Get all properties of a model that are not a number

Assuming I have a model like this (I shortened it a bit):  class NewsletterDatum {     public string FullName{ get; set; }     public string Email { get; set; }     public string OptOutLink { get; set; }     public long ConciergeId { get; set; }     public long AwardCount { get; set; }     public int YearsMember {get; set; }     public string CardNumber { get; set; }     public string MemberName { get; set; }     public string PointBalance { get; set; }     public List<string> StoredKeyWords { get; set; }     public List<string> FriendIds { get; set; } }   I want to get the list of properties of this model that are not numerical, is there a way of doing this without comparing types with int, long, decimal, etc..?


Why are we able to use Components of Vectors?

Last year, I took physics and over the summer I have started to wonder about why many phenomena work the way they do (such as why is $\mathrm{KE} =\frac{1}{2}mv^2$, etc.). I have found answers to all of my questions, except for this one:  Why are we allowed to use trigonometry to get vector components? I understand that if we draw a right triangle, then we can express the adjacent side with $\text{length of hypotenus} \times \cos(\theta)$. But why does this work with velocity and with forces? I have tried to reason through this many times, but I am not able to figure out why we are able to do this. Any ideas?   BTW: My attempts for reasoning through velocity were as follows: If we have a ball moving in two dimensions, and we are given that the ball has $\sqrt{3}$ the speed in the x-direction than the y-direction, then we can conclude that the ball will move in a 30-degree angle. I am not sure how to apply this to forces or acceleration though. For example, why is it that in the case of a ball spinning horizontally while attached to a string, that the y component of the strings tension gets smaller as the centripetal force increases? I can see how we can prove this by using trigonometry, but why does this trig work in the first place?


Is screen sharing under Sierra secure, i.e., a fully encrypted connection?

I'm trying to figure out if the screen sharing data is encrypted when I connect to my Mac at home from another Mac at work. I've seen a lot of questions and answers but I can't really find a definitive answer. Basically, I just have my Mac sitting at home with Screen Sharing turned on and I'm port-forwarding 5900. It works but again, I'd like it to be secure.   Now, before anyone mentions SSH tunneling, I had it set up the first day I tried this (Remote Login, port-forwarded 22, tunnel created, etc) but then it stopped working. I'm still trying to figure out what's going on there but if Screen Sharing is completely encrypted, then I'm not going to worry about the tunnel anymore.


Points/Circles in graph with TikZ based on table within .tex-file?

Suppose I have a table such as  \documentclass[ a4paper ]{scrartcl}  \usepackage{ tgheros, booktabs } \usepackage[T1]{fontenc}  \begin{document} \begin{center} \begin{tabular}{lrrrrr} \toprule Unit & Thing & Word & More & Things & Letter\\ \toprule A & 4 & 15 & 10 & 0.4 & 1.5 \\ \midrule B & 2 & 12 & 7 & 0.29 & 1.71 \\ \midrule C & 6 & 3\\ \bottomrule \end{tabular} \end{center}     \begin{center}     \begin{tikzpicture}         stuff.     \end{tikzpicture} \end{center} \end{document}   Is it possible to feed the last 2 columns as x- and y-values as (data) points to a TikZ figure in the same document? Or maybe even another .tex-file?  In the end, what I would like to do within the tikzpicture-environment would be something like  \node (A) at (x-value-from-above,y-value-from-above) {}; \filldraw (A) circle (0.1cm) node[stylething] {Something};   And all in all, is it maybe automate the procedure? I think what it could lead to would be a giant macro which I could not program anyway. How does anyone else do it? Is it always the pgfplots-table method?


I have this HTML:

   The CSS is:   .page-title .title_right {   width: 55%;   float: left;   display: block; }  .mid_center {     width: 370px;     margin: 0 auto;     text-align: center;     padding: 10px 20px; }  div.top_menu {     height: 167px;     vertical-align: middle; }   How can I center those buttons vertically? I don't want to patch it using padding.


How is it possible for my multi-distro system to have more than 4 primary partitions?

I have a multi distro laptop (Ubuntu MATE / Mint Cinnamon / Debian) (32-bit Inspiron 6400 2Gb ram 320GB WD HDD) that ignores the alleged limit of 4 primary partitions. I have 15 and counting.   I'm new to modern Linux and am having a play. I last had a play back in the 90s with GNU Slackware I also have an old Acer 64-bit desktop which will only allow 4 primary partitions. I might try loading another 2 distros on to see if the 5th one boosts. Any ideas why this one machine allows over 4 primary partitions and the other does not?


Thesis: What are the requirements before saying "There is no research on that" and how to phrase it?

I'm writing my masters thesis in computer science and I haven't found a good source for evaluation criteria of the protocols I'm looking at in my thesis.   What are the requirements before I can say "There is nothing on evaluation criteria in the literature."   Is the fact that I couldn't find any enough? When do I know that I put enough effort into searching?


How does one change the frame size and colors in the frame option of titlesec as in MWE?

%---------------------------------------------------------------------------------------------------------- % \documentclass[11pt,a4paper,reqno,fleqn,xcolor=x11names]{book} % %---------------------------------------------------------------------------------------------------------- % % \usepackage{amsthm,amsmath,amsfonts} % \usepackage{titlesec} % \usepackage[dotinlabels]{titletoc} % more advanced but essential here \usepackage[english]{babel} %   \titleformat{\section}[frame] % {\bfseries\itshape\fontsize{12.8}{14}\selectfont}         {}{8pt} {\;\;\thesection\hskip 0.7em}  \begin{document}  \chapter{This is Chapter No 1}  \section{A titlesec section in a frame - too tall and not shaded}  \end{document}


Relation between $X\in L^p$ and $n^{-1/p}\sum X$ for i.i.d. sequence.

Let $X_n$ be i.i.d. sequence of random variables and $p\in(0,2)$.   \begin{equation} \lim_{n\to\infty} \frac{1}{n^{1/p}}\sum_{k=1}^n X_k \label{limit}\tag{1} \end{equation}   exists and finite with probability one, if and only if $E|X|^p<\infty$ and either $p\leq 1$ or $EX_k=0$.    Small Step If (\ref{limit}) exists finite, and $p>1$,  \begin{equation} \lim_{n\to\infty} \frac{n}{n^{1/p}}\frac{1}{n}\sum_{k=1}^n X_k \end{equation} since $n^{1-1/p}\to\infty$, $\frac{1}{n}\sum X_k\to 0=EX_k$.  Question I am not sure what is the relation between (\ref{limit}) and $E|X|^p$. I tried to use the fact that $n^{-1}\sum |X_k|^p \to E|X|^p$ however couldn't bound it. Statement suggests that if $p\leq 1$, $E|X|^p<\infty$ iff (\ref{limit}) exists immediately hence I expect it to be rather straightforward. I appreciate if one can advise a path for it.


Let's suppose that $a_n$ satisfy $|a_{n+1}-a_n|<2^{-n}$ for all $n$ . How can I prove that $a_n$ is a cauchy sequence?


Are mountain bikes good for urban riding?

I'm planning to buy a bike - mostly using it in the city on a daily basis - sometimes long roads - But I want a cool bike and I think mountain bikes look very cool.  I would like to know how mountain bikes do on normal roads, especially in the city? Is it more tiring than a regular bike, or what are my other options for city commuting with the occasional touring ride?


How do I expand a macro into a tabular head?

I would like to be able to define a macro that can be used in the tabular definition. How can I do this?  This does not work:  \documentclass{article}  \begin{document} \gdef\buildtabularhead{|||}  \begin{tabular}{\buildtabularhead} 1 & 2 &3\\ \end{tabular} \end{document}


Suppose I want to quote a text that begin with a word embedded within quotation marks. Let the text e.g. be: "House" is a four letter word. Should my quotation of it be ""House" is a four letter word.", or is it better to use different quotation marks or is there some better solution?


Where to post questions asking for expert opinion?

After my lie down, I posted  on SO. As I suspected would happen, it got moved to programmers. Unfortunately, the kind of people I'm interested in getting answers from (litb,skeet et al - the top SO programmers in their respective disciplines) don't frequent Programmers much. So my question is, where to ask somewhat non-specific questions of high-powered users?


Why doesn't the String helloWorld change in this example?

class OtherObject {     String innerString;     OtherObject(String x) {innerString = x;} }  class Playground {     public static void mutate(OtherObject toMutate) {         toMutate.innerString = toMutate.innerString.substring(toMutate.innerString.length()/2);     }      public static void mutate(String toMutate) {         toMutate = toMutate.substring(toMutate.length()/2);     }      public static void main(String[] args) {         String helloWorld = new String("Hello, World!");         OtherObject helloWorld2 = new OtherObject("Hello, World!");         mutate(helloWorld);         mutate(helloWorld2);          System.out.println(helloWorld);         System.out.println(helloWorld2.innerString);     } }   In this example, I have set two objects through method mutate and only one of the objects changed, as shown in this output:  Hello, World!  World!  Process finished with exit code 0   This confuses me because if I remember correctly:   Objects, when passed into methods are passing references, therefore even without returning, the object itself can be changed This is the same reason I can pass an ArrayList into a method and manipulate it without having to return the same ArrayList and assigning it to the previous ArrayList in main. String is an Object.   Why didn't the String helloWorld change?


Isomorphism of hom sets implies objects are isomorphic

Suppose we have   $$Hom(x_0, y) \simeq Hom(x_1, y)\ \forall y \in \mathcal{C}$$  Does it follow that $x_0 \simeq x_1$ in $\mathcal{C}$?   Now suppose that $F, G: \mathcal{C} \rightarrow \mathcal{D}$ are two functors such that $Fx \simeq Gx\ \forall x\in \mathcal{C}$. Does it follow that any natural transformation $\epsilon: F \Rightarrow G$ is a natural isomorphism?


transform simple matrix to simple picture

Assume I have a very simple file with a matrix like  00011000 00022000 00011000 12100121 12100121 00011000 00022000 00011000   I want to import it to TikZ and transform it to a picture, where each cell in the matrix is interpreted as a small square with a color, defined by the content of the cell (e.g. 0 white, 1 gray, 2 black or so). I think that there is a quite simple solution for it. Probably I do not need a complete solution, some hints should be sufficient. Thanks in advance!


Linearly independent eigenvectors of $2 \times 2$ matrix with same eigenvalue

Suppose $M$ is a $2 \times 2$ matrix over $\mathbb{C}$ with characteristic polynomial $\chi =(x-\lambda)^2$ and minimal polynomial $m= (x-\lambda)^2$. My text claims that the geometric multiplicity of $\lambda$ is $1$.   I can only show this by "cheating":  $M$ diagonalizable (here) iff $\lambda$ has geometric multiplicity $2$ iff $m$ decomposes into distinct linear factors. Since $m$ does not decompose into distinct linear factors, we know that $\lambda$  can't have geometric multiplicity $2$.  Is there a way to show this without "cheating"? A more direct solution? Many thanks!


Let mods see the names of the flaggers for chat offensive flags

There have been    (not to pick on the Bridge, just that these are the ones I found) occurrences where users abuse chat flags to cause drama. Random stuff gets flagged, and users from other rooms are needlessly summoned into the room. The issue is, while mods can tell the room to stop flagging random things, there's no way to enforce this. Spam/offensive flags in chat are anonymous, and can be abused with impunity without the mods finding out. I don't think there's anything stopping a user from letting out an endless stream of flags, annoying everyone. Can mods have the ability to see who flagged a message in chat?


I have learnt that at room temperature there are some free electron(not bound to any nucleas) in a conductor and when an electric field is applied they form an electric current.I am quite comfortable with this theory but then I am introduced to band theory which talks of valence and conduction band and they write when electrons can jump from valence to conduction band they conduct electricity.I cannot get what these bands are and why that jump causes current flow?I think the energy level of the valence electrons of all the atoms in the crystal form valence band(correct me,if wrong) but I have no idea about conduction band.Is it allowed energy levels of free electrons present in the crystal or something else?Please clarify


I need nth term for the below sequence  $1,2,(3/2),(5/3),(8/5),(13/8),(21/13),(34/21)........nth term$   I know [(present number)=  sum of previous(numerator + denominator ) / previous numerator]  Thanks before


What is Homomorphic encryption evaluation key

In some homomorphic encryption schemes (e.g , ), it defines an encryption key, a decryption key, and an evaluation key to perform an evaluation f on the encrypted data. Could you please explain what is the difference between the evaluation key and the other keys?


Prove if $ p$ is a prime of the form $3n+1$, then $p$ is also of the form $6m+1$

Prove that if $p$ is a prime of the form $3n+1$, $p$ is also of the form $6m+1$.  I guess one could use the division algorithm for this; but, what's the best method?


Set a polygon's normal's orientation as the objects local rotation orientation (if every polygon is an object)

So,  Each of my polygons is a separate object. Their default normals point like this:   But their orientation or local axes are like so:   How can I make their local axes to be like so, but automatically?   I guess particles might be one solution for this exact case (if you emit new objects on top of the existing ones) but let's say the original objects are triangles and I wouldn't want to change their shape and pointing direction at all, only their local orientation axes, would that be possible?  Cheers!


Suppose $f_n(x)=\sin(nx)$ on $[0.2\pi]$. Is the sequence of functions $\{f_n\}_{n \geq 1}$  equicontinuous on $[0.2\pi]$?  I try to compute derivative, which is $$f^{\prime}_n(x)=n\cos(nx)$$ which gives us $\sup_{x\in [0,2\pi]}|f^{\prime}_n(x)|=|n \cos(nx)|$, which is unbounded. So can we conclude that the sequence of functions is not equicontinous?  Remark: I don't know whether we can use derivative to show equicontinuity of a sequence of functions or not. I saw this somewhere else but I don't know why it works and why it doesn't.  EDIT: Is it always true that $|f_n(x) - f_n(y)| \leq \int_x^y{|f_n^{\prime}(t)|dt}$? So if $|f_n^{\prime}(t)|$ is bounded for all $n$, then the sequence of functions is equicontinuous?


Rules to decide which wonder side (A or B) to play in 7 Wonders?

In the rules it is recommended for the first games to use side A of the wonders only. After these first games (if I understand the rules correctly) players play the side that is at the top of the wonder card they draw. So some would play side A and some side B (probably). This question discusses .  I wonder if this is really the best way?  I see several possibilities how to handle which side to play:   randomly drawn wonder cards, but all players use side A (recommended for the first games) randomly drawn wonder cards, but all players use side B randomly drawn wonder cards, all players use the side that is at the top when the card is revealed (the normal rule) randomly drawn wonder cards, all players use the side they like more   I feel like variant 4 would be the best (each player may select the side) for a casual playing group, as otherwise some side A players might feel that the side B players have an "unfair" advantage (as the special abilites on B seem to be better). Would it be problematic/unbalanced to use variant 4?  How does the side get selected in tournaments?    EDIT: The rules also allow that players (if all agree) can choose which wonder to play. In this case, variant 4 is probably used (variants 1 and 2 would be possible, too), while variant 3 would be rather pointless (you'd select a wonder yourself but randomize which side to play). Anyhow, this question is about randomly chosen wonders.


Why would someone want to use a linked-list over an array?  Coding a linked-list is, no doubt, a bit more work than using an array and one may wonder what would justify the additional effort.  I think insertion of new elements is trivial in a linked-list but it's a major chore in an array. Are there other advantages to using a linked list to store a set of data versus storing it in an array?  This question is not a duplicate of  because the other question is asking specifically about a particular Java class while this question is concerned with the general data structures.


Calculating variance from standard error of pearsons r correlations z scores

I understand that to calculate the standard error of a pearsons r correlation converted to a z score you follow -  1 / (√N−3)  But how do you calculate the variance from the standard error please? I have instructions to follow -  1 / standard error squared. Is this correct please?  Thanks


How do I get the generic, T, of a List field and use it as a generic of another constructor?

I am writing a JsonMapper in order to map a JSON String to the fields of a C# class using , similar to JSONUtility so that I can have greater control over the mapping. I'm not inclined to write the code for mapping each class as I will have many multiple classes with varying fields.  public class JsonMapper<T> {     public string jsonString;     public T mappedObj;      public JsonMapper(string json)     {         jsonString = json;         JSONNode jn = JSON.Parse(json);          Type t = Assembly.GetExecutingAssembly().GetType(typeof(T).FullName);         mappedObj = (T) Activator.CreateInstance(t);          foreach (FieldInfo field in typeof(T).GetFields())         {             switch (field.FieldType.Name)             {                 case "Int32":                     field.SetValue(mappedObj, int.Parse(jn[field.Name]));                     Debug.Log(field + ": " + field.GetValue(mappedObj));                     break;                     ...   I've used reflection in order to map primitive data types so far, but currently I am stuck trying to map lists. I'm trying to obtain the generic, T, of the List, and recursively create another instance of my JsonMapper. Below is an example of what I am trying to achieve:  case "List`1":     Type genericType = field.FieldType.GetGenericArguments()[0];     foreach (var genericJson in jn[field.Name])     {         //This line does not work, it is pseudocode         JsonMapper<genericType> recurJM = new JsonMapper<genericType>(genericJson.ToString());     }     break;   To do so I have referenced  to invoke generic methods using reflection and  to invoke constructors. However, I can't seem to find a way to invoke a constructor with generics.   My question is: How do I achieve this particular line of code in the above code snippet?  JsonMapper<genericType> recurJM = new JsonMapper<genericType>(genericJson.ToString());


I guess the website got this wrong. It says that the Earth is a common noun. In my view it should be a proper noun. Please see the .          The earth moves round the sun.           • Earth is a common noun   • Earth is an abstract noun   • Earth is a proper noun


For continuous distribution $P(X_3<X_2<\max(X_1,X_4))$ equals?

Let $X_1,X_2,X_3,X_4$ be i.i.d random  variables have a continuous distribution. Then $P(X_3<X_2<\max(X_1,X_4))$ equals? $A=\dfrac{1}{2}$ $B=\dfrac{1}{3}$ $C=\dfrac{1}{4}$ $D=\dfrac{1}{6}$  My attempt: $P(X_3<X_2<\max(X_1,X_4))=F_{X_{2}}(\max(X_1,X4))-F_{X_{2}}(X_3)=P(X_{2}<\max(X_1,X_{4}))-P(X_{2}<X_{3}))=1-P(\max(X_1,X_{4})<X_2)-P(X_{2}<X_{3}))=1-P(X_1<X_2)P(X_{4})<X_2)-P(X_{2}<X_{3}))=1-P(X_1<X_2)^2-P(X_{2}<X_{3}))$ I am blank now. No distribution is provided I don't know what I am missing here. I know the fact that $Z=F_{X}(x) \sim U(0,1)$ but how do I use that here?


selecting in python: ask to pick an object?

How do I create a picking session in python? Say I have a script that does some operations, but its want the user to pick first a source object and then a target? How do I invoke the picking? My guess is bpy.ops.view3d.select(), but I get a context error all the time... What is the secret?


Deleted Ubuntu prtition from machine and going back to Win - can't get past "grub rescue" on startup

I wanted to go back to an all Windows machine after trying Ubuntu 15.04. It was a good experiment, but not for me.  I had installed Ubuntu 15.04 on its own partition and it put in a dual boot menu. At start-up I chose either Ubuntu or Win 7.  After making the decision to delete Ubuntu, I went into the Disk Manager in Windows and used the Delete Volume command to free up the space. That left me with all free space where I had Ubuntu.  When I rebooted thinking I would go straight to windows, I get the "grub rescue >" command and can't figure out what to do to get back into Windows.  I have read several of the other fixes in this forum, but they all seem to be aimed at recovering the Ubuntu partition and not to getting past the rescue screen and back to Windows.  Any assistance will be appreciated.


Measures of Uncertainty in Higher Order Moments

Suppose I have a sample of data and compute the mean. I am able to quantity uncertainty in this by computing the variance. I am wondering if known methods exist for evaluating the uncertainty associated with other moments. Specifically, if I compute the variance, skewness and kurtosis of a sample, is there some known formula to determine how uncertain each result is? Any help and associated references would be very helpful.


How do I know if I've failed, passed, or even had an audit?

I spend most of my time on the culture and religion Stack Exchange sites.  I'd like to think I've done my fair share of reviewing.  Here on M.SO, I keep seeing questions about 'failing audits.'  I can't for the life of me remember actually even seeing if I've been audited!  So, three questions:   Is automated Review Auditing part of all graduated sites, or just SO? How do I know if I had one? How do I know if I passed?


PYTHON py2exe makes too many files.. how do I execute only one .EXE file?

After I make an exe file, there are many files such as .pyd that my exe depend on them.. I want to make a program with only one exe file which will be handie.. please help me


Enable hyphenation like in Word/OpenOffice/Libre Office

But then, I fould out that it is normal for (La)TeX and Babel to hyphenate (microtype) text in a different way than software like Word, OpenOffice or Libre Offices does it.  Even when it would be possible to correctly hyphenate a word, (La)TeX sometimes does not do it, because it tries to make some kind of “aesthetic” hyphenation.  The word “hyphenation” could already be a good example. Its syllables are, according to  source, hy-phen-a-tion. (La)TeX may refuse to hyphenate this word as, for example, hy-phenation. But in software like Word, OpenOffice or Libre Office, the software would hyphenate a word wherever it is possible. So, seeing something like hy-phenation in a document created by these computer programmes may be quite common.  I would like to have this kind of hyphenation for (La)Tex, too. That is: Keep a minimum space between words in (justified) text and hyphenate the text wherever it is possible (that is, in terms of hyphenation like in Word, OpenOffice or Libre Office). If I do not like the hyphenation of a particular word, I would like to be able to manually suppress that hyphenation locally but not globally.  I have played around with \pretolerance=0, \hyphenpenalty=-10000 and \setlength\spaceskip{.3em plus .1em minus .1em} as  suggested, but nothing has worked so far. I even got some results where correct hyphenation has been totally ignored. For example, the word “standard” has once been hyphenated as stand-ard. I would like to avoid that.


Dirac Delta function inverse Fourier transform

We know that the Fourier transform of the Dirac Delta function is defined as $$\int_{-\infty}^{\infty} \delta(t) e^{-i\omega t} dt = 1,$$  and if I were to reconstruct the function back in time domain, the inverse Fourier transform is defined as  $$\delta(t) = \frac{1}{2\pi}\int_{-\infty}^{\infty} e^{i\omega t} d\omega.$$  How do I compute this integral analytically?


Proof of equal characteristic polynomials for congruent matrices?

It is probably a very elementary question but I cannot figure it out: my book gives a proof for the theorem that congruent matrices have the same determinant, characteristic polynomial ($\phi(X)$) and the same trace. However, I do not understand the second and third operation they conduct in the proof. How do they go from $(X \mathbb{I_n} - P^{-1}\cdot A \cdot P)$ to $(P^{-1}\cdot (X \mathbb{I_n} -  A) \cdot P)$ and why is $det(P^{-1})\cdot\det(X \mathbb{I_n} -  A) \cdot det(P)$ equal to $\phi_A(X)$?   Many thanks for your help in advance!  Consider two matrices $A$ and $B$ ($\in \mathbb{R^{m \times n}}$) to be congruent. If there is an invertible matrix $P$, such that $B = P^{-1} \cdot A \cdot P$, then: \begin{equation} \begin{aligned} \phi_B(X) &= det(X \mathbb{I_n} - P^{-1}\cdot A \cdot P) \\ &= det(P^{-1}\cdot (X \mathbb{I_n} -  A) \cdot P) \\ &= det(P^{-1})\cdot\det(X \mathbb{I_n} -  A) \cdot det(P) \\ &= \phi_A(X) \end{aligned} \end{equation}


How matrices operations are defined using ZFC axioms?

In my algebra book matrices operations looks like a kind of "algorithm". How do matrices operations are defined under ZFC ? Are they applications ? Are they Turing machine ? Are they something else ?


How to make crispy chicken wings like KFC?

I want to prepare Chicken wings more crispy without using micro oven. Can anyone tell me how to prepare it?


Shadowmere fell off a cliff and died. How do I get him back?

I was riding Shadowmere near Alftand and I accidentally fell into that canyon near the abandoned tower. The fall was enough to kill Shadowmere.   I have done a lot of quests and other things such as fast travel, waiting, and sleeping so I am wondering if that interrupted his respawn. Also if I come back to that point before he respawns, is that bad?   Can Shadowmere just go away and never come back after his death?  I tried waiting in-game for 11 days in Solitude and then returning to Shadowmere's death point, but it did not work.   I do not want to use script commands because I consider that 'cheating' and I don't want to cheat.


How to find the equation of tangent line?

Q: find the equation of the tangent line to the graph of $f$ at the indicated point. Then verify your answer by sketching both the graph of $f$ and the tangent line. [PS: the point of tangency (x,y)] $$f(x)=x^2+1 ,\quad (2,5)$$  So I got the $f'(x)=2x$ But how can I find the tangent line?  Thank you so much!


Do different databases use different name quote?

For example, mysql quote table name using   SELECT * FROM `table_name`;   notice the `   Does other database ever use different char to quote their table name


Ubuntu: Resize the root LVM(2?) partition

I have an Ubuntu virtual machine running in VirtualBox 2.2.4, and I created it on an 8gb virtual disk which is too small.  So, I am trying to increase the size of the disk.  So far, I have done this:   Created a new larger virtual disk Added the 2nd disk to the machine Used CloneZilla to clone the first disk onto the 2nd disk Removed the first disk Booted up off the 2nd (larger disk)   But now I'm still stuck with an 8gb partition on my new 100gb virtual disk.  Whats the easiest path from here to having a 100gb partition? :) I gather GPart can resize partitions, but it doesn't seem to support LVM2 partitions, which mine seems to be.  thx   Alex


What hardware specs is needed to serve 100,000 clients on OpenVpn?

Serving vpn clients (tcp connections) with OpenVpn server relies on what ? Or how can we calculate the clients count with hardware specs ?  Does it rely on server bandwidth speed, like if we have a server with 1 GB (1024MB/PS) we can serve 1024 user (every user can get 1MB)? Or something else?


running bash script from cron job not working properly

I have the following script:    #!/bin/bash echo "$(date +"%r")"  if [ "$FOLDER_ID" != "0" ] then   node /sync.js -d $FOLDER_ID -l /Downloads fi     I'm using docker container and I have passed the env variable FOLDER_ID  when started the container. This variable supposed to be set when starting the docker container by passing it as ENV.  When I run this script, the node command runs as expected, but when the cron job runs the script, it prints the date at but doesn't execute the node command correctly (I think the issue is related to the $FOLDER_ID variable).


Android : On orientation change always webservice is called

When I change device orientation, I am able to change layout properly but its also load data every time from  web service. There is no need to call  web service  each time.  So please suggest.


Given two correlations in a 3 by 3 correlation matrix, what are allowed values for the third correlation?

For a random number experiment, I want to simulate from a trivariate Normal distribution with correlation matrix.   $\left(\begin{matrix}1&a&b\\a&1&c\\b&c&1\end{matrix}\right)\quad (a,b,c > 0)$  The correlations $a$ and $b$ are parameters in my experimental setup, and the third value, $c$, I can choose somewhat freely. Obviously, for any given values of $a$ and $b$, there are values of $c$ for which the matrix is not positive definite. I am wondering if I can somehow work out the "allowed" values of $c$, if $a$ and $b$ are given.  I tried to find conditions that make all eigenvalues positive. The characteristic polynomial of the eigenvalue problem is  $x^3 - 3x^2 + x(3-a^2-b^2-c^2) + (a^2+b^2+c^2-2abc-1)$  That only told me that the problem is symmetric in $a,b,c$. But for my actual question, it didn't really get me anywhere. Any help how to approach this is much appreciated.    Answer: Thanks for the links to duplicated questions. In particular  has the bounds on correlation I was looking for:  $ab - \sqrt{(1-a^2)(1-b^2)} \le c \le ab + \sqrt{(1-a^2)(1-b^2)}$


Incorrect query filter according to the requirement

My requirement wholly depends on the QUERY.  I am filtering my gridview on the basis of three parameters.   Project_name (Always required) Date (Not always) Vehicle_No (Not always)   So, what my requirement is,      With project_name either any one can be used for filtering my gridview.   Currently my debugged query works exactly fine for any two parameters.  Below is my debugged query:-  SELECT DISTINCT sv.mkey, vehicle_no,                TO_CHAR (date_in, 'dd-MM-yyyy')             || ' & '             || time_in vehicleindate_time,                TO_CHAR (date_out, 'dd-MM-yyyy')             || ' & '             || time_out vehicleoutdate_time,             gate_no_in || ' & ' || gate_no_out ingate_outgateno,             gd.good_type goods_type, net_weight netweight,                TO_CHAR (challan_date, 'dd-MM-yyyy')             || ' & '             || challan_no challandate_no,             remark_in remarkin, NULL receipt_no, date_in        FROM xxcus.xxgid_supinv sv,             xxcus.xx_supinv_goodtype gd,             xxcus.xxacl_xxgid_user_mst ms       WHERE (gd.good_type_code(+) = sv.good_type)         AND (       sv.project_id = '1368'                 AND TO_CHAR (date_in, 'dd-MM-yyyy') = '26-11-2015'              OR vehicle_no = '0'             )         AND sv.delete_flag = 'N'    ORDER BY date_in DESC, vehicle_no   The above query shows me the exact result for project_name and Date which I entered.  But when I add the third parameter say Vehicle_no it doesn't show the data for that exact vehicle_no it still shows me the same data which I looked for 2 parameters.  I am using Oracle for the database.  LATEST UPDATE WHICH IS NOT WORKING  I am confused as how to deal with the query, as Balazs' solution was working fine when I selected, Project_name, Date and then vehicle_no (not necessary). But it was not fetching proper result when I took first as Project_name, and Vehicle_no. Any guesses why?     The issue  is when I only filter with Project_name and Vehicle_no the date_column value comes as 0 so it doesn't show me any row, which is incorrect as I have data for that Project_name and Vehicle_no.   I have used Balaz's second query for the solution which is below  WHERE (gd.good_type_code(+) = sv.good_type)     AND (       sv.project_id = '1368'             AND TO_CHAR (date_in, 'dd-MM-yyyy') = '26-11-2015'          AND vehicle_no = decode(:vehicle_no, '0', vehicle_no, :vehicle_no)         )


get Nullpointerexception while insert records

I trying to insert data to my database using prepare statements but I get Nullpointerexception    My  Database connection code   public class DBConnect {     Connection conn=null;        public static Connection connecrDb(){           try{           Class.forName("org.sqlite.JDBC");           Connection conn = DriverManager.getConnection("jdbc:sqlite:E:\\NetBeansProjects\\Abdo`s Project\\project.sqlite");               System.out.println("connection success");               conn.setAutoCommit(false);           return conn;           }           catch(Exception e){               JOptionPane.showMessageDialog(null, e);               return null;           }       }  }   and my code in Main Class  public class Items extends javax.swing.JFrame {       Connection conn =null;     ResultSet rs = null;     PreparedStatement pst=null;     public Items() {         initComponents();         DBConnect.connecrDb();     }      private void SaveBtnActionPerformed(java.awt.event.ActionEvent evt) {                                                  try{              String sql = "INSERT INTO test (name) values(?)";            pst=conn.prepareStatement(sql);            pst.setString(1,item_name.getText() );            pst.executeUpdate();             conn.commit();         }         catch(Exception e ){                       System.out.println(e);             System.out.println(e.getStackTrace());           }       }    Output is  java.lang.NullPointerException  [Ljava.lang.StackTraceElement;@7da469fe   what is wrong in my code ?


How does the notation i[array] work in C?

I haven't come across a similar notation in any other programming language, i.e., I am used to seeing the subscript within the brackets (and not the other way round). I understand how given an array foo, foo essentially is a pointer to the base address of the array; and how pointer notations correlate to array notations, i.e. I get the rationale behind why foo[i], *(foo + i), *(i + foo) are all equivalent... But I don't understand the rationale behind how i[foo] is also equivalent to the three mentioned above, or how it works. Maybe rephrasing this notation in English will help, but I don't see how to do that.


There exists only two groups of order $p^2$ up to isomorphism.

I just proved that any finite group of order $p^2$ for $p$ a prime is abelian. The author now asks to show that there are only two such groups up to isomorphism. The first group I can think of is $G=\Bbb Z/p\Bbb Z\oplus \Bbb Z/p\Bbb Z$. This is abelian and has order $p^2$. I think the other is $\Bbb Z/p^2 \Bbb Z$.   Now, it should follow from the fact that there is only one cyclic group of order $n$ up to isomorphism that these two are unique up to isomorphism. All I need to show is these two are in fact not isomorphic. It suffices to show that $G$ as before is not cyclic. But this is easy to see, since we cannot generate any $(x,y)$ with $x\neq y$ by repeated addition of some $(z,z)$.  Now, it suffices to show that any other group of order $p^2$ is isomorphic to either one of these two groups. If the group is cyclic, we're done, so assume it is not cyclic. One can see that $G=\langle (1,0) ,(0,1)\rangle$. How can I move on?


When reading the documentation for fread , it explains that the two arguments after the void *ptr are multiplied together to determine the amount of bytes being read / written in the file. Below is the function header for fread given from the link:  size_t fread(void *ptr, size_t size, size_t nmemb, FILE *stream);   My question is, other than the returned value from the function, is there really a behavior or performance difference between calling each of these:  // assume arr is an int[SOME_LARGE_NUMBER] and fp is a FILE* fread(arr, sizeof(arr), 1, fp); fread(arr, sizeof(arr) / sizeof(int), sizeof(int), fp); fread(arr, sizeof(int), sizeof(arr) / sizeof(int), fp); fread(arr, 1, sizeof(arr), fp);   And which one would generally be the best practice? Or a more general question is, how do I decide what to specify for each of the arguments in any given scenario?  EDIT  To clarify, I am not asking for a justification of two arguments instead of one, I'm asking for a general approach on deciding what to pass to the arguments in any given scenario. And  that Massimiliano linked in the comments and cited only provides two specific examples and doesn't sufficiently explain why that behavior happens.


How to read/mount full Ubuntu volume from now external hard drive

Yesterday I decided to upgrade my laptop hard drive to an SSD. I was previously running Ubuntu 14.04 on the HDD that came with it. I have installed Ubuntu 14.10 on the SSD.  I would like to mount the old HDD so that I can copy over all my files. So I purchased an enclosure that lets me treat it like an external USB drive. I put the HDD into the enclosure and plugged it in. It is detected and it sees all of the volumes. But it only mounts the boot volume for read/write.  The HDD is 750GB and the SSD is 120GB. When I inspect it in the "Disks" utility I see both hard drives and can easily tell the difference between the two. When I inspect the HDD I see: Partition 1 Ext2 (boot volume), Extended Partition 2, and Partition 5 LVM2 PV.  So clearly it can see the volumes as well. It reports that the disk is ok but has one bad sector. The drive is not encrypted. I am not sure why it shows two volumes of the same size. Probably has to do with it being an LVM volume.  How do I get it to let me read the files from my old installation of Ubuntu?  $ sudo fdisk -l Disk /dev/sda: 223.6 GiB, 240057409536 bytes, 468862128 sectors Units: sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disklabel type: dos Disk identifier: 0x7f79a18e  Device     Boot  Start       End   Sectors   Size Id Type /dev/sda1  *      2048    499711    497664   243M 83 Linux /dev/sda2       501758 468860927 468359170 223.3G  5 Extended /dev/sda5       501760 468860927 468359168 223.3G 8e Linux LVM  Disk /dev/mapper/ubuntu--vg-root: 215.6 GiB, 231479443456 bytes, 452108288 sectors Units: sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk /dev/mapper/ubuntu--vg-swap_1: 7.8 GiB, 8317304832 bytes, 16244736 sectors Units: sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk /dev/sdb: 596.2 GiB, 640135028736 bytes, 1250263728 sectors Units: sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disklabel type: dos Disk identifier: 0x0004f632  Device     Boot  Start        End    Sectors  Size Id Type /dev/sdb1  *      2048     499711     497664  243M 83 Linux /dev/sdb2       501758 1250263039 1249761282  596G  5 Extended /dev/sdb5       501760 1250263039 1249761280  596G 8e Linux LVM


I need help to answer the following problem:  Let $F$ be a field and $n\ge 2$.   Define $\phi:GL(n,F)\to GL(n,F)$ by $\phi(g)=(g^{-1})^T$, where $T$ denotes the transpose.  Suppose that $F$ has at least four elements and $n\ge 3$. Show that the restriction of $\phi$ to $SL(n,F)$ is an outer automorphism of $SL(n,F)$.


Let $f(x)$ be a real valued function defined on $(-1,1)$ such that   $e^{-x}f(x)=2+\int_0^x{\sqrt{t^{4}+1}}\;\mathrm{d}t$ for all $x$ belonging to   $(-1,1)$ and $g(x)$ be its inverse function.   How to find the value of $g'(2)$ (the derivative of $g(x)$ at $x=2$)?  I tried writing $f(g(x))=x$ and then took derivative on both sides of original equation. But it's not working. I think I'm missing something important.  And please don't use hyper-geometric functions.


Import Google Chrome bookmarks from Windows into Mozilla Firefox in Ubuntu

I was a Windows user for last 5 years but wanted to switch into Ubuntu World. I saved too many (around 100) bookmarks into chrome while using Windows. Now I want to import those bookmarks into Ubuntu browser (Firefox).  How can I achieve this?


I'm having this problem for the first time. After rebooting my laptop I stuck with endless login loop (black screen shows up for 2 seconds and then it throws me back to login screen).   I didn't find Xauthority in my home folder. So I've created a new user and logged in - everything's fine except I can't login with my main user.  What should I check?


Align by the top borders of figures when using subcaption

I'm using the subcaptionpackage to have figures side-by-side. The problem is that the package aligns the figures to their subcaptions (should I be taking a hint for the package name?) rather than the top of the pictures.   How can I algin the subfigures by the top border?  MWE:  \begin{figure}[h] \begin{subfigure}[b]{.5\linewidth} \centering\large A \caption{A subfigure}\label{fig:1a} \end{subfigure}% \begin{subfigure}[b]{.5\linewidth} \centering\large B \caption{Another subfigure with a long, long, long, long caption.}\label{fig:1b} \end{subfigure} \caption{A figure}\label{fig:1} \end{figure}   Result:


How to detect if the user entered the space bar?

in a program that takes a character and prints the equivalent ASCII value.  ASCII value for the space bar is: '32'.  but if i press the space bar then the enter key, program still waits for an input, and doesn't get the space bar character recognized.  #include <iostream>  using namespace std;  int main() {     char ch;       cout << "Enter the character: ";     cin >> ch;      cout << "ASCII code is: " <<(int)ch << endl;       return 0;   }


Can three dots be used for context menu?

Does three dots in linear make sense "more" in web applications, i have seen them only in mobile design?


Prove if nonempty $K \subset\mathbb{R}$ is compact, then both sup $K$ and inf $K$ exist and are elements of $K$.

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


Why is gamma function defined such that $\Gamma (n)=(n-1)!$ rather then $\Gamma(n)=n!$, The latter ssems far more logical.


What does $\Bbb Z^\ast$ mean? I would think some subset of the integers but I cannot find a definition. Thank you.


rsync two existing directories copying everything

I have two file servers in two locations. Currently both have the same data, which generally is unmodified (used for read only access).When the second server was set up (the one I'm sshing to) the data was copied over LAN and has since been moved geographically.  I'm trying to use rsync for the first time on the required directories. An example command;  sudo rsync -avz --ignore-existing -P --dry-run /media/Storage/OSs/ user@mydomain:/mnt/Storage/OSs/   I've tried using -c -t -u (Additionally went on the remote server and updated the timestamps to today) also but every time I execute a dry run it wants to copy everything!  Additionally the user is the same for both machines with the same UID.  *Edit  After playing around a bit more, I've found that rsync does not like the whitespace in the subdirectory names; For instance if I use ' to escape local shell & \ to escape remote shell     sudo rsync -avz --ignore-existing -P '/media/Storage/OSs/Windows/Windows server 2011/' 'user@mydomain:/mnt/Storage/OSs/Windows/Windows\ server\ 2011/'   Then all is well, my theory is then that rsync does not like the subdirectories with whitespaces. I have thousands of subdirectories; the only solution I can think of is to write a small python/shell script to run each sub directory separately but is undesirable.


I don't understand why this happens, value l/m does not get truncated to two decimals after the dot...  root@OpenWrt:~# python3 Python 3.7.4 (default, Sep 15 2019, 18:13:03)  [GCC 7.4.0] on linux Type "help", "copyright", "credits" or "license" for more information. >>> l = round((69.2222222/100),2)                   >>> print(l) 0.68999999999999995 >>> type(l) <class 'float'> >>> m = 69.22222222/100 >>> print(m) 0.69222222220000007 >>> type(m) <class 'float'> >>> round(m,2) 0.68999999999999995   This happens on a custom openWRT 18.6 build with  installation.  Why does that happen?   Am I missing any packages?


How to remove chat icons from messaging menu in 13.10 saucy

Upgrading from 13.04, the chat items (Available,Away,Busy,Invisible,Offline) re-appeared in the messaging-menu. I use Pidgin for chat, the icons do not reflect pidgin status changes. For Thunderbird I want to keep the envelope.  I already tried:  sudo apt-get remove empathy* sudo apt-get remove gwibber* sudo apt-get remove telepathy-indicator   I never had to change and recompile the messaging/indicator code as suggested e.g. in


Example "server.php" from ReactJS tutorial has syntax error

thank u for taking time to read my question. It is probably a beginner level question, but I did a lot of search without finding an answer.   I am starting to learn React, and at the very beginning of the ,  it requires a running server.  I have Apache installed and running in my Ubuntu System.  Also, I put all needed example files from the tutorial including the "server.php" in my local "/var/www/react-tutorial-master" folder.  And finally, in the terminal, I entered to the folder above, and executed "php server.php" as the tutorial says.  BUT, the terminal tells me that      "PHP Parse error:  syntax error, unexpected '[' in   /var/www/react-tutorial-master/server.php on line 37 "   I didn't do any mdodification to the file. And I am not familiar with PHP, but I don't think the example "server.php" has any syntax error.  So propably I am missing something, could you please tell me what I am missing.  Here is a  that describes my problem.  Thanks a lot!  The "server.php" looks like this:  <?php /**  * This file provided by Facebook is for non-commercial testing and evaluation  * purposes only. Facebook reserves all rights not expressly granted.  *  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL  * FACEBOOK BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN  * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION  * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.  */ $scriptInvokedFromCli =     isset($_SERVER['argv'][0]) && $_SERVER['argv'][0] === 'server.php';  if($scriptInvokedFromCli) {     $port = getenv('PORT');     if (empty($port)) {         $port = "3000";     }      echo 'starting server on port '. $port . PHP_EOL;     exec('php -S localhost:'. $port . ' -t public server.php'); } else {     return routeRequest(); }  function routeRequest() {     $comments = file_get_contents('comments.json');     $uri = $_SERVER['REQUEST_URI'];     if ($uri == '/') {         echo file_get_contents('./public/index.html');     } elseif (preg_match('/\/api\/comments(\?.*)?/', $uri)) {         if($_SERVER['REQUEST_METHOD'] === 'POST') {             $commentsDecoded = json_decode($comments, true);             $commentsDecoded[] = [                 'id'      => round(microtime(true) * 1000),                 'author'  => $_POST['author'],                 'text'    => $_POST['text']             ];              $comments = json_encode($commentsDecoded, JSON_PRETTY_PRINT);             file_put_contents('comments.json', $comments);         }         header('Content-Type: application/json');         header('Cache-Control: no-cache');         header('Access-Control-Allow-Origin: *');         echo $comments;     } else {         return false;     } }   Line 37 is      $commentsDecoded[] = [


Get value based on max of a different column grouped by another column

I want to get the values of a column based on max of a different column grouped by another column.  I have this table:  KEY NUM VAL A   1   AB B   1   CD B   2   EF C   2   GH C   3   HI D   1   JK D   3   LM   And want this result:  KEY VAL A   AB B   EF C   HI D   LM   I could actually use this query to get it.  select KEY, VAL from TABLE_NAME TN where NUM = (     select max(NUM)     from TABLE_NAME TMP     where TMP.KEY = TN.KEY     )   However is there a more elegant way in ORACLE SQL (10g or above) to get the result?  Reason behind it is that there are actually multiple KEYs and it just looks a bit ugly.


Is there a list of ALL standard commands of LaTeX 2e?

I am looking for a list of all commands available in LaTeX 2e, commands available without packages. I am creating a parser for latex therefore I need to know all commands and the corresponding arguments. For instance:  \newcommand{name}[num]{definition}   I searched for a long time and didn't find such a list.


Moving std::clog in source to output file

I have a basic debug message in my code that prints a message as to what function is called.   #ifdef _DEBUG      std::clog << "message etc" << std::endl; #endif   How do I redirect the output to send the message to a textfile?


How to get list of the range consisting of floats? Why the below code is not working?  lons = list (range(80.0,90.0,0.05))  print (lons)


I'am a maths undergraduate and trying to self study  fundamental physics.One with the first unituitivle statements i  stumble upon was ."friction does not have anything to do with the area an object takes up"  I thought the that friction was proportional to the area that touches the ground .Sometime bigger area might mean  more mass that is why the miss conception.But consider a runner or car .The more the runners  feet touch the ground the more power he can get from friction or a car with the same weight as another car having bigger wheels that the other. or a climber who is told to step on the rock with as much area his shoe can take up so he won't slip .Are these statements wrong or they are right but there is another explanation because i just learned that the area does not create more friction. only mass and normal force.


How linux knows the name of my hardware?

Let's say I run lspci command. This command reports names and models of the devices in my system. Output may look like:  03:00.0 Network controller: Intel Corporation Centrino Ultimate-N 6300 (rev 3e)   This string "Centrino Ultimate-N 6300" - where it came from? Was it originally stored somewhere inside the network card's ROM? If not, the card must have provided some information which allowed linux kernel to uniquely identify it. What information is that, how can I get it?


change space between tabs, align environment

I have a problem formatting a few equations the right way. I have equations with 5 variables which should be displayed among themselves. I tried it with the align environment  and ended up using a lot of tabs. Is there a prettier solution? I guess reducing the space between the tabs would help a bit.  \documentclass[12pt,a4paper]{article} \usepackage{amsmath}  \begin{document}  \begin{align*} 200 &x_R + &150x_C& + &200x_M& + &100 x_T& + &100x_L& &\le& 250000 \\ 150 &x_R+ &100x_C& + &100x_M& + &100x_T& &&&\le& 5000000 \\ 4 &x_R + &4x_C&  + &4x_M& + &4x_T& &&&\le& 20 000 \\ 15 &x_R + &10x_C& + &10x_M& + &15x_T& + &5x_L& &\le& 129600 \\ 2 &x_R + &1x_C& + &1.5x_M& + &1.5x_T& + &1x_L& &\le& 129600 \\  \end{align*}  \end{document}   EDIT:   \documentclass[12pt,a4paper]{article} \usepackage[german]{babel} \usepackage[latin1]{inputenc} \usepackage{amsmath} \usepackage{siunitx}     \begin{document}  \[ \setlength\arraycolsep{0pt}\renewcommand\arraystretch{1.1}   \begin{array}{*{4}{r<{{}}}l}     -4 u_1 + & 2u_2 - & 3u_3 + & 4 u_4\le & \num{9} \\     -3 u_1+ & 1u_2 + & 4u_3 + & 5u_4\le & \num{4} \\     \multicolumn{4}{r}{( u_1,\, u_2,\, u_3, \,u_4\ge{}} & 0)\\   \end{array} \] \end{document}


Proof for $\frac{a}{b} < \frac{a+1}{b+1}$

Supposing $b > 0$ and $a < b$, how could I prove:  $$ \frac{a}{b} < \frac{a+1}{b+1} $$


Pages 24-25 of my textbook, Optics by Hecht, says the following:     Using the above definitions we can write a number of equivalent expressions for the traveling harmonic wave:   $$\psi = A\sin k(x \mp vt)$$   $$\psi = A\sin 2 \pi \left(\dfrac{x}{\lambda} \mp \dfrac{t}{\tau} \right)$$   $$\psi = A\sin 2 \pi (\kappa x \mp vt)$$   $$\psi = A\sin (kx \mp \omega t)$$   $$\psi = A\sin 2 \pi \nu \left( \dfrac{x}{v} \mp t \right)$$   ... Note that all these idealized waves are of infinite extent. That is, for any fixed value of $t$, there is no mathematical limitation on $x$, which varies from $- \infty$ to $+ \infty$. Each such wave has a single constant frequency and is therefore monochromatic or, even better, monoenergetic. Real waves are never monochromatic. Even a perfect sinusoidal generator cannot have been operating forever. Its output will unavoidably contain a range of frequencies, albeit a small one, just because the wave does not extend back to $t = - \infty$. This all waves comprise a band of frequencies, and when that band is narrow the wave is said to be quasimonochromtic.   These are the problems I'm having:    It does not explain how time is relevant to a wave being monochromatic; so why does the fact that physical waves do not extend back to $t = -\infty$ mean that physical monochromatic waves are an impossibility? As relating to 1, how do the equations of the idealized harmonic waves imply that the wave exists for all time? Time $t$ is an independent variable of the equations, which is free to be selected by us, so I'm a little confused about this.    I have read several explanations of this, both on  and on others, but these explanations do not seem to sufficiently clarify my two points above.  I would greatly appreciate it if people could please take the time to clarify this.


Where did the horizontal bands come from?

I've got horizontal colored bands in photos copied to my computer that were not there when I viewed the photos on the camera.  I eventually ruled out everything else and determined that the USB card reader was the problem.  How do the photos get changed during the copy process?  The card reader claimed to be USB 3.0 compatible.  The computer in question has USB 2.0 (Lenovo X220).  The images in question are all JPG.  I got rid of the problem by copying the photos with another reader.  Here's the photo with the colored bands:


Open specific links in specific browsers

Is it possible to tell OS X to always open one site in Chrome, and always open another site in Safari?  In a nutshell, I want to set a default browser per domain rather than globally for the entire computer.  Here's why I ask:  Out of the box OS X does not come with Flash.  The Chrome browser has Flash bundled, however.  So I'd like to have domains that I know require Flash always open in Chrome, but everything else open in my preferred browser, which is Safari.  I'm okay with maintaining a "white list" of which sites need the "use chrome" exception, but right now I can't see any way to make it happen.  Any suggestions?


I tried telnet towel.blinkenlights.nl and it said telnet: command not found. Is it deprecated? It is a bit trivial, but I thought it was worth asking about at least.


Android x86 > error: SysRq: Emergency remount R/0

I have a PC with Windows 10 and Ubuntu 18.04, but would like to add more Android x86(lineageOS 14.1). The ISO file works perfectly in Live USB. After installing with USB (by selecting "Run LineageOS"), the android launches without problems. But after the restart (added lineageOS 14.1 via /etc/grub.d/40_custom), it does start with the following message:  Detecting Android-x86... found at /dev/sda7 [     3.697517] sysrq: SysRq: Emergency remount R/0   Then it reboots to the GRUB2 menu.  How do I fix this, and boot lineageOS 14.1?  My PC with an CPU Intel Celeron 2.6 GHz 1 core, 1GB ram, and I am trying to start lineageOS 14.1 on a 8GB partition (without SDcard).  My boot code is:      recordfail=1     if [ -n ${have_grubenv} ]; then save_env recordfail; fi set quiet=1 insmod ext2 set root=(hd0,7) search --no-floppy --fs-uuid --set 033e8fc7-4cfe-9454-bc59-df7329ca862d linux /cm-x86-14.1-r2/kernel root=UUID=033e8fc7-4cfe-9454-bc59-df7329ca862d ro quiet splash initrd /cm-x86-14.1-r2/initrd.img


I've got a simple login form that just won't start with blank values, no matter what I do (even after adding JavaScript).  Code  <form id="loginForm" name="loginForm" action="login.php" method="post">
         <input type="text" id="wf_username" class="form-control" placeholder="Username" value="" name="wf_username" title="Required" required>                  <input type="password" id="wf_password" class="form-control" placeholder="Password" value="" name="wf_password" title="Required" required>                  <input type="submit" value="Login" id="formsubmit" class="btn btn-success">
 </form>   But it always shows this:   I don't know if that's my MAMP MySQL password showing, but it's disturbing. In every other form where I've used value="" it works fine - what gives here?  I have cleared my cache and tried Chrome & FF - same behaviour. But Safari seems to work fine (Chrome & FF work fine for my other forms where I've set value="", though)  Edit I added the autocomplete attribute to both inputs but same result.          <form id="loginForm" name="loginForm" action="login.php" method="post">
                  <input type="text" id="wf_username" class="form-control" placeholder="Username" value="" name="wf_username" title="Required" autocomplete="off" required>                                      <input type="password" id="wf_password" class="form-control" placeholder="Password" value="" name="wf_password" title="Required" autocomplete="off" required>                                      <input type="submit" value="Login" id="formsubmit" class="btn btn-success">
         </form>   Edit 3 Autocomplete doesn't work when there is an input of type 'password'. Looks like Chrome & FF will autofill that and then an adjacent text box with a username from its saved user/pswd info. This DID work:  <form id="loginForm" name="loginForm" action="login.php" method="post">
          <input type="text" id="wf_username" class="form-control" placeholder="Username" value="" name="wf_username" style="background:none" title="Required" autocomplete="off" readonly onfocus="if (this.hasAttribute('readonly')) {this.removeAttribute('readonly');                                 this.blur(); this.focus(); }" autofocus required>         <input type="password" id="wf_password" class="form-control" placeholder="Password" value="" name="wf_password" style="background:none" title="Required" autocomplete="off" readonly onfocus="if (this.hasAttribute('readonly')) {this.removeAttribute('readonly');                                 this.blur(); this.focus(); }"  required>
             <input type="submit" value="Login" id="formsubmit" class="btn btn-danger"

 </form>


Abbreviated current directory in shell prompt?

vim has a really nice feature which it utilizes in its paths when they're a bit long:    It abbreviates the path to the document in the tab at the top. Is there a way to do something similar to this so my bash prompt doesn't look like this:  rfkrocktk@work-laptop ~/Documents/Projects/Work/maventest/src/main/java/com/tkassembled/ $


Understanding STM32 datasheet regarding decoupling capacitors

I'm trying to understand what ST recommends for decoupling caps for STM32F030CC.  The diagram in the datasheet shows "2x100 nF" caps on the Vdd/Vss pairs. Does this mean 2 parallel 100nF caps per Vdd/Vss pair? Or are they referring to the total number of 100nF caps needed, i.e. if there are 2 Vdd/Vss pairs then it's 1 100nF cap per Vdd/Vss pair, for a total of 2 100nF caps?


I am using Visual Studio Code for my Python programming and the problem that I am facing is that on terminal when I type the command python, by default Python 2.7 is loaded. So because of this I am not able to debug my Python 3 commands on my Ubuntu Budgie.  What should I do in order to uninstall Python 2.7 and make 3.7 as my default Python? I have uninstalled Python 2.7 by using the command sudo apt-get remove python. Even after doing this, I have to type python3 to load Python 3.7 and I get an error when just I type python.  How do I make my Python 3 default so that when I type python, Python 3.7 starts?  -Codec Leaper


Is there a global timer for Stack Overflow?


Questions about the dihedral group $D_8$

Consider the dihedral group $D_8$ of order $16$.  Consider $D_8$ with the presentation $D_8=\{r^i s^j : i=0,...,7; j=0,1; r^8=s^2=e; sr=r^7s=r^{-1}s\}$, where $\{e\}, \{rs, r^3s, r^5 s, r^7s\}$ and $\{s, r^2s , r^4s, r^6s\}$ are three of its conjugacy classes (here $r$ is a rotation and $s$ is a reflection).   1) Find the remaining conjugacy classes.  2) Find the centre and class equation for $D_8$.  3) Find the subgroups of order $4$ and explain which is normal and why.


How to get the best enchantment on your pickaxe

I have asked this to myself many times, how do I get the best enchantment on my pickaxe? I just have no idea, I have tried getting a good enchant but all I got was efficiency 1 for level 30 enchant


right hand to God - what does this mean?

From the science fiction movie  (2003):     — Nine miles to Hole in the Wall.   — I think I can manage it.   — I'll bring the snowmobile back and get you both. Now, Pete, you listen to me. Don't go back to the car for beer. Stay with her. Keep her warm.   — Right hand to God, Dr. D.   What exactly does this expression mean?


How to disable the keyring for SSH and GPG?

How to disable the keyring for SSH and GPG ?  I would like to keep the keyring for the wifi and other stuff. I'm using Ubuntu 12.04.


WiFi on my MacBook Pro (13-inch, Mid 2010) has stopped working.  When I click the WiFi button I see the message "Wi-Fi: no hardware installed"   I have attempted many things, including other questions in this StackExchange site ( was the first answer I found and I followed but didn't solve my issue. Ultimately it suggests replacing my Airport card, but I'd rather eliminate all software/logic possibilities before getting to replacing the Airport adapter or buying a USB wifi adapter).   The detailed steps I've taken:  - MOVING/DELETING SystemConfiguration  I've followed  to check whether my en1 (airport adapter) exist and was working:  ifconfig -a - it showed up  ifconfig en1 inet up or ifconfig en1 up - both resulted in the same error: interface en1 does not exist'  Then I moved/deleted the files located at /Library/Preferences/SystemConfigurations as instructed.   Removed the preferences.plist and restarted. Since it didn't resolve I continued. Removed NetworkInterfaces.plist & com.apple.airport.preferences.plist and restarted. Lastly, I attempted to remove the whole SystemConfiguration folder, but Mac didn't allow it. So I removed as many files as possible and restarted. Didn't resolve the problem, but en1 disappeared for good from System Preferences -> Network.   - NVRAM & SMC reset  Followed several guides, but ultimately this one and it didn't work. I have reset NVRAM & SMC countless times.  - AHT  Some guides suggest running Apple Hardware Test. I've tried, but it doesn't work, returns the error -3403D: as I've researched, it means AHT can't be run in my system.  QUESTIONS  Backing up and reformatting has any chance to resolve the problem? Is it worthy of trying? Any other suggestions? I'm considering to buy an USB wifi adapter.  As a last resort and hoping that my airport adapter is still working and not faulty, I'm asking here.  SYSTEM INFO  MacBook Pro (13-inch Mid 2010)  macOS High Sierra 10.13.6  NETWORK WINDOW


About unnecessary tags and the minor edits adding them

I was just reviewing some suggested edits, and then a lot of edits that were just meant to add the  tag came in for review. Because of that, I decided to check what was the deal with this tag, and from what it seems, it's a tag that doesn't really seem to be necessary at all. I then saw that all of these tags were added by the same user, who seems to have been suggesting a lot of these kinds of tags. Here's a list of the tags I'm talking about in particular:           (should perhaps be voronoi-chart?)  (parallel-coordinates-chart?)  (force-layout-chart?) tooltip - sunburst-diagram - bubble-chart - function-overloading - bar-chart (and stream-graph)  Some of which seem to have more than one follower, but I do think all of these are quite unnecessary. These are just the tags I could easily find up to page 25 of this particular user's suggested edits, but I'm quite sure there are a lot more (including ones I might have missed on the first 25 pages). Important to note is that these tags are not accidental creations, since this user also adds the tags he makes onto seemingly every question he finds related. I've seen in this bunch of edit reviews that most of his suggestions have been rejected, but in his suggested edit history a lot of really minor edits still went through, without anybody rejecting it as a too-minor edit (which is perhaps another thing to worry about - perhaps more too-minor edit suggestion review audits?). So in conclusion, a lot of very minor edits that added quite unnecessary tags have been accepted recently, and I'd like to request some action against these tags. I don't believe these tags should have been created in the first place, but the huge amount of edits that were this minor yet were still approved so easily does seem a bit worrying. Edit: I've removed 5 tags from my list, per . The other ones are either quite unclear or ambiguous (force-layout for example could refer to the chart, but it could as well be what a "How to force div below paragraph" question could be tagged with). The ones I removed are not as much 'Meta Tags' by 's definition "If the tag can’t work as the only tag on a question, it’s probably a meta-tag." as the other ones, but the ones from highlight to label just fail miserably for either that requirement, or the one below that.


What does the "Basic Ubuntu Server" package contain in software selection during installation?

I'm installing Ubuntu from an Ubuntu Minimal image, and I've gotten to the software selection part. What I'm wondering is, which packages are included in the "Basic Ubuntu Server" option?    I'm assuming it's a bundle of packages, but which exactly are included in it?


Is it true that for any $x \in \mathbb{R}$ for all $q \in \mathbb{N}$, there exists a $\frac{p}{q} \in \mathbb{Q} : |x-\frac{p}{q}|< \frac{1}{q^2}$?

Is there a result along the lines of :     For any $x \in \mathbb{R}$ for all $q \in \mathbb{N}$, there exists a $\frac{p}{q} \in \mathbb{Q} : |x-\frac{p}{q}|< \frac{1}{q^2}$.   Thanks for any help!


Consequences of inverse square law with vast distances (Gravity); (in addition, is light speed broken)?

As is well known, the gravitational force between two masses is dependent on the spatial distance between them. Therefore, even at vast distances, the masses exert equal and opposite forces on one another. I know that our theories need for this to be the case (to derive things such as escape velocity, which calls the force at r = $\infty$ to be zero (by utilizing a limit where the distance approaches infinity)), yet the universe is so vast and complex (with an unimaginable number of masses). With so many masses in space, it seems as though this could make a huge difference (over a large distance, such as special relativity's involvement in magnetism) .  Also, say there is a supernova 400 light years away from earth. The time independent theory states that we should immediately notice a difference in the net forces acting on us, yet that would mean information travelled faster than light, correct?  My main point is this: Is it absolutely imperative that there is still a force infinitely far away? Would the universe still function if we were to cut it off at something like a light year? *(This is my main point) Does the infinite reach of the gravitational force have anything to do with the scaffolding of the universe as a whole ?


In a java regex, how can I get a character class e.g. [a-z] to match a - minus sign?

Pattern pattern = Pattern.compile("^[a-z]+$"); String string = "abc-def"; assertTrue( pattern.matcher(string).matches() ); // obviously fails   Is it possible to have the character class match a "-" ?


Wi-Fi only works after waking MacBookPro7,1 from sleep

Been having some issues with the STA drivers from bcrmwl-kernel-source. While the drivers do function, they only seem to function after putting the laptop to sleep, by either closing the lid, or manually putting it to sleep, and waking it up. The laptop here is a MacBookPro7,1 (Mid 2010 13-inch MacBook Pro), running Ubuntu 17.04.  While the issue isn't bad enough to deter me from using the laptop, it is not an elegant solution, and I believe that there can be a solution found somewhere.  For reference, here are the outputs from the Wireless Info script for both before and after: , . Hopefully these are of some use. If you need additional information about the computer, I will be happy to answer.


To write in polar form you use this formula $$z=a+bi=r \left(\cos \theta+i\sin\theta \right)$$ I want the polarform for this rectangular function$$4\sqrt2(-1+i)$$  See this for more information


Find recursive formula for sequence $a_n = \left(\frac23\right)^n + n$


How to prevent people with limited user accounts from accessing my computer

How can I stop limited user of my computer from using the F2 or F12 keys to access my computer while I'm away? They will use them to start it in safe mode and while they are in there it bypasses my password and I don't want them deleting or moving my file around. In fact all I want them to be able to do is go on the internet. They don't need access to any thing else. Can I do that?


I developed an application for Raspberry Pi with C and C++ and the OpenVG graphic library. Because of certain circumstances, I want change the platform from Raspberry Pi to Windows tablets. I don't really want to change a lot of my current program, so I'd be nice to find a way, just to compile it on Windows. Which C/C++ Compiler should I use on Windows, that also supports a graphic library like OpenVG?


I use ubuntu 16.04. My Vim doesn't have Python support. The thing is that I installed vim, vim-gnome, vim-nox, I surfed net for hours and tried to build vim from source, I deleted some stuff like vim-tiny and ubuntu-minimal, whatever I did - nothing worked.  Can anyone help me to get that Python support for Vim?


I've installed System Load Indicator and set 'autostart' in preferences. For some reason it doesn't load at starting system.  How to find out the name/command of this application and then I can add it to "Startup  Applications Preferences"? Thanks.


What is meant with unique smallest/largest topology?

I'm doing this exercise:     Let $\{T_\alpha\}$ be a family of topologies on $X$. Show that there   is a unique smallest topology on $X$ containing all the collections   $T_\alpha$, and a unique largest topology contained in all $T_\alpha$.   I have proved everything except the unique part.. I just can't get my head around what is meant with unique here. Which may sounds silly.   I have proved that the intersection is a topology. And if you are a topology that is also contained in every $T_\alpha$, than you surely are contained in the intersection, so you are not larger.  But I don't see from what it follows that this intersection is the unique largest topology contained in all $T_\alpha$. One part of my head say it is trivial, the other part gets confused. Like it is redundant to talk about unique in this context.  The same for proving the uniqueness of the smallest topology.   Edit Should I read topology $A$ larger than topology $B$ as, $A$ has more elements than $B$ ? I thought that, because the author uses the word finer for $A \supset B$.


How can I figure out what's slowly eating my HD space?

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?


Computing the Lie bracket on the Lie group $GL(n, \mathbb{R})$

Consider the Lie group $GL(n, \mathbb{R})$. Since $GL(n, \mathbb{R})$ is an open subset of the space $M_{n,n}(\mathbb{R})$ of $n \times n$ matrices, we can identify the tangent space (Lie algebra) $T_{e}GL(n, \mathbb{R})$ with $M_{n,n}(\mathbb{R})$, where $e$ is the identity matrix. I'm trying to understand the following:  For all $x, y \in M_{n,n}(\mathbb{R}) = T_{Id}GL(n, \mathbb{R})$ we have $[x, y] = xy -yx$ where $[\cdot, \cdot]$ is the Lie algebra bracket.  According to the question , this seems to be the case for matrix Lie groups in general.  So far, I've worked out the following: Let $x \in M_{n,n}(\mathbb{R}) = T_{Id}GL(n, \mathbb{R})$ and let $X \in \Gamma^{inv}(TG)$ be the left invariant vector field corresponding to $x$, i.e. with $X(e) = x$. By openness, we can choose $\epsilon > 0$ such that the curve $(-\epsilon, \epsilon) \ni t \mapsto e + tx$ through the identity is contained in $GL(n, \mathbb{R})$. For $g \in GL(n, \mathbb{R})$ let $L_g$ be the left multiplication by $g$ in $GL(n, \mathbb{R})$. Using left invariance of $X$ calculate: $$X(g) = ((L_g)_{*}X)(g) = D_eL_g(X(e)) = D_eL_g(x) = \frac{d}{dt}|_{t=0}g(e+tx) = gx$$ Now, the above implies for $f \in C^{\infty}(GL(n, \mathbb{R}))$ and $g \in GL(n, \mathbb{R})$: $$X(g)(f) = (D_gf)(gx)$$ where we identify the tangent vector $X(g)$ with the corresponding derivation at $g$.  Now how do I calculate $[x,y] \stackrel{def.}{=} [X, Y](e) \stackrel{\text{WHY?}}{=}xy-yx$ from this?


"Only by playing fair, and also without fear, will you ever win."  What is its meaning?    I don't understand the last part "will you ever win". Is it a question?


Poisson-Gamma mix conditional probability problem: Find the expected value of Λ for a policyholder having x accidents this year

An insurance company supposes that the number of accidents that each of its policyholders will have this year is Poisson distributed, with a mean depending on the policyholder: the Poisson mean Λ of a randomly chosen person has a Gamma distribution with the Γ(2, 1)-density function fΛ(λ) = λe−λ (λ > 0). Find the expected value of Λ for a policyholder having x accidents this year (x = 0, 1, 2, . . .).  I am not sure how to incorporate the gamma parameters. So far I have found P(X = n|Λ = λ) = Poisson(λ) and fΛ(λ)= Exp(λ) so by integrating P(X = n|Λ = λ)fΛ(λ) then letting the integral of Gamma (n + 2, 2) equate to 1, I have worked out P(X = n) = (n + 1)/2^(n+2). How do you find the expected value of Λ from that? I have seen that a Gamma-Poison mix has E(X) = αβ which would give 2 but I have tried integrating fΛ(λ) and can't seem to get 2.


Do the following positive series converge?

$(d_k)$ is a positive sequence in $\mathbb{R}$ with: $\lim_{n\to \infty} \sum_{k=1}^n d_k = \infty.$  Do the following series converge or not?  a) $\sum_{n\geq 1} \frac{d_n}{1+d_n}$ b) $\sum_{n\geq 1} \frac{ d_n}{1 + n d_n}$, c) $\sum_{n\geq1} \frac{d_n}{1 + n^2 d_n}$ d) $\sum_{n\geq 1} \frac{d_n}{1+d_n^2}$


I wanted to design a simple website but I've been struggling to change font. I looked many tutorial and read documentation but I don't understand what I'm doing wrong!  this is my html:        <title>My website</title>     <link rel='stylesheet' href="style.css">
Perchè non si riesce a cambiare font??
      and this is the style.css   @font-face {   font-family: 'Inter';   font-style:  normal;   font-weight: 400;   src: url("fonts/Inter-Regular.woff2") format("woff2"),        url("fonts/Inter-Regular.woff") format("woff"); }  .par {     font-size: 100px;     font-family: Inter; }   I can't really figure out how to make it work.  I'm currently testing it on windows 10 on Firefox and Chrome browsers (both updated)  Do you guys know what I'm doing wrong?  thanks!


How to prove that these ratios are the same?

As we know, the measures of central angles of the arcs of a circle is proportional to the lengths of the arcs  How to prove that those ratios are the same?


How to use testfor with a mob with a two-word name?

How can I test for mob who has a name with two words? For example villager named Grumpy Bill. For example I want to kill this villager.  This command   /kill @e[name=Bill]   would work just fine but when I try  /kill @e[name=Grumpy Bill]   it says "The entity UUID provided is in an invalid format"  What is the proper command for this action?


I had a question put on hold. When I tried to comment it, it was not possible since the comment button was covered by the hold notification panel.  I could solve it by logging in through a Web browser.  Stack Exchange App, Android Kit-Kat, Galaxy Note 3  Suggestion: Rewrite the app so questions on hold can be commented using the app.


Cannot select text in Safari address bar

All of a sudden, Safari on my Mac has started misbehaving. I can't select the text in the address bar, and so I can't go to any new websites. When it redraws, it goes all weird:    I've tried deleting the cache, clearing all cookies, disabling all plugins and rebooting. These things didn't help. I've had to switch to Chrome for the time being. Can anyone suggest some other possible remedies?


Preserve upvotes as stars when moving comments to chat

Moving comments to chat is a somewhat destructive operation since the upvotes on the comments are lost.  In some cases – especially when there are a lot of comments – this is rather annoying, because it becomes much harder to distinguish the insightful "gems" from the "noise".  Could upvotes be preserved as chat stars when moving the comments?


Cannot edit title of the question if the body is defective

I tried editing the title of , but was precluded by doing so.  The following was the error message:     ×   Body cannot contain "".      Please use example.com (or .org or .net) for fake URLs. More info         This seems like a wrong kind of UX -- if you didn't add any invalid domains, and didn't even touch question body, why should you be precluded from fixing the title?  (In the above question, the change may be trivial, but I don't want to assume the responsibility for editing a body of a really poorly-written question, as that's a sure rabbit hole.)


How to compute $\lim_{n\rightarrow\infty}e^{-n}\left(1+n+\frac{n^2}{2!}\cdots+\frac{n^n}{n!}\right)$

There is a probabilistic method to solve it. But I am not familiar with probability. I am trying to compute it by analytic method, such as using L Hospital's rule or Stolz formula, but they are not working.


Application of Kirchhoff's laws in circuits with inductors

As we know, the  are applicable for conservative electric fields. Now it is applicable for circuits where inductors are present but the field there is not .  So how are the  Kirchhoff's laws  applicable there?


$T$ is compact iff $\langle Te_i,e_j\rangle\to 0$ as $i,j\to\infty$

Let $H$ be a separable Hilbert space and $T:H\to H$ be a bounded operator. Suppose $(e_i)$ is a countable orthonormal basis in $H$. Show that $T$ is compact if and only if $\langle Te_i,e_j\rangle\to 0$ as $i,j\to\infty$.  Note: I could prove that if $T$ is compact then $\langle Te_i,e_j\rangle\to 0$. I am stuck at the converse part.


I managed to reduce it to the form $$\cot(\frac{1}{7})<7$$ But I still don't know how to prove it


Would it be possible to randomize LOD distance in unity like in BOTW grass

I was studying the BOTW grass shader and noticed how the . From watching gameplay it appears the . I can't find any way to do something like this in unity and am wondering if anybody has advice, or can guess as to how they did it. Thanks!


Sci-fi movie from 1980's about killer robot in space

This one is very vague because it's been at least 20+ years since I saw this movie, and I was very young. But it's a sci-fi movie that I believe starts with a mummified/dessicated/skeletal body floating in space, and a ship retrieves what I remember as a reddish, football shaped object from it that turns out to be a killer robot that starts murdering people once it forms itself. This sound at all familiar to anyone?


Let $A$ be a nonempty subset of real numbers which is bounded below. Let $-A$ be the set of of all numbers $-x$, where $x$ is in $A$. Prove that $\inf A = -\sup(-A)$   So far this is what I have  Let $\alpha=\inf(A)$, which allows us to say that $\alpha \leq x$ for all $x \in A$. Therefore, we know that $-\alpha \geq -x$ for all $x \in -A$. Therefore we know that $-\alpha$ is an upper bound of $-A$. $\ \ \ \ $  Now let $b$ be the upper bound of $-A$. There exists $b \geq-x \implies-b \leq x$ for all $x \in A$. Hence, \begin{align} -b & \leq \alpha\\ -\alpha & \leq b\\ -\alpha & = - \inf(A) = \sup (-A) \end{align}  By multiplying $-1$ on both sides, we get that $\inf(A) = -\sup (-A)$  Is my proof correct?


Option to delete an answer only visible after a reload

I used to be able to cast the first downvote on an answer with zero-score and then immediately click the delete link under the answer.  Now, I cast the first downvote and then need to refresh the page for the delete link to be visible.  Is there a reason why the delete link isn't added when casting the first downvote? I liked the faster behavior of the old mechanism.


How to use .click() on element in front of another jQuery element

I'm working on a page that displays a map via jQuery, and I have a div layered in front of the map, with an x in the corner to be used to close it. When I disable the map, clicking the x closes the div (via jQuery's fadeOut() function), but when the map loads, the x does nothing.  Is there any way to enable the .click() function on a layered div like this? Using a delegated event handler does not solve the problem.  $('#close_btn').click(function() {     $('#msg1').fadeOut('fast'); });   or  $(document).on('click','#close_btn',function() {     $('#msg1').fadeOut('fast'); });

         Some stuff!         Some other stuff.


. I know that $C^1([a,b])$ is a Banach space with the $C^1$ norm. But is it a Banach space with the usual norm $||f||_\infty=sup|f|$ ? I think it shouldn´t be, but when trying to prove it I always get that it is. Any idea of a Cauchy sequence in $C^1[0,1]$ which is not convergent  ?


If $\lim_{x \to \infty}f'(x)=+\infty$ then $\lim_{x \to \infty}(f(x)-f(x-1))=+\infty$ and $\lim_{x \to \infty}f(x)=+\infty$.

Let $f$ be differentiable and let $\lim_{x \to \infty}f'(x)=+\infty$ prove that: 1) $\lim_{x \to \infty}(f(x)-f(x-1))=+\infty$ and 2) $\lim_{x \to \infty}f(x)=+\infty$.  1) I'll prove by contradiction. Let $\lim_{x \to \infty}(f(x)-f(x-1))=a$, where $a$ is from and $\Bbb R$. $\lim_{x \to \infty}(f(x)-f(x-1))=\lim_{x \to \infty}\frac{f(x)-f(x-1)}{x-(x-1)}=\lim_{x \to \infty}f'(c)=a$, where c is from $(x-1,x)$ (mean value theorem). As $x$ goes to infinity so does $c$ i.e. we have that $\lim_{x \to \infty}f'(c)=\lim_{c \to \infty}f'(c)=a$. Which is a contradictition since we have that  $\lim_{x \to \infty}f'(x)=+\infty$ .   2) I will also prove this by contradiction. We have that $\lim_{x \to \infty}f(x)=a$ This is equivalent to $\lim_{x \to \infty}f(x)-f(x-1)=0$. I use mean value theorem and get $\lim_{x \to \infty}(f(x)-f(x-1))=\lim_{x \to \infty}\frac{f(x)-f(x-1)}{x-(x-1)}=\lim_{x \to \infty}f'(c)=0$, where c is from $(x-1,x)$. As $x$ goes to infinity so does $c$ i.e. we have that $\lim_{x \to \infty}f'(c)=\lim_{c \to \infty}f'(c)=0$. Which is a contractition since we have that  $\lim_{x \to \infty}f'(x)=+\infty$ .


Safari IOS keeps redirecting to https to non-supported http site

I'm using Cloudflare, i have set redirect https to http and it just ends up in a redirect loop on Safari,  Neither removing cache worked. Its very annoying , for a service status page of my web.  But what, it works on Chrome, Puffin and a lot of other thirdy parties browsers..  Safari just tries to redirect HTTP to HTTPS.  Is there any way to stop this?


When doing ANOVA, what do we need to assume is normally distributed?

Do we assume that the population distributions are normal, or that the sample distributions are normal, or that the sampling distribution is normal? If the latter, what do we mean by sampling distribution in this context?  Why do we need to assume this?  Does the normality of these things entail or suggest the normality of others?


An increasing function on a closed interval has countable many points of discontinuity.

An exercise from "Mathematical Analysis" of T. M. Apostol.     Let $f$ be an increasing function defined on $[a, b]$ and let $x_1, ... , x_n$ be $n$ points in the interior such that $a < x_1 < x_2 < ... < x_n < b$.      a) Show that $\sum_{k=1}^n [f(x_k+) - f(x_k-)] \leq f(b-) - f(a+)$.       b) Deduce from part (a) that the set of discontinuities of $f$ is countable.       c) Prove that $f$ has points of continuity in every open subinterval of $[a, b]$.   Here $f(x-)$ and $f(x+)$ mean the left-hand and right-hand  limit of $f$ in $x$.  Solution for (a)  For (a), by $f$ increasing, we have $f(b') - f(x_n) + \sum_{k=1}^{n-1} [f(x_{k+1}) - f(x_k)] = f(b') - f(x_1) \leq f(b') - f(a')$ for every $a' \in (a,x_1)$ and $b' \in (x_n, b)$. Hence taking the supremum of $f(b')$ for $b' \in (x_n, b)$ and the infimum of  $f(a')$ for $a' \in  (a,x_1)$, calling $b'=x_{n+1}$, we have:  $\sum_{k=1}^{n} [f(x_{k+1}) - f(x_k)] \leq f(b-) - f(a+)$  Notice that $f(b-)$ must exist and can't be infinity because $f(b') \leq f(b-) \leq f(b)$, the same for $f(a+)$.  For $f$ is increasing, $f(x_{k+1}) \geq f(x_k+)$ and $f(x_{k}) \geq f(x_k-)$ hence $f(x_k+) - f(x_k-) \leq f(x_{k+1}) - f(x_{k})$, and we have:  $\sum_{k=1}^{n} [f(x_k+) - f(x_k-)] \leq f(b-) - f(a+)$  Solution for (c)   From (b) is trivial, if $f$ is disconitnuous everywhere in an open subinterval of $[a, b]$ the $f$ has uncountable many points of discontinuity.  I'm asking for a solution for (b).


Path.Combine concatenates only last two string

Hi I have an issue with Path.Combine that it does not return the corect result. Here is what I mean.I ave to combine 4 strings into a bath:  string basePath = "D:\\Programare\\Visual Studio\\TFS Workspace\\CodeArt\\Development\\CodeArt\\Backend\\WebApi\\CodeArt.WebApi\\bin\\..\\Content\\" string userId = "4d52ec77-966a-480a-a4c3-c1ff67438fe9"; string filePath = "\\Avatar"; string storageFileName = "ffdc24a9-f553-41ce-aa33-042b07fcfdab.png";  var result  = Path.Combine(basePath , userId , filePath , storageFileName);   Now for some reason my this code returns only "\Avatar\ffdc24a9-f553-41ce-aa33-042b07fcfdab.png".  Am I doing something wrong why am aint Path.Combine concatantes all the string.


If $p$ is prime and $a \not \equiv 0 \pmod p$, then $a$ and $p$ are relatively prime (in the abstract setting)

I have come across the following remark in lecture:  Let $R$ be the ring of Eisenstein Integers. Let $p$ be a prime in $R$ and let $a \in R$ with $a \not \equiv 0 \pmod p$. Then $a$ and $p$ are relatively prime, i.e. their common divisors are units.  I do not understand why this is true. I attempted to prove it in the following way: Since $p$ is prime it is irreducible, so any divisor $d$ of $p$ has to be a unit or associated to $p$. In the first case the claim is clear, but I do not see how to prove it in case that $d$ is associated to $p$. Could you help me?


The specifications of my system say it supports 400 MHz and 533 MHz DDR2 unbuffered SDRAM. I have a 1 GB DDR2 PC2-5300 laptop RAM module. Can I use this in my desktop? If not, what exactly is the difference between desktop RAM and laptop RAM?


Vertical align center not working inside Bootstrap container

This is my jsfiddle:   I want the text Hello World to be centered vertical but somehow it is not working. How do I fix this problem?  This is my CSS:  .app-header{   height: 50px;   background: #000;   color: #fff; } .v-center{   vertical-align:middle; }


I have the habit of everytime someone answers/comment one of my questions, i go trhu their list of questions and see if I can answer/contribute to any of the unanswered ones.  A few days ago I started to have some trouble on windows and the users answering windows questions have lots of answers and reputation, but zero questions.  I thought everyone had to ask questions to even start to be able to reply... Or do they delete their old questions for some reason?


How to uninstall program, which was installed via ./

I'm using 14.04 LTS. Installed programm is truecrypt-6.3a-setup-ubuntu-x86 I installed via following command  sudo ./truecrypt-6.3a-setup-ubuntu-x86   Ubuntu software center doesn't show me installed truecrypt None of   sudo apt-get remove truecrypt sudo dkpg --remove truecrypt   works. It shows me that truecrypt doesn't installed.  apt-cache pkgnames | grep true   returns none of either truecrypt or something similar Well, it probably should go, but I cannot find /usr/bin/truecrypt-uninstall.sh as well as usr/share/truecrypt-uninstall.shsearchmonkey returns zero of truecrypt except truecrypt.mod and downloaded files What can I do?


Expectation on drawing card from a deck.

Suppose I keep drawing cards from a deck of cards(with replacement, meaning after I draw a card, I switch a new deck of cards but keep the card I draw) until I have drawn both a 1 and a 2. Then What is the expected number of times I would have to draw cards until I can stop?  I have no clue about how to compute such expectation numbers.


How to correct a mistakenly posed downvote?

And in principle an upvote too. I am on the mobile app, and sometimes it happened to me that I mistakenly evaluated an answer.  Then I found the answer locked until further editing and I can't correct my vote.  Is there a way to fix this other than inviting the author of the answer to slightly edit their work?


I'm getting a Code Coverage error - at 70% code coverge. How can I write a test class for this extension? public with sharing class ShouldShowRingSection{     public ShouldShowRingSection(ApexPages.StandardController paramController) {        Intake = paramController;}     public ApexPages.StandardController Intake {get; set;}     public Boolean getShouldShowRingSection() {        Intake__c record = (Intake__c)Intake.getRecord();                             if(             (record.Safety_Concerns__c != null && record.Safety_Concerns__c.contains('Answering the Door')) || (record.Safety_Concerns__c != null && record.Safety_Concerns__c.contains('Wandering'))             )              {             return true;             }                           return false;         }                  }


Should you ask a question asker to accept an answer?

What I often see is questions that gets answered where the asker of the question says "thank you this was exactly what I was looking for" in the comments but forgets to mark the answer as accepted/doesn't vote up.  I don't want to be a beggar so I won't beg for it in comments, I see other people ask for accepting the question.  What should you do in such a situation? Where the asker clearly accepted an answer but didn't "accept it".  Should a moderator come in and tag the answer as answered?


I created a custom form (adding some additional fields) using the Contact module from the core of Drupal 8.  When I submit the form is sent an email containing all values, but it is really bad formatted. The email only contains form's values without any field label and it is unreadable.  How can I customize the template of the email sent on the form's submit?    What I already tried  hook_mail_alter  I found some answer about the same problem for Drupal 7 suggesting to implement a custom hook_mail_alter function (for example: , ).   So I created a custom module with my function:  /**  * Implements hook_mail_alter().  */ function mymodule_mail_alter(&$message) {    // Process only 'contact_page_mail' messages   if ($message['id'] != 'contact_page_mail') {     return;   }    $params = $message['params'];    // Body   $message['body'] = [];   $message['body'][] = t('Some custom message');    // I don't know what should I do here?   // How can I access values of all fields in the form?   // ...    return; }   The function is correctly triggered before the email is sent, but I can't access field's values so I'm not able to build a custom email.  Also I can't get the form's id (only a generic 'contact_page_mail' valid on all contact forms) so I'm not able to handle different contact forms in this function.  Swift Mailer  As suggested in , I tried with the .  After , I'm able to get it working and now I have a swiftmailer.html.twig template file with this content:   <div>    {{ body }}  </div>   But as for the hook_mail_alter solution, I don't know how to access form's field values so I can't customize the email format.  Moreover, the Swift Mailer module currently is an alpha version (8.x-1.0-alpha1) and the Mailsystem module (required to get things working) is a beta version. So I would like to avoid to install unstable modules on a production website (anyway this can be the last solution, if no other works).    EDIT  Thanks to @Berdir, now within the hook_mail_alter function I can access field values with:  $contactMessage = $message['params']['contact_message'];  // Value of 'field_my_field_name' $contactMessage->get('field_my_field_name')->getString();   So I can put them inside the $message['body'].  Quite complicated, but it works.  Is there a way to get field values within the Swift Mailer template? I tried with {{ params.contact_message.field_work_with_us_name }} but it doesn't works.  What happen if I have two or more contact forms? The function hook_mail_alter will be triggered on all of them. Is there a way to have a specific function for each contact form?


The goal is to do something every time a file from a list is modified (saved).  I have no idea to proceed. The end goal should be something like this:  files = ['file1.txt', 'file2.txt', 'file3,txt']  if (one of the files in files is modified):     Print '%s has been modified' % (filename)


Memoir footnotes in margin with ragged2e

I would like to set up memoir so that when I use \footnote{foo}, foo is displayed in the margin with the proper label and preferably break over pages.  There is an option \footnotesinmargin which gives almost exactly what I need, only justified. I want it to use ragged2e and change alignment based on even/odd page so that the margin note is always flushed towards the main text area and allows hyphenation on the side of the edge.  \documentclass[12pt, draft]{memoir} \footnotesinmargin \usepackage{polyglossia} \setmainlanguage{english} \usepackage{fontspec} \defaultfontfeatures{Ligatures=TeX} \setmainfont[Ligatures=TeX,Numbers=OldStyle]{Minion Pro} \usepackage{kantlipsum}  \begin{document} \kant[1]\footnote{\kant[1]} \kant[2]\footnote{\kant[2]} \kant[3-5] \end{document}   Possible partial work-around  I have remembered a nice thesis based upon the Classic thesis template and found the  which indeed contains a possible solution:  \usepackage{marginnote} \usepackage{ragged2e} \newcommand{\sidemark}[1]{#1.{\:}}  \newcommand{\marginelement}[2][0]{%   \marginnote{%     \strictpagechecktrue     \checkoddpage     \ifoddpage%       \RaggedRight\footnotesize%     \else%       \RaggedLeft\footnotesize%     \fi%     #2%   }[#1\onelineskip]% }%  \newcommand{\sidenote}[2][0]{%   \footnotemark%   \ignorespaces%   \marginelement[#1]{%     \sidemark{\thefootnote}%     \ignorespaces#2%   }%   \unskip% }%   Nevertheless, I would still prefer a memoir-specific solution with the re-definition of footnotes when used with the option \footnotesinmargin mainly for the sake of portability. This work-around also does not work with hyperref (there is no hypertext connection) and does not break over pages automatically.


I recently wiped my computer to have 14.10 as my only OS. It has 160 GB of storage. That was a month ago. Now, I keep getting prompts that the storage is almost full. And when I look it says I only have 543 MB free. How is this possible? I haven't torrented any large files. I do have Variety to autodownload wallpapers and not erase though.  Filesystem Size Used Avail Use% Mounted on  /dev/sda1  146G  138G  554M  100%  /  none 4.0K 0 4.0K 0% /sys/fs/cgroup  udev 742M 4.0K 742M 1% /dev  tmpfs 151M 1.1M 150M 1% /run  none 5.0M 4.0K 5.0M 1% /run/lock  none 752M 540K 751M 1% /run/shm  none 100M 80K 100M 1% /run/user –  er –


What's a word for exaggerations of "worst, best, least, most, etc."?

I'm trying to recall a word used to describe cases of hyperbole where a speaker refers to a given subject as the ultimate example of something.   For example, President Trump stated, "I am the least racist person you've ever interviewed" to a reporter recently.  Or if a student were to state, "I am the most open-minded person you will ever meet in your entire life."  Thanks!


Reputation chart: columns are white in Chrome

Anyone else see this? Is this just me or is it Chrome? The bars on the lower reputation chart show in white when Chrome is set to 100% zoom. in IE8 it looks fine. The screenshot shows IE at the top and Chrome at the bottom.     When I zoom out, the bars get faintly green  at 90%    The more I zoom in, the more bars become green. Following three screenshots are at 110%, 125% and 150% resolution.      Can anyone else repro this? I see this on all sites I have an account with.  Running Chrome 29.0.1547.57 m on Win 7 Enterprise, SP1