I want to evaluate the following integral:  $$\int_0^{\pi/2} \dfrac{dx}{(1+x^2)(1+\tan x)}$$  I tried integration by parts, $u = \arctan x$ that leads to $\int_0^{\arctan \pi/2} \dfrac{du}{1+\tan(\tan u)}$, but nothing seems to work...

Evaluate the following integral $$ \tag1\int_{0}^{\frac{\pi}{2}}\frac1{(1+x^2)(1+\tan x)}\,\mathrm dx $$    My Attempt:  Letting $x=\frac{\pi}{2}-x$ and using the property that  $$ \int_{0}^{a}f(x)\,\mathrm dx = \int_{0}^{a}f(a-x)\,\mathrm dx $$  we obtain  $$ \tag2\int_{0}^{\frac{\pi}{2}}\frac{\tan x}{\left(1+\left(\frac{\pi}{2}-x\right)^2\right)(1+\tan x)}\,\mathrm dx $$  Now, add equation $(1)$ and $(2)$. After that I do not understand how I can proceed further.


So I have some logic that relies on JQuery's element.width() method. The logic is failing on me sometimes. I noticed that it is only failing when the element is hidden (inside a bootstrap collapsible element). I looked in the docs and they say:     The value reported by .width() is not guaranteed to be accurate when   the element or its parent is hidden. To get an accurate value, ensure   the element is visible before using .width(). jQuery will attempt to   temporarily show and then re-hide an element in order to measure its   dimensions, but this is unreliable and (even when accurate) can   significantly impact page performance. This show-and-rehide   measurement feature may be removed in a future version of jQuery.   So I know my problem. My plan is to check if the element is "hidden" and if so, instead of executing the logic right away, I will search for the collapsible parent and subscribe the logic to the shown.bs.collapse event.  My issue is how to check if the element is considered "hidden" by JQuery's width method (as mentioned in the docs). Is it as simple as:  element[0].style.display == "none"   I would like a check that captures all cases.   Thanks in advance.

Is it possible to toggle the visibility of an element, using the functions .hide(), .show() or .toggle()?  How would you test if an element is visible or hidden?


I am a little confused as to how we can convert from cycle notation to two row notation. say we have, $(3 1 2 4 5)(4 2 1 3)$, $3$ chooses $1$ but $2$ also chooses $1$ and the function has to be a bijection. How would I then express this in two row notation (note: I don't know if this example actually works but my point is how do I read this because in my eyes $1$ is being chosen twice).

I didn't find any good explanation how to perform multiplication on permutation group written in cyclic notation. For example, if $$   a=(1\,3\,5\,2),\quad b=(2\,5\,6),\quad c=(1\,6\,3\,4), $$  then why does $ab=(1\,3\,5\,6)$ and $ac=(1\,6\,5\,2)(3\,4)$?


Simple question (I seem have asked a few like this...)  What is $\mbox{Hom}(\mathbb{Z}/2,\mathbb{Z}/n)$? (for $n \ne 2$)

My algebra is weak I need help computing $\mathrm{Hom}(\mathbb Z_n,\mathbb Z)$, $\mathrm{Hom}(\mathbb Z_n,\mathbb Z_m)$ and also $\mathrm{Hom}(\mathbb Z,\mathbb Z)$ as $\mathbb Z$-modules. Also books suggestion to improve my basic. Thank you.  Regards


Given the speed of light is 299,792,458 meters per second and that it is constant through out the universe, (i.e a person who measures the speed of light while standing still will get the same result as a person moving through space in a rocket)  My question is: if I'm standing still, what is the speed of me moving through the universe? Compared to the speed of light?  The following variables should be taken into consideration    the speed at which the earth is rotating,  The speed at which the earth is moving around the sun, The speed at which out solar system is moving around our galaxy, The speed at which our galaxy is moving in our universe.

As the galaxy is moving and the solar system orbiting the galaxy and the Earth orbiting the sun. So how fast is each object moving and what is the fastest we move at?  Do we even know how fast the galaxy is moving that is not relative to another galaxy (although I guess velocity has to be measured relative to something).


I regrettably installed Windows 10 and would now like to install Ubuntu. However the download for desktop says it is only for Win 7 or earlier.  Is there a link to download Ubuntu without having to uninstal Windows 10?  Many thanks  Alistair

I would like to see a full how-to guide on how to install Ubuntu.


I going to sell my iPhone. I want to know if all my progress in Clash of Clans will be saved within Game Center so that I can recover everything when I buy a new iPhone and login again in Game Center.   Assume I am correctly logged in the Game Center with my Apple ID Achievements are visible in the Game Center app   I'm level 18 and have 790 trophies and I don't want to lose that progress.

I will soon buy a new iPhone. If I log in with my Apple ID in my new phone could I still access my Clash of Clans village without starting from scratch?


(abc)%n = (((ab)%n)c)%n = (((ac)%n)b)%n Means, result is always same even if I apply on each step or once at end. For Ex. a=3, b=2, c=3, n=5, always gives answer 4. Why it feels weird to me? If I assume modulo as clock with numbers from 0-4, we walk on this clock from 0-∞ and always remains on clock. But distance traveled in above cases is very different but still final position is same.  36=729 and final position is 4 32=9, and 43=64, now distance is 9+64=73, much lesser than previous but final position still 4. 33=27, 22=4, here distance is only 31, but final position still 4.  I don't know if I am using this clock process right, but it feels weird and confusing. Can anyone tell me why they gives same result or point me to some resource.

Suppose,I have a number 1256. I want (1256 % 11)! That is 2 . But, here, if i try in this way,  ( (125 % 11 ) * 10 + 6 ) % 11 = 2. That is exactly the same answer 2 as above.  I am confused , how This two process gives the similar answer ??? Even if , I try this method for any number n,m  to find (n mod m) . How this works ?? Can anybody explain ?


I noticed that over time, the thin part of the power cord for my Mac Air was turning yellow.  At the beginning I thought that I had spilled some paint or juice, but over time, the area of yellowing became more. I became worried that it might get very hot and the plastic began to melt, but I did not confirm this, since I do not particularly feel its heating. What could be the reason for the yellower wire and should I be worried about this? P.S. If the wire, wipe or wash the yellowness does not go away

Well, my MBP cable has gone yellow after a while. I've tried cleaning it with water, and also toothpaste (with whitening) and that doesn't seem to have removed the yellow stains. I guess I'll try mouthwash next; I may have to gargle that myself first. Anyone have the same problem? I haven't been keeping it in unusual places, in my bag and on the desk.  On the left is the whiter clean cable.


It is usually stated in various books or stories 'Energy can't be created or destroyed , but is conserved'. I guess this is within a closed system. Are there any axioms or principles in physics that would be contradicted if certain types of energy could be destroyed or changed into some form that is 'unusable' by any closed or open system? Are the conservation laws axioms? Saying the principles of energy conservation are valid approximations given what is presently known is only a partial answer to this question. I'm wondering if any principles are known now that would determine energy can not be destroyed in many situations not 'covered' by such approximations.  Could conservation laws be formulated 'a priori' or without empirical evidence?

My physics instructor told the class, when lecturing about energy, that it can't be created or destroyed.  Why is that?  Is there a theory or scientific evidence that proves his statement true or false?  I apologize for the elementary question, but I sometimes tend to over-think things, and this is one of those times. :)


I have a Windows 10 machine updated with the Anniversary update. When I try to copy a file from an external USB hard drive using windows explorer, I get the following Error :   Destination Path Too Long  The file name(s) would be too long for the destination folder.  You can shorten the file name and try again, or try a location that has a shorter path.  I found an article to enable long file names using the local group policy editor :    However, this doesn't work for me.  I do not see the option to enable.  SO, I manually edit the registry setting by adding the key and value.  Even after several reboots, this didn't allow the file to be copied.    The computer is part of a domain so I searched for the flag in the domain group policy editor but it is not listed.  The domain server is Windows Server 2008 R2 Standard.  Is there anything else I can do to get the file copied (in reality there are thousands of files I am trying to copy from an external hard drive to a Windows Surface Book).

This is weird.  I have a meanJs installation, the contents of which I copied to another folder.  Original folder path: C:\work\defaults\mean_0.3.3  File contents copied to: C:\work\defaults\a  As you can see it's obvious that the file contents are copied to a folder with a shorter name, so the file name too long error should not come, yet it does.  Is this a windows 10 bug?  Tried to do the it with copy-item command on the powershell and this is part of the output (it goes on for a while):  PS C:\work\defaults> copy-item .\mean_0.3.3\ -destination .\b -recurse copy-item : The specified path, file name, or both are too long. The fully qualified file name must be less than 260 characters, and the directory name must be less than 248 characters. At line:1 char:1 + copy-item .\mean_0.3.3\ -destination .\b -recurse + ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~     + CategoryInfo          : WriteError: (test-delayed-http-upload.js:FileInfo) [Copy-Item], PathTooLongException     + FullyQualifiedErrorId : CopyDirectoryInfoItemIOError,Microsoft.PowerShell.Commands.CopyItemCommand  copy-item : The specified path, file name, or both are too long. The fully qualified file name must be less than 260 characters, and the directory name must be less than 248 characters. At line:1 char:1 + copy-item .\mean_0.3.3\ -destination .\b -recurse + ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~     + CategoryInfo          : WriteError: (test-delayed-stream-auto-pause.js:FileInfo) [Copy-Item], PathTooLongExceptio    n     + FullyQualifiedErrorId : CopyDirectoryInfoItemIOError,Microsoft.PowerShell.Commands.CopyItemCommand  copy-item : The specified path, file name, or both are too long. The fully qualified file name must be less than 260 characters, and the directory name must be less than 248 characters. At line:1 char:1 + copy-item .\mean_0.3.3\ -destination .\b -recurse + ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~     + CategoryInfo          : WriteError: (test-delayed-stream-pause.js:FileInfo) [Copy-Item], PathTooLongException     + FullyQualifiedErrorId : CopyDirectoryInfoItemIOError,Microsoft.PowerShell.Commands.CopyItemCommand


Say, there's this person who is currently in disagreement with your decision. They know how to get under your skin, so they repeatedly did it on purpose in hopes eventually you'll give in and do what they wanted. I'm looking for a word that might fit this description, along with the confirmation whether this is considered a toxic behaviour or not. Apologize for that, I had thought it might be a little out of scope. I wanted to look it up myself, but it's tough without a phrase to go with. To add a little bit more context: they pester you by bringing up the topic every time they meet you in person or singing loudly nearby in order to to break your concentration when working, because they know you can't stand being in a constant presence of someone so noisy, and you give in to their demands only so they will shut up about it. I intend to use this word in a character analysis, so this is a completely fictional situation. Conclusion: There seem to be no exact word for this in English, so I will be satisfied with persistent, and manipulative if I feel like taking it up a notch. Thank you for everyone's input, I appreciate every word and phrase suggestions. Pardon me if, by any chance, I come off as obstinate and for not noticing there might be two characteristics in the above description.

Hi I'm looking for a word for someone who is constantly asking for something and keeps wanting updates about it. The closest words I can think of is pushy and, to a lesser extent, annoying. But clearly these words don't directly mean what I intend.


The semi-circle is given by $y=\sqrt{25-x^2}$  Find the length and width of the rectangle such that it's area is optimized.  How do I deal with problems such as these?

A rectangle is inscribed in a semi circle with radius $r$ with one of its sides at the diameter of the semi circle. Find the dimensions of the rectangle so that its area is a maximum.    My Try:   Let length of the side be $x$, Then the length of the other side is $2\sqrt{r^2 -x^2}$, as shown in the image.    Then the area function is   $$A(x) = 2x\sqrt{r^2-x^2}$$  $$\begin{align}A'(x) &= 2\sqrt{r^2-x^2}-\frac{4x}{\sqrt{r^2-x^2}}\\ &=\frac{2}{\sqrt{r^2-x^2}} (r^2 - 2x -x^2)\end{align}$$  setting $A'(x) = 0$,  $$\implies x^2 +2x -r^2 = 0$$  Solving, I obtained:  $$x = -1 \pm \sqrt{1+r^2}$$  That however is not the correct answer, I cannot see where I've gone wrong? Can someone point out any errors and guide me the correct direction. I have a feeling that I have erred in the differentiation.   Also how do I show that area obtained is a maximum, because the double derivative test here is long and tedious.   Thanks!


I've read that "would rather" has two different constructions; same subject and different subjects.  Some of the examples have been listed below:        I would rather they did something about it.      Question 1:  Does it mean "I would prefer them to do something about it" at present moment or in the future?         Rahul joined Engineering but he'd rather has joined medicine.      Question 2.  Does it mean "He would have preferred to join medicine but he joined Engineering"        I would rather you stayed at home tonight.      Question 3. Can't we just say "you would rather stayed at home tonight." Without changing the meaning of above sentence?  Source:   Note: I have read this question  which is a bit similar to my question because both are about "would rather". But all the example sentences and questions that  I have asked in my question are different.

Which of the following is the correct sentence:        I would rather do it myself.    I would rather did it myself.      When I meant to say that I don't know how to do this work otherwise I am well enough to do it myself.


How to prove that $f: \mathbb R^2 \to \mathbb R$ $f(x,y)= \frac{x^3y}{x^4+y^2}$ for $(x,y) \neq (0,0)$ and $f(0,0) = 0$ is continous at $(0,0)$?  By definition: Let $\epsilon>0$ I need to prove that $\exists \delta>0$ so that $\forall \vec x\in B_\delta(0,0)$ then $|f(x,y)-0|<\epsilon$  $|f(x,y)|=|{x^3y\over x^4+y^2}|$=${|x^3y|\over x^4+y^2}$ I know that $|x|,|y|\le ||\vec x||$ so $|x^3y|\le ||\vec x||^4$ then ${|x^3y|\over x^4+y^2}\le {||\vec x||^4\over x^4+y^2}$ but I don´t know how to proceed from here  Any ideas?

How would you prove the following limit?  $$\lim_{(x,y) \to (0,0)} \frac{x^3y}{x^4+y^2} = 0$$  I think the best way is using the squeeze theorem but I can't find left expression.  $$0 \le \frac{x^3y}{x^4 + y^2} \le \frac{x^3y}{x^4} \le \frac{x^3y}{x^3} \le y = 0.$$  But I'm not sure I'm right (especially at $\frac{x^3y}{x^4} \le \frac{x^3y}{x^3}).$  If I'm right - I'd glad if you can accept it.  If I'm wrong - can you please correct me?  Thanks in advance!


A thought experiment:   Take an object that is massive enough so we can detect it's position in space by measuring its gravitation field (for example, by sending almost tangential laser beams and measure how they deviate in the object's gravitation field).  Take a simple (non-rotating, non-charged) black hole. Send this object to the black hole. While the object falls into the black hole, measure the object's gravitation field (therefore, the object's position).   I'm wondering what will we see when the object:   Is getting closer to the event horizon. Crossing the event horizon. Fails to the singularity under the event horizon.   My intuition tells me following:   As time around the black hole slows down for an external observer, we may see that the object (i.e. its gravitation field) is always in the place it touched the black hole. (EDIT: According to "", this will not happen.) If my previous assumption is wrong, we may see how the object falls down to the singularity behind the event horizon. Also, the shape of the event horizon will deviate from an ideal sphere and by measuring these deviations we will see a position of the object under the horizon, which seems to contradict to the definition of the event horizon.   My questions are:   In any generally recognized theory that describes this situation? What will happen to the object and its gravitation field according to this theory (theories)? How confident we can be in the description given by this theory?

My reasoning being - lets say a rock is approaching a black hole. It would essentially stop in time for an outside observer once past the event horizon but since it would also bring along some new mass by itself, some of it should stop before reaching the event horizon, becoming the new edge of the event horizon.   Assuming that is true, if I were to feed a black hole from a single direction, it should start growing a spike, right? Going further with the same technique, you should be able to shape the black hole into a giraffe if you wanted to. Are there any flaws in this future business plan of mine?


In , DVK says:     Snoke ... we still have no idea who he is but he predates Galactic Empire...   Having seen the film twice, I can't remember how we would know that, I don't recall references to Snoke's age or past history. But  is knowledgeable about Star Wars in general, is there something that tells us this? In the film, or the novelisation, or...?

In Episode III,  explains to Anakin the power of the Dark Side to save people from death. He mentions  - the Sith who discovered this. Sidious then claims he died, which seems odd, given that kind of power.   Then in Episode VII (The Force Awakens) we find a Sith Lord who has appeared from no where. There seems to be two loose ends that fit nicely together.   My question is: Is there evidence to suggest that Supreme Leader Snoke is Darth Plagueis?


I have vector of strings. I want to match only those, that contain "features." (with optional dot). The matched strings should not contain "ONLY"  and "PRACA". feature.Agencyjna_ONLY # needs to be removed feature.UoP # needs to be matched feature.UoD # needs to be matched feature.PRACA # needs to be removed featurePRACA # needs to be removed  I used two following constructions, but both of them do not work. \bfeature\.?[^(ONLY|PRACA)]+\b \bfeature\.?\w+(?!(ONLY|PRACA))\b  Desired output: feature.UoP  feature.UoD  Example:  Would be appreciated for any help!

I know it's possible to match a word and then reverse the matches using other tools (e.g. grep -v). However, is it possible to match lines that do not contain a specific word, e.g. hede, using a regular expression?   Input:  hoho hihi haha hede   Code:  grep "<Regex for 'doesn't contain hede'>" input   Desired output:  hoho hihi haha


I need help in drawing the above figure in TikZ.

What's the best way to draw UML class diagrams in LaTeX?


I am interested in a PhD program and would like to work with a particular advisor. He is 69 years old now, and I am wondering whether he will retire soon, but I am not sure whether this is not a bit rude to ask. What can I expect, generally speaking? Shall I email him and ask him directly?

I’m thinking about taking a 70-year old math professor as my PhD advisor, in a US school. I like his teaching and research. If I don’t choose him, I would probably have to switch fields, which I can do with some pain, since I have not specialized deeply yet. My main concerns are:   As he is far more likely than a young supervisor to pass away suddenly due to his age, how should I best plan for this scenario? What will happen to me if it happens? He is also far more likely to retire than a young supervisor – could his retirement (in the unspecified future) cause problems for my future career in academia, with respect to references and networking?   Related:


When running the following Python code:  mat1=[[0]*3]*3 mat2=[[0 for i in range(3)] for j in range(3)]  if(mat1==mat2):     print("Same content")  mat1[1][1]=7 mat2[1][1]=7  print(mat1) print(mat2)   I get this result:  Same content [[0, 7, 0], [0, 7, 0], [0, 7, 0]] [[0, 0, 0], [0, 7, 0], [0, 0, 0]]   Why is there a difference in the result, and what's wrong with my first way of initializing a matrix?

I needed to create a list of lists in Python, so I typed the following: my_list = [[1] * 4] * 3  The list looked like this: [[1, 1, 1, 1], [1, 1, 1, 1], [1, 1, 1, 1]]    Then I changed one of the innermost values: my_list[0][0] = 5  Now my list looks like this: [[5, 1, 1, 1], [5, 1, 1, 1], [5, 1, 1, 1]]    which is not what I wanted or expected. Can someone please explain what's going on, and how to get around it?


I am trying to do this: protected List<T> list = new List<T>();  for (int i = 0; i < size; i++) {     list.Add(null); }  I get a compiler error saying "cannot convert from null to T". I have looked around but could not find an answer to this question.

I have a generic method with this (dummy) code (yes I'm aware IList has predicates, but my code is not using IList but some other collection, anyway this is irrelevant for the question...)  static T FindThing<T>(IList collection, int id) where T : IThing, new() {     foreach T thing in collecion     {         if (thing.Id == id)             return thing;     }     return null;  // ERROR: Cannot convert null to type parameter 'T' because it could be a value type. Consider using 'default(T)' instead. }   This gives me a build error      "Cannot convert null to type parameter   'T' because it could be a value type.   Consider using 'default(T)' instead."   Can I avoid this error?


How do I format the paragraphs so that it skips to next page.  I would like each paragraph to be on a separate page, is something like this possible?

Is there a way to force a pagebreak after every sentence or paragraph?  This may seem like an odd thing to do, but for catching typos and just general editing I find it much easier to look at a sentence or paragraph in isolation so that I am not tempted to skip ahead.  Currently, I just zoom in so I can only see a few word at a time, but this is not a perfect solution.


I am using nginx and would like all http traffic to become https using nginx. can someone post an example for nginx config file?  Here is mine. it's not working and i don't have a lot of nginx exprience:   Thanks!

I want to rewrite all http requests on my web server to be https requests, I started with the following:   server {     listen      80;      location / {       rewrite     ^(.*)   https://mysite.com$1 permanent;     } ...    One Problem is that this strips away any subdomain information (e.g., node1.mysite.com/folder), how could I rewrite the above to reroute everything to https and maintain the sub-domain?


There is a Sci-fi novel, I thought it was Ringworld but I can't find the passage.  There was, as a small plot point about the past, a bio-agent accidentally released that destroyed all the plastic bags and a lot of other polymer based articles, like Hawaiian Shirts, in the world. I don't remember if the Hawaiian Shirts were mentioned in the book specifically, or if was something I thought of immediately when I read the passage.  Anyone know where I can find this, because I recall liking the story and would like to reread it.

There was a book (it actually had a second book as well) where a guy gets paid with a group of others to go to a planet that is enclosed in a metallic sphere.   There are many species in this planet. I don't recall if they actually met the races in the first or the second book but there an incident where an alien in the first book ate fruit from a tree that removed any signs of gender from it.


Textboxes are rectangles which can contains text and other stuffs. I was wondering if there is some package that allows to create textboxes with arbitrary shapes.   I mean, can I obtain something like this?    Hope tags are correct.

I have found this in the cover of seminar(one tool to make slide) document.  The final result I have captured below:    The complete document can download .  I wonder how to make this. Is there any easy way?


Perhaps related to , this question is different in that I can click the comment link on my desktop when not logged in, but not on my iPhone. (iOS 6.1.3, built-in Safari browser).   As can be seen here, the text "show 9 more comments" is in the link colour, signifying that this can be clicked just as the name of the user who posted the last question is - but while his name can be 'clicked' leading to his profile as expected, the text "show 9 more comments" is not active:     is the question I've used as an example.  I can see this both on an iPhone and on a Windows phone, but not on an iPad.  I haven't tried to reproduce while being logged in on either of the phones.

This might be related to  but the add comment and show x more comment buttons do not work on mobile when not logged in  Images for reference:     I have so far tested this in Safari and Chrome on my iPhone


I have a Generic class of T where T is a class  i want to create an object from this Generic Class but I have Class name in string  this my code   public class GenericClass<T>:IGeneric<T> where T : class {     public IEnumerable<T> Get     {         //Whatever The Logic Is     } }

The title is kind of obscure. What I want to know is if this is possible:  string typeName = <read type name from somwhere>; Type myType = Type.GetType(typeName);  MyGenericClass<myType> myGenericClass = new MyGenericClass<myType>();   Obviously, MyGenericClass is described as:  public class MyGenericClass<T>   Right now, the compiler complains that 'The type or namespace 'myType' could not be found." There has got to be a way to do this.


How might I make an if statement with multiple conditions? I thought I would use ||, but when I use this, it says "The || operator is undefined for the argument type(s) boolean, java.lang.String"  System.out.print("Which pit would you like to select? "); String temp = input.nextLine(); {     if(temp == "A" || "a")         pit = 13;     else if(temp = "B" || "b")         pit = 12;     else if(temp = "C" || "c")         pit = 11;     else if(temp = "D" || "d")         pit = 10;     else if(temp = "E" || "e")         pit = 9;     else if(temp = "F" || "f")         pit = 12;     else         System.out.println("Not a valid pit!");

I've been using the == operator in my program to compare all my strings so far. However, I ran into a bug, changed one of them into .equals() instead, and it fixed the bug.  Is == bad? When should it and should it not be used? What's the difference?


A few days ago, an icon appeared on the status bar of my Nexus 5 (Lollipop 5.1.1). I couldn't understand why it was there and what it tried to indicate. After some time of not touching my phone, the icon disappeared by itself.  The icon in question is the one between the signal strength and the BT icons (2nd from the right).

I'm using Nexus tablet on stock Lollipop. For the life of me, I can't find what the "restricted" sign in the top right corner means. I've checked the user manual as well but still not worked out what it means.  What is the meaning of that icon?


This proposal tries to solve   If a new answer to an old question with lots of answers gets a few upvotes, it is a strong indicator that the answer is good:   it is much more recent than the fastest guns, and so had less time to get upvotes (consider how old it is) it is way further down than the fastest guns, so much fewer people have viewed it (consider answer count)   For questions less than 8 short answers or so, it does not matter much to me: my attention span is enough to scan them all.  But for larger questions, it would help. Specially on the "new technology came out that perfectly answers the question" scenario.  One may argue that such questions should be closed as too broad, but let's not touch that question here and suppose that they are valid (I think many are). In any case, as time tends to infinity, the answer count per question also does, so we either deal with it some day, or start closing them at some point.  I know it is not easy to come up with a sensible metric, and I'm not going to propose a precise equation on this question, but please do so in answers / comments if you have an idea.  The most obvious metric is to simply divide upvotes / time, but that has a few downsides:   may give too much importance to new answers that get that single upvote because they showed up on the front page. It would be cool to have a coarser method with a little more statistical significance. does not take into account the "start at bottom" (number of answers) bias   Many similar metrics also take recency into account, e.g. our , Facebook  and Reddit's . Of course, I see that their need is much greater since their updates happen much more frequently than an old questions. But maybe we could take some ideas from those metrics.  Full disclosure: I might get tons of rep if this were implemented :-)

I appreciate the mechanisms which help bring attention to new answers to old questions - front page sorting, and the moderation tool explicitly designed for it. But I wonder if we can do more. I'm particularly interested in addressing answers whose validity has changed. In the worst case, they were correct when they were posted, but no longer are, so they mislead all the current users who find their way to them looking for an answer. More benignly, perhaps the best answer was good, but slightly flawed.  At this point, a helpful user may post a new answer, which is much better than existing upvoted and accepted answers. It can be difficult to overcome that momentum. What if the default sorting method took this into account? A naive suggestion: if a new answer has a large positive vote velocity, and an old answer has a negative vote velocity, perhaps the default sorting should place the new answer above the old answer. This could help make new answers visible to users who need a correct answer, and also help garner more votes to increase the confidence of the sorting decision.  I know this would be a fairly low-impact change, but nothing is permanent, and I'm afraid of answers with 100 upvotes being pinned at the top for years after they've become obsolete.  Edit: I would welcome other proposals that accomplish the same goal - my naive suggestion wasn't intended to be a complete solution, just one thing that a better sorting method would do.


I'm familiar with the diagnostics required for OLS, however I'm in new territory with a model I'm fitting to data in R, using Poisson regression with GLM.  What are the standard methods in evaluating a WLS model?

What diagnostic plots (and perhaps formal tests) do you find most informative for regressions where the outcome is a count variable?  I'm especially interested in Poisson and negative binomial models, as well as zero-inflated and hurdle counterparts of each. Most of the sources I've found simply plot the residuals vs. fitted values without discussion of what these plots "should" look like.  Wisdom and references greatly appreciated. The back story on why I'm asking this, if it's relevant, is .  Related discussions:


We can define trace if $A =\sum_{i} \langle e_i, Ae_i\rangle$ where $e_i$'s are standard column vectors, and $\langle x, y\rangle =x^t y$ for suitable column vectors $x, y$. With this set up, I want to prove trace of AB and BA are same, so it's enough to prove that $$\sum_{i} \langle e_i, ABe_i\rangle =\sum_{i} \langle e_i, BAe_i\rangle$$ but how to conclude that?

there is a similar thread here , but I'm only looking for a simple linear algebra proof.


I used this command for downloading software center    sudo apt-get install software-center   this error pops up   python-lxml but it is not going to be installed   Tried     sudo apt-get purge python   sudo apt-get install python2.7   and now I got more errors   software-center :Depends: gvfs-backends                  Depends: python-lxml but it is not going to be installed                  Recommends: update-notifier but it is not going to be installed

Occasionally, when I'm installing stuff, I get an error like the following:  Some packages could not be installed. This may mean that you have requested an impossible situation or if you are using the unstable distribution that some required packages have not yet been created or been moved out of Incoming. The following information may help to resolve the situation:  The following packages have unmet dependencies:  package1 : Depends: package2 (>= 1.8) but 1.7.5-1ubuntu1 is to be installed E: Unable to correct problems, you have held broken packages.   How can I resolve this?


How to compute $5^{64} \pmod{193}$?  My idea was:  $5^{64} = (5^4)^{16} \equiv 625^{16} \equiv 46^{16}\pmod{193}$.  Now I don't understand why it's $46^{16} \equiv (-7)^8 \equiv 49^4 \equiv 85^2 \equiv 84 \pmod{193}$.  How to get it here and how can the power be reduced?

How do I efficiently compute $a^b\bmod c$:  When $b$ is huge, for instance $5^{844325}\bmod 21$? When $b$ is less than $c$ but it would still be a lot of work to multiply $a$ by itself $b$ times, for instance $5^{69}\bmod 101$? When $(a,c)\ne1$, for instance $6^{103}\bmod 14$?  Are there any other tricks for evaluating exponents in modular arithmetic?  This is being asked in an effort to cut down on duplicates, see  and .


Example:   User A gives a not-great but working answer User A gets upvotes User A gets accepted answer User B gives the quantifiably best possible answer User B gets more upvotes User A edits answer to include answer B   Is this acceptable by the SE community? I can think of pros & cons for each.  How should this be handled?

How should I act if I discover a user plagiarizing fellow users' posts? What if I find someone plagiarizing external resources without attribution?  See also:


In my program, I'm trying to add a comma for a number that's length is more than 3. For example if number is 1000, it should output 1,000. However I can't find out how to add on remaining numbers after I put comma into first one. The code below is what I've got: // if the answer is more than 999 string answerThousand = Convert.ToString(lbl_NumResult.Text);  if (answerThousand.Length > 3)  {     lbl_NumResult.Text = answerThousand[1] + "," + answerThousand[ /* What must be here to add remaining numbers? */]; }

I want to add a comma in the thousands place for a number.     String.Format()?


I created a deck that creates lots of tokens (mono-white servos), and I don't want to buy 50+ servo tokens. Is it tournament-legal to put 1 servo token with a d20 or two on top of it to track the amount of servos I create?

Many spells or abilities cause one or more creatures to join the battlefield (i.e. 1/1 white Soldier creature tokens, 3/3 green Beast creature tokens, etc.). These token cards are not included with the cards that require them.  What do MtG players use instead to represent token creatures?  A quick search shows you can buy packs of such cards, but I'm wondering what convenient ways exist to represent these tokens without actually having to buy more cards?


We defined an abelian category as one who is (i) additive, (ii) every morphism has a kernel and a cokernel,  (iii) and every monomorphism is a kernel and every epimorphism is a cokernel.  I'm given a morphism $f: A \rightarrow B$ is an abelian category $\mathcal{C}$.  I need to show that there is a natural (isomorphism) map $\overline{f}$ between the image and the coimage of $f$.  Attempt: I know the image of $f$ is the kernel of its cokernel, and the coimage of $f$ is the cokernel of its kernel.  So I have arrows $$ \ker(f) \xrightarrow{k} A \xrightarrow{f} B \xrightarrow{q} coker(f). $$ I also have maps $$c: A \rightarrow coim(f) = coker(k)$$ and $$ m: im(f) = ker(q) \rightarrow B. $$   Now we know that $f \circ k = 0$, since $k$ is the kernel of $f$. Since $c$ is the cokernel of $k$, by def. of cokernel there exists a unique factorization such that $f =  \psi \circ c. $   Since $q$ is the cokernel of $f$, we have $q \circ f = 0$. Since $m$ is the kernel of $q$, we have a unique factorization $f = m \circ \phi$.   Now I'm stuck. I have these two unique morphisms $\psi: coim(f) = coker(k) \rightarrow B$ and $\phi : A \rightarrow im(f) = ker(q)$.   But how do I construct a morphism $\overline{f} : coim(f) \rightarrow im(f)$ ?? And how do I show it is an isomorphism?  Thank you for any help.

Let's fix some terminology first. A category $\mathcal{C}$ is preabelian if:  1) $Hom_{\mathcal{C}}(A,B)$ is an abelian group for every $A,B$ such that composition is biadditive,  2) $\mathcal{C}$ has a zero object,  3) $\mathcal{C}$ has binary products,  4) $\mathcal{C}$ has kernels and cokernels.  A category $\mathcal{C}$ is abelian if it is preabelian and satisfies:  5) every monomorphism is a kernel and every epimorphism is a cokernel.  Define the coimage of a map to be the cokernel of its kernel, and the image to be the kernel of its cokernel. We have the following commutative diagram:    where $\overline{f}$ is the only existing map (because of universality of kernel and cokernel).  I'm having trouble proving the following:     A preabelian category $\mathcal{C}$ is abelian iff $\overline{f}$ is an isomorphism.   The converse is easily shown, I'm having trouble proving $\Rightarrow$...


I dont know much about paper submission as I am not that matured enough.  Can someone kindly say what does it mean for a paper to be "under review"?  First I was informed that it was "Initial version" and now the status says "under review". How long will the tag "under review" stay?  As I am a Master's student I dont know much about publication.Can someone please say what does the above means and what are the steps that follow in order for a paper to be accepted in a journal.  Do editors send the authors mail keeping them informed about the steps that are being done ?  I will be grateful if someone helps me here.

What steps does a manuscript typically go through from submission to publication (or rejection) in a typical journal? How are these steps referred to, in particular by editorial systems, and how long do they each typically take?  Note that this question is about the typical situation and hence not about:   Journals with an atypical workflow, e.g. those that allow for an instantaneous reviewer–author interaction. Exceptional steps or rare occurrences such as withdrawal or .   This is a canonical question on this topic as per . Due to its nature, it is rather broad and not exemplary for a regular question on this site. Please feel free to improve this question.


My sister and I have been playing Minecraft LAN together easily for the last six months. And then suddenly a week ago, it just stopped working. Anytime we try to connect, we get the message: "Connection timed out; no further information."  We don't know what has happened. It was working fine, until it wasn't. I've looked at over 20 different forums and help sites, and I've even tried just trying out my own solutions. Nothing has worked. We're on the same network, in the same room, different player names, Java can get through our firewall, we're on the same version, we're both playing vanilla Minecraft, and we don't know what's gone wrong. All of the forums I've looked at have all just been stuff like "Me too!" or "Have you solved it yet?" or "Woopsie! It couldn't get through our firewall! Thanks!"... Nothing useful to our situation.

My friend had hosted a Minecraft server before and brought it back up today with my help. He and anyone in his LAN can connect. However we have had a few people try to connect, including me, and when we try to connect it gives the message:  Failed to connect to the server Connection timed out: connect  What does this exactly mean? How do we fix this?


Iḿ Using an EEE pc and dropped my win device. I dont have a disk drive as y'all may know..  I just want to reload my windows 7 from a bootable usb, which I wanna create on ubuntu 13.04.  After that I wanna Reinstall Ubuntu next to win7.  Iḿ not that kinda hardware person who fixes it in a moment. So if you guys could explain it easily and usuable, you will help me a lot.  Thanks a Lot From Holland

I'd like to create a Windows bootable USB stick, but I don't have a Windows machine with me at the moment to do so. How could I achieve the same using Ubuntu?


$\Bbb{R} / \Bbb{Q}$ is a quotient set of $\Bbb{R}$ with the following equivalence relation $\sim$ :   $$r \sim s \Longleftrightarrow r-s \in \Bbb{Q}$$  Then is there a bijection between  $\Bbb{R}$ and $\Bbb{R} / \Bbb{Q}$?  I know that, with Axiom of Choice, there exists an injection from $\Bbb{R} / \Bbb{Q}$ to $\Bbb{R}$.   Thus $|\Bbb{R} / \Bbb{Q}| \leq |\Bbb{R}|$.   But I'm not certain that there exists an injection from $\Bbb{R}$ to $\Bbb{R} / \Bbb{Q}$.

I was wondering if it is possible to produce an explicit bijection $h\colon \mathbb{R} \rightarrow \mathbb{R}/\mathbb{Q}$. If we can produce an explicit injection $i\colon \mathbb{R} \rightarrow \mathbb{R}/\mathbb{Q}$, can the  be used constructively?  It is clear that the two sets have the same cardinality, so the existence of such a bijection is trivial. What I am really looking for is a nice-looking bijection, or a proof that no such nice-looking bijection exists, for a definition of "nice-looking" which I cannot quite figure out.  One problem which I think makes finding such a bijection difficult is that any natural injection of $\mathbb{R}/\mathbb{Q}$ (ie, those injections in which one representative is chosen from each coset) produces a non-measurable set, specifically a .  I hate to ask such a vague question, but I'm really not sure about whether the correct answer is constructive, or whether it is a proof that any such bijection is in some sense "very complicated."  As a final note, the motivation for this question came from , in which I was somewhat astonished to see such a clear, constructive bijection given between $\mathbb{R}$ and $\mathbb{R} \setminus S$, where $S$ is countable.


I am very surprised that I could not find any similar question here.  It seems to me that researchers from all universities are willing to write papers about their research for free and hand them into a journal to gain reputation. On the other hand, some other researcher do voluntary check the paper in order to examine if the paper is acceptable for the journal. Therefore, the main work is done by researches.     The remaining work for the journal is to offer a platform where researchers can communicate and making sure that the reviewer is selected anonymous and to bundle many articles to a journal.   Now everyone has to pay a huge amounts for the papers, they are not accessible for free to the general public, even though that most researchers are financed by taxes and only the journal is making profit.  Now I wonder, should it not be possible to create a network page for researchers which contains methods to imitate the review process of a paper? So that all papers can be downloaded at the website for free. I guess most researchers would be very happy if everyone could read their work. Also the money that is spend on journals by universities could be spend to this huge network page instead in order to keep it running.

Obviously this is a question in the light of the recent Elsevier boycott. Currently we do have an arXiv, maintained by academia and where researchers regularly upload parts of their work. In such a case,   Why do universities spend lots of money to publish in third-party journals?   The question especially applies to journals that operate with a rigorous profit motive. The subscription is very high, so wouldn't publishing in such journals affect the paper's citation count and deter the spread of knowledge about the work within academic circles?   Why should not universities collaborate to create free, open access, peer-reviewed journals?   Moreover, given the need to conserve paper, why should journals spend on printing research papers? Wouldn't an online version suffice, as most people use only local computer printouts anyway? In other words, why can't we have a Wikipedia-like system of sharing research knowledge, having properly established standards for such journals?


Is it possible to add a combination of tags as a favorite? for example adding the combination of c# and android will highlight question with these 2 tags attached to them.

I can understand that Favorite tags option helps us to highlight the questions on the list with selected tags. I'd like to know if we can add multiple tags to that. For eg., adding java+multithreading should highlight only those question which is both tagged as java and multithreading.


In layman's terms, what is the difference between predicting and explaining in statistics?  I was looking for the differences between AIC and BIC and found  with an answer stating:  My quick explanation is AIC is best for prediction as it is asymptotically equivalent to cross-validation. BIC is best for explanation as it is allows consistent estimation of the underlying data generating process.  This makes me think that in the same vein as precision and accuracy there is some core distinction here that significantly effects when and how to use a lot of statistical procedures.  I googled it and only found a variety of papers including , but this is far too rigorous for my question given my current knowledge.  Could anyone provide an intuitive exposition of the difference and perhaps some examples of how it affects the use of statistical methods and tools?

Back in April, I attended a talk at the UMD Math Department Statistics group seminar series called "To Explain or To Predict?". The talk was given by  who teaches at UMD's Smith Business School. Her talk was based on research she did for a paper titled , and a follow up working paper titled .   Dr. Shmueli's argument is that the terms predictive and explanatory in a statistical modeling context have become conflated, and that statistical literature lacks a a thorough discussion of the differences. In the paper, she contrasts both and talks about their practical implications. I encourage you to read the papers.   The questions I'd like to pose to the practitioner community are:   How do you define a predictive exercise vs an explanatory/descriptive one? It would be useful if you could talk about the specific application. Have you ever fallen into the trap of using one when meaning to use the other? I certainly have. How do you know which one to use?


Show that the number of permutations of $n$ numbers, for $n ≥ 2$, with two cycles is at most $(n−1)!\log n$. I know so far that from my notes that $S(n,1) = (n-1)!$ and that $S(n,2) = (n-1)!H_{n-1}$ also according to them. I assume you can make $H_{n-1}$ equal $\log n$. And also understand that $n ≥ 2$. Any help would be appreciated.

Show that the number of permutations of n numbers, for n ≥ 2, with two cycles is at most (n−1)!logn. Unsure as to were to start any help would be appreciated.


I have a rooted phone, and I was playing around with Terminal Emulator. I tried writing a simple shell script (test.sh) :  #!/bin/sh echo "Hello, World!"    Then I opened terminal emulator, cd'd to the directory my script was in, and typed:  ./test.sh   and I got a  "permission denied"  error. So I tried:  su ./test.sh   Somehow, still permission denied. So I tried (still as root) :  chmod 775 test.sh busybox chmod 775 test.sh busybox chmod +X test.sh   None of the 3 gave errors, but ./test.sh still gave permission denied!  As a last resort I tried  sh test.sh   That ended up working. Finally.   I'm curious why permission was denied for my own shell script chmodded to 775 when run as root. How can permission be denied for anything as root? How can I fix this and make ./test.sh work?

I tried executing a script on the sdcard as is because on FAT, everything is 777.  ./.profile ./.profile: permission denied   I added this as the initial command for the Android shell and it executes it just fine:  eval "$(cat /sdcard/.profile)"   So what I'm wondering is: Is there a way I can execute a script on the sdcard (other than the way I found out) and be able to pass arguments to it or do I need to do it the normal BTEP way (in its data directory)?


Given a matrix in $M_{n \times n}$ which is nilpotent. Prove that the Linear Transformation $T:M_{n \times n} \rightarrow M_{n \times n}$ given by $T(X) = X -NX$ is an isomorphism.  Shouldn't be answered with Eigenvalues and Eigenvector, it should only be answered using matrices, vector spaces, Linear transformations.

Possible Duplicate:          Given $A^{2012}=0$ prove that $A+I$ is invertible and find an expression for $(A+I)^{-1}$ in terms of $A$. ($I$ is the identity matrix).


I've recently installed Ubuntu 16.04 and I cannot get Nautilus to open. Clicking on the icon does nothing and I've already tried un-installing and reinstalling it and the error persists. So I have tried to to launch it from the terminal and these error messages are returned:   (nautilus:27014): GLib-GIO-CRITICAL **: g_dbus_interface_skeleton_unexport: assertion 'interface_->priv->connections != NULL' failed (nautilus:27014): GLib-GIO-CRITICAL **: g_dbus_interface_skeleton_unexport: assertion 'interface_->priv->connections != NULL' failed Could not register the application: Timeout was reached (nautilus:27014): Gtk-CRITICAL **: gtk_icon_theme_get_for_screen: assertion 'GDK_IS_SCREEN (screen)' failed (nautilus:27014): GLib-GObject-WARNING **: invalid (NULL) pointer instance (nautilus:27014): GLib-GObject-CRITICAL **: g_signal_connect_object: assertion 'G_TYPE_CHECK_INSTANCE (instance)' failed   I'm not certain if I should just scrap nautilus for some other file manager or perhaps there is a solution to this problem?

When I launch nautilus from terminal the following error is printed and nautilus doesn't open up.  (nautilus:25179): GLib-GIO-CRITICAL **: g_dbus_interface_skeleton_unexport: assertion 'interface_->priv->connections != NULL' failed  (nautilus:25179): GLib-GIO-CRITICAL **: g_dbus_interface_skeleton_unexport: assertion 'interface_->priv->connections != NULL' failed Could not register the application: Timeout was reached  (nautilus:25179): Gtk-CRITICAL **: gtk_icon_theme_get_for_screen: assertion 'GDK_IS_SCREEN (screen)' failed  (nautilus:25179): GLib-GObject-WARNING **: invalid (NULL) pointer instance  (nautilus:25179): GLib-GObject-CRITICAL **: g_signal_connect_object: assertion 'G_TYPE_CHECK_INSTANCE (instance)' failed   What could be the problem??


I have a jungle tree farm, but all of the trees that grow are short and they're not producing any cocoa beans.  How can I farm tall jungle trees and cocoa?

I found a jungle biome in my new Minecraft world, but I'm afraid of cutting down the big trees (the ones that are 2 squares wide and long), because I don't know if I can replant them.  So is it possible to grow new ones with saplings or to spawn them in any other way?


Is the new map function for compute slower than using a combination of containsKey, get and put  counter.compute(tree[j], (k, v) -> {   if (v == null) {     v = 0;   }    return v + 1; });   I tend to use containsKey, get and put in this combination  if (counter.containsKey(tree[j])) {   counter.put(tree[j], counter.get(tree[j] + 1); } else {   counter.put(tree[j], 1); }   I feel that compute tends to work a bit slower but I don't know how to benchmark to actually understand the performance difference

How do you write (and run) a correct micro-benchmark in Java?  I'm looking for some code samples and comments illustrating various things to think about.  Example: Should the benchmark measure time/iteration or iterations/time, and why?  Related:


I have a friend who has asked my help to find a sci-fi story; this would be a short story, more likely to be an episode on television. It has many similarities to Twilight Zone (any of the versions over the decades) or Amazing Stories, etc. This story involves aliens coming to earth and telling us that we've messed up / we're doing things all wrong. They leave, and come back some time later to find that earth has become united and humans have created world peace. The ironic twist: they say that we misunderstood them - we were meant to be war-like and we weren't doing enough fighting or self-destruction. Can anyone help me find this story? Again, my friend doesn't recall whether it was on television (he remembers it being on TV), but it could have been a radio show or a short story in a collection.

I'm sure it was a book, but it could have been a film, or even a video-game plot element. Apologize if I've mixed up any facts – I don't think I've come across this again in the last 20 years!  I read this "book" a long time ago, and a small part of the story refers to the Earth being visited by aliens, who (IIRC) told us that they were disappointed in how we had progressed as a species, and gave humanity the chance to repair their culture…  I believe, they left the Earth and came back after a time to be told that humanity had worked hard and had now declared a full and lasting world-peace and equality. However, the aliens wanted the opposite, they wanted us to be even more vicious to be used as soldiers or something along those lines.  I believe that they then promptly destroyed either the planet or the species!


Just wondering if  the Earth's gravity affects the photons? We can obviously think about equivalent mass of photons by using de broglie relation and then use it to calculate force of gravitational interaction. But still this thought is very revolting. Help would be appreciated?

Light is clearly affected by gravity, just think about a black hole, but light supposedly has no mass and gravity only affects objects with mass.  On the other hand, if light does have mass then doesn't mass become infinitely larger the closer to the speed of light an object travels. So this would result in light have an infinite mass which is impossible.  Any explanations?


I was wondering if anyone can help with this problem. So far I've had no luck experimenting and looking on forums. I have a client that had an old website. I made a new website for him with a new domain. He asked me to redirect everything on his old site, including all the pages such as website.com/shop or website.com/about. So far I've had no luck automating this. Is there any way I can redirect every page on his old site to just the homepage of the new site?

I need to (permanent) redirect all of the following:   www.example.com www.example.com/folder sub.example.com sub.example.com/folder   Basically, all URLs that are reachable without being intended to: www.new-example.com, I want to do this within Apache and using the mod_rewrite module via the .htaccess file.


A lot of words for laziness (thesaurus: apathy, lethargy, negligence, indolence, sloth) carry some serious negative connotations. However, some forms of laziness are not necessarily that bad: for example if you have the money for it, eating out for dinner when you don't feel like cooking is not some mortal sin; it's relatively neutral. In fact in my chosen profession of programming, some forms of laziness are downright meritorious; "I quickly pasted a couple of things together that will let a computer solve this problem over the next week, rather than spending two days slaving over getting it Done Right" shows an excellent frugality-of-time. What is a good  for the adjective "lazy" so that I can better deal with the "I" and "you" cases (positive, neutral) when we all know how to deal with the "he/she" case (negative)? More examples:  "I'm going to buy a new shirt from the clothing store across the way because I spilled some tea on this one; it's [neutrally-lazy] and ideally I'd go home and change, but I have an important meeting in a few hours and I don't want to spend time stressing about being in too many different places at once." "Yeah, those search phrases you put in the system overnight generated lots of garbage." "Can you run it again by hand with these phrases?" "Well, I'm trying to be [positively-lazy], so why don't I just set that client to run on Wednesdays rather than Tuesdays, and it will just run like usual tonight? It's not urgent, right?"  Ideally I would like an answer to take the form of an emotive conjugation, so that it's clear that the denotation is remaining the same (some answers like smart seem to be straying a bit from laziness per se), such as the examples "I am well-traveled; you are a sightseer; he is a tourist" or "I'm intelligent; you're intellectual; she is a smarty-pants." So I'm looking for something like "I am [positively-lazy]; you are [neutrally-lazy]; she is downright lazy."

Is there a word or phrase to describe someone who is willing to do extra work in the short term to avoid work in the long run? I have seen "lazy" used for this, but I'd like to know if there's a more precise term.


I got a 3TB ST3000DM001 Hard. I formatted it using USB interface (SATA to USB3), then I copied my files to it.  Now, when I install the hard into my case using regular motherboard SATA connector it showed "Unallocated". I tried the USB interface again and it showed my files and everything as expected.  How can I fix this?  Note: When I formatted using the USB interface I used "Minitool Partition", and made 1 Logical partition 2794.52GB since I'll use it for storage.

I have a 3TB Seagate Backup Plus Desktop USB 3.0 drive, which works fine when in its enclosure, but when I get it off its enclosure and directly plug it as an internal SATA drive, it's just not properly recognized (it works again when used in the enclosure). My systems’s motherboard is an , which has two SATA 6.0 Gb/s and four SATA 3.0 Gb/s ports.  When used as an internal SATA drive Windows 7 asks if I want to format the drive, as if it didn’t have a proper filesystem, and if I use the DISKMGMT.MSC tool (typing that in the start menu) I get completely wrong information about the drive.  It says the drive has 3 partitions (349,31GB of RAW data and two unassigned partitions of 1698,68GB and 746,52GB). This information is plain wrong, since the drive, when used in the USB enclosure, works as a single NTFS partition (2794,52GB). How come it’s shown as 3 partitions without filesystem when connected through SATA?!  Is Seagate using some proprietary way of storing the data when using the drive in its provided USB 3.0 enclosure? I didn’t use any kind of encryption. I just plugged the drive with USB 3.0 and started using it straight away, since it apparently came pre-formatted with an NTFS filesystem.


I just tried to write a simple . And the result is not correct. For SO it displays the reputation count less than what it is now. And the last access date is 2015-02-04 06:57:45 , but I'm using it regularly. My SO id is 2523147. And some fields are not updated yet. Why is this? Are those not the original current data?

When I use , the results I get don't reflect recent activity. Sometimes the data I get back are two months out of date. What's wrong? This is intended to be a canonical reference for questions about SEDE not reflecting real-time results.


This is my code, where the problem comes up.   public void onClick(View arg0) {     switch (arg0.getId()){         case R.id.login:             String nama = user.getText().toString();             String sandi = pass.getText().toString();             new AttemptLogin().execute(nama,sandi);             break;  }   and then this is my code on the AttemptLogin()  class AttemptLogin extends AsyncTask<String,String,String>{     boolean failure = false; protected String doInBackground(String... args) {         int success;         String username = args[0] ;         String password = args[1];         try {             List<NameValuePair> params = new ArrayList<NameValuePair>();             params.add(new BasicNameValuePair("username",username));             params.add(new BasicNameValuePair("password",password));              ...etc             }   and this is the LogCat,     So, I want get the String from onClick(), and pass the value to the doInBackground() on attemptLogin(). What is the solution about it? I'm sorry, it's newbie's question, please help us Thank you so much for your atention :)

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?


Let $A$ be a normal matrix. Then I want to show that, if $A$ has real eigenvalues, $A$ is Hermitian. (Notation: * denotes the complex conjugate, T denotes the transpose, and $\dagger$ denotes the conjugate transpose.)  Suppose that $A$ has only real eigenvalues and let $\lambda,v$ be a nonzero eigenvalue-eigenvector pair of $A$. Then we have   $\lambda(v,v)=(v,\lambda v)=(v,Av)=(A^\dagger v,v)$.  $\lambda(v,v)=\lambda^*(v,v)=(\lambda v,v)=(Av,v)$.   Thus, $(Av,v)=(A^\dagger v,v)$ and hence $\sum_i (Av)_i^*v_i=\sum_i (A^\dagger v)_i^* v_i$.   Write this as a matrix product: $(A^*v^*)^Tv=(A^{\dagger*}v^*)^Tv\implies (A^*v^*)^Tv-(A^{\dagger*}v^*)^Tv=0\implies ((A^*v^*)^T-(A^{\dagger*}v^*)^T)v=0$.  Since $v$ is nonzero, we have $(A^*v^*)^T-(A^{\dagger*}v^*)^T=0\implies A^*v^*-A^{\dagger*}v^*=0\implies (A^*-A^{\dagger*})v^*=0$   Since $v$ was nonzero, we have $v^*$ is also nonzero, so $(A^*-A^{\dagger*})=0\implies A^*=A^{\dagger*}$. Thus, we have $A=A^\dagger$ so $A$ is hermitian.  I've seen (, for example) a much simpler proof. However, I can't find where I use that $A$ is normal, but I know that normality is required. Could anyone could point out where I made this assumption or where I've made a mistake?

$A$ is a normal matrix (i.e. $AA^*=A^*A$, where * denotes the hermitian conjugate). If all its eigenvalues are real, prove that it is Hermitian (i.e. $A^*=A$).  I have tried many things but could not complete a proof. Could anybody please provide some help?


Recently I raised a flag to (for moderator attention) this question () saying,     This question is about geometry which shall be migrated to   math.stackexchange.com   Since math.stackexchange.com is missing in Migration popup, I flagged it under moderator attention    But it was , saying      declined - a moderator reviewed your flag, but found no evidence to   support it   I thought this question will be suitable for math.stackexchange.com right? Can someone advice on this?

I posted a question which was closed as off-topic and it seems like it could fit on another site in the network. How can I go about moving it there?   What is migration? When can a question be migrated, and who can migrate it? When should I consider migration, and when is it inappropriate? What causes a migration to be blocked and what happens after? What causes a migration to be rejected and what happens after? Anything else I should know about migration?


I know that I can get the SHA256 sums (and MD5 sums) from  as they are provided now within the folders, but is there any way of automating the checking process so that the download of the SHA sum is automatic and so is the checking part? I know that you can 'semi-automate' the process with , but I don't know how to fully automate it, nor how to even get semi-automation with SHA256.  Something like a script that you can input the release and flavour into (including unsupported releases) and it automatically downloads the SHA256 sum and checks would be good.

I just downloaded the ubuntu-10.10-desktop-i386.iso, and am having a hard time burning it, so I'd like to check that the file is intact, but I cannot find the md5sum of the file.    Is there a URL or official FTP mirror which includes the md5sum of the Ubuntu disk images?


I remember reading somewhere about someone who started publishing referee reports they had written online, along with sending them to the journal (or after). Unfortunately I do not remember where I saw this and can't seem to find it now.  I see strong arguments for this practice.   A lot of time and effort is spent on report writing, so why not list them. Transparency for its own sake. Transparency for the sake of increasing quality.   Obviously there are issues:   Copy right or other legal issues with journals prohibiting the publication of reports [has to be taken up with the editor] If the paper itself is not published, publishing the report might be harmful to the authors [one could wait until the final version of the paper is published]   My question: Is this already common practice somewhere and do repositories exist where one can upload reports? Are there other strong counterarguments I am missing?

This is a follow-up question to , and is somehow related to   However, my question does not concern the reviews I receive for the papers I submit, but concerns the reviews I write for papers I have been assigned. Since the whole process is done under confidentiality, it is not clear who owns the copyright on a review I wrote, and what does the review include.   For instance, let us assume that X is member of a PC of a conference Y, and assigns to me a review of a paper Z, written by A and B (assuming it's not a double-blind). Can I publish on my blog: "Here is my review for Y, asked by X, on the paper Z, written by A and B"?   I think that there are two points here:    Is it legal? (for instance, publishing the camera-ready version of a paper might be illegal due to the copyright transfer, would it be also the care here?).  Is it ethical? (who should I ask in order to do so? X? Y? A and B? everybody?).    EDIT: There is been several comments/answer wondering why I would like to publish a review I wrote. To give a bit of background of this question, I believe that the current reviewing system, created when the academic community was small and there was no Internet (i.e. no easy access to information), might not be the best, although clearly working. This is for me a very interesting debate, but somehow out of the scope the Q&A format of Academia SE, which is why I tried to focus on my question on whether it was possible to do so, not if it was the best thing to do in the current system (and just to be clear, I don't plan to do it, but I just like to know what are my options). Anyway, thanks for the answers bringing a different light on this debate.   EDIT 2: After seeing the update in Jeff's answer, I just realised that I didn't make it explicit that I was talking about reviews after the reviewing process. Jeff says that it's ok if the paper is accepted, and although I clearly understand the argument of why I shouldn't publish a review of a rejected paper, the question still holds: by publishing a review of a rejected paper, I publish the information that these authors submitted this paper to this conf/journal, which is supposed to be confidential between the authors and the editors. Would I break any rule by doing so?


Having the table foo like:  | id | name | |  1 | Foo1 | |  2 | Foo2 |   And the table bar like:  | id | foo_id | key | value | |  1 |      1 |   a | foo1a | |  2 |      1 |   b | foo1b | |  3 |      2 |   a | foo2a | |  4 |      2 |   b | foo2b |   How can I mount my SQL in a way that produces an output like:  | id | name |   a   |   b   | |  1 | foo1 | foo1a | foo1b | |  2 | foo2 | foo2a | foo2b |   I have no idea even if it is possible.    On a high-level problem (maybe there is a better solution) I want to make the keys on a entity dynamic.

I have an output of a query as follows:  bid  | code | amount        | ----------------------------- 2915 | BF   |   -10700.00   | 2915 | YQ   |   -300.00     | 2915 | YR   |   0.00        | 2915 | YM   |   0.00        | 2915 | WO   |   -153.00     | 2915 | IN   |   -329.00     | 2915 | K3   |   0.00        | 2915 | CUTE |   -50.00      | -----------------------------   I need to convert the values in code column to individual columns with column name as corresponding code and amount shall be the value.  bid  | BF       | YQ     | ... | CUTE  | ---------------------------------------- 2915 | -10700.00| -300.00| ... | -50.00|   The issue is that the result of my initial query has dynamic codes and hence need to generate columns accordingly.  Already tried the following logic but couldn't achieve the goal:   , ,   All the above links use some expression or the other to generate the columns.   My original resulting rows are result of simple select on multiple joined tables, and has no calculation or expression scope.  Kindly suggest some pointer or hint on how to achieve this.  Many thanks in advance.


I have noticed an increasing trend the last year towards emphasizing the "register" button rather than "log in".   Often log in is not even a button, just a link. I understand the desire to simplify the process for first time users, but I find it strange, since you typically will register once, but log in several times.   What is the rationale behind this practice?

Recently I've noticed more and more sign-in / sign-up workflows defaulting to the sign-up option first and providing a minimal "Sign-In / Login" action somewhere else on the page. What's the reason behind this practice?  Examples where I've seen this recently:


Below is the code. I don't understand the meaning of the last bracket in [::-1][:-1], and how come can you write two brackets at the same time. I understand that the first slice bracket reverses the order of the string, but what does the second do?  for i in range(n,0,-1):     temp = list(alphabets[:n][i-1:])     print('-'.join(temp[::-1][:-1]+temp).center(4*n-3,'-'))   Thanks for cooperation!

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


I'm not as active as I used to be on places like the Ubuntu forums and Launchpad, so I'm not sure where the best place to direct a feature request is. Currently Ubuntu 20.10 ships with freeglut 2.8, which dates all the way back to 2013. Current version is 3.2. Oddly enough, freeglut 2.8 is listed as freeglut3 in the repositories, even though it's still technically freeglut2. Reason for the query: the version of Asymptote (2.67) that ships with Ubuntu 20.10 (via TeXLive 2020) throws a segfault whenever you try to compile a 3D image to PDF. In particular: take any Asymptote example that loads the three library and run asy -f pdf -noprc example.asy. You'll get output, but you also get a segmentation fault. (I learned after plenty of correspondence with one of the Asymptote devs that it's actually a floating point exception, but in any case...) If you install the latest freeglut3 from source, using the instructions provided on the Asymptote website, everything works fine. I'm not really sure why freeglut has been held back to a version that's 7 years old.

Why are packages in the official Ubuntu repositories older than the latest (upstream) versions from Debian Sid, PPAs, the authors, etc.?


I'm writing a high school history textbook. While writing my book, I'm finding its becoming very heavily laden with sources. If I used Turabian's footnote style, they tend to fill half the page. Perhaps 1 source per 2 lines of text. My reasons for this are:  The history involved three different groups of people, but typically only one point-of-view has been presented in most general sources, so I'm having to check more sources from these other points of view (which has revealed to me that a lot of sources are missing important details). There is heavy bias in much scholarship, because the scholars are writing about their own ancestors, or have much local pride, they ignore facts that contradict their developed image of their ancestor as a "hero". Indigenous groups with no written language were part of the history, so the facts can be difficult to pull out, and requires cross-checking and confirming information across multiple sources while filtering out the biases mentioned above. Sometimes a great source ignores the basic details, like the date of the event, so I have to include cite general sources for the date alongside the more thorough detailed source with better analysis of the event.  Is too many sources frowned upon? Most secondary textbooks I see are strangely quite absent of sources. Is there some way this is bad practice?

I'm currently reviewing a paper that has an uncommonly large number of references compared to the average number for that particular venue (more than 60 versus around 30). This is a regular paper, not a survey one, and although there does not seem to be wrong references, it feels like some are not really necessary, and the fact that one particular author is cited more than 15 times makes me worry that this paper is used to inflate the number of citations of that author (the submission is anonymous).   Should I mention this in my review, and try to examine which submissions are "abusive", or just let it go?


I am using QGIS 1.8.0 on Windows 7 (32-bit) but am unable to install the OpenLayers plugin.  The Python plugins menu does not include OpenLayers on the plugin list.  Can it be somehow added manually?

After having installed QGIS 1.8 I am not able to find the OpenLayers Plugin. In "the old days" I know I was supposed to check "add 3rd party repositories", but that button has disappeared. I tried adding the following repositories without luck:  http://pyqgis.org/repo/contributed ..openlayers.org/api/2.12 ..github.com/sourcepole/qgis-openlayers-plugin.git ..github.com/nvkelso/qgis-openlayers-plugin.git ..plugins.qgis.org/plugins/plugins.xml ..plugins.QGIS.org/plugins/plugins.xml ..github.com/openlayers/openlayers   I hope someone can help me locate the OpenLayers plugin as I desperately need it.


I've seen  with  (i.e. presented at certain angle). How to achieve this?  I've tried to manipulate with mouse on current hat, but I see only drag cursor and I can only move or drag my hat or I can resize it, if I reach borders of my photo. Clicking right mouse on either current hat or on any of received hats doesn't bring anything around rotation.  Am I that blind? Where is the Rotate Hat button?

I just got a new hat! :D screaming with joy Looking at so many users looking all exquisite with their stunningly 'fitted' hats, I'm wondering if there's an option to resize or rotate a hat?  PS: Happy Winter Bash everyone! :)


I recently posted a question on StackOverflow. However, it was flagged as duplicate. The reason mentioned in the comments was that another, different question, has the same answer. Is that right? Does the same answer make two different questions duplicate?

In other words, should we now look at the content of the answers when we are evaluating questions for possible duplication?  Is it sufficient to say "Your answer can be found in this question over here, therefore your question is a duplicate?"  The new guidance is here:    Among other things, it describes the new close banner:     This question already has an answer here:   Link to the Duplicate Question   ... which seems to suggest that, if some other question in the system answers the OP's question, then the OP's question can be closed as a duplicate on that basis (even if the question itself is not necessarily duplicated).  Example Here:    Note the comments below the question, where I dispute the assertion made there that it is a duplicate question.  The original question doesn't mention unit testing.


I have just started the game and I need to find fuel for my ship. Where can I get This, can it be crafted? Can it be obtained early in the game?

I'm stuck on a planet with no wood trees and no resources that are easy to exploit, and I want to get off of it as quickly as possible.  What do I need to do to get my spaceship enough fuel to go to another planet?


What I mean by this is an area where people can ask questions about music on a non-technical level. I know there's an area for music theory and performance but what I'd like is an area where general questions can be asked.  For example:   What is the song 'free falling' by Tom Petty about ? Is there a definative list of different recordings of 'house of the rising sun' ?

I have an idea or subject that should have a Q&A, and want to propose a new site. How can I do this?  Related:


I am trying to understand greatest common divisor so If a=bt+r for integers t & r then why gcd(a,b)=gcd(b,r).I am unable to understand it.

My problem is how to somehow relate the the gcd and congruence. I know that $(a,b) = ax + by$. I also know that $a \equiv b \pmod n$ means $n\mid a-b$. Any hints?  Thanks!


I'm stuck on a Null Pointer Exception problem. The tests are run through JUnit, but I didn't manage to debug properly and find out the reason of it.  Test class  ExcelActions excelActions; Excel_Import excel_import;  @Test public void addResultsToExcel() throws InterruptedException {     searchAfterLogin(); // works fine until the next method     excelActions.addToExcel();  //thats where NPE begins...     excel_import.importExcel(excelActions.addToExcel());  }   Excel Action (Webdriver part)  public class ExcelActions extends BaseAction {  public ExcelActions(WebDriver driver) { super(driver); }  public Map<String, Object[]> addToExcel(){      String beforeXpath_pageName = "//*[@id=\"mw-content-  text\"]/div[3]/ul/li[";     String afterXpath_pageName = "]/div[1]/a";      int rowCount ;     rowCount = 20;     Map<String, Object[]> data = new TreeMap<String, Object[]>();      for(int i = 1; i <= rowCount; i++){          String actualXpath_pageName = beforeXpath_pageName + i +  afterXpath_pageName;         String pageName =  driver.findElement(By.xpath(actualXpath_pageName)).getText();         System.out.println(pageName);          data.put("" + i, new Object[]{pageName});     }     return data; } }   Excel import class  public class Excel_Import extends BaseAction {      public Excel_Import(WebDriver driver) { super(driver); }  public void importExcel(Map<String, Object[]> data) {     XSSFWorkbook workbook = new XSSFWorkbook();      //Create a blank sheet     XSSFSheet sheet = workbook.createSheet("Data");      //Iterate over data and write to sheet     Set<String> keyset = data.keySet();      int rownum = 0;     for (String key : keyset)     {         //create a row of excel sheet         Row row = sheet.createRow(rownum++);          //get object array of particular key         Object[] objArr = data.get(key);          int cellnum = 0;          for (Object obj : objArr)         {             Cell cell = row.createCell(cellnum++);             if (obj instanceof String)             {                 cell.setCellValue((String) obj);             }             else if (obj instanceof Integer)             {                 cell.setCellValue((Integer) obj);             }         }     }     try     {         //Write the workbook in file system         FileOutputStream out = new FileOutputStream(new  File("D:\\Projects\\Cucumber\\src\\main\\resources\\ImportedResults.xlsx"));         workbook.write(out);         out.close();         System.out.println("howtodoinjava_demo.xlsx written successfully on  disk.");     }     catch (Exception e)     {         e.printStackTrace();     } } }   Could you guys have a look at it?

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 have a Canon 40D, a tripod and a Canon 70-200mm f2.8L IS II USM lens.  I wanted to take pictures of the moon on a clear night, when there is a full moon.  I wanted to capture the details on the moon.  What settings should I use to get the shot.  Are there any tips anyone can give me?  I've never done this kind of thing before and my lens is totally new, so I have not had much experience with it yet.

I just purchased a D5100 and I am  slowly learning the basics.  I mostly shoot landscape/scenery shots.    I have been trying to capture the full moon unsuccessfully.  It looks focused in the viewfinder and I've experimented with slow shutter speeds and large apertures but the resulting image always comes out as a bright glare.  I'm never able to see the details of the moon.  How can I improve my shots?


Apparently I had problems with the lxd service, so I restarted the service  Service lxd restart   And now if it shows the network adapter, but is no longer called eth0, now has a similiar name to: "dbr0" but because of screen problems I cannot see the full name of the adapter.  My question is: can I send the output of the command   ifconfig -a   to a file so I can read it later with a file editor like nano or mc?

How do I save the output of a command to a file?  Is there a way without using any software? I would like to know how.


If I take the Magic Initiate feat and choose a different class's spell list, but pick a spell that's also on my class's spell list, can I cast it using my class's spell slots?  I have read this question and answer:   If a Druid takes the Magic Initiate feat, choosing the Cleric list, and takes a spell that's on both lists (such as Healing Word), can they cast that shared spell taken from the Cleric list with their class's spell slots?  The following leads me to think this is subtly different: the previous question dealt with a wizard taking a spell that was not a wizard spell. It was Not On His List. The Druid is taking a Druid spell off the Cleric list; it is still a Druid spell and available for the Druid to prepare.

Can you cast a spell learned from the Magic Initiate feat using spell slots? Say I play a wizard who learns cure wounds by taking the Magic Initiate feat. Could I cast that spell using the Wizard's spell slots?


In Fraleigh's A First Course in Abstract Algebra he solves the problem    $z^4=-16$    by rewriting in polar form that gives   $z^4=|z|^4(\cos(4\theta)+i\sin(4\theta))$ $|z|^4(\cos(4\theta)+i\sin(4\theta))=-16+0i = 16(-1+0i)$    He then says that we can immediately conclude that $|z|^4=16$. He does not go through the process of taking the absolute value of $z$. Assuming that it is $16$ just because it is in the right form seems strange to me. If you can conclude this based on form then why couldn't you factor out some other number like $-16$?

Probably dumb question, but I would like to ask it anyway.  I was to solve this equation:  $z^4 = -16$  At first glance, the way to solve it would be (as any other equation):  $z^2 = \sqrt{-1} * 4 \lor z^2 = -\sqrt{-1} * 4$  $z^2 = 4i \lor z^2 = -4i$  $z = 2\sqrt{i} \lor z = -2\sqrt{i} \lor z = 2i\sqrt{i} \lor z = -2i\sqrt{i}$  However, in suggested answers, there are $z_1, z_2, z_3$ and $z_4$ found using trigonometric formulas. Is there something particulary wrong in my solution and the only proper one uses trigonometric form of complex number?


I have created 3 different Objects from either 3 different Classes. I want to save these in a map. Like so:  ObjectA abjectA = new ObjectA(); ObjectB abjectB = new ObjectB(); ObjectC abjectC = new ObjectC();  Map<Integer, Object> map = new HashMap<>();   map.put(1, abjectA); map.put(2, abjectB); map.put(3, abjectC);   It doesn't work anyway, so how could I change my code? In general, is there a way, and how would you implement that in the code.  Thanks in advance

I have seen this mentioned a few times and I am not clear on what it means. When and why would you do this?   I know what interfaces do, but the fact I am not clear on this makes me think I am missing out on using them correctly.   Is it just so if you were to do:  IInterface classRef = new ObjectWhatever()   You could use any class that implements IInterface? When would you need to do that? The only thing I can think of is if you have a method and you are unsure of what object will be passed except for it implementing IInterface. I cannot think how often you would need to do that.   Also, how could you write a method that takes in an object that implements an interface? Is that possible?


I see that a ring is a triple $(R,\cdot,+)$. I am confused by the terms abelian group and semigroup. Does this mean for $x \in R$ and $y \in R$, $x \cdot y$ and $x+y$ are defined?  If so, how is this a ring? When I imagine a ring, I think of some kind of cycle data structure. Like a matrix that is looped shape. Does this sort of thing come into play?  Of course, I should point out that I have not studied ring theory or anything. I just noticed the concept and I find it strange that a "ring" does not seem to be something resembling a loop.

I've done some search in Internet and other sources about this question. Why the name ring to this particular object? Just curiosity.  Thanks.


I try to install Ubuntu 16.04 as a dual boot with Windows 10.  Unfortunately the  installer can't identify the partition I set unallocated with the build-in Windows 10 disk manager. When I come to the installation it directly sends me to Something else without giving me the opportunity to choose Install alongside Windows.  Searching for this problem I discovered that fast startup & secure boot must be disabled, but still the same error remains.    I also noticed an additional error I could not interpret when wanting to start the installation:    I'm using an Dell Inspiron with Windows 10, UEFI and using an SSD.  It would be very nice if you could explain:   What exactly is the problem? How do I troubleshoot this? How do I solve this problem?   I'm still a beginner to Ubuntu so thanks a lot for your time!  ---------- EDIT ------------ Here are all partitions shown. The dark Part with 30 GB is unallocated. Even through this I still should be able to see the partitions in the "Something else" part. But I can not choose anything in the dropdown "Device for boot loader installation:" If I click "+" / "-" / "Change" it basically crashes as it doesn't react anymore to clicking on new objects.

Whenever I startup from the LinuxLive USB, and try to install Ubuntu 12.04, it only gives me two options instead of the usual 3 or 4. My options are "Replace Windows 7 with Ubuntu" and "Something Else". Whenever I go into "Something else", it looks extremely confusing. How do I install it side-by-side while using the "Something else" section? These are my partitions.   /dev/sda /dev/sda1 ntfs (104Mb, System Required Partition) /dev/sda2 ntfs (1000097Mb, Windows 7 Partition)   Or should I try reinstalling my installer on a CD rather than USB and maybe then it will have the "Install alongside" function?


I remember reading in the late 80's / early 90's a trilogy (I think) about some teens in a spaceship that was sentient / had AI, and they weren't allowed in one section of the spaceship because it was dangerous.   Some of the teens came awake at different times, and were in a sarcophagus like bed for a while, and when they were in there, they were back on Earth or something?  There was something in the other part of the spaceship that wanted to attack them, and part of me thinks that they were shadow-type creatures.  Argh, it's annoying me that the memories are so vague and that I can't remember, I loved the trilogy as a kid!

It was written in English and likely a young adult series. I believe it was a hardcover book and possibly from an Australian author, though I could easily be wrong. I have a feeling it was a series, but I'm not sure if I'm confusing it with other books from the author (see below). I believe it has been out for at least 10 years, probably longer, because I read it in middle school.  The book begins with a school boy seemingly hallucinating seeing a futuristic, armed girl. I think she might have been on the cover of the book, but again I could easily be wrong. The boy is later pulled into the space ship she is on (the school scenes were not real, I believe).  As I remember there was no real adults on the ship, although it might have been because they had all been killed off previously. I realise this seem similar to . Later in the book, or perhaps it was a later book in the series, other children joined the crew.  At the end of the book/series, it is revealed that Earth had been ecologically devastated (possibly by industrial pollution). The cloned (I think) children were on a return trip in space, so that by the time they get back to Earth, the planet is ready for human habitation again.  I recall reading in the afterwords that the author was writing some books set in the same universe, but about early space colonisation of the solar system.  I think it was set before the above scheme to recolonise Earth was enacted. The author said we'll see "familiar names", presumably because the characters were later cloned for the recolonisation mission.   I read a couple of these "prequels" (or at least other books from the same author) but don't recall seeing such names. One of the books mentioned the Earth's oceans had turned toxic, though.


In physics, we can probably write things like this: ds=vdt. And then we can substitute the expression of ds into the integrand.In mathematics,this is known as integration by substitution. However,during my math lesson, my teacher told me that dx was only a symbol.Then, why can we operate ds like a real number(if dx is not a symbol, it should be an infinitesimal  quantity.This differs from real number)? What on earth is the real meaning of dx in integration? Why integration by substitution is just like changing dx to another expression(by exactly following the calculation of real number)? Especially in physics, we actually do not need to consider the phrase "integration by substitution" , but just simply think about the physical meaning of ds=vdt,dm=pdV,dW=Fds ect. and do the substitution. Why we can do these incredible things ?I am very perplexed. SOS!   AND THX A LOT FOR YOUR HELP!

In the book Thomas's Calculus (11th edition) it is mentioned (Section 3.8 pg 225) that the derivative $dy/dx$ is not a ratio. Couldn't it be interpreted as a ratio, because according to the formula $dy = f'(x)dx$ we are able to plug in values for $dx$ and calculate a $dy$ (differential). Then if we rearrange we get $dy/dx$ which could be seen as a ratio.   I wonder if the author says this because $dx$ is an independent variable, and $dy$ is a dependent variable, for $dy/dx$ to be a ratio both variables need to be independent.. maybe?


I would like to do something similar to the following:  which someapplciation | cd outputfrompreviouscommand   The command which provides a directory and I would like to be able to make that output my current working directory without using a programming language i.e. awk, bash, perl, etc. and to only use the pipe command.  To further give an example:  which vi   provides the output  /some/dir   I would like my working directory to be moved to that directory which I can test by using the pwd command which should have the output that matches of /some/dir.

I've a command that outputs data to stdout (command1 -p=aaa -v=bbb -i=4). The output line can have the following value:  rate (10%) - name: value - 10Kbps   I want to grep that output in order to store that 'rate' (I guess pipe will be useful here). And finally, I would like that rate to be a value of a parameter on a second command (let's say command2 -t=${rate})  It looks to be tricky on my side; I would like to know better how to use pipes, grep, sed and so on.  I've tried lots of combinations like that one but I'm getting confused of these:  $ command1 -p=aaa -v=bbb -i=4 | grep "rate" 2>&1 command2 -t="rate was "${rate}


is a good system. But when a gold badge holder closes a question, a comment still gets created on the voter's behalf, even though it will be immediately deleted by the system due to the question being closed as a duplicate. This is contrary to what normally happens when a moderator closes a question - no comment is ever created or deleted.  This is problematic because the comment's creation (even though it gets deleted in the same instant) still causes notifications to be sent out:   The owner of the question receives an inbox notification telling them that there is a new comment on their post, which doesn't actually exist anymore. Anyone viewing the question at the time  that there is a new comment on the question, only to have nothing new at all load when they click to load the new comments.   I propose that all binding close votes refrain from leaving a comment, not only those cast by diamond moderators.

This happened to me twice. Someone flags my question as duplicated and only when I visit the question I notice the comment. Before I had no proof, but today I have *evil laughter*.  This is the notifications:        I count 4, remember this number.        Lets see... umm... 1, 2, 3... 5! HA! So, there are 5 comments and one of them (the one that flagged the question as dupe) didn't get into my inbox. So, is this by design or I really should get notified?  If this is by-design, I disagree.  Note to self: I suspect other canned comments doesn't reach the OP, like the custom close reason.


The method __getattribute__ needs to be written carefully in order to avoid the infinite loop. For example: class A:     def __init__(self):         self.x = 100      def __getattribute__(self, x):         return self.x  >>> a = A() >>> a.x    # infinite looop RuntimeError: maximum recursion depth exceeded while calling a Python object   class B:     def __init__(self):         self.x = 100      def __getattribute__(self, x):         return self.__dict__[x]  >>> b = B() >>> b.x    # infinite looop RuntimeError: maximum recursion depth exceeded while calling a Python object  Hence we need to write the method in this way: class C:     def __init__(self):         self.x = 100      def __getattribute__(self, x):         # 1. error         # AttributeError: type object 'object' has no attribute '__getattr__'         # return object.__getattr__(self, x)                  # 2. works         return object.__getattribute__(self, x)                  # 3. works too         # return super().__getattribute__(x)  My question is why does object.__getattribute__ method work? From where does object get the __getattribute__ method? And if object does not have any __getattribute__, then we are just calling the same method on class C but via the super class. Why, then calling the method via super class does not result in an infinite loop?

I want to override access to one variable in a class, but return all others normally.  How do I accomplish this with __getattribute__?  I tried the following (which should also illustrate what I'm trying to do) but I get a recursion error:  class D(object):     def __init__(self):         self.test=20         self.test2=21     def __getattribute__(self,name):         if name=='test':             return 0.         else:             return self.__dict__[name]  >>> print D().test 0.0 >>> print D().test2 ... RuntimeError: maximum recursion depth exceeded in cmp


using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Threading.Tasks;  namespace FloatConversion {      class MainApp     {         static void Main(string[] args)         {             float a = 69.6875f;             Console.WriteLine("a : {0}", a);              double b = (double)a;             Console.WriteLine("b : {0}", b);              Console.WriteLine("69.6875 == b : {0}", 69.6875 == b);              float x = 0.1f;             Console.WriteLine("x : {0}", x);              double y = (double)x;             Console.WriteLine("y : {0}", y);              Console.WriteLine("0.1 == y : {0}", 0.1 == y);                Console.ReadLine();         }     } }   I just started learning C#. As a Newbie, I was wondering that what a : {0} means in Console.WriteLine() method.  similarly, what does 69.6875 == b : {0} mean? how can it be displayed as a boolean?  Thank u in advance.

In a dictionary like this:  Dictionary<string, string> openWith = new Dictionary<string, string>();  openWith.Add("txt", "notepad.exe"); openWith.Add("bmp", "paint.exe"); openWith.Add("dib", "paint.exe"); openWith.Add("rtf", "wordpad.exe");  Console.WriteLine("For key = \"rtf\", value = {0}.", openWith["rtf"]);   The output is:     For Key = "rtf" value = wordpad.exe   What does the {0} mean?


I noticed I have a very faulty rc.local and would like to have the package releasers version right now, and not when it has to upgrade. Can someone hint me to the options, or the full command it needs to renew/reset these essential files?

By accident, I messed up a configuration file. How do I recover the default version without reinstalling or affecting other things?


I have looked through a post of structure padding in geeksforgeeks,   But I don't know why in this case:  int main()  {       struct C {          // sizeof(double) = 8          double z;           // sizeof(short int) = 2          short int y;          // Padding of 2 bytes           // sizeof(int) = 4          int x;      };       printf("Size of struct: %d", sizeof(struct C));       return 0;  }    I know y (short int) is followed by x (int) and hence padding is required after y. But why the padding here is 2?

Why does the sizeof operator return a size larger for a structure than the total sizes of the structure's members?