurious solutions can be generated when ab overflows the integer limit. I ended up checking for this using code like:  unsigned long b, c, c_test; ... c_test=c*b;         // Possible overflow if (c_test/b != c) {/* There has been an overflow*/} else c=c_test;      // No overflow   Is there a better way of testing for overflow? I know that some chips have an internal flag that is set when overflow occurs, but I've never seen it accessed through C or C++.    Beware that signed int overflow is undefined behaviour in C and C++, and thus you have to detect it without actually causing it. For signed int overflow before addition, see .


I want to define a couple of variables in a list alongside a equation. Here's my current code  \begin{figure} \[ e = m c^2 \] \begin{description}     \item[e] energy     \item[m] mass     \item[c] light speed     \end{description} \end{figure}   This mostly works, but the text doesn't align with the figure, and the font is too big compared to the equation.   Adapting the code from  mostly works, but I can't use \description and text is interpreted as a formula.  Is there a better way to do this?

Equation's symbols or parameters description are shown below, however, the = and the details of parameter are not aligned.     I want to make a parameters list for a equation like this, in which symbols, = and detail information are aligned in terms of vertical position.  where    ...    P   =   notional permeability factor    N   =   number of waves    Sd  =   damage level    ...   A tabular environment will produce more spacing before and after text. So how to make the = vertical aligned?   The codes is provided:  \begin{equation} \frac{H_s}{\Delta D_{n50} } = 1.0~ P^{0.13}~ \left(\frac{S_d}{N} \right)^{0.2} \xi_m^P~ \sqrt{\cot \alpha} \end{equation} where:   $H_s$ = significant wave height, equal to the average of the highest 1/3 of the waves  $\Delta$  = relative buoyant density, equal to $\rho_r / \rho_w - 1$, where     $\rho_w$ is the water density  $D_{n50}$ = nominal  diameter defined in Equation (2)  $P$ = notional permeability factor  $S_d$ = damage level   $N$ = number of waves  $\xi_m$ = breaker parameter based on mean wave period $T_m$  $\alpha$ = slope angle


How did Newton get $F=\frac{Gm_1m_2}{r^2}$? What is intuition behind it? What kind of experiment or thought experiment can I do to derive this?

This question is puzzling me since I learnt about the gravitation law in school. Why did Newton guess/assume that gravitational force is inversely proportional to the square of distance?  Did he verify that experimentally? (I remember hearing that the first experimental verification of the law of gravitation was after Newton's death.)  If the answer to the above question is no, is it for example more plausible to suppose that $F\propto1/r^2$ than to suppose that $F\propto1/r^4$? Did Newton carry out a thought experiment that makes $F\propto1/r^2$ a plausible guess?  So in summary: Why did Newton choose exponent of $-2$ instead of any other exponent? Was it a guess that depended on pure luck or an educated guess?


I am new to blender and this forum so be gentle. I am designing a planet with the typical "Saturn-ring". I put some stones via particle-system onto the ring. Now I want to only show the stones not the circle mesh I put them on. How can I do that? Thank you!

I have a surface with particles. But I don't want to see the original object in the render. How to fix it?   Transparency, other collection / scene doesn't work.


We have these two sites:       I just cannot discern if there is a meaningful difference between the two sites. From a random sample of questions on the front page, it seems as if there is an enormous overlap in their content. Additionally, neither site has a large number of questions: so, should the two sites be merged?

Possible Duplicate:          Title says it all. From what I can see, "theoretical computer science" questions seem to be slightly more isolated to discussing algorithms, whereas "computer science" seems to have questions that are slightly broader and higher-level. Is there any place on the Stack Exchange sites where they give a longer description?  I'm just curious as to what niche the beta "computer science" site is meant to fill, as I see many topics in both forums that overlap.


I am a user of the social network Snapchat and would like to be able to upload screenshots and other items from my gallery up to my story.   I have noticed that users of iOS have done it and I was wondering if that there is some kind of iOS emulator that would allow me to run this application (which I believe is LaterSnap/LaterPic or Upload Snap).  If there isn't a way to run the application on Android, is there any free application that would allow me to upload pictures to my Snapchat story? (SuperSnap doesn't allow that and has become obsolete with the latest Snapchat update)

Most apps are made for iPhone but i would like to know if there is still a way to make iPhone apps work on Android? Emulator maybe?


When I read proofs about the direction of gradient , the top rated answer shows that the direction of grad$(f)$ should be the same as vector $v$ so that $f$ changes fastest along $v$ direction. However since $v$ is arbitrary I don't see why it is the direction for the maximum function increase. Also I was wondering why grad$(f)$ is the same direction as the normal vector instead of tangent vector. Any help or hint is appreciated.

$$f(x_1,x_2,...x_n):\mathbb{R}^n \rightarrow \mathbb{R}$$ The definition of the gradient is  $$ \frac{\partial f}{\partial x_1}\hat{e}_1 +\  ... +\frac{\partial f}{\partial x_n}\hat{e}_n$$  which is a vector.  Reading this definition makes me consider that each component of the gradient corresponds to the rate of change with respect to my objective function if I go along with the direction $\hat{e}_i$.  But I can't see why this vector (defined by the definition of the gradient) has anything to do with the steepest descent.  Why do I get maximal value again if I move along with the direction of gradient?


So I came into the problem of having functions with very similar names. For example, "func_this()", or "func_that()", and I wanted to create another function that would generate the string names of these functions, so that I can use it to call these functions. Here is an example code:  rand_var1 = "foobar" rand_var2 = "this" rand_var3 = "that"    def func_foobar():     print("Hello Foobar.") def func_this():     print("Hello This.") def func_that():     print("Hello That.")  def func_rand(var):     local_var = "func_" + var1  # to produce the func name     local_var()  # to call the func  func_rand(rand_var1)   Through "func_rand()", I want to create a "local_var" string that has the same name as a previously defined function. I want to then use this to call the function.   For example, if I pass in func_rand(rand_var1), it would create a variable, "local_var", that refers to the string "func_foobar". I want to then use "local_var()", hoping that it would do that same as "func_foobar()", but it does not work. I am new to Python and am not sure if there is any other way to do this. Help please :3

What is the best way to go about calling a function given a string with the function's name in a Python program.  For example, let's say that I have a module foo, and I have a string whose content is "bar". What is the best way to call foo.bar()?  I need to get the return value of the function, which is why I don't just use eval. I figured out how to do it by using eval to define a temp function that returns the result of that function call, but I'm hoping that there is a more elegant way to do this.


public class Main {  public static void main(String[] args) {     float sum = 0.0f;     int i;     float[] sumarray = {1.0f, 2.9f, 64.8f ,23.4f};     for(i = 0 ; i < sumarray.length ; i++) {         sum += sumarray[i];     }     System.out.println(sum); }   The output coming is:  92.100006  But if we manually add the elements of the array: it comes out to be 92.1  How is this possible... Please explain in detail I have just started learning java

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


I'm thinking of purchasing a photo on iStock to make a poster size print. I'm pretty familiar with resolution and how it works, but before forking out the money and ending up with a print that might not be how I want, I just want to see how much I can scale the image, which is now 5474 x 3649 px (18.25 x 12.16 in.) @ 300 dpi, before the quality shifts. I'd like to keep it as sharp as possible, but I did want to have either the height or width at least 30in. If I try to do that with this particular image will it noticeably ruin/distort the quality?

(This question is meant to be a resource to direct others to given that this is a common question.)  Given the task of creating an image that will be printed at a certain size, what pixel dimensions and resolution should I be setting my file at?


Hey guys i am new to SEO , i have done SEO for a couple of sites and basically here is my understanding of the to-do's i have to do :  On page SEO :    XML sitemap robots.txt custom 404 page. htaccess that redirects to http or www check page speed .  6   Site structure -- One H1 tag -- Minimum One or Two H2 tag missing -- images alt tag -- Navigation link and  tag link tittle missing. Google map address was not there, but it’s been created now. Meta tag analysis -- Title should be 10-50 characters, -- Description should be less than 150 characters. -- Keywords should be below 20 words,   Off page  SEO :    citations  backlinks.   Is this all i need to do ? i know the off page SEO takes time and tricks and good marketing skills and is not just all about submiting your URL to backlink farms .   Am i missing anything important here ?   Thank you.   Alex-Y.

What are the best ways to improve a site's position in the Google search results?


Is it possible to automatically (re)classify the data of a layer? (properties-symbology-delete all-classify) Because now I have to do this manually each time my data source changes.

I have some layers in my project and I would like to alter their styles, since ranges of values for underlying columns have changed.  Normally it would require to enter each layer style settings separately and trigger "Remove All", and "Classify" button, however I would like to execute it from the code.   I found such method for graduated symbol:  renderer.updateClasses(layer,0,bins)   ,however I'm having trouble to find corresponding method for categorized symbol class  Is there any way to do this from pyqgis without the need to specify the layer style from the scratch (create category, label etc.) ? Some equivalent of "Classify" button from below screenshot:


GIMP 2.10 (snap version) doesn't allow me to open the /media directory, so I'm unable to access my external USB drive. I get the following error message:  I get the same error message if I try and open an image file in Nautilus from the USB drive by Right-Click image file > Open with GIMP I installed GIMP 2.10 with snap: sudo snap install gimp  There's obviously something I'm missing in terms of configuration, but I can't find a similar question posted yet. Update: I was pointed to the solution to resolve the problem:  You need to give the snap GIMP package explicit permission to access external media once installed: sudo snap connect gimp:removable-media  Why we have to do this extra step, is alluded to by N0rbert:  "...if the application does not have auto-connect of removable-media we need to connect it manually" My question is why would an application package be created without the ability to access external media by default?

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


#include <stdio.h>  int evenDigits1(int num);  int main() {     int number;     printf("Enter a number: \n");     scanf("%d", &number);     printf("EvenDigits(): %d\n", evenDigits1(number));     return 0; }  int evenDigits1(int num) {     int x, result, i = 1;     float evenNum = 0;     while (num != 0) {         x = num % 10;         if (x % 2 == 0) {             evenNum += x;             evenNum /= 10;             i *= 10;         }         num /= 10;     }     result = evenNum * i;     if (result == 0) {         return -1;     } else {         return result;     } }   Why is it when I enter 4488 or 1144889, it will display 4487 instead of 4488? For other number such as 44488 or 123456, it will show correctly (44488 and 246).  How do I display 4488 as 4488 instead of 4487?  Thanks for your help.


Can we use REST API to get all site collections in sharepoint tenant.? I don't want powershell script basically i want to bind all asite collections to a dropdown.  my code looks like bleow.

Created a Flow by using the below REST call and stored the title and Urls in another list  /_api/web/lists/getbytitle('DO_NOT_DELETE_SPLIST_TENANTADMIN_ALL_ SITES_AGGREGATED_SITECOLLECTIONS')/items?$select=Title,SiteUrl   Here the problem is it is returning only 100 items but I have 360 site sollections.   Not sure what I am doing wrong