I have the following code that reproduces a PyCharm warning,  Expression can be simplified This expression detects equality comparison with a boolean literal.  seq_group = [] if seq_group == []: # warning here    print("it is empty.")  if I change the code to, if seq_group is None:  will fix the warning, but the real question is are None and []emplty list the same thing? cheers

For example, if passed the following:  a = []   How do I check to see if a is empty?


I saw this answer () that said that $R^2$ can be negative if it's defined as $1-\frac{SSR}{SST}$. SSR is the sum of squared residuals which is defined as  \begin{align} SSR &= \displaystyle\sum\limits_{i=1}^n (y_i - \hat{y}_{i})^2 \\ &= \displaystyle\sum\limits_{i=1}^n (y_i - \hat{\beta_1} x_{i1}   - \hat{\beta_2} x_{i2} - \ldots - \hat{\beta_k} x_{ik}     )^2 \\ \end{align}  when theres no intercept, and SST is the total sum of squares, or   \begin{align} SST &= \displaystyle\sum\limits_{i=1}^n (y_i - \bar{y})^2 \\ \end{align}  Also SSE, or the explained sum of squares, is  \begin{align} SSE &= \displaystyle\sum\limits_{i=1}^n (\bar{y} - \hat{y}_i)^2 \end{align}  in the notation of my book. I just got to the section in my textbook that mentions this too and I'm confused. Why is this true?  Here's what I could work out. I know that  \begin{align} R^2 &= 1-\frac{SSR}{SST} \\ \end{align}  So for $R^2 < 0$, we need $\frac{SSR}{SST} > 1$. Here's what I worked out:  \begin{align} SSR &> SST \\ \displaystyle\sum\limits_{i=1}^n (y_i - \hat{y}_{i})^2 &> \displaystyle\sum\limits_{i=1}^n (y_i - \bar{y}_{i})^2 \\ \end{align}  Here's the proof I tried to work out:  \begin{align} SSR &> SST \\ SSR &> \displaystyle\sum\limits_{i=1}^n (y_i - \bar{y})^2 \\ &> \displaystyle\sum\limits_{i=1}^n \left[ (y_i - \hat{y}_i) - (\bar{y} - \hat{y}_i)\right]^2 \\ &> \displaystyle\sum\limits_{i=1}^n (y_i - \hat{y}_i)^2 - 2\displaystyle\sum\limits_{i=1}^n (y_i - \hat{y}_i)(\bar{y} - \hat{y}_i) - \displaystyle\sum\limits_{i=1}^n (\bar{y}_i - \hat{y}_i)^2 \\ &> SSR - 2\bar{y}\displaystyle\sum\limits_{i=1}^n (y_i - \hat{y}_i) + 2\displaystyle\sum\limits_{i=1}^n \hat{y}_i(y_i - \hat{y}_i) - \displaystyle\sum\limits_{i=1}^n (\bar{y} - \hat{y}_i)^2 \\ &> SSR - 2\bar{y}\displaystyle\sum\limits_{i=1}^n (y_i - \hat{y}_i) + 2\displaystyle\sum\limits_{i=1}^n \hat{y}_i(y_i - \hat{y}_i) - SSE \\ 0 &> -2\bar{y}\displaystyle\sum\limits_{i=1}^n (y_i - \hat{y}_i) + 2\displaystyle\sum\limits_{i=1}^n \hat{y}_i(y_i - \hat{y}_i) - SSE \\ SSE &> -2\bar{y}\displaystyle\sum\limits_{i=1}^n (y_i - \hat{y}_i) + 2\displaystyle\sum\limits_{i=1}^n \hat{y}_i(y_i - \hat{y}_i) \\ \end{align}  This is where I get stuck. Is the proof on the right path, or is there a mistake before I got stuck? Hints would be great.  I'm starting to get why this is the case logically. SSR is the sum of the squares of the distances from the points to the regression line, while SST is the sum of the squares of the distances from the points to a line drawn through $\bar{y}$. $R^2$ is negative because $SSR > SST$, which means that because we impose the limitation that the regression line MUST pass through the origin, our regression line is an even worse fit than if we just drew a horizontal line at $y =\bar{y}$ and used that. The distances from the points to the regression line are higher than the distances from the points to the line at $\bar{y}$ (ok thhe sum of squares of the distances is larger). Is that the right logic?

I understand from this question -    that the R squared value of a linear regression model can be negative if the intercept is constrained. And this makes sense if you define R squared as -   $$R^2 = 1-\frac{SSE}{SST}$$  One says $SSE>SST$. But then,  $$SST = SSA + SSE $$ Total Sum of squares  = Sum of squared errors + Sum of squared residual. And with this we get -  $$R^2 = \frac{SSA}{SST}$$ And now it is hard to imagine how $R^2$ can be negative. Aren't SSA and SST >0 always?


I am looking for resolution for a constant problem at work. When writing algebra questions I will say something like  "Find a Cartesian equation of the plane passing through the points (1,2,3), (4,5,6) and (7,8,9)." But the applied mathematicians on the exam committee ALWAYS want to change it to  "Find a Cartesian equation of the plane passing through the points with position vectors (1,2,3), (4,5,6) and (7,8,9)." WHY? I don't see the problem?? They are constantly agonising over points vs position vectors of points. What's the point? Or is it What's the vector?  Do not get it. Why burden both yourself and the students with this distinction? Surely a plane is a collection of points not position vectors of points. ??

I understand that a vector has direction and magnitude whereas a point doesn't.  However, in the course notes that I am using, it is stated that a point is the same as a vector.  Also, can you do cross product and dot product using two points instead of two vectors? I don't think so, but my roommate insists yes, and I'm kind of confused now.


I've heard that the universe is expanding constantly and that galaxies are moving further and further away from each other because of this. However, does the universe expand in every direction evenly or does it expand in one direction more than another direction?

Does space expand equally in every direction, so that it draws a perfect sphere or is expansion asymmetric, so it creates "bubbles" (when seen from the outside)?


I have seen the post here:  It is now possible to tag faces that have been detected, but not recognized. However, sometimes a face isn't even detected. Is there any way to fix this? Or is there any alternative to photos that offers similar features, and also this?

I have "Face grouping" enabled in my Google account and I can see around 10 faces successfully tagged when I go to my Albums. However, there's a lot of other people who are not tagged, as well as some unrecognized photos of people who are already tagged.   Is there a way to force Google Photos to run the facial recognition algorithm on a given photo, so that it adds new faces or maps a new photo to an existing face?


I'm making three dropdowns on HTML and I make a JavaScript program to alert when there has a duplicate selected value. What should I do If after the alert the selected dropdown return its default value after the alert.    function hey() {    var count = document.getElementsByClassName('data').length;   //var cars = document.getElementsByClassName('data')[0].value;   var arr = [];   var text = "";   var i = 0;   while (i < count) {     if ((document.getElementsByClassName('data')[i].value) == "") {} else {       arr.push(document.getElementsByClassName('data')[i].value);     }     i++;   }   document.getElementById("demo").innerHTML = arr;   var uniqueval = arr.filter(function(itm, i, arr) {     return i == arr.indexOf(itm);   });   if (arr.length > uniqueval.length) {     alert("Has duplicate")   } }
   <select name="type" class="data" onchange="hey()">     <option value="">---select---</option>     <option value="teacher">Teacher</option>     <option value="student">Student</option>     <option value="students">Students</option>   </select>   <select name="class" class="data" onchange="hey()">     <option value="">---select---</option>     <option value="teacher">Teacher</option>     <option value="student">Student</option>     <option value="students">Students</option>   </select>   <select name="class" class="data" onchange="hey()">     <option value="">---select---</option>     <option value="teacher">Teacher</option>     <option value="student">Student</option>     <option value="students">Students</option>   </select>

When I select another dropdown and its been already selected
  Theres have an alert message and when I click OK I want to return its default value which is --select--
     I want to return the --select-- value after the alert of the selected dropdown.

I have the following HTML <select> element:  <select id="leaveCode" name="leaveCode">   <option value="10">Annual Leave</option>   <option value="11">Medical Leave</option>   <option value="14">Long Service</option>   <option value="17">Leave Without Pay</option> </select>   Using a JavaScript function with the leaveCode number as a parameter, how do I select the appropriate option in the list?


I am making a template for several books. I have a mainfile which includes the .tex files for my chapters. For each book, some chapters are always almost the same except for a few subsections.  How can I define a macro or something to only include this subsection under a specific condition?  It should be like this pseudo code:    type=(A,C) <-- defined at the beginning of each book    \chapter{blabla}    if type=B, include: \section{first}    \section{second} <-- this is included always   if type=B,C, include: \section{third}   if type=A, include: \section{fourth}   so only sections second, third and fourth would appear in this particular case. Any idea how to realize that?

Let's say I have .tex file which is a set of problems and solutions, of which I want to make two pdf files, one which includes the solutions and one which doesn't. so I need to build the .tex file under two different modes, and specify that parts of the document be ignored under one of the modes.  This is something common in programming context. e.g. in C++ i can code  #ifdef DEBUG   // do this additional stuff ... #endif   How can I do something equivalent in latex?


Got this question during Python Dev interview.     If you have to chose what to return from function tuple or list, what   considerations would you have? (Other than the fact list is mutable   and tuple is not.)   Different performance? Something else?

What's the difference?  What are the advantages / disadvantages of tuples / lists?


I usually hear people talk about Newton's 2nd Law like it's a, well, law, as in it relates several defined concepts. I had always thought of it as the definition of force. I'm pretty sure I'm wrong in this respect, but I can't figure out how. If mass times acceleration isn't the definition of force, it must have another definition, and Newton's 2nd Law relates these two concepts. Is it incorrect to think that every physical value that doesn't have base units must have a definition? If not, why not? And if so, what is the definition of force?  I asked my professor this question, and he said that force is defined to be something that changes the velocity of an object. Given that acceleration is the time derivative of velocity, this sounds like a roundabout way of saying $F=ma.$   If I'm actually right, and Newton's 2nd Law is a definition, why do people treat it (and name it) like a law?

If you consider  as laws, then there must be independent definitions of  and  but I don't think there's such definitions.  If you consider them as definitions, then why are they still called laws?


I'm aware of the established array-shuffling algorithms, such as Knuth-Fisher-Yates. I'm interested in proving (or disproving) that my self-made shuffling algorithm is broken. It seems to be the reverse of KFY and requires the same number of random numbers. Here's the algorithm:  for i from 0 upto n-1 do:   j = random integer such as that i ≤ j ≤ n-1;   exchange a[j] and a[i];  Extra: If this algorithm is indeed the reverse of KFY and working, are there any general properties, something like "the reverse of a random shuffling algorithm is also random shuffling"?

This is a follow-up to a Stackoverflow .  There are established algorithms (such as the ) that one should use to shuffle an array, rather than relying on "naive" ad-hoc implementations.   I am now interested in proving (or disproving) that my naive algorithm is broken (as in: does not generate all possible permutations with equal probability).  Here is the algorithm:     Loop a couple of times (length of array should do), and in every iteration, get two random array indexes and swap the two elements there.   Obviously, this needs more random numbers than KFY (twice as much), but aside from that does it work properly? And what would be the appropriate number of iterations (is "length of array" enough)?


The solution here  for getting a "Table of Contents (Continued)" heading in the text of the second page of the table of contents works very well and is the best solution I have found after quite a lot of research, but are there any ideas on how I get this on to the third page of the table of contents?

I'm finalizing my dissertation, and they require that the "Table of Contents - Continued" heading in the ToC (that shows if it flows onto a second page) be centered.  I thought I could find the code that generates the ToC and just customize it a bit, but I can't even find what's generating it...  Anybody have any ideas how I could work this out, or where the code is?


I know this question has been posted many times, but I don't understand it.  Two trains travel on the same track towards each other, each going at a speed of 40 kph. They start out 180km apart. A fly starts at the front of one train and flies at 100 kph to the front of the other; when it gets there, it turns around and flies back towards the first. It continues flying back and forth till the two trains meet and it gets squashed.  How far did the fly travel before it got squashed? I must do it John von Neumann's way but I don't get it.. Help maybe ?

The Problem:  Two trains travel on the same track towards each other, each going at a speed of 50 kph. They start out 50km apart. A fly starts at the front of one train and flies at 75 kph to the front of the other; when it gets there, it turns around and flies back towards the first. It continues flying back and forth til the two trains meet and it gets squashed (the least of our worries, perhaps).  How far did the fly travel before it got squashed?  Attempt at a solution:  I can do this by summing the infinite series of the fly's distance for each leg. I get an answer of 37.5 km: but that's so nice! There must be a more intuitive way...is there?


I installed a new single pole switch with pilot. Now he pilot of the new installed switch is on all the time. Did I do something wrong?

First off I know the switch the works I plugged it into a different circuit where I have another one and the pilot light turned on when the switch was on. However when I have it installed in the problem circuit the indicator light is switched and is illuminated when the light is off instead of it being illuminated when the light is on.  The circuit is for the downstairs lights in an older building so I am thinking it has to be something with how the lights are wired. The switch works the lights just fine so I am figuring it is something to do with the neutral side. I am unfamiliar with this light switch and how it works internally.   What would make the light come on one way in one circuit and opposite in another? I am unsure the exact brand I am an amateur electrician just helping a friend, but it is similar to the Leviton 15 Amp Combination Switch with 25-Watt Neon Pilot Light found on the home depot website. any help or ideas would be greatly appreciated


It seems to be the case that the equation $m^2 - n^2 = p$ where $p$ is odd has exactly one positive solution at $m = p/2 + 1/2$, $n = p/2 - 1/2$ if and only if $p$ is prime, but I'm unsure how to go about proving this true or false.

Show that the solution for the Diophantine equation $x^2 - y^2 = N$ is unique if and only if $\mid N \mid$ or $\frac{\mid N \mid}{4}$, respectively, is $1$ or prime.   I have an idea of how to show $\mid N \mid$ or $\frac{\mid N \mid}{4}$ is $1$ or prime $\Rightarrow$ the solution for the Diophantine equation is unique.  We can show this by going through the separate cases $ \mid N \mid = 1$ or $p$ and $\frac{\mid N \mid}{4} = 1 $ or $p$. For example, if $\mid N \mid = 1$, then $x^2 - y^2 = (x -y)(x+y) = 1$ or $(x -y)(x+y) = -1 $. For $(x -y)(x+y) = 1$, we have $x = 1, y = 0$ and $x = -1, y = 0$ as solutions (more than one solution? Doesn't uniqueness imply only one?).  How do I show the other direction?: The solution for the Diophantine equation is unique $\Rightarrow$ $\mid N \mid$ or $\frac{\mid N \mid}{4}$ is $1$ or prime.


I want to show that  $$\forall_{\varphi, \eta \in \mathbb{C}} \ \left | \varphi  \right |^{2} + \left | \eta  \right |^{2} = \frac{1}{2}\left (  \left | \varphi + \eta \right |^{2} + \left | \varphi -\eta  \right |^{2} \right ) $$  How can I generally prove this? Any help for a starting point of the proof would be greatly appreciated.

Ok, so I have the following proof. Let $z$ and $w$ be complex numbers. Prove $\lvert z+w \rvert ^2 + \lvert z-w \rvert^2 = 2[\lvert z \rvert^2 + \vert w \rvert^2]$. Using $\vert z \rvert^2=z\bar{z}$, I have said   $\lvert z+w \rvert ^2 + \lvert z-w \rvert^2 = 2(\lvert z \rvert^2) + \vert w \rvert^2)$  $(z+w)\bar{(z+w)}+(z-w)(\bar{(z-w)}$  $(z+w)(z-w)+(z-w)(z+w)$  $z^2 - w^2 + z^2 - w^2$  $z^2 + z^2 + -w^2 + -w^2$  $2(z^2) + 2(-w^2)$  $2[z^2 + (-w)^2]$  $2[\lvert z \rvert^2 + \vert w \rvert^2]$  I guess my question is, is my logic correct? I am not so skilled with proof writing and though I feel that this is correct, I have been known to be wrong in the past. Just need some insight. Thank you.


I have one external hard drive (Seagate 320 GB). I have used my hard drive in a Windows XP system and it works fine (Read and write). But when I used it on a Mac, I couldn't write any file on the disk and could read only.   How can I use my external hard disk on Mac OS X (both read and write)?

I would like my external drives to be readable and writable from Linux, Mac OS X and Windows.   FAT32 works, but the 4 GB file size limit is a showstopper these days. Are there any alternatives?


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?

If $x_1,x_2,x_3$ and $x_4$ are independent identically distributed  random variable with continuous distribution .what is the probability of $$P=p(x_1 < x_2< \max(x_3,x_4))$$ I know the exhaustive number of cases are $p(x_1<x_2<x_3)+p(x_1<x_2<x_4)$ and  every $x$ are iid so both have same probabiltiy so is $2p(x_1<x_2<x_3)$ is right? But  i get the $p(x_1<x_2<x_3) = 1/6$ and then my answer is $1/3$ but the answer is $1/6.$ Can we write $P$ as $p(x_1<x_2<x_3<x_4)+p(x_1<x_2<x_4<x_3)$?


I need a regex to match pattern from web page. I want to extract all name and email addresses. Text is in a HTML table like:  Name <email@test.com>   Update  Name 1 <email1@test.com> Name 2 <email2@test.com> Name 3 <email1@test.com>   Like this.  Thanks, Uday

Over the years I have slowly developed a  that validates MOST email addresses correctly, assuming they don't use an IP address as the server part.  I use it in several PHP programs, and it works most of the time.  However, from time to time I get contacted by someone that is having trouble with a site that uses it, and I end up having to make some adjustment (most recently I realized that I wasn't allowing 4-character TLDs).  What is the best regular expression you have or have seen for validating emails?  I've seen several solutions that use functions that use several shorter expressions, but I'd rather have one long complex expression in a simple function instead of several short expression in a more complex function.


How many ordered pairs $(A,B)$ are there so that they satisfy the condition $A\subseteq B$ , where  $A\subseteq S$ and $B\subseteq S$, and $S$ has $n$ elements?   How to approach this question ?  If we start with $n$ elements then there will be $n$ subsets of size $1$, $1$ subset of size $0$ , $n-1$ subsets of size $n-1$ and each subset will have its own further subset ,which will also be a subset of given set $S$ , so now how to proceed from this stage ?

Find the number of Pairs $(A,B)$ of subsets of $[n]$ such that $A ⊆ B$? I just need clarification in my thought process. My professor's wording at times can through me off. I just want to know if I am on the right track. We will have $3$ regions: 1.Outside $B$ 2.Inside $A$ 3. Inside $B$, Outside $A$ I believe the number of pairs is $3^n$ but I am not sure. Any help would be appreciated.


When people say that objects are passed by value, do they mean that the reference of the object is copied and "passed by value"? I've been searching through YouTube and StackOverflow for hours, and haven't gotten a clear source that says so. For example, when you pass an object by value, does that mean that you are actually passing a copy of the object that has the same memory code/reference? I don't know if I'm thinking about this the correct way so please let me know if there's anything that I'm misunderstanding.

I always thought Java uses pass-by-reference. However, I've seen a couple of blog posts (for example, ) that claim that it isn't (the blog post says that Java uses pass-by-value). I don't think I understand the distinction they're making. What is the explanation?


For example consider that i have created a file temp.txt and delete it later, there is still an invisible file temp.txt~ Of course I can delete it but Why do i need to do it always, So how to avoid it..

I have files ending in ~ in my home directory, and I want to delete them. How do I do that? How do I prevent this backup functionality?


Let's suppose you're facing an enemy that has resistance against non-magical weapons. Alas, you have no magical weapon, but you do have your trusty Alchemy Jug that you routinely use to produce mayonnaise. You grab the Jug and use it as an improvised weapon. Does it count as magical for the purpose of overcoming damage resistance?  (How resistant a magical item is to physical damage is a bit of DM's fiat. For the sake of this question, assume the Jug is indestructible.)

This question was triggered by .  Basically, it goes like this: If you have a weapon with a certain magical effect, let's say the minor property unbreakable (can not be broken, requires special means) or temperate (no harm in temperatures between -20 to 120 F), it can bypass the immunity of something like a Werewolf because it is magical instead of mundane. This goes for any minor property because those properties are under the Magic Items portion of the DMG on pg.143.  How does this differ from a pair of gauntlets with the exact same effect being used as an improvised weapon (emphasis added for clarity) from dealing damage in the same manner to the same Werewolf? Or something that's clearly not a weapon like a Shield of Missile Snaring being used to bash an opponent?


I have a table having business days stored into it. I want to get 5th business day based on the input date i give.  For an example please consider below table      BUSINESS DAY 8/06/2004 12:00:00 AM 8/07/2004 12:00:00 AM 8/08/2004 12:00:00 AM 8/09/2004 12:00:00 AM 8/10/2004 12:00:00 AM 8/13/2004 12:00:00 AM 8/14/2004 12:00:00 AM 8/15/2004 12:00:00 AM 8/16/2004 12:00:00 AM   Here my input date is 8/08/2004 12:00:00 AM my output should be 8/15/2004 12:00:00 AM. Please help to construct query for this.  Please note that based on the requirement i may need past dates as well.   Note: I want to fetch the record neither from top nor bottom. I have to fetch the 5th record only from the row where my input condition is satisfied

I'm interested in learning some (ideally) database agnostic ways of selecting the nth row from a database table. It would also be interesting to see how this can be achieved using the native functionality of the following databases:    SQL Server MySQL PostgreSQL SQLite Oracle   I am currently doing something like the following in SQL Server 2005, but I'd be interested in seeing other's more agnostic approaches:  WITH Ordered AS ( SELECT ROW_NUMBER() OVER (ORDER BY OrderID) AS RowNumber, OrderID, OrderDate FROM Orders) SELECT * FROM Ordered WHERE RowNumber = 1000000   Credit for the above SQL:   Update: See  regarding the SQL standard. Troels, have you got any links we can cite?


I have seen some people using them while others not. Should I still use a suspended hyphen in the following snippet?     I have used upper- and lowercase in my script.

If multiple hyphenated terms share the same latter half, and I wish to list them without repeating that latter half, how should the hyphens be placed?  For example:     I will be investigating control issues in ground-based, water-based, and air-based robots.   If I do not want to repeat based, could I write:     I will be investigating control issues in ground-, water-, and air-based robots.   Is it correct to just leave a hyphen dangling after ground and water?  If not, how should it be written? I know the original sentence doesn't sound too bad, but I really just want to know the punctuation rule (or the convention in American English if there is no rule).


Hi The GRE prep test is asking for the square root of a number.. for example $\sqrt{16}$.  It says the answer is $4$.  Couldn't the solution be both $4$ and $-4$?

Can the square root of a real number be negative?  Dealing with the questions of functions in eleventh class my maths teacher says that square root of a real number is always positive. How is it possible?


Suppose we make a linear regression model on each of the 10 folds with the same number of features (say 2 for simplification) We will therefore have 10 sets of coefficients with the optimized values of the parameters with each of the metrics (for example R2).  In the end what model do we retain? (the best, the average values obtained for each parameter, the model that obtained the average R2?) Ouvrir dans Google Traduction

When we do k-fold cross validation, should we just use the classifier that has the highest test accuracy? What is generally the best approach in getting a classifier from cross validation?


If an object is moving through a vacuum, can changes in the object affect this motion?  If the object is spinning could the spin be altered if the object's shape is changed?  Would this object change velocity as an ice skaters velocity changes when they pull in their arms & legs?

My friend thinks it's because she has less air resistance but I'm not sure.


I have dates in the format Y-M-D hour-minute-second 2013-09-03 12:10:28, but I need the unixtimestamp.  PHP has a slough of functions for transforming dates and times, but apprently none that can accept a date and its format and convert it into unixtime. The closest function I found was mktime(), but I would need to parse my current date into each of its components. Is there an easier way?

How do I get timestamp from e.g. 22-09-2008?


I know the passive structure and I know its application. But I've always noticed that a few sentences which have a structure similar to the passive, although they are not exactly passive. For example:     I met one really nice guy named Tony    according to my incomplete knowledge, I could rewrite it as      I met one really nice guy who is called (or) was named Tony   Now, I would like to know what the exact grammar point is here.   If I wanted to translate these two sentences in my own language, they would have exactly the same meaning, so do they really mean the same in English ?

Is it correct to say "What was your name?"? The reason I am asking this is, generally the name of the person will not change. One should say "What is your name?"


I have been studying the book named Grammar and Vocabulary for Advanced by Martin Hewings and Simon Haines. There is a exercise sentence like this "With the wind reaching hurricane force, ships have been advised to head for land." As I cannot rewrite the sentence, I'm confused. Could you rewrite the sentence above and clarify it for me please? Thank you!

I'm looking for a logical explanation of how we use the preposition "with" in the following context:  The company took the first place with their competition a distant second. North America had the greatest number of travellers over the 5-year period with Central and Eastern Europe showing a similar pattern.  I suppose my main question is how do I explain the phrase (it's not a clause) that follows the "with"? and how do I explain the function of "with" in these sentences?


Why is the following true?  Given a matrix $A \in \mathbb R^{n\times m}$ with rank $r \le \min(n,m)$, there are row and column sets $$ \{ i_1, \ldots, i_r \}, \quad \{ j_1, \ldots, j_r \}, $$ such that the $r\times r$ submatrix $$ (\hat A_{s,t})_{s,t=1}^r = A_{i_s,j_t} $$ is nonsingular.    Of course, with the column rank of $A$ being $r$, we can find $r$ linearly independent columns of $A$. But how can we know that they stay linearly independent after restricting them to the $r$ similarly chosen rows of $A$?

Let $A$ be an $m \times n$ matrix of rank $r$, let $I$ be a set of row indices such that the corresponding rows of $A$ are independent and let $J$ be a set of $r$ column indices such that the corresponding columns of $A$ are independent.  Let $M$ denote the $r \times r$ submatrix obtained by taking rows from $I$ and columns from $J$.  Then $M$ is invertible.  So far I've got: Let $B$ be the $m \times r$ matrix obtain from taking the rows from $J$.  $B$ is row-reducible to having a pivot in each column or else $Ax = 0$ has more than one solution, a contradiction.  Also, the dimension of the row space of $B$ equals $r$ as well.


I created a content type.  In the content type I have field called ingredients. Machine name is "field_ingredients".  When a user see the output of the node (not in form and not in views), the label is: "ingredients:". I want the remove the ":" or even change the label to something else.  How can I do that?  I tried the "preprocess_node" function, but it didn't succeed.

I created a custom content type with some text fields. In the view settings of that content type I defined both to appear and as well their titles (names of the fields) to be displayed above the content of the fields respectively.  But how can I remove the trailing colon of the titles? Is there a way of modifying the way field names are display just for certain content types? I do not want this altered site wide (e.g. for all fields of all content types).  PS: I'm already using the "views" module to define a special layout for this custom content type. Probably there is a way to carry out these changes with the help of the "views" module and a custom layout template?  /edit/ I did not create a view (as with the "views" module) to display that content but used Drupal's own content type view configuration (maybe called "display"). I'm working with a localized Drupal and retranslating the different words.  Remark: Using Drupal 7.10 with Views 7.x-3.0-rc3


I have to show that  $\lim_{n\to\infty} \sqrt{n}(\sqrt[n]{n}-1)=0$  We proofed that   $\lim_{n\to\infty} \sqrt[n]{n}=1$  My problem is, that I do not know how to solve that.   That $\lim_{n\to\infty}(\sqrt[n]{n}-1)=0$ is clear. But $\lim_{n\to\infty} \sqrt{n}$ is not bounded.  So I can not simply calculate:  $\lim_{n\to\infty}\sqrt{n}\cdot \lim_{n\to\infty}(\sqrt[n]{n}-1)$  right?  I would be thankfull for every hint. :-)

I want to show that $$\lim_{n \to \infty} \sqrt{n}(\sqrt[n]{n}-1) = 0$$ and my assistant teacher gave me the hint to find a proper estimate for $\sqrt[n]{n}-1$ in order to do this. I know how one shows that $\lim_{n \to \infty} \sqrt[n]{n} = 1$, to do this we can write $\sqrt[n]{n} = 1+x_n$, raise both sides to the n-th power and then use the binomial theorem (or to be more specific: the term to the second power). However, I don't see how this or any other trivial term (i.e. the first or the n-th) could be used here.   What estimate am I supposed to find or is there even a simpler way to show this limit?  Thanks for any answers in advance.


It's been 14 in-game days and he hasn't re-spawned. I died at the Wall of Flesh and I don't get the debuff when I go into Hell so the WoF isn't the problem.  I checked all the skylands, my old houses, and the default spawn point; I went the East and West ends.  There isn't a goblin invasion going on.  So I'm clueless as to what's happening.  I just want to get into Hardmode, but I can't because the dang Guide isn't spawning.  The house I made for him is suitable. 2 doors, 2 torches, table, chair, walls 6 high 10 wide.  I've been standing at the East end of the map for him to spawn, but nope. Any suggestions on what I need to/can do for this bug would be appreciated.

I am currently in hard mode and during a blood moon, several of my NPCs including my guide and my healer died. it's been several in game "days" now and they have yet to respawn. Is there a way to check why they aren't respawning?   Is there a list of reasons for the NPCs to not respawn?   Edit in reponse to lunbok's answer:  1. They don't have appropriate housing - There is an in-game housing query function (changes your cursor into a ?) that lets you click on your house to see if it is still a suitable house and I clicked in every room in my house and they are all listed as "This housing is suitable" or "This housing is already occupied".  2. Their spawn conditions aren't met anymore. - This doesn't explain why my guide isn't respawning since they don't need a condition to respawn (other than having a suitable housing which the point above already prove isn't the problem).  3. There's a goblin invasion going on. - Do the invasions last that long? It has been about two reals days and a lot more in-game "days" now. As far as I can tell there shouldn't be an invasion going on.  4. It could be because you built your house in a part of the world that is now corrupted


After formatting from windows7 I installed ubuntu 15.10 from a usb drive. Although everything seems to be installed correctly after booting all I see is my wallpaper. Unity, no launcher, no dash appears. I have tried to Install compizconfig-settings-manager but when I switch back to the graphical server I see nothing. Any ideas oh what I am doing wrong?

When I login, nothing happens.   I am presented with my desktop wallpaper.    No Dash, no Launcher, nothing.


I have to prove that $\cos(x)<\frac{\sin^2(x)}{x^2}$ for $0<x<\frac\pi2$. By using the MVT I got that $\frac{\sin^2(x)}{x^2}=\cos^2(c)>\cos^2(x)$ for a $c\in[0, x]$ but this doesn't help since $\cos^2(x)<\cos(x)$ because $0<\cos x<1$. The derivative didnt help either, since the derivatives of both $\cos(x)x^2-\sin^2(x)$ and $\cos(x)-\frac{\sin^2(x)}{x^2}$ don't have roots that I can easily find/I don't see a way to prove that they don't have roots. Any help is appreciated!

Prove $\sin(x)\tan(x) > x^2$ for $x \in ( \,0, \frac{\pi}{2}) \,$  So I did the following: Let $f(x) = \sin(x)\tan(x) - x^2$.  Then of course $f(0) = 0$ and I want to show that for $x \in ( \,0, \frac{\pi}{2}) \,$ $f'(x) > 0$ but I don't really know where to go from here as I can't get anything reasonable done with the derivative.  I was thinking of approximating it using the following inequality $\sin(x) < x < \tan(x)$.   Is that a good direction?


I know it was chasing the Tantive IV, but had it already been there before the Tantive IV arrived or did it chase the Tantive IV to Tatooine? Did it have something to do with Vader ordering the execution of Owen and Beru Lars? Does anyone think that this question will be answered in Rogue One?

At the beginning of Star Wars: A New Hope, we see the Rebel Blockade Runner with Princess Leia and the Droids being pursued by a Star Destroyer above the planet Tatooine.  Practically directly above it, close enough that it could almost be in orbit.    It seems an incredibly strange coincidence that they should run so close to a planet that just happens to play host to Darth Vader's estranged son and former mentor before his turn to the Dark Side.  Moreso that they'd fly so close to any planet at all, when space is so vast and empty.    What reason did the Rebel Blockade Runner have for being so close to Tatooine during this chase?


For example, there is 10 fields in a table. I want to select 9 fields except one(a9). a1 a2 a3 a4 a5 a6 a7 a8 a9 a10   select a1,a2,a3,a4,a5,a6,a7,a8,a10 from t1   Is there simple way to get the result? Notice: there is no rules for fields(like aN ). It's just convenient to make an example.

I'm trying to use a select statement to get all of the columns from a certain MySQL table except one. Is there a simple way to do this?  EDIT: There are 53 columns in this table (NOT MY DESIGN)


My question is based on what I know from this  where the question is     Are omniscience and omnipotence mutually inconsistent?   And in the link there is The God Delusion by Richard Dawkins, where in short :     If God is omniscient then He is not omnipotent.   To be honest I agree with Richard's conclusion above IF I use the understanding of omniscience and omnipotent like this :   A. Omniscience = know all things happen absolutely B. Omnipotent = a power to do anything if desired   Since (to me) if the understanding is like A and B then A and B cannot go side by side ....so, how to understand Omniscience and Omnipotent (which is not like A and B) in order Omniscience and Omnipotent can go side by side ?  Thank you.

I see this in The God Delusion by Richard Dawkins:       If God is omniscient, he must already know how he is going to intervene to change the course of history using his omnipotence. But   that means he can't change his mind about his intervention, which   means he is not omnipotent.   Is this argument sound?


Is it possible to record video of the iPhone screen, and if so how?  I'm talking about video screen capturing, not using a camcorder or any app that requires jailbreaking my phone.

OS X Yosemite brought support for recording iPhone/iPad screen natively without having to using AirPlay applications like AirServer or Reflector.   How do I record the iPhone screen on macOS ?


I am trying to compile a document which has this reference:  @article{7103024,     Abstract = {The complexity of indoor radio propagation has resulted in location-awareness being derived from empirical fingerprinting techniques, where positioning is performed via a previously-constructed radio map, usually of WiFi signals. The recent introduction of the Bluetooth Low Energy (BLE) radio protocol provides new opportunities for indoor location. It supports portable battery-powered beacons that can be easily distributed at low cost, giving it distinct advantages over WiFi. However, its differing use of the radio band brings new challenges too. In this work, we provide a detailed study of BLE fingerprinting using 19 beacons distributed around a ~600 m2 testbed to position a consumer device. We demonstrate the high susceptibility of BLE to fast fading, show how to mitigate this, and quantify the true power cost of continuous BLE scanning. We further investigate the choice of key parameters in a BLE positioning system, including beacon density, transmit power, and transmit frequency. We also provide quantitative comparison with WiFi fingerprinting. Our results show advantages to the use of BLE beacons for positioning. For one-shot (push-to-fix) positioning we achieve <; 2.6 m error 95% of the time for a dense BLE network (1 beacon per 30 m2), compared to <; 4.8 m for a reduced density (1 beacon per 100 m2) and <; 8.5 m for an established WiFi network in the same area.},     Author = {R. Faragher and R. Harle},     Date-Added = {2017-10-27 13:12:59 +0000},     Date-Modified = {2017-10-27 13:12:59 +0000},     Doi = {10.1109/JSAC.2015.2430281},     Issn = {0733-8716},     Journal = {IEEE Journal on Selected Areas in Communications},     Keywords = {Bluetooth;indoor navigation;indoor radio;mobility management (mobile radio);radiowave propagation;BLE radio protocol;Bluetooth low energy radio protocol;WiFi signal;continuous BLE scanning;dense BLE network;empirical fingerprinting technique;indoor radio propagation complexity;location awareness;location fingerprinting;one-shot positioning;radio map;Advertising;Aggregates;Batteries;Bluetooth;Fading;IEEE 802.11 Standards;Interference;Bluetooth Low Energy Positioning;Bluetooth Positioning;Indoor positioning;Location fingerprinting;bluetooth low energy positioning;bluetooth positioning;iBeacons;location fingerprinting},     Month = {Nov},     Number = {11},     Pages = {2418-2428},     Title = {Location Fingerprinting With Bluetooth Low Energy Beacons},     Volume = {33},     Year = {2015},     Bdsk-Url-1 = {http://dx.doi.org/10.1109/JSAC.2015.2430281}}   But lualatex somehow crashes after I run the biber command. But if I remove the entry named above everything works. Does the abstract somehow contain a character which is not allowed?

I'm trying to use biblatex (v1.5a) with biber (v0.9.3) instead of BibTeX but I am having a problem with bib entries, where the abstract contains a percent sign. In that case, in the bbl file the corresponding entry will have a line with \field{abstract}{ ...% ...} with the percent sign causing the quotes not to be closed. And pdflatex complains with an error "Runaway argument" (see error message and minimal example below).  So here is my question: How can I either make biblatex ignore the abstract entries (as BibTeX does) since I do not need them in my LaTeX document or  tell biblatex to add an escape character automatically?   Or am I missing something here? Any help is appreciated! Thanks.  The error message is:  Runaway argument? {Limit Cycle Walkers are bipeds that exhibit a stable cyclic gait wit\ETC. ! File ended while scanning use of \field. &lt;inserted text&gt;                  \par  l.51 \begin{document}  ! Undefined control sequence. &lt;argument&gt; \blx@bbl@data    Here is a minimal working example:  \documentclass{scrartcl} \usepackage[utf8]{inputenc} \usepackage[american]{babel} \usepackage{graphicx} \usepackage{amsmath}  \usepackage{booktabs} \usepackage[citestyle=authoryear,%numeric-comp,  bibstyle=authoryear,%numeric backend=biber, natbib=true, hyperref=false]{biblatex} \bibliography{myref} \listfiles \begin{document}  adsf asdf asdf asdf asdf asdf  asdf \citep{Hobbelen2008b}  \printbibliography \end{document}   with the corresponding conflicting entry (abstract shortened) given as:  @ARTICLE{Hobbelen2008b,   author = {Hobbelen, D.G.E. and Wisse, M.},   title = {{Ankle Actuation for Limit Cycle Walkers}},   journal = {The International Journal of Robotics Research},   year = {2008},   volume = {27},   pages = {709-735},   number = {6},   abstract = {Limit Cycle Walkers are bipeds that exhibit a stable ... by at  least 60%, without increasing ...     of 5% of its leg length, while walking efficiently at a mechanical     cost of transport of 0.09.} }   (some other package versions: etoolbox v2.1, logreq v1.0)


Can my sister under age 21 bring me back alcohol to the United States from Germany when she returns? Would there be any issue? What if I met her at the gate?

I overheard a friend asking another friend whether she, being of legal age here in Spain, would have any trouble taking wine purchased here back to the USA where she is not allowed to buy it.  The response was merely anecdotal, so I decided to try to find better information.  A person over eighteen can legally buy alcohol in Spain. If under 21, can she (USA citizen) bring some back to USA? If not, what are the consequences for the attempt?


Given $G,H_1,H_2$ finite abelian groups and $G\times H_1 \cong G\times H_2$   Show $H_1 \cong H_2$   I think the proof would go something like this: $H_1\cong(G\times H_1)/(G\times\{e_{H_1}\})\cong(G\times H_2)/(G\times\{e_{H_2}\})\cong H_2$  Though the first and third isomorphisms are somewhat obvious, I'm doubtful about the second isomorphism because Given $\Phi:G_1 \to G_2$ is an isomorphism, I only know that (this is a guess) $G_1/H\cong G_2/\Phi(H)$ (is this true? I have not verified) But $\Phi((G,e_{H_1}))$ may not be equal to $(G, e_{H_2})$  So how do I show this?

I'm currently reviewing my algebra for my last prelim and came across the following problem that has me stumped:  If $A,B,C $ are finite Abelian groups such that $A\oplus B \cong A\oplus C$ then show that $B\cong C$.  I'm not really sure where to start; the only thing that comes to mind is the fundamental theorem of finitely generated Abelian groups, I'm not sure if that's useful though.   I really only want a good hint.


I would like to draw graphs in a table similar to Table 1 (page 4), "Distribution" column as given in this paper -   Is this an image or can this be drawn using some math LaTeX code?

I have recently started using the tufte-latex package for various science writing and, while I love the package generally, am dismayed that it does not include the ability to produce graphics (charts, sparklines, etc.) in the style of Tufte.  While his typesetting is wonderful, it seems to me that the plots are the primary focus of his work.  Is there a readily available package that allows for easy production of Tufte-style plots? Perhaps using pgfplots or sageTeX?


On the page  there's a list of the questions that match my Watched Tags across all sites. I'd like to get these questions emailed to me instead of having to check the page. I used to be subscribed to some other tags, which worked fine, but I changed my mind and wanted to be subscribed to all my Watched Tags. So I clicked "Subscribe" on the Email Updates section on the right hand side of the page, entered my email address (and checked "every 3 hours") and hit "subscribe".  I didn't get a confirmation email and haven't been receiving any emails. I retried a few times in case I entered my address wrongly, but nothing worked.

I have created a custom filter in  and specified that I would like to get email updates:  However, I never got a confirmation mail nor any notifications based on my filter. I tried the "resent confirmation mail" button on the right hand sidebar:  But again nothing happens. The mail address should be fine  I used it for all kinds of notifications from Stack Exchange. For example the rep recalculation email arrived just fine on this address.  I retyped it several times to make sure there really isn't any typo  I double checked that it did not end up in the spam filter  I don't think it is a problem with my particular email provider, users with other mail providers seem to have the same problem, see     This is possibly related to , but this claims to be "status complete".   EDIT: Although the "status-completed" tag was added, the problem still persists  EDIT 2: As of Feb 2020, it finally works


Is there a way to start a VNC session but without have the remote computer (an iMac) screen turn on ?  I tried to reduce the brightness to min on the physical machine but is not good enough.

Let's say I have 2 MacPros:   MacPro at work MacPro at home   I wonder if there is any way I could access my MacPro at work from home using the screen sharing method, without anything being visible on the monitors of MacPro at work.  I am currently able to do the standard screen sharing using my work MacPro from home, and can also normally access its folders etc. My question relates to ensuring privacy of the work content in case someone walks by while I'm using that remote computer. Unplugging the work computer's monitors would not be a fully working solution, as it would only partially resolve this issue.


$CP^2$ and $\bar{CP^2}$ are not diffeomorphic since they have non-isomorphic intersection forms. so why do we call the latter $CP^2$ with reverse orientation? it seems like we are not just reversing a given orentation on $CP^2$ to get $\bar {CP^2}$.

I am confused by the orientation of a topological manifold. My understanding is: An orientation of a topological manifold is a choice of generator of the $H^n(M,\mathbb Z)$. So given a manifold, we could have 2 orientation defined on the manifold. For $\mathbb{CP}^2$ on orientation is determined by the complex structure, the other orientation is denoted by $\overline{\mathbb{CP}}^2$. And it is well known that there is no orientation reversing map from $\mathbb{CP}^2$ to itself.  My question is: are they homeomorphic? I guess they are not homeomorphic. But I am confuesed, doesn't the orientations defined on the same manifold, how come after reversing the orientation they become not homeomorphic?


I want to know what kind of power supply I have and what wattage it has. I tried:    sudo dmidecode -t 39   but that didn't show any specs. What do I need to do? I am on Ubuntu 13.10

Is there a tool to print the power supply information, such as brand/model name and maximum (supported) output voltage? I need to add a second GPU and I would like to make sure it does support the extra voltage. P.s: I already installed a secondary GPU when I had the access and I rushed outside the server room. When I later checked, the second GPU was not recognized (now that I don't have the access anymore!! :P) I wanted to make sure if the problem was the lack of power voltage as the GPU was working on another machine and is not faulty. Currently, I don't have physical access to the PC currently (ssh only). I have tried to see other posts, also the other exisiting tools, i.e., sudo dmidecode -t 39, sensors, and ipmitool, but none of them show the information I'm looking for.


I have this values with DNS entries (The point at the end must be there): DOMAIN="_my-smtp.sub.domain.com." DOMAIN="_my-smtp.sub.domain.co.uk." DOMAIN="_my-smtp.sub.domain.eu."  Now I need two values. One is the subdomain and the other is just the domain Subdomain: sub.domain.com sub.domain.co.uk sub.domain.eu  Domain domain.com domain.co.uk domain.eu  For the subdomain I tried what works. SUB_DOMAIN=`echo $DOMAIN| perl -p0 -e 's|^_my-smtp\.||g' | perl -p0 -e 's|\.$||g'`  But there are many different domain endings (TLDs), sometimes with two (co.uk) TLDs and sometimes with one (com). How could I solve this?

Getting the subdomain from a URL sounds easy at first.  http://www.domain.example   Scan for the first period then return whatever came after the "http://" ...  Then you remember  http://super.duper.domain.example   Oh. So then you think, okay, find the last period, go back a word and get everything before!   Then you remember  http://super.duper.domain.co.uk   And you're back to square one. Anyone have any great ideas besides storing a list of all TLDs?


Host: Mac OSX 10.9 Guest: Ubuntu 13.04 VirtualBox: 4.3.4 (just updated)  I'm having issues when I install guest additions (via device > add guest additions)  at the very beginning it tells me that it can't find the host kernel (with a message saying that if the installation of guest additions fails it may be because of this) - but then it seems to install the rest fine. the only issue is after I install guest additions and reboot my guest device, there seems to be an issue displaying my mouse.  The click works fine if I manage to navigate it over to where it should be - but I just can't see where my mouse is.  Any help? :|  Also, for some reason I'm unable to disable mouse integration (it's just greyed out under my Machine tab).

I installed Ubuntu 14.04.2 (64 bits) to my Mac OS X 10.9.5 (64 bits) using Virtual Box version 4.3.24. I am not an experienced Linux user. When I start Ubuntu, I cannot make my mouse work in the window that it operates; it disappears in the window most of the time. My keyboard works fine. I checked other questions on similar problems, but couldn't find a suitable solution. I cannot use mouse in Ubuntu (I installed it using my keyboard).  Here are the two messages that appears when I start Ubuntu; the first one relates to keyboard (mostly), the second one relates to mouse:   You have the Auto capture keyboard option turned on. This will cause the Virtual Machine to automatically capture the keyboard every time the VM window is activated and make it unavailable to other applications running on your host machine: when the keyboard is captured, all keystrokes (including system ones like Alt-Tab) will be directed to the VM.    You can press the host key at any time to uncapture the keyboard and mouse (if it is captured) and return them to normal operation. The currently assigned host key is shown on the status bar at the bottom of the Virtual Machine window.    The virtual machine reports that the guest OS supports mouse pointer integration. This means that you do not need to capture the mouse pointer to be able to use it in your guest OS -- all mouse actions you perform when the mouse pointer is over the Virtual Machine's display are directly sent to the guest OS. If the mouse is currently captured, it will be automatically uncaptured.    Any advices?  Solution Edit: I found one way to use mouse in the Virtual Box guest OS window. On the left above menu under the section Machine (on Mac) I clicked the button that says Disable Mouse Integration (Host key + I, Host key is left command key for me). After that I acted as if mouse integration was not available in my machine. Like stated in message 1 (in the above question) I pressed host key. I clicked capture in the box that appears. I can only use mouse in the window, when I want to use it in my host OS I need to hit the host key again. My new question is how can I make Mouse Integration really work?


I would like to know how do I start a for-loop from 0 if the if condition is True  for i in range (3):    if a=1:       #leave if-condition and start from beginning in for-loop with i=0   Break doesn't help here, because with break I only can leave the if Condition, but I also want to start the for loop from beginning.

i have:  for i in range(2,n):     if(something):        do something     else:        do something else        i = 2 **restart the loop   But that doesn't seem to work. Is there a way to restart that loop?   Thanks


My App gets crashed when I have set intent to go from one fragment to another activity. I have set onClickListener on it. and It shows me no error what is the problem. Here is the code for it. Whenever a user clicks on an image he is taken to another activity this is what I am trying to do.       public class HomeFragment extends Fragment  {       private ImageView images;       public HomeFragment() {      // Required empty public constructor      }      @Override      public View onCreateView(LayoutInflater inflater, ViewGroup container,                          Bundle savedInstanceState) {      View view = inflater.inflate(R.layout.fragment_home, container, false);     images = (ImageView) view.findViewById(R.id.complaint_posted);       images.setOnClickListener(new View.OnClickListener() {         @Override         public void onClick(View v) {         Intent intent=new Intent(getActivity(), DetailPost.class);         startActivity(intent);         }     });     return view; }   ` This is my logcat

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


PS: I don't want to use CSS. I put borders for my image and now I can't make it appear at the center of the page. No matter what I do it stays on the left side.This is my code:

``   Les fraise des bois sont souvent de petite taille.
   source:Wikimedia, licence CC BY-SA

How can I horizontally center a
 within another
 using CSS?

Foo foo


I have had to buy a new freezer as mine broke last night, a new one will be delivered tomorrow morning, but I have to unplug it tonight. Will it be safe to put the meat in the new freezer possibly 10 hours after turning freezer off? Or should I just bin it all and go shopping? (I love to shop so that's fine...lol) I hope someone can help me. I am 37 yrs old, you would think I would have had to do this before but no! - lol

We were on vacation for a week. The neighbor said we were out of power the whole time.  We have a chest freezer full of beef. It thawed but remained in the freezer unopened the whole time. Is the meat bad if it is thawed but still cold? Can we refreeze it and eat it?


I read that NASA looks for water on Mars or other planets as a sign of a life.  I wonder why scientists look for water as proof of a life? isn't there any animal that drinks another liquid like alcohol or something?

Inspired by an   It's hypothesized that extraterrestrial life could be based on silicon rather than carbon as its main structural element.  Are there similar theories about an alternative "life solvent" rather than water?


In 2012 the answer was NO!   My data is in a SHP file, I want to sort by 3 fields.  Has this changed in the last 4 years?  A solution like in ArcMap would be ideal -so it can be redone as required without hardcoding

Is it possible to sort multiple fields at the same time in QGIS?    For example, I'd like to sort a table by state name, and then within each state, sort by county name.    This would be the same as the Advanced Sort option available in ArcMap.


At the end of X-Men: Days of Future Past, we see Wolverine      wake up in a new timeline.   After a few “surprises”,      he sees Professor X, and Professor X senses that this Wolverine is not the Wolverine from his timeline.   What happened to the Wolverine in this timeline?

At the end of X-Men: Days of Future Past, Professor X asks Wolverine what he remembers, and he replies "Everything".  However, the Trask incident happened in 1973 and the events of X-Men Origins: Wolverine happened after 1975.  It was shown in Origins that Stryker put adamantium inside his body and wiped his memory. Therefore, how could Wolverine say that he remembers everything that happened in 1973?  Kitty says only someone who time-travels remembers everything. Does this mean that Wolverine came from 1973 to 2023 directly, or did he live through those years again?


What is the term for a cut from one close-up object to another absurdly similar close-up object? For example, in the movie "A Christmas Story", I think there is a cut from a close-up of a toilet lid closing, to a close-up of a kitchen cooking pot lid opening, momentarily fooling the viewer into thinking it's one continuous scene, and then bringing on thoughts of mild disgust and humor over the absurd juxtaposition.

Although I don't have a clear example, I'm looking for a transition which is somehow a mix of:   Cross-cutting: where two scenes in different locations happen at the same time Graphic match : where "two successive shots joined so as to create a strong similarity of compositional elements (e.g., color, shape)"   Basically, we have two scenes which happen at the same time and the transitions back and forth between the two scenes are done through similar looking elements of each scene (for example, between a barrel rolling and a vehicle wheel). I can't manage to find the actual name of such transitions.


I have a very simple comment form, which submits through $.ajax. However, I'm having some problems with it refreshing on submit.  This happens even though I am using both e.preventDefault() and return false within my submission script.   I have looked at every single post I can find on StackOverflow and even various Fiddles, but have come across no solutions.  This is my JavaScript:  $(".f-track-actions__form").submit(function(ev){     ev.preventDefault();      var wave = $.cookie("cv"),         wave = eval(wave),         waveDuration = wave.getDuration();      var child = $(this).children(".f-track-actions__form-comment");     var cTime = (wave.getCurrentTime() / waveDuration) * 100;     var pD = {         'c': comment.val(),         'i': child.attr('id'),         't': cTime     };      $.ajax({         type: "post",         url: "/spectrum-rr/core/_func/functions/actionTrack.php",         data: pD,         success: function(data) {             alert(data);         }     });      return false; });   HTML:  <form method="post" class="f-track-actions__form">     <input class="f-track-actions__form-comment" type="text" placeholder="Comment on this track..." name="comment" id="c-1"> </form>   Thanks.

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


I am trying to split the strings in a column tweet_text if the column lang is en Here is how to do it on a string: s = 'I am always sad' s_split = s.split(" ")  This returns: ['I', 'am', 'always', 'sad']  My current code which does not work: df['tweet_text'] = df.apply(lambda x: x['tweet_text'].split(" ")  if x['lang'] is 'en' else x['tweet_text'], axis = 1)  Dictionary of data: {'lang': {1404: 'en',   1943: 'en',   2169: 'en',   2502: 'de',   3981: 'nl',   4226: 'en',   7223: 'en',   8557: 'de',   11339: 'pt',   11854: 'en'},  'tweet_text': {1404: 'I am always sad when a colleague loses his job and Frank is not just a colleague he is an impoant person in my',   1943: 'It remains goalless at FNB Stadium between Kaizer Chiefs and Baroka at halftimeRead more',   2169: 'Which one gets your vote 05',   2502: 'Was sagt ihr zu den ersten Minuten',   3981: 'En we gaan door speelronde begint vandaagTegen wie speelt jouw favoriete club',   4226: 'Quote tweet or replyYour favourite Mesut Ozil moment as a Gunner was',   7223: 'How to follow the game live The opponent Current form Did you know The squad Koeman said It must b',   8557: 'BAYERN BAYERN BAYERN BAYERN BAYERN BAYERN BAYERN BAYERN BAYERN BAYERN BAYERN BAYERN BAYERN BAYERN BAYERN BAYERN',   11339: '9o golo para',   11854: 'have loads of boss stuff available on their store products available including the m'}}

My  has failed me.  In Python, are the following two tests for equality equivalent?  n = 5 # Test one. if n == 5:     print 'Yay!'  # Test two. if n is 5:     print 'Yay!'   Does this hold true for objects where you would be comparing instances (a list say)?  Okay, so this kind of answers my question:  L = [] L.append(1) if L == [1]:     print 'Yay!' # Holds true, but...  if L is [1]:     print 'Yay!' # Doesn't.   So == tests value where is tests to see if they are the same object?


Exception in thread "main" java.lang.NullPointerException     at tab.setTable(tab.java:36)   My code:  import java.awt.; import javax.swing.; import javax.swing.table.; import java.awt.event.; import javax.swing.; import javax.swing.event.; import java.net.*; public class tab extends JFrame  {     int a;     JTable jt;     Container c;     static int k = 0;     static int l = 0;     static DefaultTableModel df;      tab()      {         df = new DefaultTableModel(50, 0);         jt = new JTable(df);         df.addColumn("Request");         df.addColumn("Acknowledgement");         jt.setAutoResizeMode(JTable.AUTO_RESIZE_ALL_COLUMNS);         c = getContentPane();         JScrollPane jsp = new JScrollPane(jt);         c.add(jsp);         setVisible(true);         setSize(800, 800);     }      static void setTable(String s) {         df.setValueAt(s, k, 0);         k++;     }      static void setTable1(String s) {         df.setValueAt(s, l, 1);         l++;     }  }

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


I am trying to do a full system image backup of a Samsung Galaxy Tab 4. It is unrooted at present, and is running Android Kitkat 4.4.2 . I have no desire of rooting it as of now.   I have tried creating a full image backup of the device using the ADB (Android Debug Bridge) method (adb backup -apk -shared -all -f C:\backup.ab), which looks like it works, but when it completes, no backup files are created (Although the backup process is shown as having been completed).  Can anyone either offer advice on why the adb method doesn't work, or present an alternative solution to this? The end result should be a full backup image (including all apps and data) that I can use to restore the device back to its exact backup state.

I know I'm asking for the close-to-impossible -- as a real full-backup certainly requires root permissions. But still there are many folks around not wanting to root their devices -- afraid of voiding their warranties or bricking their devices, or just not having their devices supported by any rooting method.  I also know there were a lot of questions asked already on this topic, and I checked all of them having the backup tag -- none covers the entire topic, all just have pieces, and especially people new to Android (but other non-power-users as well) would have a hard time figuring out the best way.  So I want a detailed canonical answer to the question:  Not involving root-solutions, how to achieve a backup as close as possible to a full backup?  Please do not give simple one-liner answers like "Use app xyz [full-stop]." If mentioning an app (and I doubt a single app would be the answer here), include what parts are covered by it -- as well as ideas on how to fill the gaps it leaves. (And to make it absolutely clear: I know the first thing coming to mind is Titanium Backup -- I use it myself, but this does not apply here: This question is strictly about methods for non-rooted devices!) Moreover, the answer should be as generic as possible in terms of applying to a wide range of devices (i.e. it should not be restricted to one device or manufacturer).  I already mentioned having investigated all questions here tagged backup. These will certainly be helpful providing details for answers here, so I will list up the topmost ones concerning my question:            All these provide some details for my question (so feel free to get inspired by them) -- but I feel there are still details missing. Also it would be helpful to have a summary -- say, an answer including the full description of "the maximum possible".  A last criterium: While I'd consider cloud-based solutions legit, I'd favour local solutions. If you can provide both: all the better. But some people value privacy quite high (I'm one of them), and thus would not trust their data to some cloud service.    Thanks to Ryan, we now have a solution for a really complete backup of all apps and their data -- which I didn't dare to hope for! The only disadvantage: His solution only works for less than 10% of all Android users; namely those whose devices are running at least with Android 4.x.  So again, I ask the close-to-impossible: Any solutions applicable at least on Gingerbread (2.3.x) or, better, even Froyo (2.2.x) -- so they cover the majority of current devices? These solutions may involve multiple tools (try to keep it as simple as possible though; think of your mother to follow your instructions ;)  And keep in mind: NO ROOT!    To further motivate high-quality answers (and hopefully avoid low-quality ones), I will be a harsh one here: As I rarely do, I will down-vote answers not fitting the mentioned criteria on one end -- but on the other end, I will setup a bounty for the best answer (which cannot be done immediately, but earliest after 2 days).


I would really love to play wizard/warlock multiclass with low charisma (just 13 for mutliclass). The handbook says that I can use Pact Magic slots to cast wizard spells, but doesn't specify which ability I use for spellcasting.     Pact Magic.   If you have both the Spellcasting class feature and the Pact Magic class feature from the warlock class, you can use the spell slots you gain from the Pact Magic feature to cast spells you know or have prepared from classes with the Spellcasting class feature, and [vice versa].   When I cast wizard spells using Pact Magic slots (or warlock spells using wizard's "Spellcasting" slots) do I use spellcasting ability of the slot, or do I get to choose?

Can a multiclass character use either of its spellcasting modifiers for spells?  When character multiclasses into multiple classes that can cast spells, which modifier do you use for casting the spell? Or do you use whichever you prefer?   Say, for an example, someone multiclasses Wizard into Warlock. Does the combination of classes even matter?  Is it the same for exclusive spells too? Like using Eldritch Blast, can you use your intelligence modifier instead of charisma?


I came across this phrase on the website:      Over all, this site is sure to be appreciated by anyone that needs to take his or her mind off of more pressing matters.   I looked it up into the dictionary, and the explanation for take his mind off is "if an activity takes someone's mind off their problems, it stops them from thinking about it".  But why does of exist in the sentence above?

What is the difference when you say "get off of something" and "get off something"?


Before you read I want you to know that here I'm a layman and I was just wondering.  It is often visualized, how wormhole works using a curved paper like C, and making a short cut through there:    But I don't understand, how this shortcut is made by itself. I mean why spacetime is supposed to be like C in first place?  But I can speculate. If there is a large enough black hole at top of the C, it can make its path through bottom of C, thus making a wormhole? (But probably it would still be a black hole, visible at two sides of spacetime.)

Lately I encountered a few times references to wormholes as a way to reach distant places in the universe in a short time. I have to admit I don't have a proper knowledge of the mathematics behind wormholes (although I won't mind a complete GR explanation in the answer, if necessary). All I know is that wormholes are usually compared to something analogous to a tunnel through the planet Earth to reach distant places in less time. The problem is, if I want to reach the other side of the planet I have to travel 20.000 km on its surface and "only" 12.000 km through its center. While the latter is surely shorter, it's still more than 50% of the initial value and this is the best-case scenario. For shorter distances, the difference becomes more and more negligible.  Now, I know enough of GR to understand that this explanation could be a simplification so extreme that any comparison makes little to no sense, but I'm curious to understand if the same problems arise for wormholes too. I don't really care if wormholes exist, are traversable by spaceships and both the crew and the vessel can survive the travel undamaged, I know they are still a theoretical construct and probably there is more than one formulation for it. What I'm really interested in is:   How much shorter will the travel be? I'm interested in Earth proper time, because if the reduction is only in the spaceship proper time, the we can achieve the same result "simply" by traveling closer to the speed of light. Does the amount of reduction in time depend on the distance between the endpoints? If so, it seems unpractical to travel to near stars through wormholes, if the spacetime geometry of our galaxy doesn't help somehow (local curvature should be higher than global curvature).


Let $n$ be a positive integer and let $d$ be some divisor of $n$. Consider the group of units modulo $n$, which we shall denote by $U(n)$. Likewise, denote the group of units modulo $d$ by $U(d)$.  Consider the homomorphism $f:\ U(n)\rightarrow U(d)$ given by reducing modulo $d$, $$f(u) = u \pmod{d}$$ I wish to show that this map is surjective. Can anyone supply a simple proof of this fact?  Alternatively, it is sufficient to prove that the set $$S = \left\{u\in U(n) \mid u\equiv 1 \pmod{d} \right\}$$ has cardinality $|S| = \phi(n)/\phi(d)$ where $\phi$ is the totient function.

I'm trying an old problem here:   Suppose $n\mid m$, and I have a natural ring homomorphism $\varphi\colon \mathbb{Z}/m\mathbb{Z}\to\mathbb{Z}/n\mathbb{Z}$ defined by $\varphi(j)=j\mod{n}$. I can verify that this is a ring homomorphism, but why does it induce a surjective group homomorphism on the unit groups $(\mathbb{Z}/m\mathbb{Z})^\times\to(\mathbb{Z}/n\mathbb{Z})^\times$?  My question in particular is why is it surjective? I take $k\in(\mathbb{Z}/n\mathbb{Z})^\times$. Then there exist integers $s,t$ such that $sn+tk=1$. Since $n\mid m$, I can also write $m=na$. So multiplying through I get $sm+tka=a$. I'm lost here. How can I find a unit in $(\mathbb{Z}/m\mathbb{Z})^\times$ which maps to $k$ to show surjectivity?


I connected a 1.3" SH1106 Oled via the I2C pins to a i2c-to-usb adapter (UMFT201XB from FTDI) and on my Linux Box (Z83 mini pc with Ubuntu 18.04) I can see the device under /dev/ttyUSB0.  This is the dmesg output:  [16123.056915] usb 1-2: new full-speed USB device number 15 using xhci_hcd [16123.212789] usb 1-2: New USB device found, idVendor=0403, idProduct=6015 [16123.212806] usb 1-2: New USB device strings: Mfr=1, Product=2, SerialNumber=3 [16123.212816] usb 1-2: Product: UMFT201XB [16123.212825] usb 1-2: Manufacturer: FTDI [16123.212834] usb 1-2: SerialNumber: FTWCN8T5 [16123.216185] ftdi_sio 1-2:1.0: FTDI USB Serial Device converter detected [16123.216361] usb 1-2: Detected FT-X [16123.216947] usb 1-2: FTDI USB Serial Device converter now attached to ttyUSB0   Now I want to write text/graphics to the OLED screen but I cannot find the i2c device with i2cdetect -l. After plugging in the USB, I don't see a extra device there (maybe there should not even be one?).  I use the luma.oled library on the Linux Box, but for the initialization, I need the i2c port and i2c address (somewhere in the docs they mention 0x22, but what port?).  How can I find the port for the USB adapter, if there is even one. I am a complete noob with i2c and virtual serial ports, so maybe my approach is completely wrong.

I got the  in order to interface with an I2C peripheral through a USB port on my Windows 7 computer.  The VCP drivers seem to install correctly, and a COM port is assigned to the module, and can be opened by a terminal emulator. However, I cannot seem to get any signal in or out of the module. That is, I see no activity when I send data through the port, or receive any data when I connect an I2C device to it (this was debugged using a scope). I have also verified that the RESET isn't on.  I found very little helpful information out there on how to get this module to work, so if anyone has experience with it, or with similar FTDI modules, my question is: what are the steps that I need to take in order to get the module to communicate?


When I was in America, I began reading a book series. It was a fantasy fiction series about some people who could use other peoples attributes, like their beauty or their intelligence by tattooing a rune on the pair  (so one person would have the rune to take beauty and someone else would have the rune to give beauty and someone would cast a spell or something?)  There were also people who thought it was wrong to take from other humans so they took their attributes from dogs. (Like sight, strengh, speed, smell etc)  It's been bugging me for years and any searches for "rune casting" or "rune masters" just turns up books on how to read runes. Any one got any ideas?

I read a fantasy novel years back. I honestly don't remember much of the plot (it was SEVERAL years back) but I remember the magic system that was used.  It was possible for an individual to grant portions of their physical and/or mental powers to another person.  For example, a person could grant his/her sight to someone else and spend the rest of their life blind (or with exceedingly poor vision) while the recipient would see twice as well as anyone else. In the book there were whole cities devoted to enhancing the nations army, or a specific person, etc.  Anyone have a thought what this book or series is?


I am having issues whenever I put a ' in text on a page that updates the database,  $query = "UPDATE news SET news1_title='$news1_title', news1_info='$news1_info', news1_body='$news1_body', news2_title='$news1_title', news2_info='$news2_info', news2_body='$news2_body' WHERE id=1";   As it cuts off and ends up throwing the text into the code.  Is there a way that I can add things like this safely, I know I can use ' but then when it shows it back in the page it returns as ' and I have to update them every time to ' otherwise it errors.  Thanks.

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


hi guys, is there any possibilities to change these mirror ball reflections to my interior scene reflections. as you can see this doesn't looks very good... thanks

I've made a roughness 0 glass pane, when I'm in lookdev mode it's reflecting a background that I didn't put there. I know I could just ignore it, but I'd rather be able to see what it'll mostly look like when I'm in the later stages. I also just want to know how on Earth I managed to set this background without realising it  Reflection completely ignores any objects I put in front of it. If I placed this glass inside my house, it would still just reflect trees (This is the point where I felt I couldn't ignore it - reflections are going to play a big part in my project and I don't want to be in render mode all the time)  The nodes are the default glass BSDF, except I set roughness to 0  The glass is set to 20mm thick, if that makes a difference  The background moves with my perspective and moves when I relocate the glass  I have a few HDRI's on my PC, but none look remotely like this   Also, I'm using cycles as I find Evee buggy as hell


I would like to define an expression for find which includes a wildcard in a -name subexpression: find_expression="-type f -name *.csv -mtime +14"  And then use it in a couple of places later on: find /var/data $find_expression -delete -print  If i don't quote the use of $find_expression, then when the variable is expanded, the glob is resolved, and if there happens to be a CSV file in the current directory, that find command is going to do the wrong thing. If i do quote the use of $find_expression, then when the variable expanded, it is not split into multiple arguments to find, and the find command does the wrong thing. This doesn't help: find_expression="-type f -name '*.csv' -mtime +14"  I believe because it results in a fourth argument which actually starts and ends with single quote characters. I could surround the invocation of find with a set -f / set +f pair. However, that means i couldn't then use a glob for the paths given to the find expression, so it's not a general solution. Perhaps i could use an array here. But is there any way to specifically expand a string into arguments without resolving globs?

$ ls -l /tmp/test/my\ dir/ total 0   I was wondering why the following ways to run the above command fail or succeed?  $ abc='ls -l "/tmp/test/my dir"'  $ $abc ls: cannot access '"/tmp/test/my': No such file or directory ls: cannot access 'dir"': No such file or directory  $ "$abc" bash: ls -l "/tmp/test/my dir": No such file or directory  $ bash -c $abc 'my dir'  $ bash -c "$abc" total 0  $ eval $abc total 0  $ eval "$abc" total 0


Give the ISIN of a stock I would like to download the stock prices of, for example, the last 30 days. Is there a simple way to do this?   Requirements - Must take the ISIN as input - Should be available as simple web download (wget, curl) or via a simple python script

How can I can convert ticker symbols (which include information on the exchange) to an International Securities Identification Number (ISIN) (which contains no information on the exchange)? Also I am interested in the other way round — given an ISIN and a market identification code (MIC) how can I determine the ticker symbol? Any databases around?


I have a samsung i9100 phone. The screen is broken. Usb debug mode is not enabled. So is it possible to enable usb debug in such situation? I don't want to replace the screen now.

The screen of my phone is physically broken, so it doesn't display anything, but the touch aspect does seem to be working, as I can unlock my phone, and get haptic feedback.  Before I go to get it replaced, I'd like to back up some personal data from the built-in memory to the SD card. I'm fairly certain that if I can get adb to recognize the device, then I can use  to see where I am touching the screen and do what I need to do. Problem is, when I plug it in, it's not recognized, while my emulator is.  I suspect that I might not have USB debugging enabled, which I think is necessary for adb to work. If this is the case, can someone give me screenshots of their Droid X (running 2.3.X) going from the home screen, through all the menus, to activating debug mode? Hopefully I can do it by dead reckoning and adb from there.  Edit: I haven't changed anything about the ROM or launcher; it's all stock.


In the book that I'm studying from it defines $\forall x \in A: P(x)$ equivalent to $\forall x (x\in A \to P(x))$ without any explanation as to why it is that way. The same thing for the existential quantifier: $\exists x \in A: P(x)$ is equivalent to $\exists x(x\in A \land P(x))$.  I attempted to understand these definitions by applying to real world examples.  Example for $\forall x \in A: P(x)$ equivalent to $\forall x (x\in A \to P(x)) $:  [Example One] All cars have wheels  Let $C$ be a set of all cars and $P(x)$ stand for "$x$ has wheels."  Then the English statement analyzed in logical form is $\forall x \in C: P(x)$ is equivalent to $\forall x (x\in C \to P(x))$. Translating the statement means "If $x$ is a car, then $x$ has wheels." However, sometimes when I analyze it I get "For every $x$, $x$ is a car and $x$ has wheels." (In logical form, $\forall x(x \in C \land P(x))$) which book says it's wrong.  Again, I have the same trouble with the existential quantifier definition as well.  [Example Two] Some cars have three wheels.  Let $C$ be a set of all cars and $P(x)$ stand for "$x$ has three wheels."  Then the English statement analyzed in logical form is $\exists x \in C: P(x)$ which is equivalent to $\exists x(x \in C \land P(x))$. This translates to "There exists at least one $x$ such that $x$ is a car and $x$ has three wheels." But sometimes I translate these kinds of statements as $\exists x(x \in C \to P(x))$, which is wrong according to the book's definition.  I'm asking how can I make it clear these two definitions are different. Also, why $\forall x \in A: P(x)$ is not equivalent to $\forall x (x\in A \land P(x))$ and that $\forall x \in A: P(x)$ is equivalent to $\forall x (x\in A \to P(x))$. Similarly, why $\exists x \in A: P(x)$ is equivalent to $\exists x(x\in A \land P(x))$ and that $\exists x \in A: P(x)$ is not equivalent to $\exists x(x\in A \to P(x))$? In short, can you help make it clear to me why these definitions are defined the way they are.

And the same goes for the existential quantifier: $\exists x \in A : P(x) \; \Leftrightarrow \; \exists x (x \in A \wedge P(x))$. Why couldn’t it be: $\exists x \in A : P(x) \; \Leftrightarrow \; \exists x (x \in A \implies P(x))$ and $\forall x \in A : P(x) \; \Leftrightarrow \; \forall x (x \in A \wedge P(x))$?


How risky is it to share a .blend file?  Does it hold a variable some where with your computer name?  If Blender is installed through Steam does it hold your Steam username as a variable somewhere in your blend files?   I searched around and couldn't find any information about this. If this is the case, how can I remove my personal information from the project file.

Since I download from time to time example files from blogs, wikis etc. I would like to know how I can avoid execution of malicious code.   Is it enough to disable the  and see what is in the text editor?


I want to buy a new computer - this computer  Is Ubuntu suitable for it in terms of video card, network card, sound card and the like? Thank you!

I'm thinking about installing Ubuntu Desktop, but I don't know what flavor is the best for my system. What are the minimum and recommended hardware requirements? What kind of CPU? How much memory? Should I have Hardware Acceleration? What flavor should I use?  This is an attempt of a canonical answer. My answers have the "official  requirements", the recommended are a mix of official sources and opinion based (along with the answer it's told the source). You can comment or edit if you feel that the information is obsolete or incomplete. It is a good rule of thumb that any system capable of running Windows Vista, 7, 8, x86 (Intel) OS X will almost always be a lot faster with any Ubuntu flavor even if they are lower-spec than described below.


I need to shrink a linux partition. All gparted options are greyed out. I see "greyed out" questions being asked for gparted in this forum since 2012, and no one fixed it, 8 years latter. No gui option should ever be greyed out. Use an error message instead. Now how can I shrink the partition, or even debug anything, if there is not even an error message?

Previously, I have installed Windows 7 on my 320 GB laptop with three partitions 173, 84 and 63 GB each. The 63 GB partition was where the Windows was installed. The rest were for file containers.  Now I changed my OS to Ubuntu 12.04 LTS. I installed Ubuntu by replacing the entire Windows 7 on the 63 GB partition. The rest of the partitions remain as an NTFS Windows partition and I can still access them both (the 173 and 84 GB partitions).  Now I want to change the two partitions of Windows into an Ubuntu format partitions plus most importantly, I want to extend the 63 GB partition to more than a 100 GB because at the moment I am running out of disk space. Whenever I try to install any application, especially using wine, it always complains for a shortage of disk space.  How do I do the extending activity before I entirely format my laptop again and lose all the important files on my partitions?


There are two $n$-components column vectors $u$ and $v$. $I_n$ is the $n\times n$ identity matrix. Find the inverse of $I_n – uv^T$.

I'm trying to understand the alternate proof of the formula $(A+uv^T)^{-1} = A^{-1} - {A^{-1}uv^T A^{-1} \over 1 + v^T A^{-1}u}$ found on . The closest I can find on stack exchange is the  of the identity but not its proof. Does someone know how $$(I+wv^T)^{-1}=I-\frac{wv^T}{1+v^Tw} \tag{1}$$ is easily proven? I don't see it.  You can mark the question as duplicate if you want but all the proofs are proving the Sherman-Morrison formula, not the intermediate identity given in (1). The two are similar as I see now that someone proved it, but it still is worth showing explicitely how to prove the identity.


My understanding is that generalized linear modeling (GLM) is recommended for proportion data.   However, this seems to run into problems when a set of data is full of zeros (or ones). For example, a data with two classes (A and B) with six data points each - all 0 alive and 10 dead for A and all 5 alive and 5 dead for B.  Using R to analyze this ...  alive <- c(0, 0, 0, 0, 0, 0, 5, 5, 5, 5, 5, 5) dead <- c(10, 10, 10, 10, 10, 10, 5, 5, 5, 5, 5, 5) type <- rep(LETTERS[1:2], each = 6) model <- glm(cbind(alive, dead) ~ type, family = binomial) summary (model)   Here's the summary  Call: glm(formula = cbind(alive, dead) ~ type, family = binomial)  Deviance Residuals:         Min          1Q      Median          3Q         Max   -9.528e-06  -9.528e-06  -4.764e-06   0.000e+00   0.000e+00    Coefficients:             Estimate Std. Error z value Pr(>|z|) (Intercept)   -26.12   36754.57  -0.001    0.999 typeB          26.12   36754.57   0.001    0.999  (Dispersion parameter for binomial family taken to be 1)      Null deviance: 5.1783e+01  on 11  degrees of freedom Residual deviance: 5.4466e-10  on 10  degrees of freedom AIC: 20.825  Number of Fisher Scoring iterations: 23  output is that A and B are not statistically different (p = 1).   I am pretty sure that the problem is too many zeros (or ones). What is a better way of analyzing this?   I have seen , but I am unsure if it's appropriate (AND I couldn't figure out how to use stan_glm under the same data context).  is similar but was never answered.

If you have a variable which perfectly separates zeroes and ones in target variable, R will yield the following "perfect or quasi perfect separation" warning message:  Warning message: glm.fit: fitted probabilities numerically 0 or 1 occurred    We still get the model but the coefficient estimates are inflated.   How do you deal with this in practice?


$f:\Bbb R\to\Bbb R$ maps every open subsets to open subsets, then $f$ may not be continuous?  How to construct such an example? what happens if $f$ has discontinuities?

What is an example of an open map $(0,1) \to \mathbb{R}$ which is not continuous? Is it even possible for one to exist? What about in higher dimensions? The simplest example I've been able to think of is the map $e^{1/z}$ from $\mathbb{C}$ to $\mathbb{C}$ (filled in to be $0$ at $0$). There must be a simpler example, using the usual Euclidean topology, right?


Minimal example:  \documentclass{memoir} \usepackage{tabu} \usepackage{threeparttable} \begin{document}  \begin{table} \begin{threeparttable} \caption{Problematic table} \label{tab:lf_mikrofone} \begin{tabu} {l l}   Heading 1 & Heading 2 \\   \midrule   a\tnote{1} & b\tnote{2} \\   \bottomrule \end{tabu} \begin{tablenotes}   \item [1] qwerty   \item [2] asdf \end{tablenotes} \end{threeparttable} \end{table}  \end{document}   This produces the expected output, but with an error:  Extra }, or forgotten \endgroup. \end{tabu}     If I change \begin{tabu} to \begin{tabular}, it works, but I would prefer tabu.  Exchanging \usepackage{threeparttable} for \usepackage{threeparttablex} makes no difference.  Can threeparttable and tabu be used together without errors?

threeparttablex can be used to add table notes to tabu tabulars*. If the tabular spans \textwidth, the output is as expected. It seems however that the tablenotes environment does not adjust its width if the tabular is narrow, although of course this would be desirable.  1) Is there any option/command which is intended to automatically adjust the tablenotes environment's width?  2) If not, is there a workaround?    @ 2) According to , threeparttablex does know the tabular's width. Moreover, given that for the threeparttable package, which threeparttablex supposedly builds upon, the package documentation states "you can redefine the whole tablenotes environment", it seems that it should be possible to find a workaround.  \documentclass{article} \usepackage{booktabs} \usepackage{tabu} \usepackage{threeparttablex}  \begin{document}     \centering \begin{ThreePartTable}     \begin{tabu} to .4\textwidth {XX}         a & b   \\\toprule         0 & 1   \\\bottomrule     \end{tabu}     \begin{tablenotes}         \footnotesize         \item[*] This is a long table note text, long enough to exceed the table's width.     \end{tablenotes} \end{ThreePartTable} \end{document}   *threeparttablex is designed to extend threeparttable to longtable. Even though the manual does not mention it, threeparttablex works with tabu, which threeparttable does not. Replacing threeparttablex's ThreePartTable environment in the above code with a threeparttable environment gives an "Extra }, or forgotten \endgroup." error.


I'm trying to implement Caesar cipher using PHP, but my scrips's got problem with polish signs. I'm using UTF-8 charset but signs like "ĄŚĆŃ" are displayed like '�' anyway.  Here is my code:  $text='MYCODE'; //code to crypt $alphabet="AĄBCĆDEĘFGHIJKLŁMNŃOÓPRSŚTUWYZŹŻ";  $n=strlen($text); $new_text=''; for ($i=0; $i<$n; $i++)      $new_text.=$alphabet[(strpos($alphabet,$text[$i])+5)%32];  echo $new_text; echo "</br>";   and that's the result of it: '�E�SGH'  When I work with english alphabet it works correctly.

I'm setting up a new server and want to support UTF-8 fully in my web application. I have tried this in the past on existing servers and always seem to end up having to fall back to ISO-8859-1.  Where exactly do I need to set the encoding/charsets? I'm aware that I need to configure Apache, MySQL, and PHP to do this — is there some standard checklist I can follow, or perhaps troubleshoot where the mismatches occur?  This is for a new Linux server, running MySQL 5, PHP, 5 and Apache 2.


How does one show  $$\lim_{\alpha \to \infty} e^{-t\sqrt{\alpha}}\left(1-\frac{t}{\sqrt{\alpha}}\right)^{-\alpha} = e^{t^2 / 2}?$$  Not homework, this is from this  as $\alpha \to \infty$. It suggests using numerical techniques to find the limit of the above, but I would like to know if there is a good way to solve this manually. I tried L'Hopital's rule but got $e^t$, which is obviously incorrect.

Q1: Could someone provide a proof for this equation (please focus on this question):   $$e^z = \lim \limits_{x \rightarrow \infty} \left( 1 + \frac{z}{x} \right)^x$$  Q2: Is there any corelationn between above equation and the equation below (this would benefit me a lot because i at least know how to proove this one):  $$e = \lim \limits_{x \rightarrow \infty} \left( 1 + \frac{1}{x} \right)^x$$


In The Final Problem, Sherlock, John and Mycroft trick their way into the facility at Sherrinford. Once captured, Mycroft reveals himself and begins to demand an account of events from the governor.  Since the whole facility is accountable to Mycroft anyway, why does he have to trick his way into Sherrinford?

In Sherlock S04E03 we see Mycroft disguised as a fisherman along with John Watson to let Sherlock (impersonating a security official) meet Eurus. Time and again in this episode as well as the previous ones, it has been clearly mentioned that Mycroft holds a respectable position in the government; infact he himself is the British Government. Without the direct orders of Mycroft, no one is allowed to diagnose Eurus or even talk to her.   So couldn't Mycroft just order the Sherrinford authorities to let Sherlock meet Eurus.  Why did they undertake so much trouble for the meeting?


I'm using Lyx and I want to have the reference format similar to This is the reference to equation 2.1  My LaTex file is %% LyX 2.2.3 created this file.  For more info, see http://www.lyx.org/. %% Do not edit unless you really know what you are doing. \documentclass{article} \usepackage[T1]{fontenc} \usepackage[latin4]{inputenc} \setcounter{secnumdepth}{5} \setcounter{tocdepth}{5} \setlength{\parskip}{\bigskipamount} \setlength{\parindent}{0pt} \usepackage{amsmath} \usepackage{amsthm}  \makeatletter %%%%%%%%%%%%%%%%%%%%%%%%%%%%%% Textclass specific LaTeX commands. \numberwithin{equation}{section} \numberwithin{figure}{section}  \makeatother  \usepackage[latvian]{babel} \begin{document}  \section{Section}  This is a formula \begin{equation} y\left(x\right)=x^{2}\label{eq:foo} \end{equation} This is a cross-reference \ref{eq:foo} \end{document}  I've been trying different options, eg. changing the LaTex preamble, the document class, adding/removing modules like Number Equations by Section, etc. but nothing seems to work. What I can get is 2..1 => <Reference> on Page <Page> 2 => <Reference> (2) => (<Reference>)  What should I do to get my equations in <section>.<number> format? UPDATE The problem was caused by \usepackage[latvian]{babel}. Solution: .

I'm writing a document using the copernicus_discussions.cls document class. This document class doesn't work when using babel. So I need to keep LyX from automatically using babel. However, even though in Tools->Preferences->Language I selected "Language package: None" and disabled all checkboxes on that page, and even though in my document preferences, I selected "Language package: None", the generated LaTeX source still contains the line  \usepackage{british,english]{babel}   How can I prevent LyX from inserting that line?


I was reading a book where Precession of Mercury's perihelion was described using general relativity. There I found the following equation:  $$ F \approx \frac{G M_m M_s}{r^2}\left(1+\frac{\alpha}{r^2}\right) $$ Where $\alpha$, he states to be expressed by speed of light, mass of sun, eccentricity of the orbit. This equation seems to be an extension of Newton's Gravitational Law but the author didn't specify how the equation came. Can anyone provide with the derivation of this equation or any reference?

The gravitational force on your body, called your weight, pushes you down onto the floor. $$W=mg$$ So, what is the weight equation through general relativity?


I received today for  the following Inbox message:    I am surprised because:   I didn't even know the question was closed (I neither saw any counter on the close flag, nor the [closed] suffix in the question title) this is the first time I get such a message, despite having had questions closed and reopened in the past

Do users get notified when their question is reopened? I know there are no notifications , and that makes sense because 1) you assume the user is paying attention to their open, unanswered question, and they'll probably notice it's been put on hold and 2) it follows with the SE policy of (in general) not sending notifications for negative events.  However a reopening is a good thing, and once a question is closed it becomes less likely that the OP will be coming back to check on it often (so they might not notice the reopening otherwise). If there are not reopen notifications, why not? Or can we add them?