Neural Network in classification task behaves "weird"

I am trying to segment an image by first dividing it into superpixel, and than classifying those superpixel to merge them together. If I am doing it for example with a SVM or a Decision Tree, it works fairly well, but is still doing some mistakes.  Now I wanted to use an Neural Network, to do the task, but after a few iterations it almost always gets stuck in the local minima and "maps every input to the same class".   It behaves in general really weird, because sometimes the accuracy first increases, but than steadily decreases again, till it reaches one of the minima from above (I am talking about the train accuracy, not the test accuracy, so overfitting is not an explanation, I also don't use Stochastic gradient descent but use all train data for an weight update, so fluctuations cant really explain the decreasing accuracy)  That looks like this:  617/617 [==============================] - 1s - loss: 1.1174 - acc: 0.2690       Epoch 2/1000 617/617 [==============================] - 0s - loss: 0.8662 - acc: 0.8169      Epoch 3/1000 617/617 [==============================] - 0s - loss: 0.5829 - acc: 0.8136      Epoch 4/1000 617/617 [==============================] - 0s - loss: 6.3685 - acc: 0.9060      Epoch 5/1000 617/617 [==============================] - 0s - loss: 9.0494 - acc: 0.4036       Epoch 6/1000 617/617 [==============================] - 0s - loss: 4.4840 - acc: 0.1297      Epoch 7/1000 617/617 [==============================] - 0s - loss: 1.9398 - acc: 0.1167      Epoch 8/1000 617/617 [==============================] - 0s - loss: 1.8809 - acc: 0.1167    (It stays at the same loss and acc from there)  The NN I am using looks like this (even though I also tried many others):  from keras.models import Sequential from keras.layers import Dense, Dropout from keras.optimizers import SGD enc = OneHotEncoder() labelOH = enc.fit_transform(label.reshape(-1,1)).A  clfN = Sequential() clfN.add(Dense(32, input_dim=feature_array.shape[1])) clfN.add(Dense(64, activation="relu")) clfN.add(Dense(64, activation="relu")) clfN.add(Dense(32, activation="relu")) clfN.add(Dense(labelOH.shape[1]))  sgd = SGD(lr=0.0001, decay=1e-10, momentum=0.9, nesterov=True) clfN.compile(loss='categorical_crossentropy',               optimizer=sgd,               metrics=['accuracy']) clfN.summary() clfN.fit(feature_array, labelOH,  epochs=1000, batch_size=617)   What could be the cause for this behaviour, and what could I do about it?


Glossy BSDF not found in Blender 2.79 Cycles

Simple (and may be stupid) question - how to include (if it should be included or plugget in) Glossy BSDF in my Blender 2.79?  I'm follow a manual video (), where user just input "glos" in Cycles search and Glossy BSDF appears at search result.  So, I can't repeat that because can't find Glossy BSDF by search menu (look at screenshot below).  Please, help!  Thank you!


We let $f:\mathbb{R}\to\mathbb{R}$ be infinitely often differentiable function and we let the Taylor series be: $$\displaystyle\sum_{n=0}^{\infty}\left(\left(\frac{f^{n}(0)}{n!}\right)x^n\right) $$Let $\{a_n\}_{n\in \mathbb N }$ be $a_n=\frac{f^{n}(0)}{n!}$. We have to assume that the Taylor series converges toward $f$ in an open interval $(-r,r)$ around zero. Then I have to show that if $a_{2n-1}=0$ for all $n\in \mathbb N$ so is $f(-x)=f(x)$ for all $x\in(-r,r)$. How can I do it? I think I maybe can see on $kx^{2n}$ while all odd joints are zero while $a_{2n-1}=0$? But how can I prove it?


Consider the following situation,     A batsman's bat breaks while hitting the ball after which a piece of the   bat flies in the air, hits the stumps and the bails fall down.   Is this a dismissal by hit wicket?


$$\begin{align} \int \sec x \, dx  &= \int \cos x \left(  \frac{1}{\cos^2x} \right)  \, dx \\ &= \int \cos x \left(  \frac{1}{1-\sin^2x} \right) \, dx \\ & = \int\cos x\cdot\frac{1}{1-\frac{1-\cos2x}{2}} \, dx \\ &= \int \cos x \cdot\frac{2}{1+\cos2x} \, dx  \end{align}$$  I am stuck in here. Any help to integrate secant?


Distinct permutations of the word "toffee"

What does distinct permutations mean and how many distinct permutations can be formed from all the letters of word TOFFEE?


How to find $\lim\limits_{n \to \infty} n^2 \Big[ \big(1+\frac{1}{n+1}\big)^{n+1}-\big(1+\frac{1}{n}\big)^{n}\Big]$?

I would like to evaluate $\lim\limits_{n \to \infty} \Big(n^2 \Big[ \big(1+\frac{1}{n+1}\big)^{n+1}-\big(1+\frac{1}{n}\big)^{n}\Big]\Big)$.


Find classes which inherits from a generic class using reflection

I need a way to filter my assemblies to get all classes that inherits from a generic class. I have found some posts but they are most like how to check the inheritence(e.g.  and ). But these posts didn't helped me.  All my classes inherits from a specific one, called BaseRepository<T>, but some classes can inherit from InterventionBaseRepository<T>(which inherits from BaseRepository<T> as well). I need to find them. This is my code until now:  var q = from t in Assembly.GetExecutingAssembly().GetTypes()         where t.IsClass &&               (t.Namespace != null &&               t.Namespace.StartsWith("AgroWeb.Core.Data.Repository"))         select t;   So, in short, the query above gets all my classes by namespace which I need to find among them those who inherits from InterventionBaseRepository<T>.  An example of a signature of a class which must be found:  public class CityRepository : InterventionBaseRepository<City>, ICityRepository   And the InterventionBaseRepository declaration:  public class InterventionBaseRepository<T> : BaseRepository<T>     where T : Entity   I tried to use  as said in those posts linked above in the query like this:  t.IsAssignableFrom(typeof(InterventionBaseRepository<Entity>))


So I've been having this problem for a while. The problem is, I can't save an username to MySQL field. Correct username: Vėdarėlis  Field result: VÄ—darÄ—lis  As you can see below, my collation is set to utf8   And I'm pretty sure the PHP itself is working fine, because in the general mysql log, I have this line:  168308 Query    UPDATE users_steam SET name='Vėdarėlis', ......rest of the query....   So how do I properly set user name with proper encoding? Thanks


No matter how I do it, I always end up with $x = 0, 90, 270$ and $360$. All of those except $270$ is right, but I can't quite figure out how to get the $270$ degrees out of the answer. I've tried using trig identities, I've tried squaring both sides, but I always end up with $$2\sin x\cos x$$ which then leads me to $x = 0, 90, 270, 360$. But $$\sin (270) + \cos (270) = -1$$ so I'm doing something wrong.


restore data from internal storage of android phone

I am struggelling with the file recovery of an internal storage of an android phone.  I made a dd copy of the /dev/sda device which includes the system and userdata and some other partitions of the phone.  bla@bla:/media/Volume$ mmls sda.raw  GUID Partition Table (EFI) Offset Sector: 0 Units are in 4096-byte sectors        Slot      Start        End          Length       Description 000:  Meta      0000000000   0000000000   0000000001   Safety Table 001:  -------   0000000000   0000000005   0000000006   Unallocated 002:  Meta      0000000001   0000000001   0000000001   GPT Header 003:  Meta      0000000002   0000000002   0000000001   Partition Table 004:  000       0000000006   0000000015   0000000010   padding0 005:  001       0000000016   0000016399   0000016384   recovery 006:  002       0000016400   0000032783   0000016384   boot 007:  003       0000032784   0001011727   0000978944   system 008:  004       0001011728   0001026063   0000014336   apppreload 009:  005       0001026064   0001041423   0000015360   cota 010:  006       0001041424   0015447055   0014405632   userdata 011:  007       0015447056   0015450106   0000003051   reserve0 012:  -------   0015450107   0015450111   0000000005   Unallocated   I am able to mount some partitions:  bla@bla:/media/Volume$ sudo fsstat -b 4096 -o 32784 sda.raw  FILE SYSTEM INFORMATION -------------------------------------------- File System Type: Ext4 Volume Name: system Volume ID: 7019a2b4b48a33b92c4409cbe0a229c7  Last Written at: 2020-05-28 21:04:07 (CEST) Last Checked at: 2019-07-22 16:11:16 (CEST)  Last Mounted at: 2020-05-28 20:55:42 (CEST) Unmounted properly Last mounted on: /system  Source OS: Linux Dynamic Structure Compat Features: Journal, Ext Attributes, Resize Inode, Dir Index InCompat Features: Filetype, Extents, Flexible Block Groups,  Read Only Compat Features: Sparse Super, Large File, Huge File, Extra Inode Size  Journal ID: 00 Journal Inode: 8  METADATA INFORMATION ...   But not the userdata partition. Are there any tricks I missed so far?  TestDisk 7.0, Data Recovery Utility, April 2015 Christophe GRENIER <grenier@cgsecurity.org> http://www.cgsecurity.org  Disk sda.raw - 63 GB / 58 GiB - CHS 7694 255 63      Partition               Start        End    Size in sectors >P MS Data                   262272    7971615    7709344 [system]  P MS Data                  8093824    8208511     114688  D MS Data                  8208512    8331391     122880  D MS Data                  8331390  123576413  115245024    Outputs for userdata:  bla@bla:/media/Volume$ sudo fsstat -b 4096 -o 1041424 sda.raw Cannot determine file system type   Thanks for any hints in advance!  Klaus


Filter Custom Objects in Array list or List

I have 50 Custom Class(class name : Student) objects in array List .   public class Student {      private String name;     private String age;     private String parent;       public String getName() {         return name;     }      public void setName(String name) {         this.name = name;     }      public String getAge() {         return age;     }      public void setAge(String age) {         this.age = age;     }      public String getParent() {         return parent;     }      public void setParent(String parent) {         this.parent = parent;     } }   I want to filter the students array list whose age is 20  and store it into another array list.  Note :   I have tried with for loop. its working fine. But I want to know Is there any fastest way other than looping array list to filter student age.  I have some experience in iOS. In iOS, NSPredicate is there to filter student age from NSArray. I just started learning android since last month. I am not getting any answer other than looping array list over internet to achieve the same.


java: error while loading shared libraries: libjli.so: cannot open shared object file: No such file or directory i followed these steps  Installed deb from oracle sudo dpkg -i jdk-16_linux-x64_bin.deb sudo update-alternatives --install /usr/bin/java java /usr/lib/jvm/jdk-16/bin/java 1 sudo update-alternatives --install /usr/bin/javac javac /usr/lib/jvm/jdk-16/bin/javac 1  after these steps i run the command java --version then it promts java: error while loading shared libraries: libjli.so: cannot open shared object file: No such file or directory some one help me... i am new to linux


If N and every subgroup of N is normal in G then G/N is abelian .

Let $N$ be a normal subgroup of a group $G$ such that every subgroup of $N$ is normal in $G$ and $C_G(N)\subseteq N $. Prove that $G/N$ is abelian.   Here, as usual, $C_G\left(N\right)$ means the centralizer of $N$ in $G$ (i.e., those elements of $G$ that commute with everything in $N$).  I think we need to use that every subgroup of $N$ is normal in $G$ but i can't use .Please help me with Hints.


Why is the following sentence correct: "The forum was a success as it had generated a plethora of ideas."      Why is the sentence, "The forum was a success as it generated a plethora of ideas." not correct.


Data, Lore, and B4 all have yellow eyes and white metal exoskeletons. Why did Noonien Soong give them yellow eyes instead of blue or something natural? The Androids were supposed to be as human looking as possible but I don't see many people with yellow eyes. Wouldn't they have had a solution for their eye color and exoskeleton to appear more human in the future? In the TOS episode I Mudd, the Androids had a human exoskeleton color and normal eyes and that is earlier than TNG. Brent Spiner told a story of him asking Gene Roddenberry why did he have to have a different skin color but the answer he gave didn't really suffice.


How can I use stackexchange as notes repository?

I have tried mails to self and text files to keeping notes in one place, which I can reuse. However I have found them getting lost as time passes by. The "Anwser your own question" in stack exchange is good way of keeping notes to self. However if the question is simple e.g. "how to do something", stack exchange do not allow to post the question. I was wondering if there are guidelines to post simple questions with answer, which I and others can use.


Occasionally I change my mind about the value of a question, or about which concern I have with it. We let folks retract/correct up or down votes (though we limit that on comments); we should have an undo capability on close votes, which are arguably more critical.


how to get values from DB and add those in array in C#

I was googling for and found no results for this.  most of the people declare the array inside the void. like this  private void Something(){                 ArrayList list = new ArrayList();                 list.Add("awdawd"); }   but I have to declare the array outside of it because it would be used from different voids. this is my code:   public string[] Names= { "Rick", "Morty", "John" };   and for the db:   private void GetNames() {          string cmdText = "SELECT * FROM Login";          // using (SqlConnection cnn = new SqlConnection("Server=.\\SQLEXPRESS;Database=TestDB"))         using (SqlCommand SelectCommand = new SqlCommand(cmdText, connectionstring))         {             SqlDataReader myReader;             connectionstring.Open();             myReader = SelectCommand.ExecuteReader();          }      }   I tried to make it Names.add("Mario"); but it didnt work.  any suggestion?


Robinson arithmetic and its incompleteness

Wikipedia in Italian has a  that Robinson arithmetic is not complete, since commutativity of addition is undecidable. The sketch of proof creates a model that adds two elements, $a$ and $b$, to the usual natural numbers: then it goes on by defining   $\mathsf{S(a)=b}$   $\mathsf{S(b)=a}$   $\mathsf{\forall n\in N \; (a+n = a)}$   $\mathsf{\forall n\in N \; (b+n = b)}$   $\mathsf{\forall n\in N \; (n+a = b)}$   $\mathsf{\forall n\in N \; (n+b = a)}$   $\mathsf{a+a=b}$   $\mathsf{b+b=a}$   $\mathsf{a+b=a}$   $\mathsf{b+a=b}$    and saying "we could also define multiplication, but it is useless, since we already have that  $\mathsf{b+a} \ne \mathsf{a+b}$". But I am not sure that the model may actually be extended to multiplication. I tried with   $\mathsf{a\times b=b}$   $\mathsf{b\times b=a}$   $\mathsf{b\times a=a}$   $\mathsf{a\times a=b}$   $\mathsf{\forall n\in N \; a\times n=b}$   $\mathsf{\forall n\in N \; b\times n=a}$    [EDIT]: of course $\mathsf{ a\times 0 = b\times 0 =0}$  but I am stuck with $\mathsf{n\times a}$ and $\mathsf{n\times b}$; it seems to me that setting all of them to $\mathsf{a}$ should work, but I am not sure about it. Could someone help me?  P.S.: I read , and I understand that just a single element $\mathsf{a}$ may be added. But I'd prefer to have the implicit axiom that $\mathsf{\forall x  \; (S(x) \ne x)}$.


Looking for an obscure mecha manga from the 90s or earlier

So I have a real challenge for the mecha manga/anime buffs around here. Here goes:  Way back in the mid 1990s, I borrowed a VHS tape from a schoolmate that was some kind of mecha anime. The only things I really remember about it are that it featured a robot character called "The Colonel", who said something along the lines of "your world has become entangled in our problems", that there was a human character called Karachi, and that it involved a subplot of a man who pretended to be mentally enfeebled in order to keep some sort of aristocratic woman from assassinating him. He later got rid of her and assumed power, and controlled a giant floating mecha without legs (a giant flying robot torso with arms basically) called "Libo" or something similar. One other scene I distinctly remember was that this aforementioned aristocratic woman went insane, was holding her dead infant son in her arms, convinced herself that the boy was still alive, and asked her terrified handmaidens to go get him something to drink.  This isn't much to go on, but if any of the above rings a bell, please let me know. I've been browsing mecha anime lists like crazy, but haven't been able to find anything so far.


I'm a German native speaker and sometimes I'm confused about how to use the above-mentioned  words.  For example,      This idea is good, and that idea is good too   Is this OK, or should I use, instead of too,  the word also?  Please give some examples and explanations.


Height and Weight — How to write them when abbreviations are not used.  He was a 6-foot 5-inch man.   (Not: 6-foot-5-inch man, with three hyphens.)  She gave birth to a 7-pound 11-ounce baby.  (Not: 7-pound-11-ounce baby, with three hyphens.)  And, it should be, I believe:  He is 6 feet 5 inches tall. (Not: 6 feet, 5 inches tall.)  The baby weighed 7 pounds 11 ounces. (Not: 7 pounds, 11 ounces.)  Despite variations in punctuation, I believe that we do not separate singular units of measurements like these with commas.  Good to all?


How significant is the fact 1 isn't a prime number? What will happen if it is? What areas of Mathematics are affected by changing the fact? I know why and how 1 isn't a prime. My question is how significant is the fact.


I have a large hole in a mesh that I'm trying to fill:    I've been trying an approach like this:    I'm finding it quite tough, since the number of vertices around the perimeter of the hole don't match a grid.  Is there a better approach to filling a hole like this?


In the following, I haven't defined the type doesntexist.  void myfunction(doesntexist argument) { }   GCC 4.7.2 says "error: variable or field ‘myfunction’ declared void"  My question is this: What's going through the compilers mind here to refer to the function name being void and not the argument type?  [EDIT] Before downvoting, be aware the answer to this issue is related to the order of the errors and -Wfatal-errors stopping the more immediately relevant message from being printed. This is not simply me having a go at a slightly vague compiler message.


Python lists and computational complexity

I'm writing a program in Python. The algorithm that I use is very slow (and it can't be faster for what I want to do) so how quickly the program will execute is important (in other words: computational complexity matters) and this is what I need to do:   I have a list. I need to iterate the list and do some operation on every element. When iterating the list, I need to remove some elements from the list.   This can be done very easily, but the problem is that I want removing element to have computational complexity O(1), not O(n), so that the entire process of iterating the list and removing some elements has computational complexity O(n). Now, I don't know what the internal implementation of python lists is, but I'm almost sure that when I remove element like that:  del list[5]   or like that:  list.pop(5)   It will probably have to move all of the elements after fifth element one position back which results in computational complexity O(n).  If it was C++, then I would use list that is implemented using pointers, so that I could go through the entire list and remove the elements that I want to remove in the most quickest way. But in Python, there are no pointers, so I can't implement this list on my own. So is there a way to do the above process in Python with computational complexity O(n)?  In other words:  In C++, there are two ways how you can implement a list: using pointers and using an array. The first implementation is faster for some operations, and the second is faster for other operations. I need to use the first implementation, but I don't know if it's possible in Python.


Compute $\lim_{x \rightarrow +\infty} \frac{[\int^x_0 e^{y^{2}} dy]^2}{\int^x_0 e^{2y^{2}}dy}$

I've tried to apply L'hopitals rule on this one, as this get's $\frac{\infty}{\infty}$  $$\lim_{x \rightarrow +\infty} \frac{[\int^x_0 e^{y^2}\mathrm{d}y]^2}{\int^x_0 e^{2y^2}\mathrm{d}y}$$  $\frac{\mathrm{d} }{\mathrm{d} x}[\int^x_0 e^{y^2}\mathrm{d}y]^2 = 2[\int^x_0 e^{y^2}\mathrm{d}y] * [\frac{\mathrm{d} }{\mathrm{d} x}\int^x_0 e^{y^2}\mathrm{d}y]=2(e^{x^2}-1)(e^{x^2})$ and $\frac{\mathrm{d} }{\mathrm{d} x}[\int^x_0 e^{2y^2}\mathrm{d}y]=e^{2x^2}$ so $\lim_{x \rightarrow +\infty} \frac{[\int^x_0 e^{y^2}\mathrm{d}y]^2}{\int^x_0 e^{2y^2}\mathrm{d}y} = \lim_{x \rightarrow +\infty} \frac{2(e^{x^2}-1)(e^{x^2})}{e^{2x^2}} = 2\lim_{x \rightarrow +\infty} \frac{(e^{x^2}-1)}{e^{x^2}}=2\lim_{x \rightarrow +\infty} (1-\frac{1}{e^{x^2}})=2$  But the answer is $0$, so I think I've done a mistake somewhere I can't figure out where.


Putty Login error through SSH (Network error: Connenction timeout)

I am trying to login into one(X) server using putty (port 22), it is showing Fatal Error. In Pop-up (Network error: Connection timed out).  But when I am in different server(Y) on command prompt using  ssh (X)hostname   it is working, only issue with the putty.  At the same time, I am able to logged into some different servers(Y,Z) through putty.


What's the term given to names with "The" in the middle of them, for example; "Robert The Red" or "James The Great"?


How long before I can re-enter the US on a B visa?

I'm a 24 year-old Australian traveller. I just spent a full 6 months in the US, mostly around LA. I stayed the full length of my allowed stay on a B2 tourist visa. I'd never ever been the States before!  I'm now back in Australia and wondering if I should wait another 6 months before coming to the US. I understand that is the general suggested guideline and that there are no real rules. I met a girl I really like there and would love to see her again. I'm not sure if anyone has any experience telling that to immigration on their next arrival.


How much mana should I put in a deck with Mountains and Forests? How much of each? I counted the mana in my black deck to see how much I need, but I still don't know.


Why doesn't Newton's third law mean a person bounces back to where they started when they hit the ground?

When we drop a ball, it bounces back to the spot where we dropped it, due to the reaction forces exerted on it by the ground. However, if a person falls down (say, if we push them), why don't they come back to their initial position where they started their fall?  According to Newton's 3rd law of motion, to every action there is always an equal but opposite reaction. If we take the example of ball then it comes back with the same force as it falls down. But in the case of a human body, this law seems not to be applicable. Why?


Why don't big bang photons conserve mass and energy?

A photon from the big bang has lost most of its momentum and energy. What does it push against? Does it break the 'laws' of conservation of energy and momentum? Is there any possibility that momentum is conserved or that in any other way these ancient photons are not precisely identical modern photons of the same wavelength?  If the photon's momentum and energy is given up to expand the universe, but the flux of photons at a point of empty space is not perfectly even over a long time scale, what does this imply?


If it doesn't allow for transmitting of any information, what was/is "spooky" about it? Is there anything spooky about it at all in the end?


I started my Minecraft server a little while ago. So I flew a good distance away from the place I started and began to build. Later I died down at the bedrock, and so spawned at my starting point again, and now I can not find my buildings!   How do I find the home I built again?


Is image of recursive set under recursive function recursive?

Given $A$ - recursive set and function $f$ which is also recursive. Is $f(A)$ recursive?  I think that it isn't recursive, but how to prove it?


I want to run a script when I log out through unity.  I read something about lightdm but I don't really know what it is and the config file didn't exist. The config file mentioned  doesn't exist! And manualy creating it doesn't solve my problem.


Is there a way how to return full enum by property? Here is example of what I want to do:  // MyEnums.cs public enum Languages {     cs = 0,     pl = 1,     en = 2,     de = 3, }  // General.cs public static MyEnums.Languages Languages {     get     {         return MyEnums.Languages;     } }


Minecraft commands: server log in titles

I'm trying to write a command that will display a title that says "welcome" when you log into my server, but only on the screen of the player that just logged in. I want this to happen every time anyone logs into my server. how can I do this?


Ode to tags Let's say pygtk doesn't compile for you on osx due to an obscure automake error. Would you send it to the python mailing list? or perhaps to the gtk mailing list? etc. No, you ask it on Stack Overflow and give it all the relevant tags! Contradiction But hey, does it belong on Stack Overflow, or on Server Fault. It's related to programming but you are installing pygtk because you are the sys-admin, so maybe it should be on Server Fault, but on the other hand, one might face this problem when trying to install it for his personal reasons, so maybe it can belong on Super User? Conclusion It seems like the split to several "topic sites" goes against the philosophy of tags. Perhaps there's a better solution than splitting to different sites, one that is consistent with the tags philosophy. Maybe like: Suggestion Instead of splitting to different "topic sites" (SO/SF/SU/MSO), create "master tags" (programming, sysadmin, power-user, meta-stackoverflow). Each question must have at least one master tag. Users can not create "master tags", they are "fixed", or decided by the site admins, to maintain order. If someone is only interesting in viewing power-user questions, he'll view the questions belonging to the "power-user" master tag (currently he goes to superuser.com). In the case of the example question (the "python gtk osx automake" question), it may belong to all three master tags mentioned (or maybe there would be parent master-tags, like "computing"). This may also give more freedom to the site's admins to easily extend the scope of the SO family websites. Perhaps they would want to also allow science questions, or even heated political debates, in this awesome platform. In this way it won't require separate domains and accounts, and would allow the users one convenient gateway to the "internet questions world". Comparison to current solution and backwards compatability The way I see it, this solution can be implemented in a totally backward compatible way. Everything in SO gets assigned the "programming" master tag, etc. The topic sites can resume to exist as a site where the default shows question of their respective master tags. When asking a question, it can get a default master-tag from the domain you used to access the site. Tag auto-completion is only offered for tags that "belong" to this master tag (A tag can belong to several master tags. It belongs to it if any question was asked with this tag in that master-tag) So I don't see how this will cause clutter as . In fact, if you limit a question to have only one master tag then imho this is (almost) exactly equivalent to the current "topic sites" solution. The only difference is that karma will be shared. But if this is seen as a bad thing then this can be solved too, with master-tag specific karma. This idea can be extended to tag specific karma as well.


Continuous functions are differentiable on a measurable set?

I came across the following challenging problem in my self-study:  Let $f: \mathbb{R} \rightarrow \mathbb{R}$ be continuous. Then the set of points where $f$ is differentiable is a measurable set.  I am having trouble thinking of where to begin in proving this result, and wanted to see if anyone visiting had some suggestions on how to proceed.


Customize Apex Exception Messages from Javascript Buttons

My application has javascript button that call Apex code.  Exceptions from web services are sometimes thrown and the user is shown a detailed exception message like this:  A problem with the OnClick JavaScript for this button or link was encountered: {faultcode:'soapenv:Client', faultstring:'HttpException: Example Error Message Class.BananaWebService.fetchBanana: line 22, column 1', }   Is there a simple way to create friendly error messages for my users when exceptions are thrown like this:  Example Error Message   Exception Class  public class HttpException extends Exception{}   Web Service Class   @RestResource(urlMapping='/BananaWebService/*') global class BananaWebService {   webservice static void fetchBanana(Id accountId) {      throw new HttpException('Example Error Message');   } }   Javascript code   {!REQUIRESCRIPT("/soap/ajax/28.0/connection.js")}  {!REQUIRESCRIPT("/soap/ajax/28.0/apex.js")}   var accountId = "{!Account.Id}"; sforce.apex.execute("BananaWebService","fetchBanana", { accountId: accountId });  window.location.reload();


Series $\frac{k^2}{k!}$ with $ k=1$ to $\infty$

A practice Math Subject GRE asked me to compute $\sum_{k=1}^\infty \frac{k^2}{k!}$. The sum is equal to $2e$, but I wasn't able to figure this out using Maclarin series or discrete PDFs. What's the most elementary way to solve this? Thank you.


Algorithms for automatic model selection

I would like to implement an algorithm for automatic model selection.  I am thinking of doing stepwise regression but anything will do (it has to be based on linear regressions though).   My problem is that I am unable to find a methodology, or an open source implementation (I am woking in java). The methodology I have in mind would be something like:   calculate the correlation matrix of all the factors pick the factors that have a low correlation to each other remove the factors that have a low t-stat add other factors (still based on the low correlation factor found in 2.). reiterate several times until some criterion (e.g AIC) is over a certain threshold or cannot or we can't find a larger value.   I realize there is an R implementation for this (stepAIC), but I find the code quite hard to understand. Also I have not been able to find articles describing the stepwise regression.


How to delete folder from EFI partition - Microsoft

I have problem with my Fedora disto. Boot is stucked on system check on disk by UUID... I discovered that it is EFI partition and I tried to reconfigure grub2 but there are inffinite Input Outpur errors(see ) in Microsoft folder (yes, I have dual boot but each system on different disk). During my investigation I completely broke Windows so I want to delete Microsoft folder - fix Fedora and reinstall Windows. BUT when I try to delete the folder (sudo rm -rf... - also from Live CD with partition booted with RW permissions) it says that it is Read Only file system. What am I doing wrong ?


I have come across this a few times. I post a question and get at least a couple of up votes on the question but no answers. And then slowly the question disappears in the big ocean of questions that all the sites on Stack Exchange gets. The only option to bring it back to life is to assign bounty for it and that is possible only after 2 days.   What happens in the meantime? Is there any ways to attract more views? Generally SO is my fallback option when I have failed all possible attempts to solve a problem or gain enough information about something. I have seen the question die down and even not be viewed as much as I would like. Is it because the question is lacking quality ?   EDIT:  Should I put this question in different words? Assuming up votes meaning others are interested in the question too or that the question deserved credit for something, if the question has no answers, is it poorly framed ?  Especially in cases when the user (mostly me) is trying to get answers for some problem that I face trying to do something that is very common and by common I mean  everyone would at some point of time attempt to do it or have done it in their programming career.


Javascript this keyword and variables pointing to an object method

I'm trying to understand how the this keyword works in this context.  function Person(name) {     this.name = name;     this.sayName = function() {         alert('My name is ' + this.name);     }; }   var p = new Person('Smith'); p.sayName();  // 'My name is Smith'  var q = p;  q.sayName();  // 'My name is Smith'  q = p.sayName;  q();  // 'My name is'   ???   Why is the last example not picking up 'Smith'?    Is it because q is simply pointing to a function (i.e. the object the method belongs to is not recognized in this context)? Since q is in the global space, this is global within the function (i.e. the caller of sayName() is the global space or window)?


Can't edit my network profile without it syncing to my oldest account

On Stack Exchange, not this Meta, my profile keeps syncing with my oldest profile, which is my Sci Fi and Fantasy profile.   How can I fix this, or is it impossible to stop it from syncing? How can I stop the narrative I have on the Sci-Fi site from syncing to my Stack Exchange network profile?


Disabling graphical login in Debian wheezy

I have installed Debian wheezy on my machine with a netinst image, now I would like to deactivate the desktop and boot straight to the command line, not only that but I would like to not waste any resource on the X11/gnome/gdm at all if not needed.  I tried ( as root )  update-rc.d -f gdm remove update-rc.d -f gdm3 remove update-rc.d -f wdm remove   but Debian keeps booting into the login manager, I really don't need that, how I can deactivate this kind of boot and start X only when needed ?


I am having trouble with this question, please take a look at it:     Find a recurrence relation for the number of ways to arrange $n$ dominoes to fill a $2$ by $n$ checkerboard.   I have just started reading the topic and it is one of the starting problem. Please help. You can give me some hints, a complete answer is also appreciated.  Thanks


I tried proving inductively but I didn't really go anywhere. So I tried:  Let $3|n(n+1)(n+2)$. Then $3|n^3 + 3n^2 + 2n \Longrightarrow  3|(n(n(n+3)) + 2)$  But then?


How accuate is location data using gps?   My partner went to visit his young daughter at her mother's house, he says he stayed there for 30-40 mins. However, his gps location showed him going to the house, staying there for less than 10 minutes, and then leaving. By pressing the locate button on the device manager I could see the gps recorded location moving in real time. (With his permission to do this btw, his daughter's mother is still in love with him and has no respect for our relationship or our family.) This matters to me because she wanted him to take her somewhere, but he said he is just going to see his daughter and not running around after her taking her where she wants to go.  So how likely is it that he stayed at her house for 30-40 mins when gps location shows him going up the road, being at the house for around 5 mins and then going back down the road.  I know it can be a bit out because when we are home, it shows a small, dark circle and our house is not within that circle but across the street.  Edit: no its a different issue because he definately was at the location (her house).  The issue is that he says he stayed at the location for 30-40 mins before going on to his next destination and the gps data says otherwise. It says he was there for 4-5 mins and then went to his next destination, which is about 30 minutes away from her house and all the time the location was quite specific, only a couple of cars length and width. So if he really stayed at her house for 30-40 mins then the gps was tracking him going to his next destination when he was still at her house which seems unlikely.


Trying to install software, but I get an error every time ""config": /var/cache/debconf/config.dat is locked"

I tried a lot of solutions posted here, but none of them work. I am trying to install vlc. Here's the whole output.  :/$ sudo apt-get install vlc Reading package lists... Done Building dependency tree        Reading state information... Done vlc is already the newest version (2.2.2-5). 0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded. 1 not fully installed or removed. After this operation, 0 B of additional disk space will be used. Do you want to continue? [Y/n] Y debconf: DbDriver "config": /var/cache/debconf/config.dat is locked by another process: Resource temporarily unavailable Setting up libpam-systemd:amd64 (229-4ubuntu13) ... debconf: DbDriver "config": /var/cache/debconf/config.dat is locked by another process: Resource temporarily unavailable dpkg: error processing package libpam-systemd:amd64 (--configure):  subprocess installed post-installation script returned error exit status 1 Errors were encountered while processing:  libpam-systemd:amd64 E: Sub-process /usr/bin/dpkg returned an error code (1)


What motivates people to answer questions in Stack Overflow?

I want that too - motivation to answer programming-related questions. What is yours?


Lets say I do this: letter = input('Please enter a letter: ')  And I want to immediately stop the input after only one letter that the player typed. How do I do it? Thanks!!


I booted from a Ubuntu live cd to format but I used Disks to view the partitions and accidentally fast formatted the disk without saving the files to my pendrive.  Then I installed gpart to view the start and end areas so I can restore the partitions with parted.  sudo gpart /dev/sda returns:  * Warning: more than 4 primary partitions: 8. Partition(Linux ext2 filesystem): primary  Partition(Linux ext2 filesystem): primary  Partition(Linux ext2 filesystem): primary  Partition(Linux ext2 filesystem): primary  Partition(Linux ext2 filesystem): invalid primary  Partition(Linux swap or Solaris/x86): invalid primary  Partition(Linux ext2 filesystem): invalid primary  Partition(Linux ext2 filesystem): invalid primary  Ok.  Guessed primary partition table: Primary partition(1)    type: 131(0x83)(Linux ext2 filesystem)    size: 477mb #s(976896) s(6144-983039)    chs:  (0/97/34)-(61/48/51)d (0/97/34)-(61/48/51)r  Primary partition(2)    type: 131(0x83)(Linux ext2 filesystem)    size: 14648mb #s(29999104) s(983040-30982143)    chs:  (61/48/52)-(1023/254/63)d (61/48/52)-(1928/140/4)r  Primary partition(3)    type: 131(0x83)(Linux ext2 filesystem)    size: 14648mb #s(29999104) s(30982144-60981247)    chs:  (1023/254/63)-(1023/254/63)d (1928/140/5)-(3795/231/20)r  Primary partition(4)    type: 131(0x83)(Linux ext2 filesystem)    size: 19531mb #s(39999488) s(60981248-100980735)    chs:  (1023/254/63)-(1023/254/63)d (3795/231/21)-(6285/193/52)r   Then I used parted to rescue with partitions typing the start and end of this 4 partitions, the problem is the last 4 partitions that gpart doesn't show, that partitions have all the important data.  Does someone know how to get the start and end of the 4 last partitions or other way to recover them?


Continuous $f$ such that $f(x)=f(x^2)$ is constant?

Let $f:\mathbb{R}\to\mathbb{R}$ be a continuous function such that $f(x)=f(x^2)$ for all $x\in\mathbb{R}$. I've proven that also $f\left(y^{(2^{-n})}\right)=f(y)$ for all $n\in\mathbb{N}, y\geq0$. How can I deduce that $f$ is constant?


Under what conditions should I use an approximate Z-score vs a t-test?

I am struggling to understand the limiting assumptions of simple hypothesis testing using Z and T statistics under different scenarios.   In a case where X is normally distributed, and n > 30, and $\sigma^2$ is known, it is obvious a Z-test is appropriate. In the same scenario, if n < 30, a Z test is still appropriate, because we don't need to rely on CLT for a normal distribution of the sample mean and $\sigma^2$ is known.  However, in a case where X is normally distributed, n < 30, and $\sigma^2$ is not known, should I use a t-test or an approximate Z-test, substituting $\sigma$ for s, because the data are still normal? Or is the fact that n < 30 enough to warrant switching to a t-test, because s is not a good estimator of $\sigma$ for small samples normal or not?    Similarly, suppose X is not normally distributed, but n > 30, and $\sigma^2$ is not known. It seems we can still use an approximate Z-test because CLT implies that the distribution of the sample mean will be normal?   So is the only situation that I would resort to a t-test (for a single sample) one in which $\sigma^2$ is unknown, and n< 30?


How do I reference the only element in a singleton set?

You can turn any element $n$ into a singleton set by adding braces, $\{n\}$. Is there an inverse to this operation, such that if I know the set is a singleton set I can easily reference its element?  For example, say I have the set $A = \{5,6,7,8\}$, and then some process that iteratively eliminates all but one element of $A$, and then I want to see what 10 plus the resulting element is, how could I write that?  The only way I can think of is by referencing the first element by its index, e.g., $10 + A_1$. Is there another way to do it though? In my case the elements of $A$ are already indices, so I would have to index an index, like $10 + x_{A_1}$. Which is not the worst thing in the world, I was just wondering if there is a better way.


GIMP 2.10 Doesn't Have Permission To Access a USB Drive. Why? How to Resolve? (18.04)

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


I used to use InsomniaX but it doesn't work for me right now.  I want to stop my MacBook from sleeping when I close the lid.


How to clean up bootloaders & UEFI entries from other installs?

I got a new Windows laptop, and I wanted to dual boot with Linux. I installed Fedora, before changing my mind and going back to Mint. I'd like to keep Win 8.1 and Mint.  However, now my UEFI boot menu contains five entries:   The first two take me to Grub, which I guess is leftover from my Fedora install. The next two both take me to Linux Mint, and the last takes me to Win 8.1.  I'd like to remove both Fedora entries and one Linux Mint entry. The "Setup" interface makes it pretty simple to understand how, but:   I'd like to make sure deleting those entries isn't something stupid I don't know how to handle those remnants of Grub that are left from the Fedora install. Should I delete them? Ignore them?   If I do delete the Grub remnants, I'm not sure how to do so, or even which partition it's on. Here's a look at my  and my . Last but not least, here's what EasyBCD shows:  There are a total of 5 entries listed in the bootloader.  Default: Windows 8.1 Timeout: 30 seconds EasyBCD Boot Device: C:\  Entry #1 Name: Fedora BCD ID: {51954931-ff5c-11e4-8caa-f68841e7e615} Device: \Device\HarddiskVolume1 Bootloader Path: \EFI\FEDORA\SHIM.EFI  Entry #2 Name: ubuntu BCD ID: {51954933-ff5c-11e4-8caa-f68841e7e615} Device: \Device\HarddiskVolume1 Bootloader Path: \EFI\UBUNTU\SHIMX64.EFI  Entry #3 Name: UEFI OS BCD ID: {51954932-ff5c-11e4-8caa-f68841e7e615} Device: \Device\HarddiskVolume1 Bootloader Path: \EFI\BOOT\BOOTX64.EFI  Entry #4 Name: ubuntu BCD ID: {51954934-ff5c-11e4-8caa-f68841e7e615} Device: \Device\HarddiskVolume1 Bootloader Path: \EFI\UBUNTU\GRUBX64.EFI  Entry #5 Name: Windows 8.1 BCD ID: {current} Drive: C:\ Bootloader Path: \Windows\system32\winload.efi   How should I handle these extra boot options without bricking my laptop?


I have been told that modal 'would' can be used to express 'vagueness'. Its usage has been linked below but I'm not fully convinced yet with it because I don't know in what kind of context it would be approprite to use 'would' for 'vagueness'. Does 'would' carries any kind of meanings while using it in those contexts? Is it formal or natural to use?        modal verb   You use would, or sometimes would have with a past participle, when you are expressing your opinion about something or seeing if people agree with you, especially when you are uncertain about what you are saying.          [vagueness]   ⇒ I think you'd agree he's a very respected columnist.   ⇒ I would have thought it a proper job for the Army to fight rebellion.   ⇒ 'Was it much different for you when you started at the Foreign Office?'—'Worse, I'd expect.'.   ⇒ I would imagine she's quite lonely living on her own.


How to enhance VB6 programming experience?

I have an application in VB6 which I am supporting. The only environment that I know of to edit the VB6 project is "Microsoft Visual Basic 6.0" its kind of hard to navigate around compare to the modern editors.   In my projects there are VisualBAsic Module File and a ORIG FILE eg:  mymodule mymodule.bas.orig  "I will never have to modify the UI just the script"  My first question is is there are alternate Application to modify VB6 project(Without Migrating)?  If not I can see that the module file can be edited using Notepad++. So my second question is can I use Notepad++, sublime, intelij etc. To modify the module then save without any complication(character compatible issues?, file linking issues etc) ? Are there any known issues by doin this? Would you recommend Editing scripts external using a text editor?


I am a new student in the US. I noticed that a lot of bikes were left with only a tire locked on a post. Therefore, I usually locked my bike on the water pipe outside my apartment. I put a U-lock between the water pipe and my bike frame. However, after I left my apartment for a week, it was gone!  Now I have got a new bike, which is an impressive red Giant. I was really worried that it will be stolen again. Can anyone help me by telling me what else I can do to keep my bike safe in that terrible area. Thanks a lot.


I have a Gmail email address but have forgotten it? How can I find out what it was?


Grammar Term for mistakenly using one verb for two expressions in one sentence

Sorry, I am having a hard time explaining this, so bear with me.   I am looking for a term describing incorrect grammar as in the following example:     He drove the car and himself into a rage.    For the life of me, I just can't remember what it's called.


Why is it not true that if $\Phi \vdash \exists x \phi$ then there is a term $t$ with $\Phi \vdash \phi \frac{t}{x}$?

On  in XI Free Models and Logic Programming of Ebbinghaus' Mathematical Logic:  In general, the following statement is false: (*)  If $\Phi \vdash \exists x \phi$  then there is a term $t$  with $\Phi \vdash \phi \frac{t}{x}$ We  get  a  counterexample for  $S  = \{R\}$  with unary $R$,  $\Phi = \{\exists x Rx\}$,  and  $\phi  =  Rx$.  In the counterexample, why if $\{\exists x Rx\} \vdash \exists x R x $, then there is no term $t$   with $\{\exists x Rx\} \vdash R t $? On  or  the $(\exists S)$ sequent rule says $$  \frac{\Gamma \quad \phi \frac{t}{x}}{\Gamma \quad \exists x \phi}$$ Is this $(\exists S)$ rule the converse of (*) in the quote at the beginning? Thanks. I mistook $\vdash$ as $\models$ in


How to I enter hours and minutes on my Samsung range?

Why does the Cooking Time not allow me to enter hours?  All  I get is Minutes. What is that flashing arrow above where the digits are for the time? No matter when I enter amm I can get is seconds or minutes for the maximum if the three digits I can enter.  Thanks for any help


how to NOT cut off the last char with substr?

Got following String:  I want to get everything behind param2=. First thought was substr, but it never gives me all behind param2=. No matter how I use it, it always returns  (last char missing). I red the  for this, but still no success with this.  I already tried:  $url = 'http://example.de/?param=1&param2=http://example2.com/';  $piece = substr($url, strpos($url, 'param2=') + 7 ,count($url)); //+7 cause of param2= should not be included => h  $piece = substr($url, strpos($url, 'param2=') + 7 , -count($url)); => http://example2.com  $piece = substr($url, strpos($url, 'param2=') + 7 , +count($url)); => h  $piece = substr($url, strpos($url, 'param2=') + 7 , -(count($url)+1)); => http://example2.co  $piece = substr($url, strpos($url, 'param2=') + 7 , -(count($url)-1)); =>        (empty)  $piece = substr($url, strpos($url, 'param2=') + 7 , -1); => http://example2.com  $piece = substr($url, strpos($url, 'param2=') + 7 , -0); =>        (empty)   So I never get the last char, maybe you know what I am doing wrong.


Does the universe update time in some finite interval?

I was listening to a lecture by leonard susskind and one of the analogies he used was a coin having two states and he "broke" time into intervals. He continued to say that at each interval of time, if the coin has a state of heads or tails, it remains heads or tails. Is this truly how the universe works? Or could it be that time is just an idea we use to describe the changing of configuration of a system ie our universe? This probably doesn't have an answer but is there any way to test this? I know in computer programs we use a refresh rate not sure if that is measurable if you were within the program.


Resulted in "him" or "his" losing the job?

In the following sentence,     Shortly thereafter he had a car accident which resulted in him losing the job.   My supervisor wanted to change him to his saying something about gerunds. I disagreed and proved it to her by showing her a GrammarCheck I had done on the sentence. She didn't like it but she let it go.   Isn't using him correct in that sentence?


Download all my content in a compact form

The imaginary feature being proposed sounds like a lot of work to implement but I think it still can be useful as an inspiration.  Assume a user of an SE site has made some thoughtful contributions and feels like they really spent some effort on their posts. Assume the user in question does not believe in the immortality of SE and wants to have a local copy of all their contributions (questions/answers, possibly also comments). They could copy all of them by hand, or automate it somehow if they know programming but that is at least a little bit annoying. Can we make add a feature to download a .zip archive of all your content if you want to? Just like on GitHub where you can download your repo.  This leaves open the question of how exactly to represent a post in text form (tags, revision history, post time etc.) but that is technical details.  EDIT: I see that my question was closed as a duplicate. I do not think that it is a duplicate though I recognize that I may be mistaken. My reasons (a) the feature I request should not download all content, only my content (maybe I don't want to pay for extra gigabytes of traffic) (b) I also would like it to be really simple, just one click and you download it (I don't want to spend half an hour extracting what I need from the data dump through some SQL gymnastics, I would like it to be just one button).


Let $\alpha \in \overline{\Bbb Q}$ a root of $X^3+X+1\in\Bbb Q[X]$.   Calculate the minimum  polynomial of $\alpha^{-1}$ en $\alpha -1$.   I don't really understand how to get started here. I know that  $$\overline{\Bbb Q}=\{x\in \Bbb C : \text{ where $x$ is algegbraic over $\Bbb Q$} \}$$  A hint to get me started or a complete solution would be both very muchappreciated :)


var e = 10;  function sum(a) {     return function(b) {         return function(c) {             return function(d) {                 return a + b + c + d + e;             }         }     } }  console.log(sum(1)(2)(3)(4)); //logs 20    I'm not quite sure how to read this. It was one of the examples in some MDN documentation. Do you think it would be possible to give a step-by-step narration of what's going on? Here's what I think is happening: I thought sum(1) would return function(b) (which returns function(c) which returns function(d) which returns 1 + undefined + undefined + undefined + 10) but this is obviously wrong.


I have this counter which I have defined using \newcounter{myCounter}.  Printing the value of myCounter can be easily done via \arabic{myCounter}. How can I print the value of (myCounter - 2)?


I am travelling to India from the US: do I need a valid visa?

I am currently living in the US on a 24-month STEM OPT. I am travelling to India for visa renewal.   My itinerary is Dallas/Fort Worth-Washington/Dulles-Newark-Bombay. Do I need a valid US visa or a transit visa for this itinerary?


Which lens is recommendable for landscape astro photos with Sony A7Riii?

The new Sony A7R III has a 42 megapixel sensor and both a really good resolution and overall photo quality. But it is also challenging the lenses.   So far, there is only one ultra-wide angle lens for Sony, FE 16-35mm F2.8 GM, which has an aperture of f/2.8. Is it the choice to go for landscape astro photography? How would the FE 12-24mm F4 G or Vario-Tessar T* FE 16-35mm F4 ZA OSS perform in comparison?  Intended use is shots of landscapes at night, for example the milky way over a mountain, with a lot of landscape and a lot of sky in the image.


Is there a way to clone relative coordinates of a player and the command block?

Is there a way to clone with the relative coordinates of a player and the command block? I am trying to make a "one-command-creation" with those two things. I am in 1.12. Like  /clone {Relative coords of command block} {Relative coords of player}


I'm trying the free version of an app, and I'm considering to upgrade to the Premium version. The said app is .  From what I see, the Premium version in not directly available on Play Store, and it can be purchased only in-app.  How do these purchases work? If I  uninstall the app then reinstall it later, or if in the future I change my phone, this purchase will still be recognised?  Will I be able to use the full version again without having to pay once more for it?   It appears that the purchase is managed by Google Play:


Prove that $K$ is isomorphic to a subfield of the ring of $n\times n$ matrices over $F$.

$K/F$ is a field extension of finite degree $n$. How can I prove that $K$ is isomorphic to a subfield of the ring of $n\times n$ matrices over $F$, so the ring of $n\times n$ matrix over $F$ contains an isomorphic copy of every extension of $F$ of degree $\leq n$?


How to see the error messages when I get the white screen of death?

How can I see the error messages when the site I am working on gets a white screen?


Integrate $\int_0^{\pi/2}\frac{\tan x}{1+m^2\tan^2 x}dx$   $\newcommand{\intd}[1]{\,\mathrm{d}#1}$ My Attempt  Put $t=\tan x\implies\intd t=\sec^2x\intd x$ \begin{align*} \int_0^{\pi/2}\frac{\tan x}{1+m^2\tan^2 x}dx&=\int_0^{\pi/2}\frac{\tan x\cdot\sec^2x}{(1+m^2\tan^2 x)\sec^2x}\intd x\\ &=\int_0^{\infty}\frac{t}{(1+m^2t^2)(1+t^2)}\intd t \end{align*} Put $t^2=y\implies 2t\intd t=\intd y$ \begin{align*} \frac{1}{2}\int_0^\infty\frac{dy}{(1+m^2y)(1+y)}&=\frac{1}{2}\int_0^\infty\bigg[\frac{1}{1-m^2}\cdot\frac{1}{1+y}+\frac{m^2}{m^2-1}\cdot\frac{1}{1+m^2y}\bigg]dy\\ &=\frac{1}{2(1-m^2)}\int_0^\infty\frac{dy}{1+y}-\frac{m^2}{2(1-m^2)}\int_0^\infty\frac{dy}{1+m^2y}\\ &=\bigg[\frac{1}{2(1-m^2)}\log|1+y|-\frac{1}{2(1-m^2)}\log|1+m^2y|\bigg]_0^\infty\\ &=\bigg[\frac{1}{2(1-m^2)}\log|\frac{1+y}{1+m^2y}|\bigg]_0^\infty=\color{red}{\frac{1}{2(1-m^2)}\bigg[\frac{\infty}{\infty}-0\bigg]}\end{align*} I think I am getting stuck here as the substitutions does not seem to give the solution ?  Doubt $$ \lim_{y\to 0}\log|\frac{1+y}{1+m^2y}|=\log 1=0\\ \lim_{y\to \infty}\log|\frac{1+y}{1+m^2y}|=\lim_{y\to \infty}\log|\frac{\frac{1}{y}+1}{\frac{1}{y}+m^2}|=\log\frac{1}{m^2} $$ So what really we are doing with definite integrals ?. Does this mean that we are actually computing the upper and lower limits and taking the difference to find the definite integral ?  Note: Expanding in terms of $\sin x$ and $\cos x$ gives the solution, no doubt about limit going to infinity, not looking for that.


Is the Doctor younger every incarnation?

It seems to me that the Doctor looks younger at every incarnation.  Am I the only one having this sensation?


How can I open a new browser window in "F11" mode (without toolbars etc)?

I am coding a page (for internal use at my company) to try and trigger "one click" browser based video conferencing. We use a web based video conferencing solution (www.bluejeans.com). Currently to start a video session, the user navigates to a url (www.bluejeans.com/, and logs in. We use this with a camera and projector, so the user then needs to drag the browser window onto the projector screen, maximise the window, and hit F11 to remove the browser gubbins.  I want to streamline the process to the user clicks a link, and the new browser window is opened at the correct link, maximised, moved to the correct screen and "F11'd" (browser bars etc removed).  The application is a c# web application, but I assume I'll need to use javascript for this client side window manipulation. I can get a window to open maximised, but can not make it remove the border / address bar.  Having read round it looks like it's for security reasons, which makes sense. However, given that I'm in a "closed" environment, I wonder if there's any other approach I could use? For example a Windows Forms app to trigger a new window?  Edit:  This is different to other questions I have seen that resize the content within the browser to make specific elements full screen. In this case I want to interact with the browser itself, hiding the toolbars and simulating an F11 keypress.


Using external data source with Leaflet / GeoJSON?

First of all, I've been looking everywhere and I have not found a functional solution.  I need to display the points from a data file exported from Qgis.  I tried Qgis2web, but I'd like to put everything up in the Leaflet from the beginning and then just update the data from Qgis.  Explorer does not report any errors, but it does not show points with markers.  Here is index:   <!doctype html>             <meta charset="utf-8">         <meta http-equiv="X-UA-Compatible" content="IE=edge">         <meta name="viewport" content="initial-scale=1,user-scalable=no,maximum-scale=1,width=device-width">         <meta name="mobile-web-app-capable" content="yes">         <meta name="apple-mobile-web-app-capable" content="yes">         <title>PinLeX</title>                           <link rel="stylesheet" href="css/leaflet.css" />

       And here map set (leafletmap.js):  var map;    function initmap() {     // set up the map     map = new L.Map('map');      // create the tile layer with correct attribution     var osmUrl='http://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png';     var osmAttrib='Map data © OpenStreetMap contributors';     var osm = new L.TileLayer(osmUrl, {   minZoom: 8,    maxZoom: 18,    attribution: osmAttrib   })          // start the map in defined location     map.setView(new L.LatLng(48.974244, 14.478729),9);     map.addLayer(osm);    // PinLayer   var pinpoint = L.icon({   iconUrl: 'markers/pinpoint.svg',   iconSize: [26.599999999999998, 26.599999999999998],   iconAnchor: [16, 37],   popupAnchor: [0, -28]   });    L.geoJson(PinLayer, {   pointToLayer: function (feature, latlng) {             return L.marker(latlng, {icon: pinpoint});     },   }).addTo(map); }   And here GeoJson (transformed to js - PinLayer.js)  var PinLayer = { "type": "FeatureCollection", "name": "PinLayer", "crs": { "type": "name", "properties": { "name": "urn:ogc:def:crs:EPSG::3857" } }, "features": [ { "type": "Feature", "properties": { "id": null, "name": "Senovážné náměstí", "country": "Česká republika", "desc": "Popis není k dispozici.", "status": "v provozu", "photocell": "ne", "admin": "Statutární město České Budějovice (?)", "update": "7\/4\/2018", "spec": "České Budějovice", "type": "standartní pítko", "photo": null }, "geometry": { "type": "Point", "coordinates": [ 1611753.67562, 6270485.80685 ] } }, { "type": "Feature", "properties": { "id": null, "name": "Katedrála sv. Mikuláše", "country": "Česká republika", "desc": "Popis není k dispozici.", "status": "v provozu", "photocell": "ne", "admin": "Statutární město České Budějovice (?)", "update": "12\/4\/2018", "spec": "České Budějovice", "type": "standartní pítko", "photo": null }, "geometry": { "type": "Point", "coordinates": [ 1611428.44996, 6270639.98718 ] } } ] }


$SO(3)$, $SU(2)$ and symmetries in quantum mechanics

A rotation in the vector space $\mathbb{R}^3$ is represented by the known 3x3-matrices.   But at this point I'm really confused how to get from there to Quantum Mechanics. The group of $\mathrm{SO}(3)$ contains all this matrices, but the representation of the rotation operator is a $(2j+1)\times(2j+1)$ matrix. Could someone say a few words to this?  And I'm also confused what's the difference between $\mathrm{SO}(3)$ and $\mathrm{SU}(2)$. (in groups the difference is clear, but they both apply rotations to our kets?)


Error 101: Network is unreachable when trying to update

My ubuntu browsing this normally can not access any site, more apt-get update and even upgrade this giving error as shown below, what could it be?  sudo apt-get update Get:1 http://security.ubuntu.com/ubuntu xenial-security InRelease [94,5 kB] Hit:2 http://ppa.launchpad.net/webupd8team/sublime-text-3/ubuntu xenial InRelease Err:3 http://br.archive.ubuntu.com/ubuntu xenial InRelease                        Cannot initiate the connection to br.archive.ubuntu.com:80 (2801:82:80ff:8000::5). - connect (101: Network is unreachable) [IP: 2801:82:80ff:8000::5 80] Err:4 http://br.archive.ubuntu.com/ubuntu xenial-updates InRelease   Cannot initiate the connection to br.archive.ubuntu.com:80 (2801:82:80ff:8000::5). - connect (101: Network is unreachable) [IP: 2801:82:80ff:8000::5 80] Err:5 http://br.archive.ubuntu.com/ubuntu xenial-backports InRelease   Cannot initiate the connection to br.archive.ubuntu.com:80 (2801:82:80ff:8000::5). - connect (101: Network is unreachable) [IP: 2801:82:80ff:8000::5 80] Downloading 94,5 kB in 2min 0s (786 B/s) Reading package lists ... Done W: Failed to fetch http://br.archive.ubuntu.com/ubuntu/dists/xenial/InRelease  Cannot initiate the connection to br.archive.ubuntu.com:80 (2801:82:80ff:8000::5). - connect (101: Network is unreachable) [IP: 2801:82:80ff:8000::5 80] W: Failed to fetch http://br.archive.ubuntu.com/ubuntu/dists/xenial-updates/InRelease  Cannot initiate the connection to br.archive.ubuntu.com:80 (2801:82:80ff:8000::5). - connect (101: Network is unreachable) [IP: 2801:82:80ff:8000::5 80] W: Failed to fetch http://br.archive.ubuntu.com/ubuntu/dists/xenial-backports/InRelease  Cannot initiate the connection to br.archive.ubuntu.com:80 (2801:82:80ff:8000::5). - connect (101: Network is unreachable) [IP: 2801:82:80ff:8000::5 80] W: Some index files failed to download. They have been ignored, or old ones used instead.   Ubuntu:  DISTRIB_ID=Ubuntu DISTRIB_RELEASE=16.04 DISTRIB_CODENAME=xenial DISTRIB_DESCRIPTION="Ubuntu 16.04.1 LTS"


$a$ and $b$ are natural numbers, their product $a\times b$ is full/complete sqare, prove that then $a$ and $b$ are full squares. $\gcd (a,b)=1$ .  Natural number is full square if you can write it in form $n^2$.  I tried dividing with $3$, because full square when divided with three has remainder $0$ or $1$, but that doesn't help. Then i also tried to use the fact that when you divide $x\times y$ with $z$, and $(x,z)=1$ then $z$ divides $y$, but I don't know how to use it in this case.  Can anyone help me and give me instructions what to do? Thanks a lot!


CardPanel: getting Null Pointer Exception - IntelliJ

I want to create my first guy in Java and I am using the GridLayout by IntelliJ. I also have to use the CardLayout to change the panels and have different screens. I have set up everything like it is in  provided by IntellJ.  However, I get a java.lang.NullPointerException. The error message is following:   Exception in thread "main" java.lang.NullPointerException     at com.intellij.uiDesigner.core.GridLayoutManager.addLayoutComponent(GridLayoutManager.java:134)     at java.awt.Container.addImpl(Container.java:1130)     at java.awt.Container.add(Container.java:419)     at UserInferface.<init>(UserInferface.java:29)   I have six other screens set up which return the root panel, so I am not gonna copy and paste the code here. They just have a panel and a get method to return the panel. Like in the demo.  Here is my main window code called UserInterface. Can you guys tell me, where my error is and why I get a java.lang.NullPointerException?  import screens.*; import javax.swing.*; import java.awt.*; import java.awt.event.ActionEvent; import java.awt.event.ActionListener;  public class UserInferface extends JDialog {     private JPanel rootPane;     private JPanel navigationPane;     private JButton sellInterfaceButton;     private JButton restockInterfaceButton;     private JButton changeCapacityInterfaceButton;     private JButton changeStockInterfaceButton;     private JButton orderListInterfaceButton;     private JButton showStockInterfaceButton;     private JPanel cardPanel;      final static String CHANGE_CAPACITY_INTERFACE = "Change capacity";     final static String CHANGE_STOCK_INTERFACE = "Change stock";     final static String ORDER_LIST_INTERFACE = "Order list";     final static String RESTOCK_INTERFACE = "Restock";     final static String SELL_INTERFACE = "Sell";     final static String SHOW_STOCK_INTERFACE = "Show stock";      public UserInferface(){         setContentPane(rootPane);         setModal(true);          cardPanel.add(new ChangeCapacityInterface().getRootPanel());         cardPanel.add(new ChangeStockInterface().getRootPanel());         cardPanel.add(new OrderListInterface().getRootPanel());         cardPanel.add(new RestockInterface().getRootPanel());         cardPanel.add(new SellInterface().getRootPanel());         cardPanel.add(new ShowStockInterface().getRootPanel());          final CardLayout cl =  (CardLayout) cardPanel.getLayout();         cl.show(cardPanel, SELL_INTERFACE);          sellInterfaceButton.addActionListener(new ActionListener() {             public void actionPerformed(ActionEvent e) {                 cl.show(cardPanel, SELL_INTERFACE);             }         });          restockInterfaceButton.addActionListener(new ActionListener() {             public void actionPerformed(ActionEvent e) {                 cl.show(cardPanel, RESTOCK_INTERFACE);             }         });          changeCapacityInterfaceButton.addActionListener(new ActionListener() {             public void actionPerformed(ActionEvent e) {                 cl.show(cardPanel, CHANGE_CAPACITY_INTERFACE);             }         });          changeStockInterfaceButton.addActionListener(new ActionListener() {             public void actionPerformed(ActionEvent e) {                 cl.show(cardPanel, CHANGE_STOCK_INTERFACE);             }         });          orderListInterfaceButton.addActionListener(new ActionListener() {             public void actionPerformed(ActionEvent e) {                 cl.show(cardPanel, ORDER_LIST_INTERFACE);             }         });          showStockInterfaceButton.addActionListener(new ActionListener() {             public void actionPerformed(ActionEvent e) {                 cl.show(cardPanel, SHOW_STOCK_INTERFACE);             }         });     }      public static void main(String[] args) {         UserInferface userInferface = new UserInferface();         userInferface.pack();         userInferface.setVisible(true);         System.exit(0);     } }   Kind regards and Thank You!


Is there a way to access an iteration-counter in Java's for-each loop?

Is there a way in Java's for-each loop  for(String s : stringArray) {   doSomethingWith(s); }   to find out how often the loop has already been processed?  Aside from using the old and well-known for(int i=0; i < boundary; i++) - loop, is the construct  int i = 0; for(String s : stringArray) {   doSomethingWith(s);   i++; }   the only way to have such a counter available in a for-each loop?


How does Mage Armor interact with Unarmored Defense?

If a character with the Unarmoured Defence class feature casts Mage Armour, what is their AC?  Do they choose which 'base' AC they take, or do they stack somehow?  Is there rules text that explains this conflict?


Question Show that for  every $n \in \Bbb  N$ there are at least $\log_2 \log_2 (n+1)$ prime numbers between 1 and $n$.   Proof We only studied the prime number limit, and I can't see how to use it here. Also tried induction but I get stuck in the inductive step because I don't know how use the induction hypothesis in this case.  Would like some assistance (first week number theory difficulties...)


I was trying to find a proof of $a\times0 = 0$ by myself (assuming commutativity, associativity, distributivity, etc) and I came up with $$ a+0=a(1) \implies 1 = \frac{a+0}{a} = \frac aa + \frac 0a = 1 + \frac 0a \implies \frac 0a = 0 \implies a(0)=0$$ Is there anything wrong with this proof, or does it assume anything that shouldn't be assumed?


What are the rules about take a bike on the London Tube?

Can I take a bike on the Tube (underground) in London, if so how much does it cost?


I'm tired of ubuntu now and and switching back to windows. Im gonna use the OS-Uninstaller but the problem is I can't boot from my ubuntu cd. When I installed ubuntu im quite sure I pressed F11 to choose boot from cd. Now I tried all F buttons and it just boots normal or gets to a black screen with a bunch of white text and then boots normal.  Here is my motherboard:  Handle 0x0002, DMI type 2, 15 bytes Base Board Information Manufacturer: MSI Product Name: 870A-G46 (MS-7599) Version: 4.0 Serial Number: To be filled by O.E.M. Asset Tag: To Be Filled By O.E.M. Features:     Board is a hosting board     Board is replaceable Location In Chassis: To Be Filled By O.E.M. Chassis Handle: 0x0003 Type: Motherboard Contained Object Handles: 0   Any ideas on how I can boot from cd?


I have created a blog in blogspot. What I need to do is to write equation in the blog so adding  would be great to add in the blogspot.


Isn't mass a fixed and an intrinsic property of a particle? How can we talk about eigenstates of the mass in the context of neutrinos?


How can I count the swaps in a Merge Sort Algorithm in Python

I've done the MergeSort algorithm, but I don't know how to count the swaps.  My code is:  def mergesortInv(list):     if len(list) < 2:         return list     else:         middle = len(list) // 2         left = mergesortInv(list[:middle])   #definim les dues meitats         right = mergesortInv(list[middle:])         swaps=???            return mergeInv(left, right,swaps)  def mergeInv(left, right,swaps):     if len(left) < 1:         return right     if len(right) < 1:         return left     if left[0] <= right[0]:         return [left[0]] + mergeInv(left[1:],right,swaps)     else:         return [right[0]] + mergeInv(left,right[1:],swaps)   The output of this algorithm would be the sorted list(the algorithm works in this part) and the  number of swaps: mergesortInv(list) == ([1, 2, 3, 4, 5, 7, 8], 6) 6 is the number of swaps.


Beamer: including items only some slides using a relative syntax

I am looking for the syntax for making an item appear on say the next three slides. I'm imagining something like  \item<+-??>   The \item should appear here and disappears 3 slides later, in the same way it would if I used \only (i.e. the item shouldn't leave any space once it vanishes).  I'm illustrating this using \item, but I'm looking for a general syntax.


Solution for inverse square potential in $d=3$ spatial dimensions in quantum mechanics

Can a particle in an inverse square potential $$V(r)=-1/r^{2}$$ in $d=3$ spatial dimensions be solved exactly?  Also please explain me the physical significance of this potential in comparison with Coulomb potential? That problem was talking about positive repulsive potential and what I am looking for is an attractive potential.


I want to know if (hypothetically) a star appears out of nowhere at a certain distance (say 20 light seconds) away from me, how long will it take for me to get the feel of it's gravity? Will I know it before it's light will reach me (20 seconds)? or after?


Merging bib and tex files for submission to a journal

I am submitting an tex article to a journal, and they want they do not accept bib files. They also want only one source file:  1)A LaTeX submission should be a single .tex file; multiple-(.tex)-file submissions are not supported. 2)Uploading .bib files as Additional LaTeX file types is supported.  So this means I have to merge the bib and tex file into one, but I have no idea how to do this.  I looked at similar posts and people say use bbl. file and copy that into \bibliography... But I don't understand what this actually means.  Thanks!


She is reading a lot these days.   She has been reading a lot these days.      Which one is correct? Is there any real difference between them?


How to extract the audio from an mp4 video to a mp3 file?

I'd like to extract the audio from an mp4 video. Is there a software for Ubuntu, which does the job?


prove that $x^2 + y^2 = z^4$ has infinitely many solutions with $(x,y,z)=1$

Prove that $x^2 + y^2 = z^4$ has infinitely many solutions with $(x,y,z)=1$.   Do I use the terms $x= r^2 - s^2$, $y = 2rs$, and $z = r^2 + s^2$ to prove this problem?  Thanks for any help.


Select ONE most recent post for each author

I'm sure its a simple question and I suppose it was asked many times, but I just can't figure it out from other answers, sorry.  I use recent versions of PostgreSQL and MySQL. I have 2 tables:  CREATE TABLE authors (     id INT,     name VARCHAR )  CREATE TABLE posts (     id INT,     author_id INT,     text VARCHAR,     date DATE )   I need to select one most recent post for each author. Thanks!  UPDATE  Thanks, both links provide answers to my question with some exception. All the following queries give the same result (which one is the most efficient btw?) The issue is when there is more than one post from the same author with the same date. Then the returned result set contains all such posts. How should I modify these queries to return exactly one post per author?  SELECT p1.* FROM posts p1 LEFT JOIN posts p2 ON p1.author_id = p2.author_id AND p1.date < p2.date WHERE p2.author_id IS NULL ORDER BY p1.author_id;  SELECT p1.*  FROM posts p1 INNER JOIN (   SELECT author_id, MAX(date) AS max_date   FROM posts   GROUP BY author_id) p2   ON p1.author_id = p2.author_id AND p1.date = p2.max_date ORDER BY p1.author_id;  SELECT * FROM posts p1 WHERE date = (SELECT MAX(p2.date)               FROM posts p2               WHERE p1.author_id = p2.author_id) ORDER BY author_id;  SELECT * FROM (     SELECT author_id, MAX(date) date     FROM posts GROUP BY author_id ) p1 INNER JOIN posts p2 USING (author_id, date) ORDER BY author_id;


What is the difference between Private properties with set/get and private properties without set get in C#

I am new to C#. We declare Private member variable in a class to make them inaccessible from outside the class in which they are declared, but we can do this simply declaring them 'private' so what's the need of using set and get with them? for e.g i have a class customer   class Customer      {         private double TotalPurchases; // { get; set; }         private string Name; // { get; set; }         private int CustomerID; // { get; set; }         public Customer(double tp, string nam, int id)          {             TotalPurchases = tp;             Name = nam;             CustomerID = id;         }          public void value()          {             Console.WriteLine("Total purchases so far " + TotalPurchases + " " + Name + " " + CustomerID);         }     }      class Program      {         static void Main()          {             // Intialize a new object.             Customer cust1 = new Customer(20.0, "C#", 10);             cust1.value();             Console.ReadLine();         }     }   when i remove comment in customer class and allow properties to use set and get, it makes no difference at all!!!


Can an Arcane Trickster copy a Wizard spell from a scroll into their "spellbook"?

Page 200 of the DMG says that a wizard scroll can be copied into a spellbook     A wizard spell on a spell scroll can be copied just as spells in spellbooks can be copied. When a spell is copied from a spell scroll, the copier must succeed on an Intelligence (Arcana) check with a DC equal to 10 + the spell's level. If the check succeeds, the spell is successfully copied. Whether the check succeeds or fails, the spell scroll is destroyed (DMG)    Does an Arcane Trickster have a spellbook to copy a scroll into? If they do have a spellbook, is the entire Wizard list open to them, or only enchantment and illusion spells? i.e. could they copy Absorb Elements (a 1st level Wizard Abjuration spell)     You know three 1st-level wizard spells of your choice, two of which you must choose from the enchantment and illusion spells on the wizard spell list. (PHB)  If they don't have a spellbook, is there an acceptable mechanic for learning or memorizing the spell on the scroll that is similar to how a wizard would be able to learn it? (And is the entire Wizard list open to them)     Intelligence is your spellcasting ability for your wizard spells, since you learn your spells through dedicated study and memorization. (PHB)


I saw the      Let $\mathbf{A}$ be a $n\times n$-matrix, and $p(\lambda)=\det(\lambda \mathbf{I}_n-\mathbf{A})$ the characteristic polynomial of $\mathbf{A}$. Then $p(\mathbf{A})=\mathbf{0}$   and I thought it was trivial since $\det(\mathbf{A}-\mathbf{A})=0$. I checked with  and learned that this didn't work because $\lambda$ is a scalar, and $\det(\mathbf{0})$ is also a scalar, and not a matrix. This brings me to my question:  Are there any other results that seem trivial, but aren't?


How to write the path of a folder with space in its name?

I can't figure out how to write the path of a folder that includes spaces in its name (in Terminal).  I tried:  cd /path/path/path/"A Folder"/file  cd /path/path/path/'A Folder/file  cd /path/path/path/A_Folder/file   but they all return the error through the terminal:  [command]: cannot access '/path/path/path/A Folder/file' No such a file or directory    I can still access it through steps like so:  cd /home cd user cd Desktop cd "Bash Programming" bash Example


"Neither Michael nor Albert is correct" or "Neither Michael nor Albert are correct"?

What is the correct sentence?  Neither Michael nor Albert is correct.   Neither Michael nor Albert are correct.


Avengers: Endgame timeline and causality

In Avengers: Endgame,       if Thanos from 2014 was dusted in 2023 by Iron Man's snap, then how did the Thanos other 'snap' in 2018?   Does this imply that      there is a branch reality where they never bring back everyone with Professor Hulk's snap.


Launcher, top bar missing & cannot close, maximize, or move windows

I opened my laptop after a month of inactivity (Dell, running 14.04). It was in the suspended state during this time, and upon reopening it, the laptop functioned perfectly. After this initial use, I shut down the laptop. When I booted it the next time, the launcher bar had disappeared along with the top bar, leaving me a blank desktop (only the default ubuntu background remained).  I was able to create a new folder and navigate myself through to the Chromium application. I have made multiple attempts to try and fix this problem with the responses already existing on askubuntu. But my problem remains. I've tried to mess around with ccsm, and tweaking unity, but to no avail.  I have little experience with ubuntu, but I will follow whatever instructions you provide. Please help!  UPDATE I know this question has been marked as a duplicate, but I've honestly tried the solutions on that page. Since the original post, Ive moved to a different wifi zone, and as such am unable to connect to wifi from the computer. I'm posting this update from my phone. I request that those who marked it as a duplicate undo that action because it may prevent my question from being answered.


I'm testing independence in an $N \times M$ contingency table. I don't know whether the  or Pearson's chi-squared test is better. The sample size is in the hundreds but there are some low cell counts.  As stated on the , the approximation to the chi-squared distribution is better for the G-test than for Pearson's chi-squared test. But I'm using Monte Carlo simulation to compute the p-value, so is there any difference between these two tests?


$x^x = 100$.   I have no clue on how to solve this. If you guys have, please show me your solution as well.


Vertical placing of wide accents in superscript

The following code  $\widetilde{aaa} \quad L^{\widetilde{aaa}}$  $\tilde{aaa} \quad L^{\tilde{aaa}}$  $\widehat{aaa} \quad L^{\widehat{aaa}}$  $\hat{aaa} \quad L^{\hat{aaa}}$  $\overline{aaa} \quad L^{\overline{aaa}}$  $\bar{aaa} \quad L^{\bar{aaa}}$   produces the following output:    What is the reason for additional vertical spacing for \widetidle and \widehat in superscript and what can one do about it?


How to insert newline characters every N chars into a long string

Using common bash tools as part of a shell script, I want to repeatedly insert a newline char ('\n') into a long string at intervals of every N chars.  For example, given this string, how would I insert a newline char every 20 chars?  head -n 50 /dev/urandom | tr -dc A-Za-z0-9   Example of the results I am trying to achieve:  ZL1WEV72TTO0S83LP2I2 MTQ8DEIU3GSSYJOI9CFE 6GEPWUPCBBHLWNA4M28D P2DHDI1L2JQIZJL0ACFV UDYEK7HN7HQY4E2U6VFC RH68ZZJGMSSC5YLHO0KZ 94LMELDIN1BAXQKTNSMH 0DXLM7B5966UEFGZENLZ 4917Y741L2WRTG5ACFGQ GRVDVT3CYOLYKNT2ZYUJ EAVN1EY4O161VTW1P3OY Q17T24S7S9BDG1RMKGBX WOZSI4D35U81P68NF5SB HH7AOYHV2TWQP27A40QC QW5N4JDK5001EAQXF41N FKH3Q5GOQZ54HZG2FFZS Q89KGMQZ46YBW3GVROYH AIBOU8NFM39RYP1XBLQM YLG8SSIW6J6XG6UJEKXO   A use-case is to quickly make a set of random passwords or ID's of a fixed length. The way I did the above example is:  for i in {1..30}; do head /dev/random | tr -dc A-Z0-9 | head -c 20 ; echo ''; done   However, for learning purposes, I want to do it a different way. I want to start with an arbitrarily long string and insert newlines, thus breaking one string into multiple small strings of fixed char length.


Stars create heavy elements up to iron during their lifetimes, and heavier elements beyond iron during supernova events.   Are there any processes which create new hydrogen? If not, will all (or most) of the hydrogen in the universe eventually be turned into heavier forms by stars?


When I render, only some emissions and some gloss render, while others doesn't

I've worked in blender for a bit over 2 years now, and I've never encountered something like this before. I was modeling a stage (for performances, etc) and when I tried to render, some of the emissions wouldn't render at ALL. Some would, which is very weird. I'd be really grateful if anyone knew what I could do, because I'm completely lost... :/  .blend :


Auto generated close as dupe comment appears only after a full reload

I just cast a close as dupe vote on a question here on Meta. In the past it used to push the auto generated comment live but now I can't see my comment after voting, only after I reload the page.  Can we get the old behavior back please? :)  Feel free to vote to close as dupe of some random question just to test, lol!  Also worth checking if same happens with flagging.  Edit, January 2014: still happens


The Lie algebra of $SL_n(\mathbb C)$ are the matrices where the trace is $0$. But what is the Lie algebra of $SL_n(\mathbb H)$ where $\mathbb H$ is the quaternions?


Update texlive-full 2015 to texlive 2017 in Ubuntu 16.04 LTS

Good morning, I know that this might sound simple but I would like to avoid any complication since I use TeX daily and I don't want to mess all the things up. I have installed texlive-full by command line on the terminal, i.e.  sudo apt-get install texlive-full   and I have discovered that the version offered by Ubuntu is from 2015. I have seen that there is a 2017 version of TeX and I would like to install it without problem. Is there a clean way to install over the 2015 version? If not, what are the commands from the terminal to be sure that the previous version is completely purged and then what are the new commands that I have to type in order to install the 2017 version? Is there a way to add a repository (maybe an official one) in order that any new version is updated automatically without any future worry?  I'm sorry for my poor English, and I hope that this question does not result a repetition, since I would like a kind of guide to install properly the new version of TeX over the previous one, but I have not done anything for now, so I do not want to solve  problem in the installation, I would like to know I to make the installation.


Regarding ROC curve of good classifier, why TPR and FPR both increase?

As title, I haven't found a post explain about this, i.e. In the following diagram, for a point on a "better" ROC curve and I move that point along the curve toward the top-right corner, why both TPR and FPR approach 1? And what's the meaning of moving along a given curve?


How do I search all hidden files that are in hidden folders using Terminal?

I need to find some configs buried in some hidden folders and can't recall where they are to navigate to them directly Cmd+Shift+G.  I did a sudo find -name Foo* (slow), but none of the returned files were in hidden folders.  What is the easiest way to search all hidden files?


Suppose I wrote the following:     She did well in the test but Tom didn't.    Why there is no comma before "but" whereas we put it in the following example:     I saw him before war, but I haven't seen him since that time.


How can I move the axis of symmetry on a mirror modifier?

Sorry for this noob question but i really need help :( xD i want mirror this    and it mirrors like this    its supossed to be a bow so in the middle there are a heart and the other piece has to complete it but it mirrors in reverse?D:


Trying to find and print out a row from file

I have a program that does several different things, one of them being this method to find an item in the file and display the attributes of that file (there are 3) in the row.  For some reason, this is only printing out the first three strings in the file, instead of finding and printing the item I search for.  public static void findItem() throws FileNotFoundException {  Scanner kb = new Scanner(System.in);      FileReader reader = new FileReader("read_record.txt");     Scanner fin = new Scanner(reader);     System.out.println("Enter the sku of the dvd you wish to find.");     String dvdSku = kb.next();       while (fin.hasNext()){         String nextString = fin.next();         if (nextString == dvdSku); {             String skuToFind = nextString;             String titleToFind = fin.next();             String lengthToFind = fin.next();             System.out.printf("%-10s %-15s %10s %n",skuToFind,titleToFind,lengthToFind);             break;         }     } }


If $A$ and $B$ are square matrices such that $AB = I$, where $I$ is the identity matrix, show that $BA = I$.    I do not understand anything more than the following.   Elementary row operations. Linear dependence. Row reduced forms and their relations with the original matrix.   If the entries of the matrix are not from a mathematical structure which supports commutativity, what can we say about this problem?  P.S.: Please avoid using the transpose and/or inverse of a matrix.


As I am not very good with explaining things, I want to start with the code below:       public function meta ( ) {             $keywords_arr = $this->keywords();              /*             echo "<pre>"; print_r($keywords_arr);die;             gives following output:             Array             (                [0] => f                [1] => Business                [2] => AP Online Top Business Short Headlines                [3] => AP Online             )             */                            $focuskw  = is_array($keywords_arr[0]) ? $keywords_arr[0] : null;             return array(                     '_yoast_wpseo_focuskw' => $focuskw                       ); }   So now my question, is there any way i can eliminate the useless items from keyword array.  So that I can get some meaningful word that I can set as focused keyword.  In this case the first item "f" (but it can be any item) and i cannot set "F" as focused keyword.  So How to eliminate such meaningless items from array without adding complexity(i.e probably not running loop). I am not sure if it is possible.  I hope I am a bit more clear now.   Thank you


JavaScript timezone information how to get America/Los_Angeles (or equivalent)

Im wondering is there a built in function in javascript that has the timezone information such as   America/Los_Angeles (or equivalent) that can be determined on whatever factor it need be factored on?   Similar to however  does it on its home page? Or is there a list of these zones that I can attempt to build my own library off of? From what I gather  takes the vaule America/Los_Angeles for example to determine an offset, but I can't find any mention of how to do the opposite.


I need a word or a phrase to call someone an idiot, but with good humor

It's so easy to do in a chat room. I just do this: .   I want to capture that same benign, eye rolling, gently mocking disdain - but I have to stick to small words.  An example of an actual circumstance (true story) after which I might want to use such a phrase or word is when he ever-so-patiently explained to me that "rocket surgery" was an incorrect use of idiom.  Perhaps a quote?  I realize that this question is at least borderline for the site. If you feel I've crossed that line please edit if you feel that the question is salvageable.    EDIT: He's 56. Perhaps an instantly recognizable (to an American of his age) quote from pop-culture? Kind of like the way I might say, "Laugh it up, Fuzzball" to someone my age (46) who is very much enjoying the fact he's winning a card game?


Can I put a standard light switch in line with a 240v electric baseboard heater to cut power to it?

I'm installing a small baseboard heater in a back bedroom, adding it to a 240V circuit with two heaters already installed in other rooms. I mainly use the two heaters on low when I am away to prevent pipes from freezing. I heat with wood when there. I would like to be able to totally cut off power to the newly added third heater. This bedroom gets closed off when I am away and since the heater has a built in thermostat with lowest setting of 32degrees it will likely come on when the room is closed off. I don't need or want that...waste of electricity! No pipes back there. I would like to install a switch to the line before it reaches the heater to simply cut the power to that back bedroom heater when I'm away.   Would there be any issues with this type set up?  Do I need any special kind of switch or will a basic 20amp 120/240V light switch do the trick?  Thanks.


Matrix over division ring having one sided inverse is invertible

I want to see if there is any elementary way to prove the following assertion about matrices over division rings (such as not using Wedderburn's theory or tensoring techniques).  If an $n\times n$ matrix over a division ring has left inverse, then it also has right inverse.  The assertion has elementary proof for matrices over fields, but I am considering over division rings.   One can give some hints also.


Find a combinatorial proof for $\binom{n+1}{k} = \binom{n}{k} + \binom{n-1}{k-1} + ... + \binom{n-k}{0}$

Let $n$ and $k$ be integers with $n \geq k \geq 0$. Find a combinatorial proof for $$\binom{n+1}{k} = \binom{n}{k} + \binom{n-1}{k-1} + \cdots + \binom{n-k}{0} .$$  My approach: I was thinking to use the binomial formula as in $$2^n = \sum{\binom{n}{k}1^k1^{n-k}} .$$ I also tried to use  $\binom{n}{r}=\binom{n-1}{r-1}+\binom{n-1}{r}$.


The question is simple. I caught an Eevee CP282 so I potentiate and maybe reach a 320-330 CP (I have just 2-3 extra candy) or evolve right now and potentially after?


How do you add emission to singular faces

So i'm trying to make assets for a video game and I recently hit an obstacle, and that obstacle was adding emission to a certain face on my 3D model.... Can anyone help me out?


Why does Yahoo Finance and Google Finance not match historical prices?

Was working on a different question to ask on here, and realized I might be completely wrong when I realized the historical data on Yahoo and Google are completely different. Therefore I have no idea which is true.    And to confirm I understood Google right I went into their actual Historical price lookup:    Does anyone know which is correct? Are they using two different calculations?


How to copy file/folder permissions and ownerships from one folder to an other (recursively)

How do I copy all the folder, subfolders and files permissions (recursively) from /www_03062018 to my new /www ?  I came across this post:   chmod --reference=RFile file   Which didn't help much, it did apply a change for the main folder /www but didn't apply on its subfolders and files.    i have tried:   chmod -R --reference=/www_03062018 /www   and it didn't work.   My situation:   I have 2 folders on my Ubuntu machine: /www and /www_03062018.   /www is a "git clone" from the production machine.   /www_03062018 is my old directory that i used to work on and upload files via FTP.   I started to use GIT and when I clone a directory - all its folder ownerships and file accesses settings doesn't get cloned too.


I have searched the site and found numerous posts on this issue, but none really answer what I am experiencing.  Background  ( I know shrinkfile is bad, but in this case, it makes sense)  Our client has an .mdf file that is 1.65 TB in size, 1.26 TB is used, and about 390 GB is available in that file.  This data file is not intended to grow much at all, and should only contain the system objects. Unfortunately there are large tables created in that file by mistake totalling about another 800 GB that need to be moved to a different file group in order to take advantage of multiple files in the correct file group and a faster disk subsystem.    I wanted to test the shrinkfile before moving the clustered indexes to a new file group so we didn't end up with 800 GB larger DB if the shrink didn't work, which is exactly what is happening.  We are doing this on a new Prod server they will be migrating to shortly, and are using SA credentials with Sysadmin rights.  No matter what commands we run to shrink the file, the command takes about 10-15 seconds to execute it successfully. No errors show up, but the file does not shrink. I have tried the below commands in SSMS, tried to use the GUI shrink file directly, scripting out the GUI commands, and straight T-SQL with no movement on the data file size. Initially I had thought that truncate option was the problem, as their might not have been free space at the end of the file.  But even after running the notruncate keyword first, then using truncate, the file still did not shrink.  The following query shows that the database file does indeed have space available in the file:   SELECT [Segment Name] = RTRIM(name) ,AllocatedMB = CAST(size / 128.0 AS DECIMAL(10, 2)) ,UsedMB = CAST(FILEPROPERTY(name, 'SpaceUsed') / 128.0 AS DECIMAL(10, 2)) ,AvailableMB = CAST(size / 128.0 - (FILEPROPERTY(name, 'SpaceUsed') / 128.0) AS DECIMAL(10, 2)) ,PercentUsed = CAST((CAST(FILEPROPERTY(name, 'SpaceUsed') / 128.0 AS DECIMAL(10, 2)) / CAST(size / 128.0 AS DECIMAL(10, 2))) * 100 AS DECIMAL(10, 2)) FROM sysfiles ORDER BY groupid DESC   Result:     Segment Name    AllocatedMB UsedMB  AvailableMB PercentUsed   Prod1            1657703.06 1269089.75  388613.31   76.56   ShrinkFile commands Run:    DBCC Shrinkfile (N'Prod1', 0, Truncateonly)   Result: (file did not shrink)     DbId FileId CurrentSize MinimumSize UsedPages   EstimatedPages   5       1              212185992        384         162439904       162439904   Additional ways I've tried running the shrink file:  DBCC SHRINKFILE (N'Prod1' , 0, TRUNCATEONLY)   DBCC SHRINKFILE (N'Prod1' , 1396001)   DBCC SHRINKFILE (N'Prod1' , 0, NOTRUNCATE)   DBCC SHRINKFILE (N'Prod1' , 1600000) -- done to try a smaller shrink amount   Questions   I would expect if this was indeed shrinking the file by almost 400GB, SSMS would take more than 10-15 seconds to run, it would take hours before they query completes correct?    Is there some sort of data type issue that might prevent a shrink from working?  I found this article:  and it mentions LOB data (there is LOB data in that file) but this should just take a longer time to complete, nor prevent a shrink as I see it.   Anything else I am missing here? The syntax works correctly when I try it on my laptop, albeit with my small test DB, so its not the syntax of the commands from what I can tell.


Consider the following MWE  \documentclass{article} \usepackage{tikz} \begin{document} \begin{tikzpicture}  \draw (0,0)--(1,1) node[auto,midway] {$A$}  -- (2,0) node[auto,midway] {$B$}; \end{tikzpicture} \end{document}   I am using auto here to get automatic left/right positioning. However, I am not satisfied with the distance between the edge labels and the edge itself, which is a bit too large (my real example is a picture with much more nodes in it, so there is room for confusion if they are not very close).  Is there a way to alter this distance? I tried adding node distance=something almost everywhere, but it seems to be ignored.