Can you really trust WhatsApp's end-to-end encryption?

I've seen many articles that actually trust WhatsApp's encryption and they may be right, but here is the thing that really makes me suspicious; all end-to-end encrypted apps I know, such as Telegram and Signal are blocked in China, but WhatsApp that is far more popular is not.   If China is not blocking this app in particular (and after seeing all those  by Zuckerberg) I am a little wary that your data is really end-to-end encrypted without the possibility of Facebook to intervene.   Is there any way for anyone to assess without shadow of a doubt that WhatsApp encryption is really end-to-end encrypted like there is with Signal?


What does "Warning: untrusted X11 forwarding setup failed: xauth key data not generated" mean when ssh'ing with -X?

When I use ssh -X on my Mac (running OS X 10.6.7) to connect to my Ubuntu (11.04) box, I get the following warning:     Warning: untrusted X11 forwarding   setup failed: xauth key data not   generated Warning: No xauth data;   using fake authentication data for X11   forwarding.   Is there something I can do to make this warning go away?  If not, can I safely ignore it?  X11 forwarding seems to work fine, though I do see this message:     Xlib:  extension "RANDR" missing on   display "localhost:10.0".   Is that related to the warning?  (I'm guessing not.  If it's not, I'll file a new question about that.)


Let interaction with new user's posts in Q&A count towards review badge

On any SE site, in the First Posts review queue we review new user's posts. As with any queue, we can get the Custodian, Reviewer, and Steward badges for reviewing a certain number of items in this queue.  However, most of the time, especially when using smaller SE sites, I comment, vote on, flag, or vote to close a new user's post before going through the First Posts review queue. I am then unable to review this post in the First Posts review queue because I've already interacted with it.  Given we're fulfilling the purpose of the review queue by interacting with the new user's post on the Q&A, I think interacting with new user's posts on the Q&A should count towards the reviewing badges.  This would help improve the quality of the site in general because users will be further encouraged to upvote, comment, and help new users while on the Q&A portion more than they currently do.


what is the basic difference between a mapping and a function? many say they are same but the opposite views are also seen. is mapping a restricted version of a function?


Can you get into a phd program in engineering with a failed semester

I really want to get my PhD in mechanical engineering. I have a good amount of research done but my GPA is only a 3.0. My first semester of my junior year my husband suddenly deployed right after we closed on our first home, I started a new job, and got a dog. I got a D and an F that semester and my GPA dropped to a 2.0. The following semester I retook the classes and got all A's and a B. I made the deans list and brought my GPA up to a 3.0. Did that one semester kill my chances of getting into a PhD program for mechanical engineering?


If $f:W\rightarrow X$, $g:X\rightarrow Y$, and $h:Y\rightarrow Z$, does $h \circ (g \circ f) = (h \circ g) \circ f$? How can I justify this?


Receiving Chinese blocks of texts in the Messaging app

My wife is getting some weird text messages as replies in middle of conversations with her friends. The messages are blocks of Chinese characters. She gets these in the stock messaging app from friends that use Samsung phones and iPhones. She is using a Nexus 5X on AT&T. (N.B. Other users have asked the same question about the Samsung Galaxy S7, so it's not a phone-specific issue.)  Here is a screencap from today from an iPhone user, and translating the text does not make sense (though I did image translation): :      (Click to see the image in full size)    Here is one from a Samsung phone and from their end:       (Click to see the image in full size)  Does anyone know why this is happening? Is it some weird thing when someone with a weird texting app replies with some emoji/GIF/image?


Will one 'C' grade due to health issues ruin my chances of admission into a top grad school?

I am in the third year of my undergraduate degree now, and in the process of applying for Graduate schools and Med schools. I have a burning questions about a creepy "C" in my transcript.   To summarize my story: I was recovering from a biopsy operation back then. Though I was advised to take one semester off to rest physically and mentally (I was extremely paranoid waiting for the pathology report, and luckily it came back benign), I still decided to take all the courses and the heavy research that I had started before. I performed so badly that semester that I received a C. That is like the most embarrassing element in my transcript.   Some told me that such a bad grade is a disadvantage for admissions. Do I still have a chance to make it to top grad and med schools?  With extra effort (I have managed to pull up my GPA to 3.8 now, I have been on the Dean's list for some semesters, have 3 publications, and 2 poster presentations at symposium, my GRE and MCAT are good too), can I cover that ugly spot?


How to get permission to make a file in C:\\Program Files using Python?

How do I get access to create a file in C:\Program Files in Python? I have compiled my program to exe.  My console is showing:  Python 3.7.0 (v3.7.0:1bf9cc5093, Jun 27 2018, 04:06:47) [MSC  v.1914 32 bit (Intel)] on win32 Type "copyright", "credits" or "license()" for more information.  >>> fl = open('C:\\Program files\\example.example', 'w')  Traceback (most recent call last): File "<pyshell#0>", line 1, in <module> fl = open('C:\\Program files\\example.example', 'w') PermissionError: [Errno 13] Permission denied: 'C:\\Program files\\example.example'   I mean that how can I create a file in there? Or how can I get permission as a admin? Without right clicking and selecting run as admin? Like other applications do?


R is commutative ring with identity & define $\circ$ on $R$ by for any $a,b \in R$ $a \circ b=a+b-ab$ Prove the following

Let R be a commutative ring with identity. Define a new operation $\circ$ on $R$ by for any $a,b \in R$  $$a \circ b=a+b-ab$$  a) Prove that $\circ$ is associative  b) Prove that R is a field iff the set $\{r \in R: r \ne 1\}$ is an abelian group with respect to the operation $\circ$  Starting with a) we must prove   $a \circ ( b \circ c)= (a \circ b) \circ c$  Left side: $a \circ ( b \circ c)=a \circ (b+c-bc)=a+b+c-bc-a(b+c-bc)=a+b+c-bc-ab-ac+abc$  Right side: $(a \circ b) \circ c =(a+b-ab) a \circ c=a+b-ab+c-(a+b-ab)c=a+b-ab+c-ac-bc+abc$ and we have thus proved that $\circ$ is associative  As for part b), I am a little confused on what is being asked exactly. Is it asking to go through ALL the properties of a field, closure, associativity, commutativity, identity, inverse, distributive, showing that all hold except for when $r \ne 1$?


remove duplicate rows in mysql table that does not contain primary key

I have a table item having just one column name:-  name ----- toys shirt mobile Shirt speaker Toys ....  ....   I am trying to delete duplicate rows except one duplicated record with the help of below query  DELETE FROM ( SELECT `name`,`rownumber` FROM (SELECT GREATEST(0,@num := IF(`name` = @NAME,  @num + 1, 1),LEAST(1, LENGTH(@NAME := `name`))) AS rownumber,`name` FROM  item ORDER BY `name`) AS result1 ) AS result  WHERE rownumber >1   The Inner query (Starts from SELECT name and ends with result1) returns individual auto incremented number for each repeating group but when i run entire query then it does not work.  I would like to know what changes i need to make in the inner query (contained in round braces) to delete duplicate rows.


How to get over "device or resource busy"?

I tried to rm -rf a folder, and got "device or resource busy".  In Windows, I would have used LockHunter to resolve this. What's the linux equivalent? (Please give as answer a simple "unlock this" method, and not complete articles like . Although they're useful, I'm currently interested in just ASimpleMethodThatWorks™)


adb device doesn't listed on cmd {Lenovo K8 Plus}

I am trying to root my Lenovo K8 Plus after unlocking bootloader. I try to install TWRP and somehow the TWRP recovery doesn't open and the phone is struck in the bootloop. I then fastboot the device and connect to PC and open minimal fastboot cmd. The phone wasn't listed in adb device, but listed in fastboot devices. I think usb debugging is not turned on because the system doesn't restart (maybe there is no ROM). What should I do?


While solving problems involving constrained motion, such as that which the following picture describes, I am always confused about one aspect of the situation in question:    In the above problem, it is given that the ring moves with a velocity of $Vr$ $m/s$ toward the right. This velocity can be resolved into two components, one along the direction of the rope extending from the string(at an angle $θ°$ with the horizontal, as shown)and one along the perpendicular to this direction.  My doubt us this; once we have resolved $Vr$ along the rope, we find that this value is $Vrcosθ$. What is the physical significance of this? I realize that the ring moves in both directions and these vector components give its velocity in those two directions but does this also imply that the rope also moves with a velocity $Vrcosθ$? I am very confused regarding this concept.   Please help. Much thanks in advance :) Regards.   Edit: I posted the picture only to illustrate my point better. This is not a homework question because it relates to the basic concept of resolving vectors.


I want to make my video to be a screensaver.  Is there any software to make it?


Is there any application to convert gif file to txt file in linux?

Is there any application to convert a gif file to txt file in linux?


Why do computers only use 0 and 1? Won't the addition of other numbers such as 2 or 3 speed up computers? Also, 2 and 3 can be used to shorten the bit-length of integers (2 and 3 can be used to end an integer, so that the number 1 only needs one two bits.)..  Why is binary computer more preferred?


How do you load a class that is not in the classpath & is in a jar?

I want to load a class that is in a jar.  I already tried to just load the class using this code:  URL dirUrl = jarFile.toURL(); URLClassLoader ucl = new URLClassLoader(new URL[] {dirUrl}, getClass().getClassLoader()); Class<?> clazz = ucl.loadClass(mainClass); ucl.close();   I get an exception that it couldn´t find the class:  java.lang.RuntimeException: java.lang.ClassNotFoundException: net.api.main         at net.al.Main.onEnable(Main.java:39) ~[?:?]         at org.bukkit.plugin.java.JavaPlugin.setEnabled(JavaPlugin.java:321) ~[spigot.jar:git-Spigot-db6de12-18fbb24]         at org.bukkit.plugin.java.JavaPluginLoader.enablePlugin(JavaPluginLoader.java:340) [spigot.jar:git-Spigot-db6de12-18fbb24]         at org.bukkit.plugin.SimplePluginManager.enablePlugin(SimplePluginManager.java:405) [spigot.jar:git-Spigot-db6de12-18fbb24]         at org.bukkit.craftbukkit.v1_8_R3.CraftServer.loadPlugin(CraftServer.java:357) [spigot.jar:git-Spigot-db6de12-18fbb24]         at org.bukkit.craftbukkit.v1_8_R3.CraftServer.enablePlugins(CraftServer.java:317) [spigot.jar:git-Spigot-db6de12-18fbb24]         at org.bukkit.craftbukkit.v1_8_R3.CraftServer.reload(CraftServer.java:741) [spigot.jar:git-Spigot-db6de12-18fbb24]         at org.bukkit.Bukkit.reload(Bukkit.java:535) [spigot.jar:git-Spigot-db6de12-18fbb24]         at org.bukkit.command.defaults.ReloadCommand.execute(ReloadCommand.java:25) [spigot.jar:git-Spigot-db6de12-18fbb24]         at org.bukkit.command.SimpleCommandMap.dispatch(SimpleCommandMap.java:141) [spigot.jar:git-Spigot-db6de12-18fbb24]         at org.bukkit.craftbukkit.v1_8_R3.CraftServer.dispatchCommand(CraftServer.java:641) [spigot.jar:git-Spigot-db6de12-18fbb24]         at org.bukkit.craftbukkit.v1_8_R3.CraftServer.dispatchServerCommand(CraftServer.java:627) [spigot.jar:git-Spigot-db6de12-18fbb24]         at net.minecraft.server.v1_8_R3.DedicatedServer.aO(DedicatedServer.java:412) [spigot.jar:git-Spigot-db6de12-18fbb24]         at net.minecraft.server.v1_8_R3.DedicatedServer.B(DedicatedServer.java:375) [spigot.jar:git-Spigot-db6de12-18fbb24]         at net.minecraft.server.v1_8_R3.MinecraftServer.A(MinecraftServer.java:654) [spigot.jar:git-Spigot-db6de12-18fbb24]         at net.minecraft.server.v1_8_R3.MinecraftServer.run(MinecraftServer.java:557) [spigot.jar:git-Spigot-db6de12-18fbb24]         at java.lang.Thread.run(Unknown Source) [?:1.8.0_211] Caused by: java.lang.ClassNotFoundException: net.api.main         at java.net.URLClassLoader.findClass(Unknown Source) ~[?:1.8.0_211]         at java.lang.ClassLoader.loadClass(Unknown Source) ~[?:1.8.0_211]         at java.lang.ClassLoader.loadClass(Unknown Source) ~[?:1.8.0_211]         at net.al.addon.AddonLoader.loadAddons(AddonLoader.java:129) ~[?:?]         at net.al.Main.onEnable(Main.java:36) ~[?:?]         ... 16 more


How does one send data through UART from MCU to your PC without any connections on TX/RX pins?

I have been reading up on UART, and I see it works by connecting TX<->RX and RX<->TX of receiver and transmitter. The example I couldn't wrap my head around though is your MCU being able to TX the data to a serial monitor that you could view on your PC using teraterm, let's say. I tried it and it does work. I did specify the TX and RX pins for UART in my code, but they're not connected to anything. Can someone help me bridge this gap? Does it work like for RX too? (receiving data from the serial monitor into your MCU)?


How to get all the records from rest api response

I am trying to get all the records(800000) updated in to a data extension but it is allowing me to get 10000 records at a time. I am using POST API call, SSJS in my cloud pages to update in a data extension. Is there any other approach which could be automated to get the complete data instead of doing separate calls for all the records?   Thanks in advance!


bash arithmetic works in loop; after loop, var has no value

I'm trying to use an integer to count loop iterations, but after the loop is finished, the variable is blank. I've googled for clues, but no luck.  I have this code:  #!/bin/bash  declare -i count  echo entering loop  while read var do   (( count++ ))   echo $count done  echo exited loop echo count is $count   When I run it interactively, pressing Ctrl+D after entering "c", I get output like this:  $ ./example entering loop a 1 b 2 c 3 exited loop count is 3   But when I pipe input into the loop:  #!/bin/bash  declare -i count  echo entering loop  ls -la | while read var do   (( count++ ))   # do something interesting here   echo $count done  echo exited loop echo count is $count   ... I get output like this:  $ ./example entering loop 1 2 3 4 5 exited loop count is $   Why doesn't it say "count is 5" here after exiting the loop?


What are the details of the recent agreement between Sony Pictures and Marvel Studios?

It was recently announced that Sony Pictures and Marvel Studios have come to an agreement whereby each of them will share the film rights to the characters relating to Spider-man.  What are the details of this agreement, as in, who has creative control, distribution rights, and how can each party use the character? Additionally, what is currently known about the future of The Amazing Spider-man franchise?


Prove that if $n>1$ then between $ n $ and $n^2$ is at least one prime.

Prove that if  postive intetger $n>1$  then between $ n $  and  $n^2$  is at least one prime. I have known this stronger reslut: But my problem is constant math test,so I guess maybe there exist more simple methods? and  I want to have prove $$\pi(n^2)-\pi(n)>1,\forall n>1$$


What are the current (technical) criteria for filtering posts into the review queues? The FAQ  covers some general discussion on the queues (but no specifics). Also,  mentions some vague selection criteria ("algorithmically determined...") and targets only specific queues. However, while some queues seem fairly obvious in their implementation, there are still . This post originates from a  where an existing, well-established user posted an answer to old question yet ended up in a late review queue (designated to catch "new user's answer to an old question"). Admittedly this user is 's  and frequently dips into the low-rep end of the pool as a result:


How to copy file with a different name, but same extension?

I would like to copy a file, but I want the new file to be named something different, like having a (1) next to the name without changing the extension.   Here is my code:   import shutil from tkinter import * from tkinter.filedialog import askopenfilename import os   filename = askopenfilename()  file_name, file_extension = os.path.splitext(filename)  dec = "_dec"  newfile = file_name + dec   copied = str.join(newfile, file_extension)   shutil.copy(filename, copied )  master = Tk()  w = Message(master, text="Copied!", width = 100) w.pack()  mainloop()   How would I get filename to have a (1) at the end of the name without touching the extension?


I was looking for an exercise book on Discrete Math like SAT questions. In particular I want questions on  Logic Set Theroy Relations (I.e., $R\subset A\times A$) Functions Combinatorics  I did not find anything like SAT questions but only "open" questions.


I followed the Pierre Hermé éclairs recipe:     60mL water    75mL whole milk    3g salt    3g caster sugar    56g butter    75g flour    A little over 2 eggs   I did the recipe and it called for 45 minutes of baking at 185°C.  I baked them for 40 minutes and left them in the oven for an extra 10 minutes before removing them.  The result was that the exterior was terrific, but the inside was too doughy and I couldn't fill it with crème pâtissière (custard).  Is skipping the 5 last minutes of baking the reason it failed?


A group such that $a^m b^m = b^m a^m$ and $a^n b^n = b^n a^n$ ($m$, $n$ coprime) is abelian?

Let $(G,.)$ be a group and $m,n \in\mathbb Z$ such that $\gcd(m,n)=1$. Assume that $$ \forall a,b \in G, \,a^mb^m=b^ma^m,$$ $$\forall a,b \in G, \, a^nb^n=b^na^n.$$  Then how prove $G$ is an abelian group?  Some context: Some of these commutation relations often imply that $G$ is abelian, for example , or . This looks like another example of this phenomenon, but the same techniques do not apply.


I've run out of space on my root partition and I want to extend it. I've seen another posts of this topic but my lack of knowledge makes it difficult for me to achieve what i want. Here's a screenshot of my GParted Window:


If I have this document    aaa   bbb   ccc     And I want to add " ddd" on the last line. My document should look like this:    aaa   bbb   ccc ddd     How can I do this? If I prefer awk or sed but i'm open to your proposals. Thanks


Give a one-to-one and onto function from $\mathbb{N} \times \mathbb{N}$ to $\mathbb{N}$

Give a function $g : \mathbb{N} \times \mathbb{N} \to \mathbb{N}$  such that $g$ is one-to-one and onto function.  the onto part I could easily solve but every function I think of, is not one-to-one.


How can I optimise a Minecraft-esque voxel world?

I found Minecraft's marvelous large worlds extremely slow to navigate, even with a quad core and meaty graphics card.  I assume Minecraft's slowness comes from:   Java, as spatial partitioning and memory management are faster in native C++. Weak world partitioning.   I could be wrong on both assumptions. However, this got me thinking about the best way to manage large voxel worlds. As it is a true 3D world, where a block can exist in any part of the world, it is basically a big 3D array [x][y][z], where each block in the world has a type (i.e BlockType.Empty = 0, BlockType.Dirt = 1, etc.)  I assume that to make this sort of world perform well, you would need to:   Use a tree of some variety (//) to split all the cubes out; it seems like an oct/kd would be the better option, as you can just partition on a per cube level not a per triangle level. Use some algorithm to work out which blocks can currently be seen, as blocks closer to the user could obfuscate the blocks behind, making it pointless to render them. Keep the block object themselves lightweight, so it is quick to add and remove them from the trees.   I guess there is no right answer to this, but I would be interested to see peoples' opinions on the subject.  How would you improve performance in a large voxel-based world?


Proving uniform continuity of $f(x) = x \sin{\frac{1}{x}}$ on $(1,2)$ directly from the definition.

Before this is marked as a duplicate, I have already looked at the answers  and .  I believe my question is different because I want to do this proof directly from the definition. The proof given at the first link uses the property of compactness, Lipschitz continuity and derivatives to support the argument. However, my professor's real analysis approach has not been that of metric spaces and, additionally, Lipschitz continuity has not been discussed yet so I'd like to avoid them for now and attempt this proof directly from the definition. I'm interested in a proof similar to the second answer given on the first link but, unfortunately, there are no comments on whether or not it is correct.     The question is to determine whether or not $f(x) = x \sin{\frac{1}{x}}$ is uniform continuous on $(1,2)$.   I present my own attempt:  Given $\epsilon>0$, let $\delta= \frac{\epsilon-1}{2}$ Then $|x-y|<\delta \implies$ $$\left | f(x)-f(y)\right | =\left | x\sin \left(\frac{1}{x}\right)-y\sin \left(\frac{1}{y}\right) \right|= \left |(x-y) \left( \sin \left(\frac{1}{x}\right)+\sin \left(\frac{1}{y}\right) \right) -x\sin \left(\frac{1}{y} \right)+y\sin \left(\frac{1}{x} \right)\right| \leq \left |(x-y) \left( \sin \left(\frac{1}{x}\right)+\sin \left(\frac{1}{y}\right) \right)\right| + \left|-x\sin \left(\frac{1}{y} \right)+y\sin \left(\frac{1}{x} \right)\right|$$  $$\leq \left |x-y \right| \left |\left( \sin \left(\frac{1}{x}\right)+\sin \left(\frac{1}{y}\right) \right)\right| + \left|-x\sin \left(\frac{1}{y} \right)+y\sin \left(\frac{1}{x} \right)\right|$$  $$\leq 2\left |x-y \right|+1 < 2\cdot (\frac{\epsilon-1}{2})+1=\epsilon$$  Any help is appreciated.


Unable to boot OS X after installing ubuntu

I installed ubuntu on my macbook air early 2014,but now I am unable to boot OSX after the installation of Ubuntu. I used a USB flash drive to install Ubuntu 15.10-amd64.ISO  When I press the 'power on' button,it boots to Ubuntu automatically But if I press and hold 'alt' after pressing the 'power on' button it shows the Macintosh HD icon , when I press enter it shoes the Apple logo and then it shows a cross circle symbol.


How can I access groups from a regex exec match in Typescript?

I'm getting Property 'groups' does not exist on type 'RegExpExecArray' when trying  const r = /\w+, (?<foo>\w+)/ const m = r.exec('hello, world')  if (m) {     const groups = m.groups }   Javascript has an option to call .groups on a regex exec result. And I know the output is actually an array... but grabbing a specific index to get the groups seems a bit hacky. Is pulling from the list the only option in Typescript?


QGIS - adding timestamps to spatialite data during data collection

I am trying to do field data collection using QGIS.  One of the features that I regard as necessary for data management is timestamps.  For example, a timestamp can indicate that an inspection record has been updated.    I have figured out how to add triggers using Spatialite to add a timestamp on update, however the timestamp is added when the edited records are saved and not when the identify dialog box is closed.  This means that timestamps can be out by many minutes.  One solution would be to force the updated record to be saved by using a custom form with an OK button (Can do the form with Qt-Designer but don't know how to add the save command to the button yet.)  However my preferred solution would be to take a timestamp for new records, when the point or line is created.  The reason for this is if I am surveying a road, I can stand on the road, collect the point and them move to the side to complete data collection.    I have been unable to work out how to get Spatialite to run a trigger that puts in the start of feature editing.  Perhaps this is also something that needs to be done by code in a custom form.  Is there an On-dirty event or signal in QGIS that indicates when someone starts editing a record and that can be used to capture the time?  Could I also ask what the Python code (and what to hook it to) that would put such a timestamp in the timestamp field.  AndrewM


trouble in prediction in neural network classifier

I am training a 4-class neural network classifier.  The details of my data are:  featurelength = 280                training      testing --------------------------------------------- no. samples      438           250 samples class1   203           135 samples class2   19            10 samples class3   16             5 samples class4   200           100         After I train the neural network.  The confusion matrices are as follows:  203 0 0 0  19  0 0 0 16  0 0 0 200 0 0 0   Similarly for test data too. All the data is predicted to be of class 1.  How can I debug this issue? What is the reason behind such performance? In addition to this, no. of samples for class 2 and class 3 are very less. How can I make sure that they are not dominated?


Right now, in iOS, the app label shows as "Stack Exc..."   While we all know what it means, it's not really nice. So how about calling it instead "StckExchg" :)  Or some other form, that will still convey "Stack Exchange", but not with all letters, or something alike...


If $x>0, y>0,x+y=\frac{\pi}{3}$ then maximum value of $\tan x\tan y$

If $x>0, y>0$ and $x+y=\frac{\pi}{3}$, then find the maximum value of $\tan x\tan y$   My Attempt  $x>0, y>0, x+y=\frac{\pi}{3}\implies x, y$ in $1^\text{st}$ quadrant.  $\tan x, \tan y>0, \tan(x+y)=\sqrt{3}, \tan x\tan y>0$ $$ \tan x+\tan y\geq2\sqrt{\tan x.\tan y}\implies \tan^2x+\tan^2y+2\tan x\tan y\geq 4\tan x\tan y\\ 2\tan x\tan y\leq\tan^2x+\tan^2y\implies \color{red}{?} $$ or $$ 1-\tan x\tan y=\frac{\tan x+\tan y}{\tan(x+y)}\implies\tan x\tan y=1-\frac{\tan x+\frac{\sqrt{3}-\tan x}{1+\sqrt{3}\tan x}}{\sqrt{3}}\\ \tan x\tan y=1-\frac{\frac{\tan x+\sqrt{3}\tan^2x+\sqrt{3}-\tan x}{1+\sqrt{3}\tan x}}{\sqrt{3}}=1-\frac{1+\tan^2x}{1+\sqrt{3}\tan x}\leq\color{red}{?}\\ =\frac{1+\sqrt{3}\tan x-1-\tan^2x}{1+\sqrt{3}\tan x}=\frac{\tan x(\sqrt{3}-\tan x)}{1+\sqrt{3}\tan x}=\color{red}{?} $$ Note: I prefer not to do differentiation


Let $(X,d)$ be any metric space and let $p\in X$ and let $d_p$ be the corresponding french railroad metric. That is, $d_p(x,y)=d(x,p)+d(p,y)$.  I'm supposed to show that $(X,d_p)$ is necessarily a complete metric space. So any Cauchy sequence in $(X,d_p)$ had better converge to some $x\in X$.  Can someone help me go about showing that there cannot be a Cauchy sequence whose limit is not in $X$?


Column name overlaps with type column in Data Explorer in PendingFlags table

In the SE Data Explorer, if you attempt to compose a query and scroll to the PendingFlags table, two columns (CloseAsOffTopicReasonTypeId and BelongsOnBaseHostAddress) overlap into the column type column:    I was able to see this in both Chrome and IE.


C#: GetCustomAttribute returns different instance?

Shouldn't PropertyInfo.GetCustomAttribute(s) return the same instance of Attribute? The following code appears it returns different instances:  using Microsoft.VisualStudio.TestTools.UnitTesting; using System; using System.Reflection;  namespace AttributeNoShared {     [TestClass]     public class UnitTest1     {         private sealed class AnyAttribute : Attribute         {         }          private sealed class AnyClass         {             [Any]             public int AnyProperty { get; set; }         }          [TestMethod]         public void TestMethod1()         {             var propertyInfo = typeof(AnyClass).GetProperty(nameof(AnyClass.AnyProperty));             var result1 = propertyInfo.GetCustomAttribute<AnyAttribute>();             var result2 = propertyInfo.GetCustomAttribute<AnyAttribute>();              Assert.AreEqual(result1, result2);  // This succeeded             Assert.IsTrue(object.ReferenceEquals(result1, result2), "Different instance of attribute"); // This failed         }     } }   Is this a bug? I'm expecting runtime Attribute to be shared because I would like to store some state in it.


How to find a explicit bijection for some $f:A\times B \rightarrow B \times A$

The question I have states:   "Describe a bijection $f:A\times B\rightarrow B\times A$"  The simplicity and lack of a domain or codomain that I can look at has caused this question to throw me off.   Is describing $f(a,b)=(b,a)$ where $a\in A, b\in B$ enough to do this? To what extent do I have to prove that this is a bijection?   I can say that $(x,y)=(x',y')$ if and only if $(x=x')\ \cap \ (y=y')$ and prove injectivity and surjectivity and so on, but I am a bit confused..


Community doesn't poke questions that are truly unanswered?

I've been going around the unanswered sections of my network, and am I right in assuming that Community doesn't poke questions with 0 answers?  Whatever the answer is, can I get an explanation of what I'm seeing?


Filling cells with sequential numbers in an Excel (2003) macro

I need to fill an excel column with a sequential series, in this case from -500 to 1000.  I've got a macro to do it, but it takes a lot of lines for something that seems like it should be a single function [something like FillRange(A2:A1502, -500, 1000, 1)].  But if that function exists, I can't find it.  Is the following as simple and elegant as it gets?  'Draw X axis scale Cells(1, 1).Value = "mV" Cells(2, 1).Value = -500 Cells(3, 1).Value = -499 Cells(4, 1).Value = -498  Dim selection1 As Range, selection2 As Range  Set selection1 = Sheet1.Range("A2:A4") Set selection2 = Sheet1.Range("A2:A1502")  selection1.AutoFill Destination:=selection2


How do I keep both the background and foreground in the image in focus at the same time?

How do you have both the background and foreground in the image in focus at the same time?  Last week I was attempting a shot where I had the back of a hat in focus and in the distance you could see a mountain. I wanted both in focus, but could either focus on the mountain or the hat. I ended up taking the in-focus shots of both and merging them in Photoshop. While that isn't difficult I would prefer to shoot the shot as accurate as possible. From what I have read aperture is important in the depth of field but what are the techniques for keeping both the background and foreground in focus?  I am using a Nikon D5100 with a 18-55mm f/3.5-5.6 (standard kit lens) and a 55-200mm  f/4.5-5.6.    almost answers my question, but I am a bit confused. Can someone explain this a bit differently? Thanks!


Can I increase my lifespan by killing myself using the Death Note?

Suppose I wrote that I will be killed by a UFO falling from space in the year 2315 while I am lifting.  Will the Note increase my lifespan? In other words, will I still be alive by then?


Today in class my professor mentioned that there are different types of infinity. This confused me at first because I always thought infinity is just infinity. What are the different types of infinity?


Prove or show a counter example for: $\forall a, b, c \in \mathbb Z$, if $ab\mid c$ then $a\mid c$ and $b\mid c$

I'm working on my Discrete Mathematics homework and they are asking me this:  Prove or show a counterexample for: $\forall a, b, c \in \mathbb Z$, if $ab\mid c$ then $a\mid c$ and $b\mid c$  I'm not completely sure how to prove it. I was thinking to find a counterexample like zero but I'm not sure if that it's going to work. Or maybe try to approach it backwards?   I'm a little bit lost


I have the label of an object's field. I want to retrieve its API name

I have a map. the string is the label of a field of an object and the integer is the value that must go into this field of that object. But i don't know how to retrieve the API name of those fields from their labels. Please help!  Thanks in advance!


How to prove that partial derivatives are zero for local max and min in 3d

I am confused on where to start on this proof. I read the proof for 2d and 1d(extreme value theorem) and it makes sense, but I cannot visualize it in 3d. Show that if $(x_0,y_0,z_0)$ is a local minimum or maximum point of $w=f(x,y,z)$, then $ \frac{\partial w}{\delta x} $,$ \frac{\partial w}{\delta y} $,$ \frac{\partial w}{\delta z} $ are all zero at $(x_0,y_0,z_0)$.


How to create custom repository on Ubuntu 14.04

How to build custom repository server so that all client install packages from my machine.  what type of URL to add in /etc/apt/sources.list file on Client Machine. to fetch that particular package


I have manually edited /etc/resolvconf/base to add openDNS name servers, and then run sudo resolvconf -u to update the /etc/resolv.conffile.  However changes are discarded on each reboot.  How do I preserve those changes?  $ cat /etc/os-release  NAME="Ubuntu" VERSION="16.04.3 LTS (Xenial Xerus)" ID=ubuntu ID_LIKE=debian PRETTY_NAME="Ubuntu 16.04.3 LTS" VERSION_ID="16.04" HOME_URL="http://www.ubuntu.com/" SUPPORT_URL="http://help.ubuntu.com/" BUG_REPORT_URL="http://bugs.launchpad.net/ubuntu/" VERSION_CODENAME=xenial UBUNTU_CODENAME=xenial   edit:  /home/pkaramol $ cat /etc/resolvconf/resolv.conf.d/base nameserver 208.67.222.222 nameserver 208.67.220.220 /home/pkaramol $ sudo resolvconf -u /home/pkaramol $ cat /etc/resolv.conf  # Dynamic resolv.conf(5) file for glibc resolver(3) generated by resolvconf(8) #     DO NOT EDIT THIS FILE BY HAND -- YOUR CHANGES WILL BE OVERWRITTEN  nameserver 127.0.1.1


What is intuition behind the power series question?

If each $a_n >0$ and $\sum a_n$ diverges, prove that $\sum a_n x^n \to +\infty$ as $x\to1^-$.  I found this question in Apostol. It can be compared to a result of Abel's theorem. What is the intuition behind this problem and how to solve this?  I saw this question in math stack exchange also:    but I did not understand its solution.So I am looking for an intuition behind this problem.  Can someone provide me with a better solution for the same problem?


Elimination of individual elements in table of contents (TOC)

Of course, one can include individual elements into a table of contents by inclusion of addcontentsline at the element to be included.  I'm seeking the opposite:  I want to prevent selected individual elements from appearing in the table of contents when they otherwise would be.    Note that changing the depth of element to be included will not work for my case.  I may want some subsections to appear in the table of contents and not others.  Changing the depth will permit or prevent all subsections from appearing in the table of contents.  Is there a command (e.g., deletecontentsline) that will allow me to selectively prevent individual items from otherwise appearing in the TOC?  For my case, there will be no problems with numbering.  In particular, I want subsections just in one section to not appear in the table of contents.  So, even though there is section 1, subsection 1.1, 1.2, etc., and section 2, subsection 2.1, 2.2, etc. I want my table of contents to have only 1, 1.1., 1.2, and 2.  (not 2.1, 2.2, etc.).


I have an iPhone 4 with iOS 71. I can't install apps from app store because when tap on install button of any app then showing error message " you most be update your iso device 8.0 or later version and try again..."  What can I do to install Facebook etc.?


How come I'm getting a null pointer exception

I am getting a NullPointerException in the hanoi function when pushing the values from the input into the stack and I'm not sure why heres my code:  public class Hanoi {  public static Stack<Integer>[] towersOfHanoi = new Stack[4]; static int moves;  public static void hanoi(int n) {      for(int i = n; n > 0; i--) {         towersOfHanoi[1].push(i);     }      moveDisc(n, 1, 2, 3); }  public static void moveDisc(int n, int j, int k, int l) {      moveDisc(n-1, j, k, l);     int i = towersOfHanoi[j].pop();     towersOfHanoi[k].push(i);     moves++;     moveDisc(n-1, l, j, k); }  public static void main(String args[]) {     Scanner in = new Scanner(System.in);      System.out.println("Enter number of discs: ");     int n = in.nextInt();     in.close();      hanoi(n);      towersOfHanoi[1] = new Stack<Integer>();     towersOfHanoi[2] = new Stack<Integer>();     towersOfHanoi[3] = new Stack<Integer>();      System.out.println(moves);


apt-get update only for a specific repository

When I add a PPA and I want to install some of its content, it is quite annoying to re-update all my apt list using apt-get update.  Is it instead possible to only sync the content of a given repository?


Comparing mixed-effects and fixed-effects models (testing significance of random effects)

Given three variables, y and x, which are positive continuous, and z, which is categorical, I have two candidate models given by:  fit.me <- lmer( y ~ 1 + x + ( 1 + x | factor(z) ) )   and  fit.fe <- lm( y ~ 1 + x )   I hope to compare these models to determine which model is more appropriate. It seems to me that in some sense fit.fe is nested within fit.me. Typically, when this general scenario holds, a chi-squared test can be performed. In R, we can perform this test with the following command,  anova(fit.fe,fit.me)   When both models contain random-effects (generated by lmer from the lme4 package), the anova() command works fine. Owing to boundary parameters, it is normally advisable to test the resulting Chi-Square statistic via simulation, nonetheless, we can still use the statistic in the simulation procedure.  When both models contain only fixed-effects, this approach---and, the associated anova() command---work fine.  However, when one model contains random effects and the reduced model contains only fixed-effects, as in the above scenario, the anova() command doesn't work.  More specifically, I get the following error:   > anova(fit.fe, fit.me)  Error: $ operator not defined for this S4 class   Is there anything wrong with using the Chi-Square approach from above (with simulation)? Or is this simply a problem of anova() not knowing how to deal with linear models generated by different functions?  In other words, would it be appropriate to manually generate the Chi-Square statistic derived from the models? If so, what are the appropriate degrees of freedom for comparing these models? By my reckoning:  $$ F = \frac{\left((SSE_{reduced}-SSE_{full})/(p-k)\right)}{\left((SSE_{full})/(n-p-1)\right)} \sim F_{p-k,n-p-1} $$  We are estimating two parameters in the fixed effects model (slope and intercept) and two more parameters (variance parameters for the random slope and random intercept) in the mixed-effects model. Typically, the intercept parameter isn't counted in the degrees of freedom computation, so that implies that $k=1$ and $p=k+2=3$; having said that I'm not sure if the variance parameters for the random-effects parameters should be included in the degrees of freedom computation; the variance estimates for fixed-effect parameters are not considered, but I believe that to be because the parameter estimates for fixed effects are assumed to be unknown constants whilst they are considered to be unknowable random variables for mixed effects. I would appreciate some assistance on this issue.  Finally, does anybody have a more appropriate (R-based) solution to comparing these models?


Calculate the RSA private exponent from the CRT parameters

I am trying to make the RSA structure of Openssl manually, knowing the public key ($n$, $e$) and the  parameters $p$, $q$, $d_P$, $d_Q$, and $u = q^{-1} \mod p$.  That is, I want to get the $d$ value (private exponent) of the RSA structure by using Openssl API. If there are already any implemented functions, it would be great to me.  Bonus question: is it possible if I have $p$, $q$, $d_P$, $d_Q$ and $u$ but not the public key? I know that $n = p q$, but what about $e$?


math.random sometimes automatically sets minimum number to zero

As a little hobby i am creating a random number generator tool using the javascript math.random script and an html form that asks for the minimum number and maximum number. But i am experiencing a problem where sometimes the minimum number is set to zero instaid of what the user inputted. Here is my html code:   <form id="form" onsubmit="return false;"> <input type="text" id="minNumber" value="Minimum number" onfocus="if         (this.value == 'Minimum number') {this.value = '';}" onblur="if (    this.value == '') " /> <input type="text" id="maxNumber" value="Maximum number" onfocus="if        (this.value == 'Maximum number') {this.value = '';}" onblur="yes" /> <input type="submit" onclick="getNumber()" value="Get random number"> </form>   And this is my JavaScript code:  function getNumber() { var minNumber = document.getElementById("minNumber").value; var maxNumber = document.getElementById("maxNumber").value; var randomnumber = Math.floor(Math.random() *( + maxNumber) + minNumber); alert("Your random number is: " + randomnumber); }   I have tried several fixes including:   Removing some unnecisary spaces, +'s, and 1's adding more variables   Any help would be appreciated. Thanks!


How to stream music over the network to multiple computers?

Results  I want to be able to walk from one room to another and hear the same song playing. Like you do if you were listening to the radio in all rooms.  I want that effect but I want to listen to my own music, can this be done?  Materials   Ubuntu laptop. Mac computer.   First alternative   I have found and setup the software according to   All of the softwares in both computers and server is setup how should I continue?


Can I shorten the large ECDSA public key output file from OpenSSL?

I am working in a very bandwidth restricted environment where I from time to time have the need to distribute public keys. The distribution happens in bit format, so there is no need for encoding, at best I would like all my data "raw".  It is my understanding that the public key, in compressed form, takes up the space of the curve size+1, e.g. 160 bit curve gives 161 bit public key. However, the output from OpenSSL gives me a much larger key size, e.g. 904 bits for the secp160r1 curve. I reckon there must be a lot of metadata involved.  Edit: I removed the "--- Public key starts here ---" etc and that almost cut the file in half ahem. But still there are 60 bytes/480 bits, a lot more than what I would think of as necessary.  Can I somehow reduce this size, getting rid of metadata? For example extract the key components of the signature and reassemble it in a compatible format on the receiver side? I assume DER encoding also adds overhead, but hardly this much?  Here arethe commands I use, in Cygwin:  $ openssl ecparam -out private.pem -name secp160k1 -genkey $ openssl ec -in private.pem -pubout -conv_form compressed -out public.pem


I'm looking for a free hosting provider which provides an SSL Certificate at no additional charge. Does anyone know of a hosting provider which can provide such a service?   Thanks in advance,  Amani Swann


My model is magneta color (MakeHuman model) and I can't put it back.  I tried to change the material and texture but it is still like this.  The magneta  color is everywhere.  I read the others answers but I have this problem


Using Fermat's Little Theorem, prove $1^{p-1} + 2^{p-1} + 3^{p-1} +\ldots+(p-1)^{p-1} \equiv -1 \pmod p$ where $p$ is a prime.    So we would use Fermat's theorem: $a^{p-1}\equiv  1\pmod p$  Would the proof go something like this....?  $1^{p-1} + 2^{p-1} + 3^{p-1} +\ldots+(p-1)^{p-1} \equiv 1+\ldots+1$  There would be $p-1$ many $1$'s so (i.e. $p-1=5-1=4$ so $1+1+1+1=4$)  $p-1 \equiv -1\pmod p$  $p \equiv 0 \pmod p$  Would that be right?


Why is the reputation page not showing + or - reputation points for this question?

On seeing @Glorfindel's Reputation page, there is no reputation change for the highlighted question.    First I thought it might have been undownvoted, but it says upvote. But there is no +5 corresponding to it. Yesterday Glorfindel earned 245 reputation points according to the Reputation page.  This +245 doesn't include that upvote.


Ubuntu 16.04 very slow to boot on my computer.

I have dvds for Linux Lite 32 and 64 bit, would 32 be faster?  (x86_64) I have 2.8 ram


The greatness of Singleton pattern is: Initialize the object (instance) only once. Then we can interact with non-static members. But what more powerful about Singleton pattern is the Constructor.  If we dont need a constructor that initialize objects, then the singleton pattern is meaningless and we can use static class.  But what if we do need to get parameters into the constructor?  The constructor has one role with two options: one to initialize objects to their initial values and the second is to initialize objecs to the values it gets via parameters, so can we say that singleton pattern omits the second one?  Otherwise, what are the diffrences between singleton pattern and static class?  Thanks, Jacob


Improving chances of entering a Theoretical Physics program in the US

I am a current undergraduate student majoring in Physics in a US institution. I am thinking of doing my PhD in Theoretical Physics also in a US institution. I think I know the basic things I should do to have a strong application:    Have a very good GRE score  Do some research in my undergrad institution (some theory research exposure would be good)  Strong letters of recommendation Take advanced courses in Physics and Math in my school.    I am currently in my senior year, is there any extra advice you might have for improving my chances of entering a Theoretical Physics PhD program? Either during my senior year or when I apply ? ( I am planning to apply next year)


Is there a way to find my last visited questions?

I always search in my history browser to find the last questions that I have visited recently, so I spend a lot of time trying to search in my history browser which contains a lot of links. Some times I can't find the link if I cleared the history cache or if I'm connected from an other PC.  It's really easy to realize this feature, this will be done, just by storing the ID of the current subject, and list all those links on a page on the activity tab, or just a client side solution that list all the recent visited subjects on the current session.


Not possible to install anything on Ubuntu 18.04 LTS

It's not possible to install anything on my Ubuntu 18.04 LTS. When I run  sudo apt-get upgrade   I get:  Reading package lists... Done Building dependency tree        Reading state information... Done You might want to run 'apt --fix-broken install' to correct these. The following packages have unmet dependencies:  wine32:i386 : Depends: libwine:i386 (= 3.0-1ubuntu1) but it is not installed  wine64 : Depends: libwine (= 3.0-1ubuntu1) but it is not installed E: Unmet dependencies. Try 'apt --fix-broken install' with no packages (or specify a solution).   When I run   sudo  apt --fix-broken install   I get the error-messages after a while:  Reading package lists... Done Building dependency tree        Reading state information... Done Correcting dependencies... Done The following additional packages will be installed:   fonts-wine libwine libwine:i386 The following NEW packages will be installed:   fonts-wine libwine libwine:i386 0 upgraded, 3 newly installed, 0 to remove and 10 not upgraded. 15 not fully installed or removed. Need to get 0 B/39,9 MB of archives. After this operation, 375 MB of additional disk space will be used. Do you want to continue? [Y/n] Y (Reading database ... 373690 files and directories currently installed.) Preparing to unpack .../libwine_3.0-1ubuntu1_amd64.deb ... Unpacking libwine:amd64 (3.0-1ubuntu1) ... dpkg: error processing archive /var/cache/apt/archives/libwine_3.0-1ubuntu1_amd64.deb (--unpack):  trying to overwrite '/usr/lib/x86_64-linux-gnu/wine/acledit.dll.so', which is also in package wine1.8-amd64 1:1.8.0-0ubuntu1~ubuntu15.10.1~ppa1 dpkg-deb: error: paste subprocess was killed by signal (Broken pipe) Preparing to unpack .../libwine_3.0-1ubuntu1_i386.deb ... Unpacking libwine:i386 (3.0-1ubuntu1) ... dpkg: error processing archive /var/cache/apt/archives/libwine_3.0-1ubuntu1_i386.deb (--unpack):  trying to overwrite '/usr/lib/i386-linux-gnu/wine/acledit.dll.so', which is also in package wine1.8-i386:i386 1:1.8.0-0ubuntu1~ubuntu15.10.1~ppa1 dpkg-deb: error: paste subprocess was killed by signal (Broken pipe) Preparing to unpack .../fonts-wine_3.0-1ubuntu1_all.deb ... Unpacking fonts-wine (3.0-1ubuntu1) ... dpkg: error processing archive /var/cache/apt/archives/fonts-wine_3.0-1ubuntu1_all.deb (--unpack):  trying to overwrite '/usr/share/wine/fonts/coue1255.fon', which is also in package wine1.8 1:1.8.0-0ubuntu1~ubuntu15.10.1~ppa1 dpkg-deb: error: paste subprocess was killed by signal (Broken pipe) Errors were encountered while processing:  /var/cache/apt/archives/libwine_3.0-1ubuntu1_amd64.deb  /var/cache/apt/archives/libwine_3.0-1ubuntu1_i386.deb  /var/cache/apt/archives/fonts-wine_3.0-1ubuntu1_all.deb E: Sub-process /usr/bin/dpkg returned an error code (1)   So something about wine....  Do you have any suggestions?


What would happen to the offspring of a Sharingan user and a Byakugan user?

If Sarada and Boruto got married, would their child get both Sharingan and Byakugan together, or would they get a fusion of these two instead?


MOSFET driving MOSFET for reduced reduced Rds

I am using a PIC to drive the gate of a logic level MOSFET. Although the 5V logic output of the pic is sufficient to exceed the threshold voltage I would like to drive the gate using 12V to reduce the Drain-Source resistance.   In order to achieve this I have drawn up the following circuit using two MOSFETs in series (as highlighted). Will this design work, and is it the best approach (keeping in mind i want to minimize the number of components).


Older movie about crew sent to research abandoned spacecraft

This is a long shot but I am looking for a movie I saw in the early 90's.  It involved a ship sent to research an abandoned ghost ship.  They go through "hyperspace" and find the ship.  The ship they find looks like pole with a ball on the end and it is spinning.  They dock with it and and find computer terminal and restart the computer.  I believe by pressing some crystals on the console.  They ask it some questions and get answers, form a bond but seem uneasy.  Eventually they crew of the rescue ship finds out the planet/star close by is about to implode and they do not have enough fuel to escape.  They end up using the abandoned ship as a booster to get away but not before the computer in the abandoned ship finds out and questions it. They proceed regardless, detaching after fuel is spent in the abandoned ship.  They escape, but the abandoned ship gets destroyed when the planet implodes.  This might be a TV movie, I am not sure.  I saw it when I was around ten so some details may not be 100% but I am pretty sure it is.


This is related to another question I just asked, but they are different enough I thought it deserved its own spot. Speaker elements seem to always be shaped like a cone with a portion of a sphere at the center. What is the physics reasoning behind this shape being so standard? Is it a precise shape that all speaker elements share (e.g. parabaloid + sphere), or just kind of a general shape that "works well"? Does it work just as well for any light solid, or is it actually tuned to the speed at which sound propogates through the speaker element?


Abiword starts automatically each restart, on any user. Already checked out Startup Applications. Remember session is turned off.   ()  Additional info, may be it'll give a clue - I configured VNC server on this machine to run, so sometimes, in additional to regular Ubuntu/Unity sessions I start XFCE4 session. I think this behavior started after VNC4 configuration, but ~/.vnc/xstartup does not contain abiword - just regular xfce startup stuff.  What are additional places where I can look?


Drupal 8 function from controller returns html markups only

I have been creating a table from mysql result , but its printing the html markup only and says controller must return a response . what may be the reason ?      LogicException: The controller must return a response ((5   rows)group_nameparent_nameEditDeleteSelect   itemsL2V9http://192.168.1.236/mailusers/usergroup/edit/6>edithttp://192.168.1.236/mailusers/usergroup/delete/6>delete           L3v3http://192.168.1.236/mailusers/usergroup/edit/7>edithttp://192.168.1.236/mailusers/usergroup/delete/7>deleteAdminsV6http://192.168.1.236/mailusers/usergroup/edit/8>edithttp://192.168.1.236/mailusers/usergroup/delete/8>deleteL4Vodafonehttp://192.168.1.236/mailusers/usergroup/edit/9>edithttp://192.168.1.236/mailusers/usergroup/delete/9>deleteVCNONetworkhttp://192.168.1.236/mailusers/usergroup/edit/12>edithttp://192.168.1.236/mailusers/usergroup/delete/12>delete given). in     Symfony\Component\HttpKernel\HttpKernel->handleRaw() (line 157 of     vendor/symfony/http-kernel/HttpKernel.php).


Reasons to own a non-dividend paying stock?

I’m sitting back doing some self-reflection (procrastination) when I start thinking about stocks. My basic understanding of stocks is that the owner ship of company is split up between owners of any class of shares (relative “power” of share determined by the shareholders agreement).   I can understand that if ever another entity is able acquire more than [insert percentage] of shares then they now control the company. I can understand a person wanting to share in the profits of the company and buys a share that pays dividends.  My curious question is why anyone not wanting to guide a company would buy shares in a company if those shares don’t pay dividends?   The only answer my brain came up with, which I hope is wrong. Is that the only reason to buy a share without dividends is the “gamble”. I equate the level of gambling  to that of poker and not lotto numbers. Skill (example: ability to read and understand a company’s quarterly report) does influence outcome greatly but in the end it is still just a gamble (The McAmazon Apple Company comes out a minute after you made a purchase and says that they’ve fired every employee and will be replacing them with imaginary Umpa lumpas… … Gamble lost).   This gamble makes a lot of sense where over time skillful and knowledgeable people profit over the ones who only think themselves to be skillful and knowledgeable. This like poker makes a medium where people can make a living off the mistakes of others.   I understand that this (gamble) is a part of the stock market and I’m not saying it is good or bad (I really don’t care) I’m just curious if there is a reason other than the gamble to own a stock with no dividends (Note: not planning a hostile takeover or ever casting a vote)  I know this questions seems very vague and broad but I'm 80% sure I'm going to get a straight up "No. People only trade dividendless stocks with the hope of making a profitable trade nothing else." I ask because I am not 100% sure and I hope that someone will show me something new.


How to informally address a mixed gender group of people?

How to informally address a mixed gender group of people in the UK? Any alternative to 'guys' in 'would you guys like to do this and that?'


I tried to make an Array template class but when I try to build the compiler fails to link the constructor and the method and I get :  undefined reference to `Array::Array()  undefined reference to `Array::getSize()  Here is the header file:  #pragma once  template<typename type, int length>  struct Array{ public:     Array();     int getSize();  private:     type data[length];     int m_length; };   The Array.cpp file:  #include "Array.h"  template<typename t, int l> Array<t, l>::Array() {     m_length = l; }  template<typename type, int length> Array<type, length>::getSize() {     return m_length; }   And the main function:  #define LOG(x) cout<<x<<endl int main() {     Array<int, 10> array;     LOG(array.getSize()); }   If someone has any idea about why I am getting this, I would really appreciate.


I am designing a robot using the PIC16F877A microcontroller that will avoid walls and obstacles.  I plan to have it run off of 4 AA batteries.  I was wondering how i would convert the 6 volt input voltage to the 5 volts that the pic needs.  I need to use 6 volts because the h bridge circuit/the motors that I am using require it.  I also need exactly 5 volts, because i need a 5 volt reference voltage for my ADC and to run my sensor off of.  Using two batteries is an option, but I would hope to avoid at all costs.  Finally SMD products won't work, because I would like to build this on a breadboard.  I did ask a similar question here  but my needs have changed since then and the answers wont fit my problem.  How would a normal project overcomethis problem.


I have tried solving the equation but I keep getting zero. I also can't find a proof online, I think because it is a rather specific question.


The easy way: Install Nvidia drivers, CUDA, CUDNN and Tensorflow GPU on Ubuntu 18.04

How can I easily get tensorflow gpu running?


I recently posted some comments to an answer on Math.SE.  I pointed out (politely, I thought) some critical errors in the answer.  Later, on my personal blog (which is linked from my profile), someone with a similar username tried to post a large number of comments containing juvenile insults.  The user's behavior on Math.SE itself has not been abusive, as far as I can tell.    Is it worth bringing this to the attention of moderators?  Should I use a flag or the "Contact Us" button?  Or is this beyond their purview, and I should just handle it like any other abuse on my blog?  I don't so much care about seeing the user punished, but it would be nice to help prevent anyone else from being similarly annoyed by this person.  (I haven't linked the answer here to avoid public escalation, but I can if it would help.  Anyway, it's since been deleted.)  Edit: michaelb958's comments below suggest the user has also been posting similar insults on MathOverflow, so his abuse does include the SE network itself.  I'm contacting team@stackoverflow.com and will pass along my logs.


Allow anonymous users to subscribe to newsletter/mailing list

My aim:  Client side: Have a block in the front page to allow any user (including anonymous users) to input their names and email addresses to subscribe the newsletter. Administration Side: being able to see the mailing list and send out newsletter to these emails.   What I have got: I downloaded and enabled the follow modules: Mail System, Mime Mail, Mime Mail Action, Mime Mail CSS Compressor, Simplenews, SMTP Authentication.   I am using Drupal 7 with Bootstrap theme.  What I have done: I have added a new simplenews block in the front page only, styled a little bit. In permission section, I ticked both ANONYMOUS USER and AUTHENTICATED USER for 'Subscribe to newsletters' option.  Problems:  I input my email and clicked the subscribe button in the block as a anonymous users, there is an error:     Unable to send e-mail. Contact the site administrator if the problem persists.   Followed by a notice:     You will receive a confirmation e-mail shortly containing further instructions on how to complete your subscription.   The SMTP Authentication module doesn't work for my account because it said my php doesn't have ssl enabled, which I don't know how to do? I have enabled ssl module in my apache, but what shall I do next?   Also I then see no subscribers added when I log on as an administrator later.   Question: How can get let anonymous subscribe to mailing list and how can I create newsletter? Any instructions on how to achieve this? Am I using the wrong modules?


Find the kernel of a ring homomorphism $f(x)\to f(\sqrt 2)$

Let $$\phi:\mathbb Z[x]\longrightarrow \mathbb R$$, where $$\phi(f(x))=f(\sqrt 2)$$  find $$\operatorname{Ker}(\phi)=\{f(x)\in \mathbb Z[x]\mid f(\sqrt2)=0\}$$  1st) I wanted to use isomorphism theorem since we have $\mathbb R$-field so $Z[x]/\ker\phi\simeq \mathbb R$ so we find that $\ker\phi$ maximal ideal so it must be irreducible minimal polynomial which has root $\sqrt2$ that is $x^2-2$ but $\phi$ is not surjective.  2nd) Let $f=f_0+f_1x+f_2x^2+f_3x^3+f_4x^4+..$ since $\\f(\sqrt2)=0$ we have $$\\f_0+2f_2+4f_4+8f_6+...=0\\ f_1+2f_3+4f_5+...=0$$but how to show $x^2-2\mid f(x)$


This message keeps appearing "java.util.NoSuchElementException"

import java.util.Scanner;  public class DisplayBox2 {  public static void box (int length, int width){       Scanner input = new Scanner (System.in) ;     String Answer;       System.out.println("Do you want to use a special character to use to display the box ?");        Answer = input.nextLine();      if (Answer == "Yes"){         System.out.println("Please enter the character that you would like to display the box");         int Char = input.nextInt();      for (int i = 0; i < length; i++) {            for (int j = 0; j < width; j++) {                 System.out.print(Char +" ");             }             System.out.println("");         }     }      if (Answer == "No"){          for (int i = 0; i < length; i++) {             for (int j = 0; j < width; j++) {                 System.out.print(" *");             }             System.out.println("");         }     }       input.close();  }  public static void main(String[] args) {     // TODO Auto-generated method stub      Scanner input = new Scanner (System.in);        int length, width ;       System.out.println ("Please enter the length of the box");      length = input.nextInt();     System.out.println (" Please enter the width of the box");     width = input.nextInt();       input.close();        box (length, width);    }   }  i dont understand what the error is in my code. can anyone please help  Please enter the length of the box  5  Please enter the width of the box  5 Do you want to use a special character to use to display the box ?  Exception in thread "main" java.util.NoSuchElementException: No line found  at java.util.Scanner.nextLine(Unknown Source)  at methods.DisplayBox2.box(DisplayBox2.java:14)  at methods.DisplayBox2.main(DisplayBox2.java:56)


How to get inverse of formula for sum of integers from 1 to n?

I know very well that the sum of integers from $1$ to $n$ is $\dfrac{n\times(n+1)}2$. What I'm interested in today, and cannot find a solution for, is performing the opposite operation.  Let $m = \dfrac{n^2 + n} 2$. Knowing the value of $m$, how do I figure out the value of $n$? I could easily program a solution but I'd much prefer an algebraic one.


So I finished making the bottle, and added a simple red liquid to it. On the render preview, it looked great, but when I hit actual render, it became weird like this:   If I add smooth shading then it looks like this:   How do I fix the reflections and the little stripes around the liquid? I rendered it in these settings: Samples: 300 render, 300 preview...Resolution: 800x800px (80%)


I'm study Learnpythonthehardway, in ex40, I met this slice of code.  for sentence in snippet, phrase:     result = sentence[:]   I'm not quite understanding sentence[:] here, especially the [:]  I've tried to figure it out by underlying test code:  sentence = 'sss errf : fe : eee' f = 33 result = sentence[:f] print result   but nothing happens, result is the same as the sentence  So, smart geeks, what does sentence[:] mean here?


So, as an exercise to greater understand some things about cryptography, I decided to try and implement GOST 28147-89, which uses eight 4x4 S-Boxes. I can grasp the concept of putting 4 bits through the S-Box and getting four out, but how would one reverse this?  Furthermore, how would one reverse uneven S-Boxes, such as DES's 6x4 S-Box, when multiple inputs give the same output (e.g., for DES's S-Box S5, where inputs of 100011, 101110, 011101, and 010000 all give an output of 1000).


Which Stack Exchange site is for asking about Facebook?

I want to ask question about problems in my Facebook account. On which Stack Exchange site should I ask?


Unable to format disk: 'The system cannot find the file specified'

I have a USB flash drive, which I may have mucked up, so I used DISKPART's CLEAN to clean it up. I created a simple volume, and tried to format it. (This is all using Windows' disk management.) I was told The system cannot find the file specified.  So I tried using DISKPART (as an admin):   DISKPART> select volume 9  Volume 9 is the selected volume.  DISKPART> format recommended  DiskPart has encountered an error: The system cannot find the file specified. See the System Event Log for more information.  DISKPART>   As you can see, no luck.  When I plug the drive in, the computer makes a beep noise as though it has recognised something, but nothing appears in My Computer  How can I format the disk so I can use it again?


I will talk to you vs I will talk with you?

Which one is correct ?     I will talk to you tomorrow      or     I will talk with you tomorrow


What's the possible reason why NPE is throwed when call CallVoidMethod with JNI in my situation

Scenario: I have built a DLL with Cpp which is used by a java applicaton with JNI. The DLL will call method in Java too. However, when I call CallVoidMethod, a java.lang.NullPointerException will be printed in java console.  The code is like below:  void CaptureCallback::ACallbackMethod(){     jvm->AttachCurrentThread((void **)&env, NULL);     jmethodID mid= env->GetMethodID(cls, "helloWorld", "()V");     cout << "The jmethodID is : " << mid << endl;     cout << "The jobject is : " << jobj << endl;     cout << "The env is: " << env << endl;     env->CallVoidMethod(obj, mid );     jvm->DetachCurrentThread(); }   What I have tried so far:   The value of jmethod is not zero. It means that I have found the method which is in Java side.(Pls correct me if I'm wrong.) Both jclass cls = env->GetObjectClass(jobj); and jclass cls = env->FindClass(absolute_path) are tried to get jclass info.   The stacktrace is so simple and it is:  Exception in thread "Thread-2"  java.lang.NullPointerException  So it's hard for me to locate the cause.  Current progress： I managed to call the helloWorld method when I put ACallbackMethod's body into the Constructor method. The constructor method is look like:  CaptureCallback::CaptureCallback(JNIEnv *p_env, jobject p_jobj){         env = p_env;         jobj = p_jobj;         jvm->AttachCurrentThread((void **)&env, NULL);         jmethodID mid= env->GetMethodID(cls, "helloWorld", "()V");         cout << "The jmethodID is : " << mid << endl;         cout << "The jobject is : " << obj << endl;         cout << "The env is: " << env << endl;         env->CallVoidMethod(obj, mid );            jvm->DetachCurrentThread(); }   The CaptureCallback is a class which inherits from an IDL generated header file and the CaptureCallback::ACallbackMethod is kept called from native side.The undeclared variable like env, jobj and so on are declared in CaptureCallback.h files.


I'd like to find all the files suffix with .md or .org    find ~ -iregex ".*\.md$" find ~ -iregex ".*\.org$"   How could combine them?


Is $(2, X)$ a prime ideal in $\mathbb{Z}[X]$?

By definition, we have that an ideal $I$ is a prime ideal if, for all $ab \in I$, either $a \in I$ or $b \in I$. However, I don't know how to use this definition to show that $(2, X)$ is a prime ideal.


Solve for $θ$: $θ − sin(θ) = \frac{2A}{r^2}$

Can someone assist here? $$ \theta − \sin{\theta} = \frac{2A}{r^2}  $$ How would I solve for $\theta$?  My precalc is quite rusty.  Basically looking for way to get either the angle of a segment or the height of one using radius and area.


Prove for that $(1 + \frac{x}{p})^p < (1 + \frac{x}{q})^q$ [without Bernoulli inequality or integrals]

Prove for $x > 0$ and  $0 < p < q$ that $$(1 + \frac{x}{p})^p < (1 + \frac{x}{q})^q$$  I think that binomial theorem might be of use in this exercise, but I'm not sure. I haven't been able to prove this on my own. Could you give me a hand with this?  EDIT: I'm not supposed to use integrals or Bernoulli inequality.


Help with installing Minecraft Mods on a Mac

Having problems with mods not appearing in Minecraft on Mac OSX 10.8.5.  I have installed Forge and the 'Mods' button appears OK under the 'Multiplayer' button in Minecraft.  I have downloaded some Mods and placed them into the ~Library/Application Support/minecraft/Mods folder.  I have tried removing the META-INF folder from the Minecraft folder.  In Minecraft, I have created and saved new profiles for Forge 1.6.4 and Forge 1.7.2  But when the game loads only the 3 default mods appear in the Mod List: a) Minecraft Coder Pack b) Forge Mod Loader c) Minecraft Forge.  No child mods.  None of my downloaded mods appear!!  I have read forums, watched videos, tried everything I can think of.  If you know how to do this on a Mac, I would really appreciate your help. Thanks.    I have also tried all the steps listed on the duplicate link below.  But this hasn't worked either. I am new here and don't have a 50 reputation to be able to comment on this thread. Also the question was asked two years ago, and wondering if the advice will still work for the latest versions of Minecraft and Forge?   1. Download the .ZIP file 2. Extract it to some directory. 3. Go to the directory you just created. 4. Open a new Window 5. Go to ~/Library/Application Support/minecraft/bin 6. Look for a file called minecraft.jar 7. Rename that file to minecraft.jar.zip 8. Unzip it 9. Drag all files ending with .CLASS into the minecraft.jar FOLDER 10. Delete the META-INF folder. You're done!


Is it OK to cross-post an old, unanswered question?

I've seen a question on a site I don't have an account on. The question was very interesting and it's also on-topic on this other site, where I am an active user on.  The question is on-topic on both sites.  Is it OK for me to post the same question (possibly with linking to the original) on the site I'm active on?


I am writing simple report for my company's board. Is that possible to simple tell what kind of license is used in Ubuntu Server? I would like to know if thats possible to let the Ubuntu Server in basic configurations is "distributed under GPL" or "distributed under AGPL" etc...


Prove the multiplicity property for $n!$

I was given this hint in a different problem,  Now use that a prime $p$ occurs in $n!$ with multiplicity exactly $\lfloor n/p\rfloor + \lfloor n/p^2\rfloor  + \lfloor n/p^3\rfloor + \lfloor n/p^4\rfloor +\ldots$ For $$P=\frac{200!}{2^{100}\cdot 100!}$$ And the prime being $p = 3$.  How is the claim for $n!$ true? Consider $n \ge 6$. $$n = 6 \implies n! = 720$$ $$720/3 = 240 \to 240/3 = 80 \implies \text{3 comes in twice.}$$ Then, $[6/3] + [6/9] = 2$. So suppose $3$ occurs in $n!$ with multiplicity,  $\lfloor n/p\rfloor + \lfloor n/p^2\rfloor  + \lfloor n/p^3\rfloor + \lfloor n/p^4\rfloor +\ldots$ It is required to show that, for $(n+1)!$, $3$ occurs in multiplicity, $\lfloor n+1/p\rfloor + \lfloor n+1/p^2\rfloor  + \lfloor n+1/p^3\rfloor + \lfloor n+1/p^4\rfloor +\ldots$ $(n+1)! = (n+1)n!$. But I cant prove anything else. Even intuitively, why does this make sense?


Error when importing photos with PhotoImport Plugin in QGIS

I have a lot of Photos with  lat, long, and altitude information. When I start the import, I get an error message. Do I need to prepare a blank point layer before importing? Is there another Python Plugin that is required? I use win7 and Lisboa.


Changing the values of an integrable function $f:[a,b] \to \mathbb R$ countably infinitely many points not a dense subset of $[a,b]$

Let $f:[a,b] \to \mathbb R$ be a function Riemann integrable over $[a,b]$ . It is known that if we change its values at finitely many points of $[a,b]$ , then the changed function still remains Riemann integrable on $[a,b]$ . My question is , suppose we change its values at countably infinitely many points of $[a,b]$ such that the set of this points is not dense in $[a,b]$ ; then is it true that this changed function is Riemann integrable on $[a,b]$ ?


How to determine CPU and memory consumption from inside a process?

I once had the task of determining the following performance parameters from inside a running application:   Total virtual memory available Virtual memory currently used Virtual memory currently used by my process Total RAM available RAM currently used RAM currently used by my process % CPU currently used % CPU currently used by my process   The code had to run on Windows and Linux. Even though this seems to be a standard task, finding the necessary information in the manuals (WIN32 API, GNU docs) as well as on the Internet took me several days, because there's so much incomplete/incorrect/outdated information on this topic to be found out there.  In order to save others from going through the same trouble, I thought it would be a good idea to collect all the scattered information plus what I found by trial and error here in one place.


I used to be able to look at the Top Challenger Players (), and click on them, but I got into Ranked and it doesn't work anymore).  How do I watch a specific player's game?


Do null and alternative hypotheses have to be exhaustive or not?

I saw a lot of times claims that they have to be exhaustive (the examples in such books were always set in such way, that they were indeed), on the other hand I also saw a lot of times books stating they should be exclusive (for example $\mathrm{H}_{0}$ as $\mu_1=\mu_2$ and $\mathrm{H}_{1}$ as $\mu_1>\mu_2$) without clarifying the exhaustive issue. Only before typing in this question I found somewhat stronger statement on the  -- "The alternative need not be the logical negation of the null hypothesis".  Could someone more experienced explain which is true, and I would be grateful for shedding some light on the (historical?) reasons for such difference (the books were written by statisticians after all, i.e. scientists, not philosophers).


After replacing my motherboard I lost the boot option for Windows 10

I just replaced my motherboard, and now my Windows hard drive (secondary) seems not to be detected. I'm running Ubuntu 16.04 on my main hard drive and Windows 10 on my 2nd.


Let $f:D \to \mathbb{R}$ be a real function with $U \subset D$ an open interval. Suppose that $f$ is $k$ times differentiable at $a \in U$. Then $$R_k(x) \in o(|x-a|^k) \  \text{as} \ x \to a$$ where $R_k(x)=f(x)-P_k(x)$ and $P_k$ is the $k$th order Taylor polynomial of $f$  evaluated at $a$.  Like , I am somewhat averse to the usage of L'Hospital's rule. Is there a proof of the above without it? Note the minimal conditions on $f$.


Finding the equation of an ellipse tangent to two lines

Find the equation of the ellipse tangent to the two lines $$x-4y=10$$ and $$x+y=5$$  I know that the equation of ellipse in general is  $$ \frac{(x-x_0)^2}{a^2} + \frac{(y-y_0)^2}{b^2}=1$$  but how can continue? I substituted for   $x $ from the equations of the two lines in the equation of ellipse but it still difficult to continue!  is it true to take $(x_0,y_0)=(0,0)$ ??


Is passing object to constructor pass by reference

Suppose I have a class and constructor called TestClass.  public class TestClass {     Foo foo;      public TestClass(Foo foo) {         this.foo = foo;      } }   Here, the constructor accepts an object which is an instance of class Foo. Suppose my static void main(String[] args) does the following, completely separate from any TestClass;   (1) Instantiate foo (2) Pass instance foo to TestClass constructor (3) Change the internal state of foo   After step (3), will the foo within my instance of TestClass also have its state changed?


I am currently working on a single page website. I am trying to retrieve the page content via AJAX.  The page URL is http://mylocalserver/sad/wp/clients.      $.get( 'http://mylocalserver/sad/wp/wp-admin/wp-ajax.php',            {             'action' : 'retrieve_content',            'page_title' : 'clients'           }, function( response ){             if ( !response.error ) {               alert ('AJAX request made! The post title is ' + response.post_title );             } else {               alert ('error: ' + response.error );                 }         });   in my php functions.php      function retrieve_content(){     $page = get_page_by_title( 'clients' );     $content = apply_filters('the_content', $page->post_content);      var_dump($content);     exit();      }   It says Page not found, whereas if I visit the page via URL the content appears. I have hard coded the page title in the PHP function as-well.


is that function must be constant under the following conditions

I'm talking about complex function   $f$ is analytic function on a region $D$ that include the point $z=0$. for every $n\in N$ such $\frac{1}{n}$ is in $D$ , the function follows this condition $|f(\frac{1}{n})| \leq \dfrac{1}{2^n}$   is that function must be constant ?


I'd like to know how to show the blue "notification" dot on a tab. Something like this  But every page I search, says something about pinning, and chrome deleted this function. Well, how is Reddit doing it then (while it's not being pinned as well)? Does someone know? It will obviously have to be JavaScript. I basically only use Chrome, so another question would be, do other browsers also have such functionality?


What is the answer of series of $n+(n-1)+(n-2)+\cdots.+1$

I need a help regarding my question I searched a lot  Somewhere I found the answer of the sequence is $\frac{n(n-1)}{2}.$


I am having trouble proving that it is equal to zero analytically. I have tried plotting and know that for $0<x<1$ the integrand is negative and positive otherwise. I have tried substitution $u\to \sqrt{x}$ but I cannot proceed further.


Windows suddenly reports "This copy of Windows is not genuine"

Recently, my Acer Aspire 5050 that came with a copy of Vista, went through a series of Automatic Upgrades.  Now, in the bottom of the desktop, I get "This copy of Windows is not genuine".  Apparently, because of this, I cannot open "Properties" on Computer, or open the Control Panel, etc.  This makes gathering information (like the Service Pack) difficult at best.  I've gone through several steps to prove/disprove that this is correct.  I've verified the product key by following the instructions on .  I did the steps with slmgr.vbs -ipk AND slmgr.vbs -ato.  This told me that my product was successfully activated.  To me, this would imply that this is a Genuine product.  I've also called the US Activation number, which gave me a response, which was successful.  Never on the phone was I given any information suggesting that the Activation code generated was invalid (I have been given the suggestion on an improper install of XP).  However, when I downloaded , it tells me that I have an Invalid License.  The product key it lists matches what I show on the bottom of the machine.  The install media was requested directly from Acer, since they didn't provide any disks initially.  Looking at the disk they sent, however, it looks like what they sent me was a Windows Anytime Upgrade disk.  Is this the correct disk?  If not, will I need to reinstall to fix the problem?  If so, does anyone know where I can get an OEM 32bit Vista ISO?


Locked out of my phone. How can I backup my sms?

I am locked out of my Samsung Galaxy y Duos Lite and I have forgotten my password. USB debugging is not turned on. Is there any way to backup my sms onto my pc??


Groups - Prove that if $G/Z(G)$ is cyclic then $G$ is abelian

Prove that if $G/Z(G)$ is cyclic then $G$ is abelian. Using this fact and $G$ is a nontrivial group of prime power order, deduce that a group of order $p^2$ , $p$ prime, is abelian.


I am developing a custom module in Drupal 8. My custom module include many JavaScript and CSS files which make the site really slow and I don't want them in all pages. I have developed some custom blocks and each JavaScript and CSS library correspond to a block. I want those files on those pages of the site where my custom blocks are visible.  In my last Drupal 8 project, I have done something like the following.  function HOOK_page_attachments(array &$attachments) {     $user = \Drupal::currentUser()->getRoles();      if(in_array("administrator", $user)){         $attachments['#attached']['library'][] = 'module/library';     } }   I am not sure how to check which blocks are visible in the page.


I am experimenting with a simple python code.  import numpy as np  x, y = np.full(5, 5.0), np.full(5, 5.0) print("{} + {} = {}".format(x, y, x + y))   I get this output, which is expected:  [5. 5. 5. 5. 5.] + [5. 5. 5. 5. 5.] = [10. 10. 10. 10. 10.]   But when I do this:  import numpy as np  x, y = np.full(5, 5.0), np.full(5, 5.0) print("{} + {} = {}".format(*x, y, x + y))   I get this output:  5.0 + 5.0 = 5.0   What does *x do in this case?


Image of complex circle under polynomial

The question is, how many times does $f(C_r)$ go around $0$ for $C_r = \{x \in \mathbb{C}: |x|=r\}$ and a polynomial with complex coefficients $f$.    The answer is clear to me when $f(x) = ax^n + b$ but I don't see how exactly middle terms affect the result. How to see this without a graph? Can this be found for any $r$?    Many thanks


I'm looking for a decent sort implementation for arrays in VBA. A Quicksort would be preferred. Or any other  other than bubble or merge would suffice.  Please note that this is to work with MS Project 2003, so should avoid any of the Excel native functions and anything .net related.


If $\{u,v,w\}$ is a basis for $V$, then $\{u+v+w,v+w,w\}$ is also a basis: is this proof correct?

Let $u,v,w \in V$ a vector space over a field F such that $u \neq v \neq w$. If $\{ u , v , w \}$ is a basis for $V$, then prove that $\{ u+v+w , v+w , w \}$ is also a basis for $V$.  Proof:  Let $u,v,w \in V$ a vector space over a field $F$ such that $u \neq v \neq w$. Let $\{ u , v , w \}$ be a basis for $V$. Because $\{ u , v , w \}$ is a basis, then $u,v,w$ are linearly independent and $ \langle \{ u , v , w \} \rangle = V$.   Let $x \in V$ be an arbitrary vector then $x$ can be uniquely expressed as a linear combination of $\{ u , v , w \}$. Let's suppose $x=au+bv+cw$ for some $a,b,c \in F$.   On the other hand, let us consider $\{ u+v+w , v+w , w \} \subseteq V$.  Then $$ \begin{align*} \langle \{ u+v+w , v+w , w \} \rangle &= \{d(u+v+w) + e(v+w) + f(w) \mid d,e,f \in F\} \\ &= \{du + (d+e)v +(d+e+f)w \mid d,e,f \in F \} . \end{align*}$$   If $x \in V$, then $x=du + (d+e)v +(d+e+f)w$ is another unique representation of $x \in V$ . Then for any arbitrary $x \in V$, we have $d=a$, $d+e=b $and $d+e+f=c \in F$.   Because $\{ u , v , w \}$ is a basis for $V$, then $\{ u+v+w , v+w , w \}$ must also be a basis for $V$.


Expected Number of Coin Tosses to Get Five Consecutive Heads

A fair coin is tossed repeatedly until 5 consecutive heads occurs.   What is the expected number of coin tosses?


How can I get data off of a damaged thumb drive?

A guy I work with just came by to ask me about a damaged thumb drive/USB flash drive.  Apparently his son dropped it on a hard surface and it won't power up anymore.  They've tried plugging it into multiple machines without success, even though each port they tried was able to power other USB devices.  He knows it's not a lost cause because a local tech store is offering to recover the data for $500, but he says they're not worth that much.  I figured someone on SU would have an idea about this; he doesn't care about using the drive in the future, just wants to salvage a few files that would be a pain to recreate.  Is this possible without advanced equipment, and if so, how?  He said he already tried the advice on the Internet about typing in different drive letters and such, but that failed because there was no power going to the drive.  He also said that he opened the case up at one point, but I'm not sure what, if anything, he did inside.


In my page I have a textfield input (with id myname). And when I writing a name in that field, I jusing $.get to get some name-suggestion to the input. All this div objects has a class "sug". And all that data is appended in a div with the id "nameHint".  $("#myname).keyup(function(t){     $.get("getname.php", {q:value}, function(data){         nameHint.removeClass("hid").html(data);      }).fail(function(){nameHint.html("").addClass("hid");});     t.preventDefault(); });   And the div nameHint is showed on the page. And is works perfectly. After that when I click on one of the div, with a class sug, I want something to happend. Lets say I want to print the current div html-cod. I would used this code:  $("div#nameHint div.sug").on("click", function(){     alert($(this).html()); });   But this on-event doesn't do enyting.  What am I doing wrong??


Need help with an exercise on a sequence with integrals.

Let $(I_{n})_{n \in \mathbb{N}}$ defined by $\forall n \in \mathbb{N}, I_{n}= \displaystyle \int_{0}^{\pi/4}\tan^n(x)dx.$  I proved that $(I_{n})_{n \in \mathbb{N}}$ decreases.   I'd like to prove that $\forall n \geq 2$, $\frac{1}{2(n+1)} \leq I_{n} \leq \frac{1}{2(n-1)}$.  Can anyone help me get started please? Thanks a lot.


I have a textbox where i write a int. I want to use this textbox to construct my object.  Main.cs :  private void SauvegarderMoto_Click(object sender, EventArgs e)         {             try             {                 Moto maMoto = new Moto(                     maMarque.Text = lesMarques.SelectedItem.ToString(),                     monModele.Text = lesModeles.SelectedItem.ToString(),                     monMoteur.Text = lesMoteurs.SelectedItem.ToString(),                     maCylindree.Text = lesCylindrees.SelectedItem.ToString(),                     monAnnee.Text = Convert.ToInt32(lesAnnees.Text)                     );                 MessageBox.Show("Moto enregistrée avec succès !", "Information");                 tabControl1.SelectTab(MaMoto);             }             catch(Exception)             {                 MessageBox.Show("Il manque des informations !", "Information");             }         }   Thanks for help


Let be D a unique factorization domain, k in D and $x=kd $ with $d$ a gcd of $a, b$ and $y$ a gcd of $ka, kb$ prove that x and y are associates; x divides y and y divides x. My attempt:  x=kd and a=dr, b=ds hence ka=kdr, kb=kds so ka=xr, kb=xs hence x divides y because y is gcd of ka and kb.  How to prove that y divides x?


How to get list of installed/enabled modules ready for repopulating new site with drush module installation?

When doing drush pm-list I get a whole list of modules but too much info also, like this:  Mail               Privatemsg filter (privatemsg_filter)          7.x-1.4 Mail               Privatemsg Limits (privatemsg_limits)          7.x-1.4 Mail               Privatemsg roles (privatemsg_roles)            7.x-1.4`    I have to edit in notepad++ and run macros...  I want the module list, but ONLY drush module names X_Y   Is there a way to get a clean list like:  module_a module_b module_c    ONLY  And then can use it as:  drush en module_a module_b module_c


Dynamic type languages versus static type languages

What are the advantages and limitations of dynamic type languages compared to static type languages?  See also:  (a far more argumentative thread...)


I did something really stupid yesterday...    I accidentally did some weird command with mv and made it so the Linux filesystem could not find anything.    Anyhow, I reinstalled Ubuntu 11.10 from the same disk I did the first time, and then upgraded to 12.04 just like last time and it hasn't been the same.     Now I have to boot into recovery mode or else I get stuck on the splash screen.   After I log in I often have strange problems with the mouse and GUI.   The other thing is I'm still left with pieces of the old filesystem on the last Ubuntu partition. I think that might be interfering with the current one. How do I delete it?     Also, could there be other causes?  Thanks.


Installing Nvidia drivers on ThinkPad w530

I am on a ThinkPad W530 and have just installed Ubuntu. Which one of these drivers do I install?   Does the command sudo apt-get install nvidia-current install current drivers?     EDIT: I used sudo apt-get install nvidia-current and now there is a nvidia_304 driver activated in Additional Drivers:  If you have Optimus enabled in the BIOS, you either have to disable it or install Bumblebee


This is my first post to stackoverflow, so please let me know if I don't follow the correct etiquette.  I am also new to Python and would like to incorporate it into a project.  I currently have a Emotiv EEG headset and would like to run a homebuilt 3-D Printer from brain signals.  To do so, the EEG headset is read by EmoKey 2.0.0.20 (see attached photo), EmoKey will then send keystrokes to the Python Shell, Python interprets this and sends commands to my Arduino run printer through a COM PORT.  This may seem to be an indirect way of doing things, but it works except for one hitch.  Lets pretend I think left, this is sent to EmoKey which types 'L' and the keystroke Enter into the Python Shell.  In theory this would then move the printer head left.  However, when EmoKey sends Enter it only creates a new line in the Shell, it doesn't actually execute.  I then have to press enter by hand, which defeats the whole point.    .getch() hasn't worked because I don't think there is an actual key stroke for it to read. The link below also seems like it would be useful, but It hasn't worked thus far.     My question is: How can I get Python to execute what is written in the shell when only something like L or R is written?  I don't think I can have it wait for a keystroke, Python would have to wait and automatically execute when it sees a specific command.   I understand that this may seem like a duplicate of the link below.  However, .getch hasn't worked with EmoKey so far (maybe it's just a mistake on my part).  Also, I wan't to find a way for my Python script to read what is put into the shell.  Although I've started this project with just the "L" and "R" commands for simplicity and prototyping, I will move into using G-code so I can communicate with other printers or CNC equipment.  That is another reason why .getch won't work in my case since it only grabs a single character (A single G-code command will be a few characters long).   I'm using Windows 10 and Python 2.7.11.   import serial  ser = 0  def init_serial():     COMNUM = 3          #Enter Your COM Port Number Here.     global ser          #Must be declared in Each Function     ser = serial.Serial()     ser.baudrate = 9600     ser.port = COMNUM - 1   #COM Port Name Start from 0      #ser.port = '/dev/ttyUSB0'       #Specify the TimeOut in seconds, so that SerialPort     #Doesn't hangs     ser.timeout = 10     ser.open()          #Opens SerialPort      # print port open or closed     if ser.isOpen():         print 'Open:'  + ser.portstr  init_serial()  while 1:      temp = raw_input('Send command + Enter:\r\n')     ser.write(temp)         #Writes to the SerialPort      #bytes = ser.readline()  #Read from Serial Port     #print 'Response: ' + bytes      #Print What is Read from Port


Using "I had rather" instead of "I would rather"

While commuting to work, I encountered a bumper sticker that said      "I had rather be on/Cape Point Fishing".   I found this curious, since I always thought that the correct expression would be "I would rather be...", instead of "I had rather be".   Is there a joke I'm not getting, or was this bumper sticker just incorrect?


I use Ubuntu-Gnome 13.04 and I can't change system language. I set it to Polish with "language & regions". It was though because there is no option for adding so i installed:  language-pack-pl  language-pack-gnome-pl  then i could pick it in "language & regions" and then reboot. However this didn't solve my problem  I also change it with gnome-language-selector and still got english.  Please help, because if the language is other than polish i will have to switch back to windows. I like the gnome3.


Is there any kind of hash code function in JavaScript?

Basically, I'm trying to create an object of unique objects, a set. I had the brilliant idea of just using a JavaScript object with objects for the property names. Such as,  set[obj] = true;   This works, up to a point. It works great with string and numbers, but with other objects, they all seem to "hash" to the same value and access the same property. Is there some kind of way I can generate a unique hash value for an object? How do strings and numbers do it, can I override the same behavior?


Is Data Normalization absolutely required for training a neural network?

I am relatively new to Deep Learning and wanted to implement a Variational Autoencoder for images. For data preprocessing I only rescaled the pixel values from the range of [0..255] to [0...1]. The training looked good. The reconstructions of the VAE were pretty good and the loss-curves also looked good. Now I read that many people tell you to normalize the data, so that the image data for example have the mean = 0 and std = 1. Is this really necessary for training and crucially changes the results from training or is rescaling the images enough?


Combinatorial Proof with Summation Identity

Must show:     $\sum_{i=0}^n i{n \choose i} = n2^{n-1}$ using a combinatorial argument. I have tried picking the problem apart by determining that the summation is equal to 1/2 of the size of all subsets of a set of size n times n.  But I am having trouble relating that to what each term of the summation represents.


Why doesn't attempting to edit count as a pass for a review audit?

I just got a question in the review queue that, though poor, I thought was potentially salvageable via editing.  However when I clicked the Edit button I got the deleted post error.  Since the post was gone, I clicked I'm Done (what is there do do with a deleted post?) only to get the review audit failed message instead.  The current behavior is also problematic in that, now that I know about it, it's a risk-free way to check if a question is an audit and not an actual review. That allows me or anyone else who knows about it to detect audits without having to recognize that the question is bad.


How does curved space make an obejct move toward Earth?

I think I understand how the equivalence principle shows how light can bend and therefore space must be curved. What I do not understand is how curved space makes an object move directly toward the center of the earth.  I think what I am missing is how time is bent in the presence of mass as well.  If some could please explain how time is bent in the presence of mass, and how curved space results in an object moving straight down when I drop it. GR is driving me crazy.


I read somewhere that mass affects gravity– if the mass of the objects are larger, then the force of gravity between them is larger. So, does this mean that the gravity between 2 massive objects is greater than the gravity between 2 smaller objects? With this, if you drop a golf ball and a rubber ball (same size) on the earth, shouldn't the force of gravity between the rubber ball and earth be greater than the force of gravity between the golf ball + earth? Therefore, shouldn't the rubber ball fall to the ground faster than the golf ball? But this was disproved, so I have some confusion about it.


I installed Ubuntu 14.04 last night on my Lenovo X200, Dual Core 2.4GHz 3GB RAM and 250GB HDD. Everything was working fine, and this morning when I powered it up to double check everything, it was all good.   I came into work and all booted up fine.   However, when I tried to login (password protected user); only user on the computer - It logged in fine but was stuck straight away, with the blank screen (the background of the login screen) and just my cursor. Nothing else.   I left it for a few minutes thinking it was just being a little slow, but to no avail nothing happened. I have tried a reboot and nothing happened.


Add an array of string with another using for loop

Hi I use for loop to add the strings which is in array. Can anyone help me for the below code it shows error.  image = new String[] {"APP","FIELD","KYC"};  image2 = new String[] {"MEMORANDUM","ASSOCIATION"};   Now using for loop or any method I need the same image array as  image = new String[] {"APP","FIELD","KYC","MEMORANDUM","ASSOCIATION"};


What is this permanent connection to Microsoft by Explorer?

Here is a screenshot of Windows Explorer looked deep into using process explorer.  I am not sure of the why a connection is required to Explorer? My OneDrive has been disabled and nothing's happening in the Explorer too. Can anyone let me know more about why msft is connected here?


Why did humans want to solve the gravity equation?

In the movie Interstellar, there's a lot of things that I don't get.   Humans, most significantly Dr Brand, were hard at work for years solving the gravity equation. Brand wanted to do something to help humans leave the Earth, he'd known for a while we were dying a slow death, and he wanted to save the species by its relocation, either with Plan A or Plan B.  The station that housed NORAD seemed to be designed to be able to take off, but why would we need the equation solved for that? Supposedly, if we never needed to come back to the Earth, we'd have a lot of fuel to burn to propel the facility out, right?  Also, how does Cooper Station tell us that we did solve gravity? It's just a huge station orbiting Saturn, so we didn't even go beyond the Solar System. So it's less than believable if we were trying to 'use' gravity to travel faster than light (I just can't see how that comes to be).  What is it, then? Were we trying to conquer time? Travel faster than light? Evolve to the beings that were shown in the movie?  The part that intrigued me the most is this dialogue:     Murph: His solution was correct. He'd had it for years.      Getty: It's worthless?      Murph: It's half the answer.      Getty: Okay, how'd you find the other half?      Murph: Out there? A black hole. But stuck here on Earth, I'm not sure you can.