Find $$\sum_{r=2}^{\infty}\ln\left(1-\frac{1}{r^3}\right)$$  I solved the simpler versions of these: $$\sum_{r=2}^{\infty}\ln\left(1-\frac{1}{r}\right)\;\;,\;\;\sum_{r=2}^{\infty}\ln\left(1-\frac{1} {r^2}\right)$$ by factorizing which yields a telescoping sum. However the cube version certainly breaks this trend. What else can be done here? Does a closed form exist?

I'm having a hard time understanding the following evaluation of the infinite product  $$ \prod_{n=2}^{\infty}\left(1-\frac{1}{n^3}\right).$$ In particular, I don't understand how you go from line 2 to line 3. Here $\omega = -\frac{1}{2}+ i \frac{\sqrt{3}}{2}$, which is a primitive third root of unity.  $$\begin{align}\prod_{n=2}^{\infty}\left(1-\frac{1}{n^3}\right)  &=\prod_{n=2}^{\infty}\frac{(n-1)(n^2+n+1)}{n^3} \\  &=\lim_{m\to\infty}\frac{1}{m}\prod_{n=2}^m\frac{(n-\omega)(n-\omega^2)}{n^2} \\  &=\lim_{m\to\infty}\frac{\Gamma(m+1-\omega)\Gamma(m+1-\omega^2)}{m(m!)^2\Gamma(-\omega)\Gamma(-\omega^2)(1-\omega)(1-\omega^2)(-\omega)(-\omega^2)} \\  &=\frac{1}{3\Gamma(-\omega)\Gamma(-\omega^2)} \\ &=\frac{\sin{\pi(-\omega)}}{3\pi} \\  &=\frac{\cosh (\frac{\sqrt{3}\pi}{2})}{3\pi } \end{align}$$ EDIT: I think I'm starting to make sense out of this by writing out the terms. $$ \begin{align} \prod_{n=2}^{m} \frac{(n- \omega)(n-\omega^{2})}{n^{2}} &= \frac{(2-\omega)(3-\omega) \cdots (m- \omega)(2-\omega^{2})(3-\omega^{2})\cdots (m- \omega^{2})}{2^{2} \cdot 3^{2} \cdot \cdots  \cdot m^{2}}  \\ &= \frac{1}{(m!)^{2}} \frac{\Gamma(m+1-\omega)}{(1-\omega)(-\omega)\Gamma(-\omega)} \frac{\Gamma(m+1-\omega^{2})}{(1-\omega^{2})(-\omega^{2})\Gamma(-\omega^{2})} \end{align}$$ Now I have to figure out how to take the limit as $m \to \infty$.


Going to DC for a family vacation and arriving into Dulles. Any input on getting from Dulles to the Falls Church area that does not include an expensive cab ride?

How do I get to/from Dulles Airport in Washington, D.C.?  I've reviewed  and it's hard to tell what's actually the combination easiest/cheapest way.  We're staying near Eastern Market if that makes a difference.


I'm unclear on what the area of effect of Spirit Guardians is on a grid.  The spell has a range of Self (15-foot radius).  Additionally, the description of the spell says that      You call forth spirits to protect you. They flit around you to a   distance of 15 feet for the Duration.   The problem here is that on a grid, an "area of effect with a 15-foot radius" is not the same as a "all targets within a distance of 15 feet".   An area of effect with a 15-foot radius would fall under the general rules for areas of effect on a grid (DMG p.251), for example as discuss .  The later could be interpreted as a range of 15 feet, or 3 squares away on a 5 feet grid.  On a 5' grid, what does the area look like?  Does it take one of the following shapes?          EDIT: this is not a duplicate of the Scroll of Protection question; the Scroll clearly has a cylinder area of effect, while the Spirit Guardians affects targets 15 feet away from the caster.

Per the 's Wild Magic Surge table (PHB, p. 104)     07-08: You cast fireball as a 3rd-level spell centered on yourself.   There's other questionable area spells in that list (grease is a 10 foot square, so your square and which three?), but I'll focus on spheres like  (PHB p. 241):     (...) Each creature in a 20-foot-radius sphere centered on the point must (...)   My problem is, the sources I found so far - including the   to similar questions here - talk about measuring spheres from grid square intersections, whereas this clearly talks about it being centered on the unlucky Wild Magic sorcerer. Plus, since it's a wild magic effect, it doesn't exactly have a caster that can pick a point of origin. Is there an accepted way to measure an effect like this?


I am writing a method that returns a String with the specified letter doubled but it only returns the original value of s. I am relatively new to java and think this is due to Strings being immutable in java but I am not sure how to work around it. Any help with this method would be appreciated.  public static String doubleSpecificLetter(String s, String letter){         String s2 = s;         for(int i = 0 ; i < s2.length() ; i++) {             if(s.substring(i, i + 1) == letter) {                 s2 = String.join(letter, s2.substring(0, i + 1), s2.substring(i + 1));             }         }          return s2;     }

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?


We are told the universe is expanding at anything between 68 and 73km per second, per megaparsec (depending on the places you look) - so by association, the space between us and anything else out there is also expanding, right?    Can anyone tell me if there has been any indication that expansion is a potential variable for any orbital change in our solar system? As the universe expands, does, as a result, the space between atoms/molecules/planets then also expanding etc.? I've heard all sorts of stories about the expansion of the universe...   it is faster than previously thought.  it is increasing in speed.  recently, I came across a publication from Oxford University from Oct 2016 that suggests it is staying at a constant speed.      I'm now waiting for it to slow down.  has anyone on here worked for or experienced first hand the collecting of that data (or similar), and possibly explain why they think so many different conclusions are being drawn from this subject. as I think I'm right in saying that they analyse the light from collapsing stars and measure their brightness.   Could this mean that the universe is expanding at different rates?

I have looked at other questions on this site (e.g. "why does space expansion affect matter") but can't find the answer I am looking for.  So here is my question: One often hears talk of space expanding when we talk about the speed of galaxies relative to ours. Why, if space is expanding, does matter not also expand? If a circle is drawn on balloon (2d plane), and the balloon expands, then the circle also expands. If matter is an object with 3 spatial dimensions, then when those 3 dimensions expand, so should the object.  If that was the case, we wouldn't see the universe as expanding at all, because we would be expanding (spatially) with it.  I have a few potential answers for this, which raise their own problems:   Fundamental particles are 'point sized' objects. They cannot expand because they do not have spatial dimension to begin with. The problem with this is that while the particles would not expand, the space between them would, leading to a point where the 3 non-gravity forces would no longer hold matter together due to distance Fundamental particles are curled up in additional dimensions a la string theory. These dimensions are not expanding. Same problems as 1, with the added problem of being a bit unsatisfying. The answer seems to be (from Marek in the previous question) that the gravitational force is so much weaker than the other forces that large (macro) objects move apart, but small (micro) objects stay together. However, this simple explanation seems to imply that expansion of space is a 'force' that can be overcome by a greater one. That doesn't sound right to me.


I recently came across the types of memory allocated to a program - Stack and Heap. But how do we know, what is the best use-case of them. What is better to use stack or heap if i have options available to me, and how do i know them while programming? I read through many articles looking for the solution, but could not find a satisfactory answer.

In C++, when is it best to use the stack? When is it best to use the heap?


Don't know why the problem occurs.  after smooth shading, this appears  I need an edge loop there for the sharp edge of the gun cut-out.

While rendering a mesh with smooth shading on, I get a dark region/shadow on certain faces. The effect is more evident when smooth shading is applied to a mesh containing ngons, with the ngons turning black when rendered.   The blackening effect is visible in the viewport too.  How can I solve this problem?


I have an stock, locked, Telstra Australian Galaxy S5 and I'm about to live in the UK.   I would like to know if there is currently a way to unlock it without code so I can use it with an English carrier.   I've searched a lot about this but results are highly polluted with commercial links.   Thank you

I bought a cheap Android handset for development and it is an exclusive to a particular network.  I would like to unlock it so I can use an existing SIM card from another network. I've done some googling and it appears that there are many services online where you can get a code from supplying your IMEI number.  Firstly, can anyone elaborate on what the unlocking process involves, and secondly, is there any application that can do this process, or are you forced to pay someone to generate a code for you?


I'm trying to get the following to run via a single pdo statement UPDATE `coin_price` SET `coin_id` = 1 WHERE coin_id = 1; UPDATE `coin_price` SET `coin_id` = 178 WHERE coin_id = 178;  and I am getting the following exception  You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near 'UPDATE `coin_price` SET `coin_id` = 178 WHERE coin_id = 178'` at line 1  I am just running $statement = $this->system[$location]["connection"]->prepare($sql); $statement->execute();  and getting an exception.  I tried with binding and without. Is what I am doing not possible? Note : Both queries run fine via PDO by themselves

I know that you can insert multiple rows at once, is there a way to update multiple rows at once (as in, in one query) in MySQL?  Edit: For example I have the following  Name   id  Col1  Col2 Row1   1    6     1 Row2   2    2     3 Row3   3    9     5 Row4   4    16    8   I want to combine all the following Updates into one query  UPDATE table SET Col1 = 1 WHERE id = 1; UPDATE table SET Col1 = 2 WHERE id = 2; UPDATE table SET Col2 = 3 WHERE id = 3; UPDATE table SET Col1 = 10 WHERE id = 4; UPDATE table SET Col2 = 12 WHERE id = 4;


Source of definition:   Definition: A connected set is a set that cannot be partitioned into two nonempty subsets which are open in the relative topology induced on the set.  I don't think I can find an open set (in $R^2$ we consider the standard topology) contains $(0,1)$ that does not contain points on $y=\sin(\frac{1}{x})$ but I'm not completely sure. Does anyone know a formal prove or intuitive explanation?

I just came across the example of the topologist's sine curve that is connected but not path-connected. The rigorous proof of the non-path-connectedness can be found .   But how can I prove that the curve is connected? To be honest, even intuitively I am not being able to see that the curve is connected. I am thinking if it is proved that the limit point of $\sin(1/x)$ as $x \to 0=0$, then it would be proved. But, why is this true? IMO, this limit doesn't exist. Intuitively also, it seems that the graph would behave crazily and not approach a particular value as a tends to $0.$  EDIT (Brett Frankel): There are a few different working definitions of the topologist's since curve. For the sake of clarity/consistency, I have copied below the definition used in the linked post: $$ y(x) = \begin{cases} \sin\left(\frac{1}{x}\right) & \mbox{if $0\lt x \lt 1$,}\\\ 0 & \mbox{if $x=0$,}\end{cases}$$


I am facing some issues when i am trying to write sudo command. Ex. If i run $ sudo -i command then i got - This errors : sudo: /etc/sudoers is world writable sudo: no valid sudoers sources found, quitting sudo: unable to initialize policy plugin  Please help to solve this errors. Thank you.

How can I fix the following error with sudo?  /etc$ sudo sudo: /etc/sudoers.d is world writable usage: sudo [-D level] -h | -K | -k | -V usage: sudo -v [-AknS] [-D level] [-g groupname|#gid] [-p prompt] [-u user             name|#uid] usage: sudo -l[l] [-AknS] [-D level] [-g groupname|#gid] [-p prompt] [-U user             name] [-u user name|#uid] [-g groupname|#gid] [command] usage: sudo [-AbEHknPS] [-r role] [-t type] [-C fd] [-D level] [-g             groupname|#gid] [-p prompt] [-u user name|#uid] [-g groupname|#gid]             [VAR=value] [-i|-s] [<command>] usage: sudo -e [-AknS] [-r role] [-t type] [-C fd] [-D level] [-g             groupname|#gid] [-p prompt] [-u user name|#uid] file ...


I'm a tunisian citizen, I'm 21 years old and I'm a student. I do not have a job - in my country you get one at age around 24 after finishing your studies. But I do have a source of money.   I am going to apply for a German short visa to visit my girlfriend. We've been together for about 5 years now but we never met because of her parents they would like to see me first.  That's why I'm applying for visa. I have no intention to stay in Germany or get a job there.   I would like just to spend a week with her to meet her and her parents. I had a tumor before but I do thank god i survived from it and she was the only person that helped me going through it. So my question is if there is a way to help me get their trust. Again I'm not a criminal I would never do something illegal or get her in trouble.

Schengen refusal formulae can be difficult to understand sometimes.    When an applicant receives a refusal with "Justification for the purpose and conditions of the intended stay was not provided", what does it mean?


I know that you can go full narrative and not use dice at all, but that's not what I'm asking about. I want to know any other (pseudo)random way to determine the result of action?  My friend suggested drawing cards of deck, but it's just dice mapped to D13/D52. You could use some random generator, but still, it is just an Dn.  Is there any crafty way, that's not (easily? at least?) mappable to dices, or if we want some randomness in our games we're stuck with those little bastards?

I am interested in using a diceless resolution system for my roleplaying, but am not sure what my options are in that vein. I can think of basically two categories of diceless tabletop role-playing systems - systems which eschew any randomisation, and those which randomise by some method other than dice.  Examples  Non-random tabletop systems  One option is of direct comparison of stats or other game statistics without a randomization factor. The obvious example here is Amber DRPG, but I suspect that there are other narrative driven RPGs out there that I don't know about.   Even in Amber, situation resolution it is rarely by direct comparison between stats. Narrative techniques can be used to manoeuvre two characters into a situation which narrows the gap between their ranking, widens it, or brings other stats into the picture - the classic example of course being Corwin relying on his stamina to stretch out conflicts with his siblings such that it becomes a dominant enough factor that he can escape.  Other randomisation techniques  I have seen card-based randomization system. Over the years, I've played quite a few home brew games based on the original SAGA Dragonlance system, which was similar to the SAGA Marvel superhero system.  The basic mechanics were that you had a hand size according to your experience, and for any skill check you would play a card from your hand and replace your card from the draw pile. If you had a card of the right suit as the skill check (a strength card on a strength check) you would also draw a card from the draw pile and add that to your skill check, so a small trump was often worth more than a medium value card not of the correct suit. When you were wounded, you would discard cards to the value of the damage, but those cards wouldn't be replenished - your hand size would be reduced until you were healed. One nice aspect of the system was that it simulated fatigue beautifully, you might start a scene with a spread of high, medium and low cards, but as your high cards were played they would more often than not get replaced by lower value cards, until you were left with a bunch of useless cards and feeling very vulnerable.    The only other system I've played without dice was Everway which, if I remember correctly, used a combination of these techniques, stats based resolution, card resolution and GM fiat.  What I would be interested in is what other diceless resolution techniques exist, ideally with examples of tabletop diceless resolution methods people have tried and how they found them to play.


I know this is an odd question I make models in blender for my game looking at the procedural nodes it seems way easier to just make the textures using the nodes in blender rather than fixing textures to match my UV's or vice versa. I was hoping there was a way to export them like a texture into ue4 or bake them into the shape of the model at least.

I have a sphere having a planet material MADE WITH NODES, and I want to convert this material into an image texture; because this material is made with nodes and only works in Blender, but I want to use in another software. This is my sphere material :   For Example : This is Jupiter :  And this is the texture :  In this case I used a downloaded image for Jupiter to be the material but I want the opposite, I want to change the material to image texture Like The shape of Jupiter texture. Is there anyway in Blender that can achieve my goal ? This is the file with my sphere material .  Textures Needed :  Albedo / Color / Diffuse Normal Map Roughness Glossines  I am using normal nodes and I am not useing the new Principled-shader


Let $\alpha(t)$ be a regular curve. Suppose there is a point a in R^3 such that $\alpha(t)-a$ is orthogonal to T(t) for all t. Prove that $\alpha(t)$ lies on a sphere.  So we know   $<\alpha(t)$ - a, T(t) > $= 0$  and so it follows that   $(\alpha(t)$ - a) ($\alpha'(t)) =0$  But where do I proceed?

Let $\alpha(t)$ be a regular curve. Suppose there is a point $a$ in $R^3$ such that $\alpha(t)-a$ is orthogonal to $T(t)$ for all t. Prove that $\alpha(t)$ lies on a sphere.  So, I let $\alpha(t)=(x(t), y(t),z(t))$ and $a=(a,b,c)$.  Since, $\alpha(t)-a$ is orthogonal to $T(t)$,  $<\alpha(t)-a,T(t)>=0$.  But I don't know how to solve this..


I'm trying to change the css rules on a class called active which have static css already but i would like to alter a rule in it to make an div animate slide. i don´t know how to target a class instead of an element with the name of the class.  Javascript  var active = document.getElementsByClassName('active'); active.style.color = 'red';   I´ve tried both these methods but none seems to work.  var i = 0;     while(i < divs.length) {         if(divs[i].className == "active") {             var b = 0;             for (var a = 0; a < 10; a++){                 divs[i].style.left = b+'em';                 b += 6;              }         }         i++;     }   I´t wont add left to the css rule nor color.  CSS  .active{ position:absolute; left:-60em;   Jquery is not an option in this case.

It's easy to set inline CSS values with javascript. If I want to change the width and I have html like this:

   All I need to do is:  document.getElementById('id').style.width = value;   It will change the inline stylesheet values. Normally this isn't a problem, because the inline style overrides the stylesheet. Example:

   Using this Javascript:  document.getElementById('tId').style.width = "30%";   I get the following:

   This is a problem, because not only do I not want to change inline values, If I look for the width before I set it, when I have:

   The value returned is Null, so if I have Javascript that needs to know the width of something to do some logic (I increase the width by 1%, not to a specific value), getting back Null when I expect the string "50%" doesn't really work.  So my question: I have values in a CSS style that are not located inline, how can I get these values? How can I modify the style instead of the inline values, given an id?


So I have a program which has a variable which can be edited by the user. The variable called 'price' is set to 2 as default. I'm trying to print the variable during sentence but it's not working. My code is below:  price = 2  #Definition of 'task_1'. def task_1():      #Welcomes the user to the OCR car park.     print("Welcome to the OCR car park.")      #Asks for a £2 ticket fee and stores the amount     #given in a variable called 'ticket_fee'.     ticket_fee = int(input("Please insert a £",price,"ticket fee: "))

The following code works as expected in both Python 2.5 and 3.0:  a, b, c = (1, 2, 3)  print(a, b, c)  def test():     print(a)     print(b)     print(c)    # (A)     #c+=1       # (B) test()   However, when I uncomment line (B), I get an UnboundLocalError: 'c' not assigned at line (A). The values of a and b are printed correctly. This has me completely baffled for two reasons:   Why is there a runtime error thrown at line (A) because of a later statement on line (B)? Why are variables a and b printed as expected, while c raises an error?   The only explanation I can come up with is that a local variable c is created by the assignment c+=1, which takes precedent over the "global" variable c even before the local variable is created. Of course, it doesn't make sense for a variable to "steal" scope before it exists.  Could someone please explain this behavior?


Given vectors spaces $V,W$ with finite dimension,is that true to claim that if $W \subseteq V$ and $\text{dim}(V)=\text{dim}(W)$ implies that $W=V$? For finite sets $A$ and $B$ with $\left|A\right|=\left|B\right|$ I know that if $A \subseteq B$  then $A=B$,but I'm not sure if the same does hold for vector spaces with finite dimension. If it does hold then please give me a proof,if it's not true please provide a counterexample.

I want to prove the fact that  If $W\subseteq V$ is a vector subspace of $V$ than   $dim(W)=dim(V)=n \implies W=V$   Without using the fact that if $dim(V)=n$ any set of $n$ indipendent vectors in $V$ is necessarily a basis of $V$, neither the fact that a basis of $\mathscr{L}=(\vec{v_1},...,\vec{v_n})$ is necessarily the set $\big\{ \vec{v_1},...,\vec{v_n} \big\}$. (Since these two facts are consequences of the proof).  By hypotesis I have that $W\subseteq V$ which means that all the vectors in $W$ are in $V$. I must prove the opposite inclusion $V\subseteq W$: all the vectors in $V$ are a linear combination of $n$ vector of a basis, but I don't know how to prove that all the vectors of that basis are contained in $W$.  Can I say that they must belong to $W$ since $W$ has $n$ vectors in its basis too? (But I think in this way I'm assuming the facts listed above).  Can you help me to finish the proof?   Thanks for your help


I was trying to watch s04e08 of The Flash and I realised that the storyline was based on something that began from another CW show. I've seen this before but, it began with The Flash so it was easier to follow. I checked The Arrow s06e08 and it seemed to be another continuation. What's the cross over sequence to follow whats happening on The Flash?

There seams to be some crossover and I'm unsure of the order of which the episodes are supposed to be watched.


I was reading this page : . The writer presented a piece of code to know the size of static arrays.  template<typename T, int size> int GetArrLength(T(&)[size]){return size;} // what does '(&)' mean ? . . . int arr[17]; int arrSize = GetArrLength(arr); // arrSize = 17   Could anyone please shed the light on this code, because I couldn't understand how it really works.

template<typename T, size_t n> size_t array_size(const T (&)[n]) {     return n; }   The part that I don't get is the parameters for this template function. What happens with the array when I pass it through there that gives n as the number of elements in the array?


Hii iam learning salesforce Which IDE is mostly used by Salesforce Developers in real time especially in India?


maybe it is simple qusetion.  I just make that  like 'you're precious in the world'  person? persons? people?  but, i confused. . pls help me

I had a little fight about persons vs. people.  Could you advise if both of the following are correct, if possible with reference to a dictionary?        A table for two people please.   A table for two persons please.      Besides that, how would you ask for a table in a restaurant?  I read  and , but they didn't really solve the question if both are correct.  I also found the last paragraph of , which suggests that (1) is "more correct", but doesn't say (2) is wrong.


I am adding a torus and in previous versions of Blender, when you added the torus, there was a tool bar on the left hand side where you could add or subtract segments.  I have moved to Blender 2.8 and I can no longer find this tool bar.

I need to find these settings in blender 2.8. When you add new object (Blender 2.79) you have this object settings, down left. But in version 2.8 I can't find it.  I need to change sphere segments in blender 2.8.  Thanks for your help.


I am a UK passport holder currently living in Canada. I recently visited Alaska and travelled via air and was issued an electronic I94. The I94 website shows that my I94 has an admit until date that's valid for another 2 months.  Now I'm looking to enter the US via a land border (rail). Last time I did this trip I was issued a paper I94 which I returned to the CBSA officer upon my re-entry to Canada.  I have a couple of questions:   Is my electronic I94 still valid for entry via a land border? If I use my electronic I94 for entry, how do I prove that I have exited the USA if there is no record of my departure?

I need to end my visa waiver period when leaving States to Canada so that I don't exceed the period of 90 days. But form I-94 is no longer a physical card, it's only online.  How do I know or ensure that it will be terminated and will not continue counting the days once I leave to Canada?


Let A be an invertible $n \times n$ matrix whose inverse is itself. Prove that $\det(A)$ is either $1$ or $-1$.    I'm really lost in class. I don't even know where to start. Please help.

I'm trying to prove that an involutory matrix (a matrix where $A=A^{-1}$) has only eigenvalues $\pm 1$.  I've been able to prove that $det(A) = \pm 1$, but that only shows that the product of the eigenvalues is equal to $\pm 1$, not the eigenvalues themselves.  Does anybody have an idea for how the proof might go?  Thanks.


Not sure what the terminology is so been unable to search the problem. I am wishing to extract the day from a datetime query (SQL), asp.net, c# etc and then display as in the following examples.   Date: 21/01/2019(UK) or 01/21/2019(US) display as 21st instead of 21 Date: 25/02/2018(UK) or 02/25/2018(US) display as 25th.   I have no problem extracting the day, I just need to know if it is possible to use the syntax as shown? Or what this syntax is even called?

Is there an easy way in C# to create  for a number? For example:   1 returns 1st 2 returns 2nd 3 returns 3rd ...etc   Can this be done through String.Format() or are there any functions available to do this?


Are "strait laced" and "straight laced" synonymous?   "Strait," as in Strait of Magellan, straitjacket or dire straits means narrow or confined while "straight" means exactly what one would think it to mean. All my dress shoes are laced straight across from eyelet to eyelet but not tightly! It would seem that these usages are not at all related.   My etymological dictionary doesn't acknowledge "straight laced" at all while the Allen Edmonds shoe website does--as a technique for tying shoes. Does strait-laced mean straight-laced?  I've been informed that this topic has been addressed in the past, so I went to that thread and it seemed that those who posted didn't seem to grasp the point that the phrases are unrelated to each other.   My thanks to Andrew for giving my post a much more graceful ending!

Why do strait-laced and straight-laced have the same meaning when strait and straight have different meanings?


Having a good understanding of how expensive DB queries are and the importance of caching static data, I can't understand how the question pages on these sites run so quickly.   We have a question with many answers. This is fairly simple for users who are no logged in. When a user is logged in, the site needs to determine whether the user has voted in each question, answer and see if they have favourited the question. I can understand how you could efficiently query this data using joins on a small scale, but these are going to be expensive joins on massive DB tables that can't be cached due to the dynamic user specific data that needs to be returned.   I'm guessing that paying for more and more servers would become astronomically expensive over time. Some sort if caching mechanism must be used to ensure a fast page load while keeping DB usage at a minimum.

I am wondering why/how Stack Overflow is so fast.     "Stack Overflow is a programming Q & A site that's free. ... And fast. Very, very fast."   -


I'm using Blender 2.81. I tried reinstalling the Node Wrangler extension multiple times. Everything works fine, but it only displayed those bendy/curvy connections/links following the first install after a fresh setup of Blender 2.81.  I couldn't find any option to fix this in the preferences.

Unitl now I haven't found the option to enable the curved representation of connectors between nodes. The  doesn't mention such an  option. Is there a keyboard shortcut?


My toddler seemingly has developed some fear to bath time.  My toddler (16 moths) used to love bath time. He would be smiling when I carried him naked to the bath and loved to play with his bath toys. Once or twice he had an unpleasant situation with soap on his eyes but apart from that, bathing him was enjoyable for him and easy for us.  He gets a short bath every other day. Around a week ago, at bath time, he started crying while sitting in the bathtub. We thought that maybe his bum was hurting (it looked a little bit red). We took him out, dried him and put the diaper with some butt paste. Two days later, he started crying as soon as his feet touched the water, and didn't event want to sit an play in the tub. We took him out, but a couple minutes later I put one of his favorite toys on the far end of the bathtub and he didn't mind being put in the tub and helped to reach the toy. He did not seem afraid of the water, just didn't seem in the mood for a bath (which was weird for us after the previous episode, specially since he always seemed to love bath time).  Tonight, after stripping him I held him to take him to the bath and he started crying when he understood where he was going. He was crying a lot and hanged really tight to me, never letting go. He got more upset as he got closer to the bath tub. He never made it to the bath and it took him a while to get calmer. He is not that upset when he falls or the like. Just being taken close to the tub seemed a very upsetting experience. If it wasn't because a week ago he loved bath time I would have said he was scared of it.  I don't know if he is going through something developmental at this stage that specifically makes him hate the bath now. He has not had scary or unpleasant experiences in the bathtub before (expect for the mentioned soap in the eyes).  Could it be that he is afraid of bath time now? If so, how do I help him to overcome this fear?

I have an 18-month-old daughter. She loved having a bath from birth, and now all of a sudden she screams her head off when I mention bath or give her a bath. It's really stressing me out. I don't know what to do.


i wish to set higher priority for my dns nameservers, or override the ones that are being set by the dhcp server. no matter which approach i took, nslookup never displays the right dns nameserver.  please see the snippet below.  $ cat /etc/*release* | grep -i dist DISTRIB_ID=Ubuntu DISTRIB_RELEASE=14.04 DISTRIB_CODENAME=trusty DISTRIB_DESCRIPTION="Ubuntu 14.04 LTS"   resolvconf:  $ cat /etc/resolvconf/resolv.conf.d/base  nameserver 208.67.222.222 nameserver 208.67.220.220 $ sudo resolvconf --enable-updates $ sudo resolvconf -u $ nslookup > server Default server: 127.0.1.1 Address: 127.0.1.1#53   dhcp:  $ tail -n 1 /etc/dhcp/dhclient.conf  supersede domain-name-servers 208.67.222.222, 208.67.220.220; $ sudo service networking restart $ nslookup > server Default server: 127.0.1.1 Address: 127.0.1.1#53   how it can be done??

I (think) that I've configured a static IP address in /etc/network/interfaces:  # The primary network interface  auto eth0  iface eth0 inet static     address 10.1.1.2     netmask 255.255.255.0     network 10.1.1.0     broadcast 10.1.1.255     gateway 10.1.1.1   And I change the file /etc/resolv.conf to include the desired nameservers.   Then I restart networking sudo /etc/init.d/networking restart  But after some hours resolv.conf always reverts back to the DHCP nameserver.   I should also say that this is Ubuntu Server with only l0 and eth0 interfaces.


I've come to the point where I need my Squarespace  to do more than the Squarespace platform is designed to do, namely provide server-side access to  and . Squarespace permits no server-side access whatsoever even from within its "Developer Platform." The critical  on the site retrieves data stored on the AWS  servers and dynamically populates a table on the page. I need secure, credentialed access to the servers, thus requiring server-side Node.js and Ajax functionality. I need a site-builder because I'm not competent to build one and my non-profit group hasn't the money to hire a professional. Those twin requirements constrain the set of appropriate site hosts. It seems that I need to migrate the site to some other website-building platform similar to Squarespace but that allows server-side access. I would like recommendations for quality website-building platforms similar to Squarespace but that provide server-side access to Node.js and Ajax functionality. I would like to solicit recommendations from knowledgeable people for three to five sights ranked from most to least preferred with reasons. I would also like to know if you believe that more information about my site and its requirements is needed for a reader to respond effectively. What Stack Exchange site(s) is (are) appropriate for this specific question? Do you believe that more information will be needed? What?

Stuff like polls, recommendations based on subjective constraints, puzzles, webcomics etc. do not belong on the serious main SE sites, where professionals should be considered at work and having just a few spare minutes ("code's compiling") to answer questions, so they should not be distracted by such things. However, I'd also like to have a home for these things still using the SE engine. For the reason I mentioned before, this needs to be a separate place though. Let's call it four.[sitename-here].com.


I know that the rule is to use "in" when we are talking about small vehicles, but is there an exception when we could use "on" like for example: "I am on my car to you."? (meaning that I am on my way to someone and I am driving).  Does using "in" or "on" depend on the fact that a car is in motion or not?

Examples:   In a car, van, etc. On a bus, boat, motorcycle, etc.   How can one decide which preposition to use? Is memorization the only way or is there a better way?  Note: People generally explain this by either distinguishing between open and closed vehicles or between large and small vehicles. However, the examples I've given defeat both explanations.


In the following code, would it be possible to automatically generate the desired output (2nd paragraph) form the given input (1st paragraph)?  \documentclass[parskip]{scrbook}  \usepackage{xparse}  \NewDocumentCommand{\mref}{ m o }{    \IfValueT{#2}{%       \textbf{#2}    }%    \marginpar{$\to$ \ref{#1}}% }  \usepackage{lipsum}  \begin{document}    Input:\\    Text \mref{foo}[Foo] with two Refs \mref{bar}[Bar-Text] in a line.    \lipsum[2]     Desired Output:\\    Text \textbf{Foo} with two Refs \textbf{Bar-Text}    \marginpar{$\to$ \ref{foo} \enskip $\to$ \ref{bar}}    in a line.    \lipsum[2]     \chapter{Foo}\label{foo}    \chapter{Bar}\label{bar} \end{document}   My idea would be to test and save the y position on the page and collect all margin pars until the shipout. Then combine this with the same y value and add them to the page as an overlay. I didn’t implement that yet as I want to wait if there is an easier more elegant way …

I'm trying to use \marginpar to annotate the line where a piece of data occurs in the text. That means, I want them in the precise line where they are declared, there will frequently be more than one in the line, and I don't know in advance how many (may change when I modify the text or change the layout). The problem is that when more than one \marginpar is used, they are pushed down vertically. Ideally, I'd wish for concatenation (with whitespace and/or a comma inbetween). I looked if the marginnote and marginfix packages, but they don't do what I want (however, it's very possible that I didn't find the right configuration arguments). This feels like something that might have been solved before, but I couldn't find it, so please point me in the right direction.  I want this:  A pendulum of length $5\,\rm cm$\marginpar{$l$} and mass $10\,\rm g$\marginpar{$m$} is displaced by $6^\circ$\marginpar{$\phi$} and released. Calculate the momentum in the equilibrium position.   to produce "l, m" in the first line margin and "φ" in the second, if the linebreak occurs  inbetween, but "l, m, φ" in the first line, if there is no linebreak (depending on the layout).  Don't pay attention to the rest of the markup, it's a stub to make the point.


I'm making a technical evaluation system for the company I worked. when I uploaded it to online host there's some error "Array string conversion".     Notice: Array to string conversion in /storage/ssd5/805/10576805/public_html/UI/data.php on line 4 Notice: Undefined property: UserData::$Array in /storage/ssd5/805/10576805/public_html/UI/data.php on line 4 Fatal error: Uncaught Error: Function name must be a string in /storage/ssd5/805/10576805/public_html/UI/data.php:4 Stack trace: #0 {main} thrown in /storage/ssd5/805/10576805/public_html/UI/data.php on line 4    I tried to run the program in PHP5 down to an older version of PHP it is worked. But in PHP7 to newest version doesn't work. I think there is the new syntax for array conversion of PHP7. can you help me please to fix this problem? Thanks a lot.  Data.php  <?php $process = new UserData();  if(isset($_GET['q'])){      $process->$_GET['q'](); //this line have an error  }  class UserData {      function deletePending(){         require '../config.php';          $trans_no = $_GET['trans_no'];         $q = $connection->query("delete from tevaluation where TRANS_NO='$trans_no'");          return $q;     }  } ?>   View.php    <title>  Technical Evaluation </title>   <?php include 'data.php'; $data = $process->pendingEvaluation(); ?>

     TE #	     QUANTITY	     UNIT	     DESCRIPTION	     DEPARTMENT	     DATE EVALUATED	     STATUS	     ACTION

     <?php if($data->num_rows > 0): ?>         <?php while($row = mysqli_fetch_array($data)): ?>         <?php if($row['STATUS'] == 2):          $stat = "
 For Approval
";                     ?>
 <?php echo $row['TRANS_NO']; ?>	 <?php echo $row['QTY']; ?>	 <?php echo $row['UNIT']; ?>	 <?php echo $row['DESCRIP']; ?>	 <?php echo $row['DEPT']; ?>	 <?php echo $row['E_DATE']; ?>	 <?php echo $stat; ?>	   <a href="data.php?q=deletePending&trans_no=<?php echo $row['TRANS_NO']; ?>" class="btn btn-danger btn-sm" title="Click to Delete">                                      Delete
 <?php endif; ?> <?php endwhile; ?> <?php endif; ?>

Is there a way to dynamically invoke a method in the same class for PHP? I don't have the syntax right, but I'm looking to do something similar to this:  $this->{$methodName}($arg1, $arg2, $arg3);


I cannot find anywhere I wish to get assistance with getting an investigation into the repeated follow to down vote me unfairly and then insult me as well as make fun of my disability making this unacceptable, violations abuse and I need a complaint immediately filed.  Can you help?

What is the best method to deal with harassing users?  For reasons unknown I have become the target of what I believe to be an abusive user.  Within a few days he had downvoted nearly all of my answers or questions.  He has left comments on a number of my questions which aided in making the connection between him and the downvotes.    I know rep isn't really a big deal, but at this point this has become absolutely obnoxious.Is there no way to limit a user from downvoting another user repeatedly?  I have emailed SO, flagged his comments, flagged my own post and left a comment for the moderator (at the suggestion of the SO staff).  But nothing thus far.  I have a record breaking ~700 rep and he ~10K.    Edit:  Just to clarify, I understand that a wrong answer or less appealing answer should be downvoted.  I have no issues with this.  The downvotes I'm referring to didn't happen over days or even hours.  The majority of them occurred in the same 30 minute time span.


Does a space require more than one dimension? For instance $\Bbb R$ is not a space but $\Bbb R^2$ is?

In Wikipedia, they say that  . But what do they mean by "with some added structure"?


I want give sound output of one android mobile to MIC of another android mobile using adapters only ( I can not build circuit). One person suggested some work around using adapters , Please find below the handmade diagram based on suggestion. Can anyone please confirm whether it will work ? Because as per my understanding we can not feed sound output directly to MIC of another mobile due to level of sound. Please guide on the same or please suggest some sample or something better whatever is in your mind or YouTube video to achieve the same. Below adapters are used in this diagram as of now - male TRRS to two female TRRS cable, male TRRS to Microphone and headset splitter, 3.5 mm mono to stereo adapter, 3.5 mm male to male TRS cable.  My target is to transcribe ( speech to text ) the voice of the caller on mobile1 to mobile2 using some speech to text software installed on mobile2. So If I will get call on my mobile1 then whatever caller will speak will be translated to text on mobile2( using some app installed on mobile2).

This question is to help the "hard of hearing community" so that they can READ the phone/mobile call because they can not hear it. Android has some really good (and free, too) apps which can convert voice to text with high accuracy and in many languages (Google Live Transcribe, SpeechNote etc.) Unfortunately as of now there is no feature to transcribe a phone call on Android (Google is working on it but it has a lot of complexities ranging from technical to privacy.) To transcribe phone calls, I need help from experts. A hard of hearing person will get call on his mobile phone. (Let us call this mobile "Mobile1.") A mobile headset will be connected to Mobile1 which will have left and right audio and a microphone. Something like this:  How can I remove Output2 and feed this output to another Android mobile (Mobile2) microphone as input so that Mobile2 can transcribe the caller's voice successfully? A picture of that case is given below where Google Live Transcribe on Mobile2 is translating the voice (which it gets it from its microphone) to text.  I read on the internet and learned some basic terminology about the headset, so based on my limited knowledge, please guide me on how to connect the left or right audio channel wire from one headset to the microphone of another mobile. Can you please give me a YouTube video demonstrating the making of that adapter or cable or some photos of how to make it so that I can connect with some local shopkeeper for the same because I am not an electronics engineer. I just want to help the deaf community around me and want to see happiness on their faces.   gave me that idea that we can achieve what I was thinking but that I think the answer is not complete.  If I did not explain myself clearly please ask so that I can do my best to clear it. Please help to support the noble cause of making someone happy.  Edit 1 - Adding a rough diagram as per the suggestion by David. @David - Can you please confirm whether my understanding is correct about the connectivity of different adapters from source to target mobile? If anything needs to be changed please let me know.


I'm running a Macbook Pro with macOS 10.7 Lion. I've already checked and it can be upgraded to the latest macOS version (Mojave). However, I want to keep as much as I can running the same (like applications), and I don't particularly care about which OS that I upgrade to. What should I look out for before I upgrade?  And if it turns out that upgrading would block me from using certain applications, would upgrading and also keeping a separate partition of macOS Lion be viable solution?

I'm going to be upgrading my Macbook Pro (mid-2012 model) from its original OS X Lion 10.7 installation to a newer version of macOS. It looks like Apple will allow me to upgrade from Lion directly to OS X El Capitan 10.11 and macOS Sierra 10.12, and from there all the way to macOS Mojave 10.14.  I have heard that upgrading to a newer OS can cause performance issues, especially on older hardware. How can I find out about these issues, so I can determine the best version of macOS to upgrade to?


I have a Python script on Windows which prints text to the cmd prompt every 60 seconds, but sometimes it hangs and doesn't print the text until I press the Return key.   Brief overview:   for i in xrange(10):       print str(datetime.datetime.strftime(datetime.datetime.now(), '%Y-%m-%d %H:%M:%S')) + "A sentence which is output to the command prompt"       time.sleep(60)   Is this normal?  Edit:  I tried running Python with -u (unbuffered mode) and added sys.stdout.flush() after each print statement, some print statements cause the script to hang. I noticed this is happening on my Windows VMware & Virtualbox machines, but not a users ESXi Windows box. –

How do I force Python's print function to output to the screen?


I would question how do I solve the following problem. This is a stylistic package where I needed to create a condition. I have made a choice of work as semestral, bachelor. When selecting semestral thesis to display only the author and supervisor. In the case of bachelor thesis is to show the author, supervisor and opponent. If there is no opponent yet specified in the header must also be displayed in the case bachelor thesis. Below you can see the result in the case of semestral and bachelor thesis.  This is a code:  \ifx\akt@type\type@semestral \else & \\% {\slshape \csname opponenttext@\orig@lang\endcsname:}     & \@Opponent \\% \fi   (\opponent@lastname\relax)-if opponent is not specify (opponenttext)-show Opponent. (@Opponent)-name of opponent. \akt@type\type@semestral-semestral thesis \akt@type\type@bachelor-bachelor thesis  I think it could be done way with two conditions, such as:  if (\opponent@lastname\relax  or \akt@type\type@semestral)  <DO NOT SHOW OPPONENT>  else  <SHOW OPPONENT>.   I do not know how to look the exact form of the condition. Can you help me?  First image is semestral thesis, it is ok, condition work, if it is a semestral thesis, opponent is not showed. Second image is bachelor thesis, where is specified a opponent (Lionel Messi for example) and it is showed. Third (last) image is bachelor thesis, where is not specified the opponent in the header, but is is showed.

I feel really stupid for asking this, but how do you form more complex if conditionals in TeX? I'm looking for something like:  \ifnum\x=1 OR \ifnum\x=14     {do this} \else     {do that} \fi   I don't want to have to resort to copy-pasting the entire condition just to change the expression when the body is the same.


I want to start sectioning with 1 instead of 0.  I start with subsections, but they start with 0.1 and 0.2 and 0.2.1 - for example - I want it to start with 1.

I'm having a bit of trouble with section numbering. When I use \section{} it starts at 0.1 rather than 1.0.   Here's my preamble:   \documentclass[12pt]{report} \usepackage{hyperref} \usepackage[landscape]{geometry} \usepackage{wallpaper} \usepackage{fullpage}   Any thoughts?


I see  occasionally, where it amounts to little more than a bunch of code.  Usually there are some end-user details, like, when I click this button, it doesn't do what it's supposed to do.  Actually, the question to which I linked is a bit better than usual.  At least he attempts to explain what should happen vs. what does happen.  Either way, though, it's still a question based on end-user results, not based on anything technical.  As such, it's not a question which will likely be of any use to anyone else in the future.    In the past, I would have voted to close a question like this as being too localized.  After that option was removed, due to certain abuses, I would have voted to close it because questions asking for code should demonstrate a minimal level of understanding, but that option has also now been removed, due to similar abuses, I'm sure.  So where does that leave us for a question like this?  The closest valid reasons for closing this question now would be that it's too broad or unclear, but neither of those reasons adequately apply.  It's not really off-topic, since it is programming-related, so the "Other..." option under there doesn't even really apply.  Since there's no good options, it seems like everyone is simply resorting to down voting, but that's not very helpful to the person posting the question.  I understand that the other options were removed for good reasons, but it seems like a question like this is now falling through the cracks.  Or am I wrong?  Is this kind of question something that should be welcomed on StackOverflow?  I personally didn't down-vote it because, as far as I can tell, it's not a bad question based on all the good reasons for closing.  Personally I don't want to waste my time debugging someone else's code for them, but I suppose if this kind of question is welcome, maybe it shouldn't even be down-voted and it should just wait until someone comes along who is bored enough to be willing to help?

...not literally, of course.  But what happened to the previous menu of close-vote options?  I find the current set unsatisfactory. Take  for example.  Obviously, the question is worthless, because it's an exception that even a n00b programmer should be able to debug on his own. There is nothing special about this bug, and it will help no one in the future.  What could I possibly select as a close reason?   duplicate of... - Maybe. There's the classic  which has been linked to . While the debugging techniques are the same, that's for .NET.  Besides, there are any number of other common exceptions / simple development bugs that wouldn't apply. off-topic because...   ... This question was caused by a problem that can't be reproduced or a simple typographical error. While similar questions may be on-topic here, this one was resolved in a manner unlikely to help future readers. This can often be avoided by identifying and closely inspecting  before posting.Notes below....  unclear what you're asking - No, it's clear that the programmer just needs to debug his code. too broad - No, it's quite specific. primarily opinion-based - Nope.   When it was introduced, I was happy to see a "typo" reason, to rid out all the stupid indentation or bracket questions. But... we no longer have a "lacks minimal understanding" reason, which I think is incredibly important. After all, Stack Overflow is here to solve problems that  encounter... not teach users how to code or debug.  So.... what do I pick?  Can we have another revision on the close vote reasons?  I did a cursory search, but couldn't find a Meta post to the intent behind this latest set of reasons. Edit: I believe this is it:     Edit 1/20  Ah, how could I forget about the classic copy & paste homework assignment?      Right or wrong, my close vote was cast with      off-topic because it shows zero desire to actually understand the problem.      we see a moderator closing a question about an incorrect number of function parameters as lacks sufficient information to diagnose the problem. Of course, there probably is sufficient information, and the wording should really be changed to You're too lazy to RTFM.


Many times I wanted to post a reply in comments to some people with a names, that contain some characters, that I don't have on my keyboard. Auto-completion with @ doesn't always work, so I'm confused - how can I mention those people?  Even if write his name - how can I be sure, that the name is correct? That he will be notified?

Once in a while you wish to address a comment to someone in particular, so you type @ and then you pause ... because the username is  or .  Short of using copy-paste to get their username right (which is even more cumbersome on a mobile device), is there another way around this? In a few cases I've noticed that the system will attempt to "promote" a comment to a reply, but I'm not sure if that's very reliable.  Should user names at least start with a normal letter?  Update  The auto-complete feature seems to normalize Zalgo'ish usernames, so typing the letter L will trigger the suggestions as expected; this is of course knowing that the name actually spells "lawrence", which may not always be obvious.  Knowing the way of the symbol ninja would surely help to type Ω using only the elbows as well, but not everyone is blessed with the same keyboard layout.  Suggestion  It would be nice to have a reply feature like this:        When ↳ reply is clicked, it will automatically populate the comment box with @username pre-filled in.   Additional notes  To clarify, I'm not suggesting to put the "reply" on all comments, as proposed , because in most cases the owner of a post is already notified of a new comment; this would strictly be to effect cross-commenter communication.


I've Ubuntu 14.04 LTS. Today I've changed My password and it contains numbers, When I set the password the num lock of numpad keys was off. Now I cannot login. I tried pressing the same keys with num lock  on or off. Any help????

I'm working on a Ubuntu system, and my client has completely forgotten his administrative password. He doesn't even remember entering one; however it is there.  I've tried the suggestions on the website, and I have been unsuccessful in deleting the password so that I can download applets required for running some files. Is there a solution?


Given the equation for a damped oscillator is $$\ddot{x}+\gamma\dot{x}+\omega_0^2x=0$$  Is the  of the system given by $\omega_0/\gamma$ or $\omega_0/2\gamma$?  I have seen both forms come up and so I do not know which one to use.

According to Wikipedia, the  is defined as:  $$Q=2\pi\frac{\mathrm{energy \, \, stored}}{\mathrm{energy \, \,dissipated \, \, per \, \, cycle}}.$$  Here are my questions:   Does the energy dissipated per cycle assume that the amplitude is constant from one cycle to the next. Is it always calculated at the resonance frequency? If the answer to 2 is yes can you explain why for a forced oscillator system with a damping coefficient of $\gamma$ and natural frequency $\omega_o$ the quality factor is $Q=\omega_o/\gamma$ and not some more complicated expression involving the actual resonant frequency (which is not quite $\omega_o$  and is given by $$\omega_r=(\omega_0^2-\frac{\gamma^2}{2})^{\frac{1}{2}}$$ of the system? Is this just an approximation i.e. are we assuming that it resonates at $\omega_o$ but in fact the actual expression is a big more complicated?   Edit: With using the actual value of $\omega_r$ I get: $Q=(\omega_0^2-\frac{\gamma^2}{2})^{\frac{1}{2}}/\gamma$  is this more correct?


The last sentence of my last chapter ends on page 118. Just after the last line I used   \clearpage \renewcommand{\bibname}{References} \addcontentsline{toc}{chapter}{References}   to get the ‘References’ on page 119. This was fine. In ‘toc’ also, it shows that the ‘References’ is on page 119. But when I click on ‘References’ in ‘toc’, it ended up on page 118 (I am using 'hyperef' package). How can I get this correctly. I also have a title page in my document (‘book’ class). The numbering starts from first page of ‘toc’ which is just after ‘titlepage’.

Inspired by question :  When do I need to invoke \phantomsection?  In what condition is invoking \phantomsection necessary?


I am trying to set up a cronjob to run on the last sunday of each month. This is what I have accomplished. Right now, it is running every sunday at 10 PM. 0 22 * * 0 /usr/basys_bin/clean_cups_cache.sh

I want to schedule my script for last Saturday of every month. I have come up with the below:  45 23 22-28 * *  test $(date +\%u) -eq 6 && echo "4th Saturday"  && sh  /folder/script.sh    Is this correct or I need to change it? I can't test it right now as it will be invoked only on last saturday. Please advise.  I have the below for last sunday of every month but i can't understand much of it. The first part gives 24 which is sunday and after -eq gives 7 which i don't know what it means:  00 17  * * 0 [ $(cal -s | tail -2 | awk '{print $1}') -eq $(date | awk '{print $3}') ] && /folder/script.sh   Can i modify the above to get last saturday?  With Romeo's help I was help to come up with the below answer:  00 17 * * 6 [ $(cal -s | tail -2 | awk '{print $7}') -eq $(date | awk '{print $3}') ] && /folder/script.sh


I would like to access my array of objects from another method in my class. My code is as follows. I get a NullPointerException error.  The nameArray is simply reading a text file, and data is being stored in it.  public class menu {      static Scanner askInfo = new Scanner(System.in);     public static Student ArrObj[] = new Student[15]; //instantiates an array of student objects       public static void main(String args[]) throws IOException {         for (int i = 0; i < 15; i++) {             ArrObj[i] = new Student(); //creates an array of student objects             System.out.println("Here is the list of all children.");             System.out.println("Which child's information do you want to enter?");             int InName = askInfo.nextInt();             switch (InName) {                 case 1:                     ArrObj[i].setName(Read.nameArray[0].substring(3));                     break;                 case 2:                     ArrObj[i].setName(Read.nameArray[1].substring(3));                     break;                 case 3:                     ArrObj[i].setName(Read.nameArray[2].substring(3));                     break;                 case 4:                     ArrObj[i].setName(Read.nameArray[3].substring(3));                     break;             }         }         for (int i = 0; i < 15; i++) {             System.out.println(ArrObj[i].getName());         }     }  }   The (important parts of) Student class:  public class Student {     private String name;      //name of student          public void setName(String name) {             this.name = name;     }      public String getName(){         return name;     } }   The Read class:  import java.io.*; import java.util.*;  public class Read {      static String nameArray[] = new String[100]; //to be safe, declare plenty      public static void ReadNames() throws IOException //method to read names     {         Scanner read = new Scanner(new File("C:\\IA\\names.txt")); //this will read the names of students         int counter = -1; //-1 so that when incremented, the first index is 0          while (read.hasNext()) {             counter++;             nameArray[counter] = read.nextLine();         }     } }

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


I want to shoot night sky photos.  I have a Nikon D3300 DSLR with 50mm f/1.8D lens. I have a tripod , and a timer cord.  Is my gear good enough to shoot night sky photos?  Is there anything more I need?

I have a Canon 20D. I'd love to take some photos of the moon and stars.   How do I get started?  I've search the web and the information is sparse and cryptic.   I'd like to know what equipment is the best for a beginner and what I should try taking a photo of first... besides the moon :).


Solve that the following integral: $$ \int_0^1 {\log x \log(1-x) \log^2(1+x) \over x} \,dx. $$  I haven't solved it yet.

How can we prove that:     $$\int_0^1 \frac{\log(x)\log(1-x)\log^2(1+x)}{x}dx=\frac{7\pi^2}{48}\zeta(3)-\frac{25}{16}\zeta(5)$$ where $\zeta(z)$ is the .   The best I could do was to express it in terms of Euler Sums. Let $I$ denote the integral.  $$I=-\frac{\pi^2}{24}\zeta(3)+2\sum_{r=2}^\infty \frac{(-1)^r (H_r)^2}{r^3}-2\sum_{r=2}^\infty \frac{(-1)^r H_r}{r^4}+2 \sum_{r=2}^\infty \frac{(-1)^r H_r^{(2)}H_r}{r^2}-2\sum_{r=2}^\infty \frac{(-1)^r H_r^{(2)}}{r^3}$$  where $\displaystyle H_r^{(n)}=\sum_{n=1}^r \frac{1}{k^n}$. I am unable to simplify these sums further. Does anyone have any idea on how to solve this integral?  Please see  for more details.    Some time ago I was able to solve the simpler integral:     \begin{align*} \int_0^1 \frac{\log(1-x)\log(x)\log(1+x)}{x}dx &=-\frac{3 \pi^4}{160}+\frac{7\log(2)}{4}\zeta(3)-\frac{\pi^2 \log^2(2)}{12} +\frac{\log^4(2)}{12} \\ &\quad+ 2 \text{Li}_4 \left(\frac{1}{2} \right) \end{align*} where $\text{Li}_n(z)$ is the .


I'm a curious programmer. So these days I was reading the documentation from the PHP site and this link was "PHP type comparisons"   I decided to do some exercises to fill the tables of comparisons but there are some answers that I can not see why, for example:  <?php var_dump(false == array()); // Okay, an empty array is considered false. True result var_dump('' == array()); // false ? Why not true if an empty string is considered false ? var_dump(0 == array()); // false ? Why ? var_dump(null == array()); // true. Why ? ?>   Can you help me about this? I can not understand why some comparisons, I can not find anywhere explanation.

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 have a thinkcentre m93p. I don't know administrator password. Maybe it is default password. I want to install windows 10 via usb but i can't open boot menu because bios ask me password but i don't know. I removed bios battery for 10-15 minutes. I put back. It is not work. How can i remove/reset bios password?

Possible Duplicate:          I want to change my BIOS setting but when I press F2 it asks for a password and I've forgotten it.  However, if I press enter it just enters the BIOS but most options are greyed out.  Is there any way to reset the BIOS password?  My BIOS is Intel BX97520J and I can start the system which has Windows Server 2008 installed.


What could be taking up 100GB+ of storage in "Other" section? How can I find out? How can I reduce it? I ended up removing a lot of unused SDKs and cachces under ~/Library but even then that was only a few GBs as much of the web searches pointed to this dir.

Every few days I get notices on my MacBook that it's running or run out of hard drive space. Curiously, restarting the computer will enable me to recover gigabytes of space (this past time, it was able to recover about 2.2GB). However, I can't identify anything in my personal activity that consumed that space.  It's possible that it's a rogue iTunes podcast or a huge software update that my Mac is automatically downloading - would either of these reclaim the space upon a restart?  One possibility that I can think of is that FileVault has some sort of disk leak, allocating but not freeing files. Does this make sense? Is there a tool that I can run to determine where this space is going? Assuming it is FileVault, should I try to disable it? What's the best way to turn of FileVault on a nearly full computer?


i have output = "70.00" i want only to get "70" through SQL server

I'm trying to determine the best way to truncate or drop extra decimal places in SQL without rounding.  For example:  declare @value decimal(18,2)  set @value = 123.456   This will automatically round @value to be 123.46, which is good in most cases.  However, for this project, I don't need that.  Is there a simple way to truncate the decimals I don't need?  I know I can use the left() function and convert back to a decimal.  Are there any other ways?


My model gives me random intercepts in which the distribution looks like:   The model is as follows: mod <- lmer(response ~ 0 + item + (1|id), family = binomial)  Is this still a valid random effects distribution or does this indicate that there's something wrong with my model ?  Edit: this is the distribution of the random intercept of the model above. It was extracted using ranef() in R. This is what it looks like in the bigger picture.     When I increase the bin size, it looks like this:   Edit2: This model is an Item Response (IRT) model (or Rasch) Basically I have a list of patients and their answers to several survey questions. The answers of this survey are binary (e.g. do you exercise at least once a week, etc)  This then transformed into item-response format (wide: patient_id, Q1, Q2, ...Qn to long: patient_id, item (which is Q1,..,Qn) and response (which is the answers to the item column)  Then I fit this data into IRT above, extract the random intercepts as an indices to measure their health level (sort of)

Parzen window density estimation is described as  $$ p(x)=\frac{1}{n}\sum_{i=1}^{n} \frac{1}{h^2} \phi \left(\frac{x_i - x}{h} \right) $$  where $n$ is number of elements in the vector, $x$ is a vector, $p(x)$ is a probability density of $x$, $h$ is dimension of the Parzen Window, and $\phi$ is a window function.  My questions are:   What is the basic difference between a Parzen Window Function and other density functions like Gaussian Function and so on? What is the role of the Window Function ($\phi$) in finding the density of $x$? Why can we plug other density functions in place of the Window Function? What is the role of $h$ in in finding the density of $x$?


I am trying to solve this using Hilbert's paradox.  Say I have a collection of countable sets: $A_1,...,A_n$.  I want to show that there is a bijective function from then union, $A=\cup{A_i}, 1\leq i\leq k$  to $\mathbb{N}$.  I'm thinking to map the elements from each  ${A_i}, 1\leq i\leq k-1$  to a prime number $p_i$ raised to a power according to the element's order in its group  ${A_i}$ (which can be ordered, since it's countable), and then use elements from group  ${A_k}$ to fill in the "gaps" in $\mathbb{N}$.  But then I have a problem with elements from ${A_k}$ whose image is a power of the prime numbers $p_1,...,p_k-1$ which I've used before. I could map them to powers of the prime $p_k$ but then I have the same problem with other elements whose image is a power of $p_k$...  How may I solve this problem (or maybe my approach is incorrect)?

Let $A_1,...A_k$ be countable sets, I need to prove that the union $\bigcup_{i=1}^{k}A_i$ is countable by explicitly building a surjection.  I can't assume that the sets are disjoint.  I can easily build an injection $g:\bigcup_{i=1}^{k}A_i\rightarrow \mathbb{N}\times\mathbb{N}$ by defining $g(a)=(f_{i}(a),i)$ where $f_i$ is the first bijection from the bijections $f_i,...f_k$ that maps $A_i\rightarrow\mathbb{N}$ such that $a\in A_i$.  However, this map $g$ obviously isn't surjective.  Any ideas for building such map?


I cannot figure out how to download this driver so that I can connect to my wireless internet:  It is the "BCM4321 80211 Linux STA driver.  I sure could use some help.  Thank you very much!  Wayne

I'm having serious problems installing the Broadcom drivers for Ubuntu. It worked perfectly on my previous version, but now, it is impossible.   What are the steps to install Broadcom wireless drivers for a BCM43xx card?  I'm a user with no advance knowledge in Linux, so I would need clear explanations on how to make, compile, etc.    lspci -vnn | grep Network showed:   Broadcom Corporation BCM4322 802.11a/b/g/n Wireless LAN Controller [14e4:432b]      iwconfig showed:  lo        no wireless extensions. eth0      no wireless extensions.   NOTE: Answer below is updated every time new information is added and confirmed working.


I'm finding experimentally that if I take two non-zero eigenvectors of a symettric 3x3 matrix from two distinct eigenspaces then they are orthogonal to each other.  (their dot product is zero). Is this true in general that any two distinct eigenspaces of a symettric 3x3 matrix are orthogonal to each other?  What about higher dimensions (2x2, 4x4, 5x5, ...)? If it is so, why is it so?

Can someone point me to a paper, or show here, why symmetric matrices have orthogonal eigenvectors? In particular, I'd like to see proof that for a symmetric matrix $A$ there exists decomposition $A = Q\Lambda Q^{-1} = Q\Lambda Q^{T}$ where $\Lambda$ is diagonal.


In the following sentence why is it at the school not at school?      They don't have to do their homework today because it's a holiday at the school.

I decided to make sure that I know this important difference between American and British English, so I wrote what I have found out so far and I would be grateful to anyone who reads this and tells me whether I am wrong, or not.  In British English when people say  to hospital or in hospital when  talking  about somebody being there as a patient they don't use the definite article : "I had to go to hospital", "She spent two weeks in hospital". And the meaning is that somebody was there as a patient.   If then for some other reasons British English speakers  will use the definite article which will change the meaning itself, I noticed that, in American English, native speakers often use the  the and if they need to show that somebody is in church to pray,  in school as a student, in hospital as a patient, in prison as a prisoner, they use 'in' and not 'at'. Do American English speakers use 'at' like British English speakers use 'the' to give the sentences a different meaning?    Are my sentences correct? Do they show American English usage?   He is in the school. (enrolled as a student) He is at the school. (for some different reasons) He is in the hospital. (as a patient) He is at the hospital. (visiting somebody) He is in the church. (to pray) He is at the church. (for some different reasons) He is in the university. (as a student) He is at the university. (not as a student) He is in the college. (as a student) He is at the college. (Not as a student) He is in the prison. (as a prisoner) He is at the prison. (not as a prisoner)


How can remove the last comma separator from a file on Linux?   Example of file :  "is_supported_kafka_ranger" : "true", "kafka_log_dir" : "/var/log/kafka", "kafka_pid_dir" : "/var/run/kafka", "kafka_user" : "kafka", "kafka_user_nofile_limit" : "128000", "kafka_user_nproc_limit" : "65536",   expected results:  "is_supported_kafka_ranger" : "true", "kafka_log_dir" : "/var/log/kafka", "kafka_pid_dir" : "/var/run/kafka", "kafka_user" : "kafka", "kafka_user_nofile_limit" : "128000", "kafka_user_nproc_limit" : "65536"

I have a very large csv file. How would you remove the very last , with sed (or similar) ?   ... [11911,0,"BUILDER","2014-10-15","BUILDER",0,0], [11912,0,"BUILDER","2014-10-15","BUILDER",0,0], [11913,0,"BUILDER","2014-10-15","BUILDER",0,0], ]   Desired output  ... [11911,0,"BUILDER","2014-10-15","BUILDER",0,0], [11912,0,"BUILDER","2014-10-15","BUILDER",0,0], [11913,0,"BUILDER","2014-10-15","BUILDER",0,0] ]   The following sed command will delete the last occurrence per line, but I want per file.   sed -e 's/,$//' foo.csv   Nor does this work  sed '$s/,//' foo.csv


I'm not a Windows guy. And all my working life was managing Mac and Linux. Why should I have a Windows domain controller?  I know what  is, but I'm not a Microsoft expert. And on paper everything is beautiful, but the reality that I have, is that it does't work, and it is not helping me doing my job. That's why I am thinking, or not, to shutdown the domain controller.  I only see disadvantages.  What I have:   90 computers to 90 people. Five printers, login is different and not centralized, because it's difficult to use a strong password in a printer. 1/3 uses  and the other use a Linux mail server. All our business applications run on Linux server. Our files are in a Linux . All the computes are different (it's a nightmare) Some have laptops and are always moving (inside and outside the company) We are behind a Cisco Adaptive Security Appliance (ASA) firewall  is on a Cisco router and I'm planning to move  to a switch (I'm not authorized to manage the router)   In my point of view:   It's just another thing to go wrong. A machine in a domain is slower to login. Less stuff is better. And less work too. We have a  licence, but it's not a very good machine and I'm removing all the applications from the Windows servers. I'm planning to buy new laptops and they have Windows 8 and in a few days Windows 8.1, and I don't know if Windows 8 behaves well with older servers! I don't like to spend money on Windows licences and servers.   For me is just a extra server consuming 400 watts... Am I wrong?

This is a  about Active Directory Domain Services (AD DS).         I find myself explaining some of what I assume is common knowledge about it almost daily. This question will, hopefully, serve as a canonical question and answer for most basic Active Directory questions. If you feel that you can improve the answer to this question, please edit away.


Consider the linear transformation $T:\mathbb{R}^2\rightarrow \mathbb{R}^3$ such that $T(x_1,x_2)=(x_1-x_2, x_2-x_1, -x_1)$. Find dimension of null space.  Now in this question, I find that the only member of the null space is the zero vector. So the dimension should be $1$. But the answer is $0$. Why is it so ?

According to C.H. Edwards' Advanced Calculus of Several Variables: The dimension of the subspace $V$ is defined to be the minimal number of vectors required to generate $V$ (pp. 4).  Then why does $\{\mathbf{0}\}$ have dimension zero instead of one? Shouldn't it be true that only the empty set has dimension zero?


Finding $\displaystyle \binom{n}{0}-\binom{n}{1}+\binom{n}{2}\cdots \cdots +(-1)^r\binom{n}{r}$   Try: using Identity $\binom{n}{r}=\binom{n-1}{r}+\binom{n-1}{r-1}$  So $$\sum^{r}_{k=1}(-1)^r\bigg(\binom{n-1}{k}+\binom{n-1}{k-1}\bigg)$$  Ciuld some help me how to find sum of that series, Thanks

It is easily checked that $\displaystyle\sum_{i\ =\ 0}^{n}\left(\, -1\,\right)^{i} \binom{n}{i} = 0$, for example by appealing to the binomial theorem.  I'm trying to figure out what happens with the truncated sum $\displaystyle\sum_{i\ =\ 0}^{D}\left(\, -1\,\right)^{i}\binom{n}{i}$.  How far away from $0$ can this get, as a function of $D$ ?.  I'm mostly interested in the case of when $D \ll n$, such as $D \sim \,\sqrt{\,n\,}\,$.  Thanks !


Which is correct: [Bonus question: should there be a question mark here instead of a colon?]     The book contains Marx and Engels' theories about the nature of   society and politics.   or     The book contains Marx's and Engels' theories about the nature of   society and politics   It seems to me that the former is more common, but I am confused here since the latter seems more logical to me (and matches what you would see in my native language Icelandic).

Which option is grammatical?        There will be readings from Nikki Giovanni’s and Alice Walker’s writings.   There will be readings from Nikki Giovanni and Alice Walker's writings.      Saying it out loud the latter sounds right, but looking at it the former looks better.


In my html I have the following ajax code which populate data into a table:  function generate_table() {        var tr;       $('#emp_body').html('');       for (var i = 0; i < displayRecords.length; i++) {         tr = $('
');         tr.append("" + displayRecords[i].id + "	");         tr.append("" + displayRecords[i].email_address + "	");         tr.append("" + displayRecords[i].mobile_number + "	");         tr.append("" + displayRecords[i].status + "	");         tr.append("" + displayRecords[i].credit_limit + "	");         var $td = $('').html('Edit');         tr.append($td);         $('#emp_body').append(tr);       }     }   I also have a jquery on click function:  jQuery('.editbtn').on('click', function() {        var $row = jQuery(this).closest('tr');       var $columns = $row.find('td');       var values = [];        jQuery.each($columns, function(i, item) {           values.push(item.innerHTML)       });       console.log(values[0]);       window.location.href = "/portal/admin/customerDetails?id=" + values[0];      });   So the issue here is that, when I click on Edit button, it does not call the on click function. How can I fix this issue ?

I have a bit of code where I am looping through all the select boxes on a page and binding a .hover event to them to do a bit of twiddling with their width on mouse on/off.  This happens on page ready and works just fine.  The problem I have is that any select boxes I add via Ajax or DOM after the initial loop won't have the event bound.  I have found this plugin (), but before I add another 5k to my pages with a plugin, I want to see if anyone knows a way to do this, either with jQuery directly or by another option.


Let us switch the positions of the minute hand and the hour hand of a calassic clock with only 12 hours, not 24. Note that most of the time we will end up with an absurd configuration. But are there any valid such configuratins? If yes, count the number of valid configurations.  Till now i got only one configuration, 12:00.  I considered 2 cases, if the clock is indicating a whole hour time, except 12:00, then it is a sure absurdity, because the hour hand will not directly point toward the time panel. Similar argument when it shows x:30. So i got only one solution 12:00. But still i am uncertain whether i have missed any and would like to know them and how ae any other solutions possible. Thanks in advance!

At 12 o'clock, the hour hand and minute hand of the clock can be swapped, and the clock still gives the same time, but at 6 o'clock, it can not be swapped. So in what cases when we swap the hour and the minute hand position does a clock still give a valid time?


I have the following limit to find:  $$\lim_{n \to \infty} n \int_{-1} ^ 0 (x + e^x)^n dx$$  Usually, when I have had to find the limit of an integral, I tried finding two boundaries for the expression inside the limit, in such a way that I could use the Squeeze Theorem, but I don't see any obvious boundaries here. Should this exercise be solved using another technique or are there boundaries which could help me?

I would like to find the following limit without using any Taylor expansion.  $$\lim _{n\to \infty }n \int_{-1}^0(x + e^x)^{n}dx = \: ?$$  I know the answer is $\frac{1}{2}$. I tried to write $-1 < x < 0$ and $0 < e^x < 1$, sum up the relations and then integrate, but I found nothing conclusive.


I want to pass a string as command line argument to a bash script; Simply my bash script is:  >cat test_script.sh  for i in $* do  echo $i done   I typed     bash test_script.sh test1 test2 "test3 test4"   Output :  test1 test2 test3 test4   Output I am expecting:  test1 test2 test3 test4   I tried with backslashes (test1 test2 "test3\ test4") and single quotes but I haven't got the expected result.  How do I get the expected output?

I have a complex command that I'd like to make a shell/bash script of.  I can write it in terms of $1 easily:  foo $1 args -o $1.ext   I want to be able to pass multiple input names to the script. What's the right way to do it?    And, of course, I want to handle filenames with spaces in them.


How to add a custom action to the list items display form ribbon?  Onclick of this it should open a application page in modal popup.

How to add a custom action to the list ribbon?  The custom action should open a sitepage in modal popup.


Problem statement is to form largest number from a given int array. For e.g. if the input array is {3, 30, 34, 5, 9} then the result should be 9534330. I tried following code but I am getting an exception in the if condition where I am trying to parse string into an int. Can you please tell how to resolve this? import java.util.*; import java.lang.Integer; public class Console2 {     public static void largestNumber(int[] array) {      int s = array.length;      String result = "0";      for (int i = 0; i < s; i++) {          int[] temp = new int[s];          temp[i] = array[i];          for (int j = 0; j < s; j++) {              if ( i != j) {                  temp[j] = array[j];              }          }          if (Integer.parseInt(temp.toString()) > Integer.parseInt(result)) { // getting exception here !!!              /*              in the inner for loop, the temp array will store possible combinations of elements of              the input array. so if i convert the temp array into string and then parse it to int, then              i should be able to compare it with a result string (parsed to int) and store the highest              possible number as string. once the outer for loop completes, the result will have highest               formed number which gets printed in this method.               */              result = temp.toString();          }      }      System.out.println(result);     }     public static void main(String[] args) {         int[] array = {3, 30, 34, 5, 9};         largestNumber(array);     } }   Exception message: Exception in thread "main" java.lang.NumberFormatException: For input string: "[I@7cc355be"     at java.base/java.lang.NumberFormatException.forInputString(NumberFormatException.java:68)     at java.base/java.lang.Integer.parseInt(Integer.java:652)     at java.base/java.lang.Integer.parseInt(Integer.java:770)     at Console2.largestNumber(Console2.java:15)     at Console2.main(Console2.java:23)

In Java, arrays don't override toString(), so if you try to print one directly, you get the className + '@' + the hex of the  of the array, as defined by Object.toString():  int[] intArray = new int[] {1, 2, 3, 4, 5}; System.out.println(intArray);     // prints something like '[I@3343c8b3'   But usually, we'd actually want something more like [1, 2, 3, 4, 5]. What's the simplest way of doing that? Here are some example inputs and outputs:  // Array of primitives: int[] intArray = new int[] {1, 2, 3, 4, 5}; //output: [1, 2, 3, 4, 5]  // Array of object references: String[] strArray = new String[] {"John", "Mary", "Bob"}; //output: [John, Mary, Bob]


When I pronounce the phrase:   "Look, it's the first day. I don't wanna be late."  I think that the /t/ in the words "first" and "don't" can be deleted. Am I right? I'm talking about casual speech.  Below is the phonetic transcription. I stressed the content words (the bolded words) without shifting stress for special meaning. I deleted the /t/ in both words, though.  lʊk, ɪts ðə fɜrs deɪ. aɪ doʊn wʌ nə bɪ leɪt.

when the phrase "Can't complain" is pronounced [ˈkænt kəmˈpleɪn] I think that the T is dropped in fast speech because of the alveolar plosives. Right? I read that when T comes before these letters: / s, f, n, l, p, k / it's silent.  I know that in American English the T is held in "I can't do it" but above I'm talking about dropping it completely. I recorded myself:  Does it sound okay?


May I make a backup from SQLExpress 2012 and restore it into a SQLExpress 2016?

I have SQL Server 2012 backup files and want to restore these to SQL Server 2016/2014. Will it work?  I need to find this out before I uninstall SQL Server 2012.


I want to access the css of * with JavaScript. I tried to access it the same way that I use for -  body{...} /css/  Can be accessed as  document.body.style.overlfow = hidden;  but  *{...} /css/  is not accessible when using  document.*.style.overlfow = hidden; /JS/  doesn't work for the *. So how can i change its css?      function myFunction() {   document.getElementById("Intro").innerHTML= ('');  // document.*.style.overflow ="visible";   }     *{    overflow: hidden;   }   .IntroText{   position: absolute; }   .IntroText{    color: blue;  margin: 20% auto 10% 10%;  z-index: 100;  }  .button {     border: 5px solid blue;     padding: 15px 32px;     text-align: center;     text-decoration: none;     display: inline-block;     font-size: 16px;  position: absolute;  color: white;  margin: 43% 40% 5% 40%;  z-index: 100;    }  .IntroImg{  position: relative;  width: 110%;  height: 110%; }  h1,h3,h4,h5{    color: blue;  position: relative;  text-transform: none;  text-align: left;  font-weight:lighter;  font-family: 'Aria';   font-size-adjust: 10%;   }  br{    display: block;    margin: 10000000px 0; }  .Section{    font-size: 100%;  text-align: center;  margin-left: 20%;  margin-right: 20%;   }  .navbar{    height: 3em;  width: 100%;  z-index: 200;  background: #BBBBBB;  position: fixed;   }  <!DOCTYPE html>      <title>Intro</title>    <link href="Style.css" rel="stylesheet">  <link href="Intro.css" rel="stylesheet">      <meta name="viewport" content="width=device-width, initial-scale=1">  <link href="css/jquery.bxslider.css" rel="stylesheet" />  <link href="css/nav.css" rel="stylesheet">  <link rel="shortcut icon" type="image/png" href="img/w3-favicon.png"/>  <meta name="viewport" content="width=device-width, initial-scale=1">     <link rel="stylesheet" href="https://www.w3schools.com/w3css/4/w3.css">  <meta charset="utf-8">  <meta http-equiv="X-UA-Compatible" content="IE=edge">  <meta name="viewport" content="width=device-width, initial-scale=1">  <meta name="keywords" content="footer, contact, form, icons" />  <link rel="stylesheet" href="css/demo.css">  <link rel="stylesheet" href="css/footer-distributed-with-contact-form.css">  <link rel="stylesheet" href="http://maxcdn.bootstrapcdn.com/font-awesome/4.2.0/css/font-awesome.min.css">  <link href="http://fonts.googleapis.com/css?family=Cookie" rel="stylesheet" type="text/css">  <meta name="viewport" content="width=device-width, initial-scale=1">  <link rel="stylesheet" href="https://www.w3schools.com/w3css/4/w3.css">
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I am wondering how I can read CSS comments out of a linked stylesheet.  I have this sample CSS loaded via:  <link rel="stylesheet" type="text/css" media="all" href="test.css" />      #test1{ border:1px solid #000; } #test2{ border:1px solid #000; } #test3{/* sample comment text I'm trying to read */}   I'm testing this in FF3. The following javascript reads the rules but doesn't read the comments in#test3.  window.onload = function(){     s=document.styleSheets;     for(i=0;i < s[0].cssRules.length;i++){         alert(s[0].cssRules[i].cssText);     } }


Is there a way to find all integer triplets of $(x, m, a)$ for the following equation.  $$\frac{2^m-1}{2^{m+x}-3^x}=2a+1$$

For what values of $m,n$ natural, do $2^n - 1$ is divisible by $2^{m+n} - 3^m$?  Thank you very much.


I want to remove the first $rmv lines of a huge text file called $filename. This text file is so big that I cannot fit two copies of it on my hard drive.   The following leaves me with a blank file called $filename:  tail -n +$rmv "$filename" > "$filename"    The following cannot execute because I do not have the storage space to fit both $filename and $filename.tmp:  tail -n +$rmv "$filename" > "$filename.tmp" && mv "$filename.tmp" "$filename"   If it matters, I'm using Mac OS X El Capitan.

I have a fairly large file (35Gb), and I would like to filter this file in situ (i.e. I don't have enough disk space for another file), specifically I want to grep and ignore some patterns — is there a way to do this without using another file?  Let's say I want to filter out all the lines containing foo: for example...


I'm trying to solve the following problem:  Let   \begin{equation*} f(x) = x^4 - 2x^2 - 2 \in \mathbb{Q}[x]  \end{equation*}  and $ E $ be its splitting field. What is the degree $ [E: \mathbb{Q}] $?  First of all, the roots of this polynomial are $ \pm \sqrt{1 + \sqrt{3}}, \pm \sqrt{1 - \sqrt{3}} $. The first two are real and the other two are complex. It looks as if $ E $ was equal to $ \mathbb{Q}(\sqrt{1 + \sqrt{3}}, \sqrt{1 - \sqrt{3}}) $. The degree of these elements over $ \mathbb{Q} $ is $ 4 $ since $ f(x) $ is irreducible by Eistenstein's criterion. However, I can't tell what the degree of $ \sqrt{1 - \sqrt{3}} $ over $ \mathbb{Q}(\sqrt{1 + \sqrt{3}}) $ is, since I don't know how to check whether $ f $ is irreducible over this field.  I'd appreciate any ideas on how to get to that

Question is to solve for Galois Group of $x^4-2x^2-2$ over $\mathbb{Q}$.  I know the roots of this polynomial are $\sqrt{1+\sqrt{3}},-\sqrt{1+\sqrt{3}},\sqrt{1-\sqrt{3}},-\sqrt{1-\sqrt{3}}$.  But, $\sqrt{2}i=\sqrt{1+\sqrt{3}}.\sqrt{1-\sqrt{3}}$. So, I concluded that splitting field would be $\mathbb{Q}(\sqrt{1+\sqrt{3}},\sqrt{2}i)$ (for some reason i am not very sure about, i have not written splitting field to be $\mathbb{Q}(\sqrt{1-\sqrt{3}},\sqrt{2}i)$).  So, i have splitting field as $\mathbb{Q}(\sqrt{1+\sqrt{3}},\sqrt{2}i)$.   What i do usually after i know that extension is of the form $F(a,b)$ with $F(a)\cap F(b)=F$, I calculate Galois group of $F(a,b)/F(b)$ and Galois group of $F(a,b)/F(a)$ and write their product as in $G=Gal(F(a,b)/F)$  I do the same here for $Gal(\mathbb{Q}(\sqrt{1+\sqrt{3}},\sqrt{2}i)/\mathbb{Q}(\sqrt{1+\sqrt{3}}))$, this is of order 2, sending $\sqrt{2}i\rightarrow -\sqrt{2}i$ (fixing $\sqrt{1+\sqrt{3}}$) So, I have $Gal(\sqrt{1+\sqrt{3}},\sqrt{2}i)/\mathbb{Q}(\sqrt{1+\sqrt{3}}))\cong \mathbb{Z}_2$.  The problem is with $Gal(\mathbb{Q}(\sqrt{1+\sqrt{3}},\sqrt{2}i)/\mathbb{Q}(\sqrt{2}i))$, I Have to prove that Galois group of $x^4-2x^2-2$ is dihedral group of order 8.I already have an element of order 2, I have to get an element of order 4 from $Gal(\mathbb{Q}(\sqrt{1+\sqrt{3}},\sqrt{2}i)/\mathbb{Q}(\sqrt{2}i))$ which is becoming more cumbersome.  Any help would be appreciated. Thank You.


I have a shp file in qgis. I would like to export that shp file into geojson. I have seen the save as option. But, my point is to create individual files for each individual shape in the gis project. Is that possible?

I have a shapefile containing contour for a large area, and I want to split it into different shapefiles each covering a 1KM X 1KM area. I have already created the required Grid shapefile in QGIS.  How do I now split the contours using the created Grid?  I am searching for something equivalent to the  in ArcGIS.


What is the method to add extra options to preexisting panels like the ones I have circled in the screenshot in your addon?

I was watching this  on making a custom UI tab using Python, and in the line from bpy.types import Menu, Panel, UIList, I see the names of objects that look like they can all be used to make different UI elements. Does bpy.types contain all the objects that people use when they want to make custom UI elements?


So the gist of my program is that it will read some commands from a file and then perform certain operations judging by the commands. My problem is that my code isn't reading all of the lines of the txt document. Specifically, it reads the first four lines which I tested by previously inputting a print statement inside of the if statement that tests to see if the input = "P". Any help would be much appreciated.  Here is the txt document as well  P e1 10 5  P e2 19 5  P e3 11 5  P e4 18 5  R mouth 10 10 10 2  S nose 14 7 2  P p3 9 9  P p4 20 9  D  Y bad command  M p3 9 12  M p4 20 12  D    public static void main(String[] args) {            String filename = args[0];           File file = new File(filename);            Scanner input=null;            try {                 input=new Scanner(file);              }           catch(java.io.FileNotFoundException ex) {                System.out.println("ERROR: Couldn't open file: " + file);                System.exit(1);           }            AsciiDisplay asciiDisplay= new AsciiDisplay();            while(input.hasNext()) {                if(input.next().equals("P")) {                      String id=input.next();                     int x=input.nextInt();                     int y=input.nextInt();                     Coordinate coordinate=new Coordinate(x,y);                     Point point=new Point(id,coordinate);                     asciiDisplay.addShape(point);                 }                else if(input.next().equals("R")) {                     String id=input.next();                     int x=input.nextInt();                     int y=input.nextInt();                     int length=input.nextInt();                     int height=input.nextInt();                     Coordinate coordinate= new Coordinate(x,y);                     Rectangle rectangle= new Rectangle(id,coordinate,length,height);                     asciiDisplay.addShape(rectangle);                 }                 else if(input.next().equals("S")) {                      String id=input.next();                     int x=input.nextInt();                     int y=input.nextInt();                     int size=input.nextInt();                     Coordinate coordinate= new Coordinate(x,y);                      Square square = new Square(id,coordinate,size);                     asciiDisplay.addShape(square);                 }                 else if(input.next().equals("M")) {                      String id=input.next();                     int x=input.nextInt();                     int y=input.nextInt();                     Coordinate coordinate= new Coordinate(x,y);                     asciiDisplay.moveShape(id,coordinate);                 }                 else if(input.next().equals("E")) {                      asciiDisplay.deleteAll();                 }                 else if(input.next().equals("D")) {                     asciiDisplay.updateGrid();                     asciiDisplay.printGrid();                 }                else if(input.next().equals("X")) {                   System.out.println("Invalid command: X");                  }             }      } }

I've been using the idiom below for some time now. And it seems to be the most wide-spread, at least on the sites I've visited.  Is there a better/different way to read a file into a string in Java?  private String readFile(String file) throws IOException {     BufferedReader reader = new BufferedReader(new FileReader (file));     String         line = null;     StringBuilder  stringBuilder = new StringBuilder();     String         ls = System.getProperty("line.separator");      try {         while((line = reader.readLine()) != null) {             stringBuilder.append(line);             stringBuilder.append(ls);         }          return stringBuilder.toString();     } finally {         reader.close();     } }


prova1 is a file with some text. When I run this code prova1 become empty:  sort prova1 > prova1   I know that to achieve the effect I can do:   sort prova1 -o prova1   I would just know the reason :)

Possible Duplicate:          I frequently connect to amazon ec2 using their public DNS names (ec2-12-34-56-78.compute-1.amazonaws.com) and because of this my known_hosts file gets overwhelmed with a lot of ec2 entries I will never use again.  I know I could probably use sed -i to edit in place but I wanted to use grep and so I did this:  grep -v ec2 ~/.ssh/known_hosts > ~/.ssh/known_hosts   That leaves known_hosts as an empty file. If I do:  grep -v ec2 ~/.ssh/known_hosts > ~/.ssh/tmp mv ~/.ssh/tmp ~/.ssh/known_hosts   then things are fine, but I am confused why reading and writing to the same file leaves it blank, and if there is any way around this when using grep, cat, etc.