I have read through other questions/answers related to the downvote system and I must say, I feel this system needs revising. Sometimes a downvote is meant with good intentions.  Before I go any further, I would like to preface this suggestion a little bit. I personally try to suggest revisions or pose a question to the author in cases that might warrant a downvote. This gives the author a chance to either revise or defend their post; thus it gives both the author and myself an opportunity to learn something new. Overall, though, I try not to downvote authors unless their question/answer is completely absurd/unrelated; however, even in these situations, I still try to provide the author some feedback, tell them why I downvoted them, and wait to hear back from them. I believe it is only fair that the author knows my thoughts and can hear my reasoning if I am going to downvote them. This is what leads me to my suggestion.  I believe the downvote system should be revised in the following ways:   Downvotes should cost slightly more reputation. (Maybe 5 reputation points to cast a downvote.) If you have downvoted a post, but you leave a comment on it, the cost of the downvote should be refunded. If you have downvoted a post and you did not leave a comment on it, you should not be refunded the cost of the downvote.   To exemplify this, let's I have 100 reputation points. If I go and downvote a post without providing feedback (a comment), my reputation should drop to 95 points. However, if I provide feedback to explain why I downvoted that post, my reputation should be reinstated to 100 points.  This proposal has two main positive benefits to the Stack Exchange community: by offering users the option to explain their downvote without losing reputation, users will be more inclined to offer feedback/advice; and by increasing the cost of a downvote, users are less likely to downvote for reasons such as, "I don't like you," and, "I don't like your post, but I don't care to explain why." Thus this revision would promote educated and healthy comments which could help the author, the voter, and readers; all of this while still preventing downvote abuse.  On the topic of educated and healthy comments, I would love to hear yours.    Update: The following two prior suggestions are strongly related to this suggestion:       Thank you to hichris123 for bringing them to my attention in the comments.


how do you spin-duplicate an object to make a grenade?

I ma making a grenade like this one in the image:   And I have the main bumpy part here:   so I want to spin them to make that shape, but nothing seems to work. Any ideas? Thanks.


In a theorem I am reading about closed subspace the author states that an infinite dimensional subspace need not be closed.  What is an example of infinite dimensional subspace that is not closed?


How do you set, clear, and toggle a single bit?

How do you set, clear, and toggle a bit?


How to list all constraints of a table in PostgreSQL?

How to list all constraints (Primary key, check, unique mutual exclusive, ..) of a table in PostgreSQL?


Does waving a magnet around create light?

If I wave around a bar magnet, the magnetic field in the space around it changes. Is this enough to go through the whole speed of light derivation implying that the motion creates an electromagnetic wave? If so how do I determine the wavelength and direction of the resulting wave?


Change in the imported function does not change the output while in python shell?

I am quite sure something like this must have been asked before but I couldn't word it properly to get to those questions. Here is my issue. Let's say I have a function called square, which returns square value of a given number. def square(number):     return number*number  I store square function in main.py file. So in the python shell, I import and run the function like this: >>> from main import square >>> square(5)  Output is obviously 25 in this case. However, when I make changes in the function, for the sake an example, let's say: def square(number):     return number*number*2  and import and run in previously opened python shell again. The result remains the same (i.e. 25). However, it should be 50. The changes take effect if the close and reopen the python shell. Is there a way to overcome this without opening a new python shell everytime for testing. I have tested this in python 2.7.14 and 3.8.3.


How to use notify-send to notify users as root?

#!/bin/bash export DISPLAY=:0 state=$(upower -i $(upower -e | grep BAT) | grep --color=never -E "state" ) stat=${state:25:32} batperct=$(upower -i $(upower -e | grep '/battery') | grep  -E "percentage:") bat=${batperct:24:26} intbat=$(echo $bat | cut -d'%' -f1) if [ "$intbat" -lt "15" -a "$stat" == "discharging" ]; then     notify-send 'battery low..! please plugin charger..... charge is only' "$intbat"     fi     The script runs fine when run as a normal user (bash script.sh). The desktop notification is displayed.  If I run it as root with sudo bash script.sh, the desktop notification is not displayed.  How can I use notify-send to notify users as root?  I am using Arch Linux.


Is test or [ or [[ more portable both between bash shells and between other shells?

I see I can do  $ [ -w /home/durrantm ] && echo "writable" writable   or  $ test -w /home/durrantm && echo "writable" writable   or  $ [[ -w /home/durrantm ]] && echo "writable" writable   I like using the third syntax. Are they equivalent in all ways and for all negative and edge cases? Are there any differences in portability, e.g. between bash on Ubuntu and on OS X or older/newer bash versions, e.g. before/after 4.0 and do they both expand expressions the same way?


How to check if a ttf file contains a certain character?

Using the command line, how can I check if a *.ttf file contains a certain character?  I want to know if the font-file Ubuntu-R.ttf contains the U+2007 (FIGURE SPACE) character.


Checking if an Object has already been Instantiated in Java

I have a problem right now in my program where a Student class is allowed 1 book and it must be stored in a variable _book however I can not seem to find a way to check if an object has already been instantiated or not without getting a run time error.  I have tried   Comparing variable to null Accessing a function inside the variable that checks if the variable is null Accessing a function inside the variable that checks if variable is 0   Simplified Code:  Student Class  public class Student {     private String _name;     private Library _collegeLibrary;     private LibraryCard _card;     private TextBook _book;      public Student(String name, Library library) {         _name = name;         _collegeLibrary = library;         System.out.println("[Student] Name: " + _name);     }      public void describe() {         String message;         message = "[Student] " + _name;         if (_book.returnTitle() == null) // returns java.lang.NullPointerException             message += " does not have a book";         else {             message += " is borrowing the book \"" + _book.returnTitle() + "\"";         }         System.out.println(message);     } }   TextBook Class  public class TextBook {     String _title;      public TextBook(String title) {         _title = title;     }      public String returnTitle() {        return _title;     } }   The above code will give me a java.lang.NullPointerException. I looked into catching the error however it doesn't seem like that is recommended.


Importing a simple SVG logo from Inkscape into Blender and converting to mesh turns messy: zigzag lines going across the surface

I wanted to convert this path to mesh to extrude it and make it 3D. The resulting mesh is a mess when i look at it in edit mode. Check my screenshots. How could i avoid all those zigzags across the surface and make this mesh something like the origin path? The original SVG file is there:  This is just one single closed 25 nodes path without any zigzag lines going across... In Blender, I did: File > Import > SVG (and re-scaled) and then: Right-click to convert to mesh, and the result is a mess:  EDIT: My logo does not have anything special or tricky. I tested a pure simple circle made in Inkscape and imported into Blender: same bad results at first, and same 5 seconds quick fix.


Optimum Bone To Water Ratio For Pork and Beef Stocks

I am tinkering with my stock recipes.   For pork stock I have been using 8 cups of water over a roasted trotter, a roasted backbone section with about 4 inches of rib attached, and a 1/4 inch slab of roasted pork belly.   For the beef stock I have been using 8 cups of water over an equivalent amount of roasted beef bones (knuckles and backbone/rib).   This gives a very flavorful stock and, for cost reasons, I want to determine how much I can reduce the concentration (by adding more water) without reaching too watery a taste.   Does anybody have any guidance on this topic?


Cite another publication in bibliography item

I would like to refer to another reference in a bibliography item. It should look like the following in the bibliography:  [30] Author (Year), Cited in [12].   How do I achieve this?


How can I change the width of page in latex

I am wring the paper that is formatted by elsarticle. However, the margin between text and left. right page look big. Hence, the text length is very narrow. Could I change it in the file     \documentclass[preprint,12pt, sort&compress]{elsarticle}   Thanks


My processor is 64-bit - does that mean I need the amd64 image?

My processor is an Intel Core 2 Duo P8600 (2.40GHz). As far as I know that's a 64-bit processor - I'm a bit confused as the architecture is called AMD 64, is this a generic name given to 64-bit architectures? I've heard of x64 but can't see a release labelled with this.


Can you quote a random string without knowing if it contains special characters?

I'm having trouble inputting random generated passwords into some scripts.  I generate the password, and paste it between "". But sometimes it contains characters that sends the whole thing crashing down, like " # or whatever.  EDIT: I have been pointed to Quoting for a solution  There are several options for Quoting ( using \ , " " and ' ' ) but each require checking the string for special characters, like single quotes in a single quote block. Is there a way to really paste a string without needing to check it or is doing that check always necessary when your random string can contain the ' character at least.


Let $a$, $b$, $c$ be nonnegative real numbers.   Prove $(a^{2}+2)(b^{2}+2)(c^{2}+2)\geq 9(ab+bc+ca)$.


What is StackOverflow's definition of duplicate question?  I noticed that there are many questions marked as duplicate just because its have the same answer. But the question with same answer doesn't always means that the question is also the same right?  Lets say I have two questions, for example:  "Who is the richest man in the world?"  "Who is the founder of Microsoft?"  We all know that these questions (may) point to the same answer. But as we can see, the questions is totally different. So, is this considered as duplicate too?  Example of ambiguously "duplicate" question:  (has been re-open)


What is the relevance of "@" in comments?

Why do users use @ ("commercial at," or "at sign") in their comments? Does it actually route the comment to the name provided after the @? What is the right format of using it?


What is the difference between spin and angular momentum, are they linked i.e. spin is a form of angular momentum. And is spin what I think it is (the way the electron/particle actually spins)


Given maximum, find minimum of cyclic sum

Let $a,$ $b,$ $c,$ $d$ be distinct real numbers such that $ac = bd$ and $$\frac{a}{b} + \frac{b}{c} + \frac{c}{d} + \frac{d}{a} = 4.$$Find the maximum value of $\frac{a}{c} + \frac{b}{d} + \frac{c}{a} + \frac{d}{b}.$ I assumed that the equality case was at $a=b=c=d=1$, but that clearly doesn't work. How do you solve this? I also this the equation is homogenous, but I do not think that helps.


Visual Studio - Output number on lines that contain at least one Chinese symbol

I'm wondering if there is an easy way to go through our project and find out exactly how many lines contain Chinese symbols?  This also needs to exclude any lines starting with /* or //


How to use drush with a specific PHP Instance

What drush command can I use to tell drush to use php 5.6 instead of 7.1 which my  site is currently running on.  A million thanks in anticipation.


How to get the official, non-development version of Focal Fossa 20.04

I followed these instructions to upgrade from 19.10 to 20.04:    I understand the  was 2 days ago. However, when I run the following as instructed:  Press Alt+F2 and type update-manager -c -d into the command box.    The popup shows:    I want the final release, not the development release.  I am following the official ubuntu instructions.  What am I doing wrong?  These are my update settings, which should just be LTS:


Some application constantly overrides a specific registry key I am interested in keeping unchanged. Is there a way to track which application it is?  The best answer from here  covers the case when the application is known. My problem is that I do know the changes but I don't know the application (an opposite problem).


I am new to latex and i have the following problem. When i use the poker package the following error occurs "poker.sty" not found. I'm using miktex and texmakerx. What is wrong ?


It apears to have been resolved by now. The issue still appears on SO The issue regressed here on MSE as well I recently got access to the 10K-tools, and the inline tag editor, which I observed to crop the suggested tags by the boundaries of the tag box on my mobile, using the responsive design. While writing this question on a desktop, I noticed the same problem on the ask a question page. See attached screenshot, where there should be a suggested design tag, but it is hidden. When I use the inline tag editor on the question using FF on a desktop, it works as expected. Regular editor:  10K inline tag editor:  Using FF 68.5.0esr on Mac and using Chrome 85.0.4183.81 on Android.


Getting trailing zero in csv file for 15 digit number

I am having a column in csv with 15 digits with value 1234567812345678 but it always coverts the last digit with zero 1234567812345670. I have formatted them as number.


Retrieving latest record using DISTINCT ON is slow

Using Postgres 9.4. I have a table cartests with 5.5M rows. Each row is a car test:  \d log.cartests;              Table "log.cartests"    Column    |           Type           | Modifiers  -------------+--------------------------+-----------  carid       | integer                  | not null  timestamp   | timestamp with time zone | not null  exhaust     | varchar                  |   brakes      | varchar   Indexes:     "cartests_pkey" PRIMARY KEY, btree (id, "position", "timestamp")     "cartests_carid_idx" btree (carid)     "cartests_timestamp_idx" btree ("timestamp")   I need to retrieve the latest log for each car.  SELECT DISTINCT ON (carid) carid, timestamp, exhaust, brakes FROM log.cartests ORDER BY carid, timestamp DESC;   This one takes ~ 6 seconds. Running EXPLAIN ANALYZE gives:   Unique  (cost=933787.06..961490.34 rows=472 width=16)           (actual time=4951.347..6072.534 rows=476 loops=1)   ->  Sort  (cost=933787.06..947638.70 rows=5540656 width=16)              (actual time=4951.345..5782.466 rows=5540656 loops=1)         Sort Key: carid, "timestamp"         Sort Method: external merge  Disk: 162504kB         ->  Seq Scan on cartests               (cost=0.00..123810.56 rows=5540656 width=16)             (actual time=0.009..620.988 rows=5540656 loops=1) Planning time: 0.107 ms Execution time: 6095.598 ms    Why must it sort if I have an index on both carid and timestamp? Is there a better method to use here?


How do I learn how to review on Stack Overflow?

On gaining extra review privileges I wanted to know the rules for reviewing. There is no link from the review privilege descriptions. After some searching I found . It would be good if the privilege descriptions had links to that question or a better one.  As I review suggested edits I see several trivial changes (eg spelling where the meaning is obvious, white space, adding or altering quote marks, changing a URL in the text to Hyperlink) and I wonder whether I should approve them or not.  Having chosen a response then how do I find out how my response affected the outcome of a review? How do I learn whether my response was correct or at least matched the majority of other responses?


Special Declaration and Variables in Common Lisp

I am reading the Common Lisp Hyperspec and am struggling to understand the concept behind the  declaration.   Namely, what are the special variables and why would we want them? I gathered that somehow we can change which scope the variable belongs to in the eyes of the compiler by using the special declaration, but the details elude me.  Could someone explain and perhaps give some examples?


Use of Semicolon in this sentence and way of spliting it

Want to know the specific meaning of the two semicolons in the sentence below. And is there any good idea to split this sentence using appropriate transitions?  The fundamental insight into the necessity of the return to consciousness; the radical and explicit determination of the path of, and the procedural rules for, this return; the principle-based determination and systematic exploration of the field that is to be disclosed11 in this return -- this we designate as phenomenology.


Hello can I install Linux by downloading the iso, then copying it on my 2nd hard drive, then booting on the 2nd hard drive ?   I believe I have something to do, since the 2nd hardrive is "controlled" by Windows (though Windows is on my 1st hdd).


I would like to insert the labels in math mode just like in a regular math expression.  \documentclass{standalone}  \usepackage{tikz,tkz-fct}  \begin{document}  \begin{tikzpicture} \tkzInit[xmin=-1.1,xmax=13.2,ymin=-2,ymax=2] \tkzDrawX[trig=1] \tkzDrawY[noticks] \tkzFct[domain=-1:13]{cos(x)} \tkzDefPoint(0,-1){-1} \tkzDefPoint(0,1){1} \tkzDefPoint(pi/2,0){pi/2} \tkzDefPoint(pi,0){pi} \tkzDefPoint(3*pi/2,0){3pi/2} \tkzDefPoint(2*pi,0){2pi} \tkzDefPoint(5*pi/2,0){5pi/2} \tkzDefPoint(3*pi,0){3pi} \tkzDefPoint(7*pi/2,0){7pi/2} \tkzDefPoint(4*pi,0){4pi} \tkzDrawPoint(pi/2) \tkzDrawPoint(-1) \tkzDrawPoint(1) \tkzDrawPoint(3pi/2) \tkzDrawPoint(pi) \tkzDrawPoint(2pi) \tkzDrawPoint(5pi/2) \tkzDrawPoint(3pi) \tkzDrawPoint(7pi/2) \tkzDrawPoint(4pi) \tkzLabelPoints[below left](-1) \tkzLabelPoints[above left](1) \tkzLabelPoints[below left](pi/2) \tkzLabelPoints[above](pi) \tkzLabelPoints[below right](3pi/2) \tkzLabelPoints[below](2pi) \tkzLabelPoints[below left](5pi/2) \tkzLabelPoints[above](3pi) \tkzLabelPoints[below right](7pi/2) \tkzLabelPoints[below](4pi) \tkzHLine[dashed]{1} \tkzHLine[dashed]{-1} \end{tikzpicture}  \end{document}   hete it is what I got


products is react state. It gives " 'products' is not defined" error, why?

This code not working. products is react state. It gives " 'products' is not defined" error. <CardTitle tag="h5">{products.productName}</CardTitle> this is working: <CardTitle tag="h5"></CardTitle> my main component code:   state = { currentCategory: "", products: [] };    componentDidMount() {     this.getProducts();   };    changeCategory = (category) => {     this.setState({ currentCategory: category.categoryName });   };    getProducts = () => {     fetch("http://localhost:3000/products")       .then((response) => response.json())       .then((data) => this.setState({ products: data }));   };


Show that $(0,0)$ is not a local minimum of $f(x,y)=(y-x^2)(y-2x^2)$

Show, that $f(x,y)=(y-x^2)(y-2x^2)$ reaches it's minimum at $M(0,0)$   for $f(t\cos\alpha,t\sin\alpha)$, but $M$ is NOT a local minimum   point.   Seemed to be an easy one, but I couldn't handle it. We have. $f(t)=(t\sin\alpha-t^2\cos^2\alpha)(t\sin\alpha-2t^2\cos^2\alpha)$ for any fixed $\alpha$ $f'(t)=8t^3\cos^4\alpha-9t^2\sin\alpha\cos^2\alpha+2t\sin^2\alpha=0$ $t_0=0$ is a root  for $f'$, and $f'(0)=0$, however it has 2 more roots since $D>0$ $f''(t_0)=24t_0^2\cos^4\alpha-18t_0\sin\alpha\cos^2\alpha+2sin^2\alpha=2sin^2\alpha>0$ so $t_0$ is a minimum. part 1 done.  $$\begin{cases}  \frac{\partial f}{\partial x}=2x(4x^2-3y)=0 \\   \frac{\partial f}{\partial y}=2y-3x^2=0 \end{cases} $$ solution is again $M(0,0)$ $$\frac{\partial^2 f(M)}{\partial x^2}=24x^2-6y=0,\frac{\partial^2 f(M)}{\partial y^2}=2,\frac{\partial^2 f(M)}{\partial x \partial y}=-6x=0$$ $$\Delta  = \begin{vmatrix} \frac{\partial^2 f(M)}{\partial x^2} & \frac{\partial^2 f(M)}{\partial x \partial y} \\  \frac{\partial^2 f(M)}{\partial x \partial y} & \frac{\partial^2 f(M)}{\partial y^2} \end{vmatrix}=0$$ I've got the determinant is zero for the particular point, and here I reached to dead end, I have no idea how to continue/conclude, please help me to finish this one. thanks


Help with the installation of Ubuntu 13.10

I'm trying to download ubuntu 13.10 on my laptop which is currently running windows 7. I want to install to where I can dual boot either.


Father is a twin, closest DNA match is 1,723 CM's

My closest DNA match is 1,723CM's across 32 segments with the longest segment being 217 CM's. My next closest match is a cousin of the first match 886 CM's across 31 segments with the longest being 78 CM's. I believe my closest match is possibly my half brother but his father is one of a twin. Could he be my cousin or is the match too high ?


How can I create that glitter tears effect and the sparkles?


I know this sounds naive but, why can't I log on as root or give my ID root permissions? Why do I have to use Terminal?  I mounted a drive and now want to give permissions to other PC on my network to access the drive.


I was thinking about the reserved character in $\LaTeX$, but I don't know the real function of ~ neither I've use it before. Then, what is its real function in general.  For math mode I found this . But in text mode?


According to Big Bang theory and The Red shift theory "space" is "expanding". Keeping this notion of "space" as physically something in and of itself(space -time did not exist before The Big Bang); what are the supposed theoretical answers for the omnidirectional expansion of this "fabric"--noting that no matter where you are in the universe "space" is expanding away from you??


How to calculate $\theta = \arcsin\left(\frac{1}{2}\right)$ with given four function calculator?

An example question is: In radian measure, what is $\arcsin \left(\frac{1}{2}\right)$? Select one: a. $0$ b. $\frac{\pi}{6}$ c. $\frac{\pi}{4}$ d. $\frac{\pi}{3}$ e. $\frac{\pi}{2}$  So, in the exam, I will be given only four function calculator. And is it possible to calculate this kind of trigo function? Or, do I have to memorise common values of trigo functions? Is there any tricks and tips for this problem?


Appropriate use of logarithmic notations in publications

Recently I was told that scientific papers in English use - log_e while French papers use - ln to denote natural logarithms.  The two notations do mean the same. But I was informed that using the notation ln for natural logarithms in scientific papers in English language is inappropriate and I should use only log_e. But I have always been using log for log-base-10 and ln for natural logarithms. (At least this was what I was taught in school)  Do such notations vary from language to language?  I am referring to the publications specific to IEEE, Elsevier etc. related to the Electrical and Electronics field.


Does the characteristic of a ring R without zero divisors 0 or prime?

This is in connection with the question: . I have found a solution without using commutativeness. I don't understand why commutativeness will be necessary to prove it. Here is my solution:  If possible let char $R = pq$ where $p,q\in\mathbb N$ such that $p,q>1.$ There exists $a,b\in R$ such that $pa\ne0,qb\ne0.$ Then $(pa)(qb)\ne0,$ a contradiction since $(pa)(qb)=(pq)(ab)=0.$ Thus char $R = 0$ or prime.  Please tell me where did I go wrong.


I have linox & want to download  Gimp. Which version should I use?


Can every uncountable set be expressed as a disjoint union of uncountable sets?

I want to show that the co-countable countable $\sigma$-algebra on $X$ is distinct from $P(X)$ whenever $X$ is uncountable. Can we express every uncountable set as the disjoint union of uncountable subsets? (no big deal if AOC is assumed) Note: A different thread on this website asks the same question but only for real numbers.


Can upgrading Ubuntu 14.0 to 16.04 affect my windows 10 installation?

Please after the Upgrade, I can no longer choose from "which Operating system" to use. Whenever I restart my laptop, Ubuntu now becomes my default Operating system and does not give me de Options to choose the OS to use at that moment. Plz help me.


How do you punctuate the end of a quote within a quote: "Billy said, 'This is acceptable.' "

At the end of such a sentence, does the single quote come before the punctuation?  If it does not, is a space between the single quotation and double quotation marks necessary?  >>, ' "   or '"?  I ask because the publisher's font does not show a space like it seems to here, which looks confusing, so I'm wondering if this is acceptable, or do we just live with the oddity of what appears to be a triple quotation mark)


/, /home and swap partition sizes when using multiple drives

I'm about to install Ubuntu 13.04 on my computer and I'm wondering how big each partition should be. I read that the swap area should be twice the size of your install RAM and I figured /home should take the space you have left, but how big should / be?    Further to this, I have two 500GB hard drives and want both of them to be available when I use the computer. Should I put / and swap on one drive while letting /home be on the other or should I put all partitions on one drive? If putting all partitions on one drive is the best option, what file-system should the other drive use?  Oh and just to clarify: I don't want to dual boot — just want the whole system to run Ubuntu.


Assume $G$ is a , i.e. a (finite) directed graph such that between any two vertices, $a$ and $b$, there is at least one edge in one of the two directions, $a\rightarrow b$ or $b\rightarrow a$.   Show that there is at least one , i.e. a path, following the direction of the edges and visiting all vertices exactly once. (This part is a classical exercise and it is here to prepare for the second part of the problem). Consider all possible losers, i.e. the set of all vertices that can be end-points of Hamiltonian paths of the tournament, see Part (1). Show that the subgraph of all losers has a , i.e. a cycle that follows the direction of the edges and passes through every vertex exactly once and returns to the initial vertex.   For example     these are all tournaments and the $\color{red}{\text{red}}$ dots are the losers. Notice how there is always a cycle joining them.


I deleted the update file for iOS 9.3. Is it possible to reinstall it?

I was having trouble installing the new iOS 9.3 on my iPhone 5 and I got the advice that I should delete the update file and try to reinstall it. The problem is now that I have deleted the file I can't find the update file for iOS 9.3 again. I have restarted the phone but it didn't help, it says I have the latest update (9.2.1). Is it possible to install iOS 9.3 now?  Update: I got the new update today randomly. The installation of 9.3 went successfull.


When I'm spam clicking on the button it sometimes changes the number of decimals. Why?    <!doctype html>         <button onmouseover="showSomething()" onmouseout="hideSomething()" onclick="addSomething()">Show something</button>


The gravitational lensing evidence suggests the existence of massive and relatively dense regions of dark matter. However, if dark matter interacts only gravitationally, what would stop it from collapsing to a black hole of any size? For example, if there is a cloud of a dark matter gas of the mass of the Moon, and this cloud over time condenses under its own gravity down to the size of the Moon, then what would hold this object from quickly collapsing to a singularity with no electroweak of strong force to resist the collapse? Would the Pauli exclusion principle apply to dark matter to create a degeneracy pressure preventing the collapse?


I would like to stop an ajax call in jquery, which is not working  var xhr = null;  xhr = $.ajax({     url : 'www.example.com?some-large-call',     success : function(responseText) {         // some DOM manipulation     } });  $("#button").click(function() { xhr.abort() });   I referred the below link


Can't flag historically locked questions

I know, it doesn't make much sense to flag a question or answer post once a question is historically locked, because in theory nothing should need to change in the question ever again.  Recently, the  tag was cleaned up.  However, there are two questions (, ) that still have the tag associated with it, which is preventing it from getting cleaned up in the nightly cleanup.  Since the questions are historically locked, I can't even flag them for moderator attention.  Two questions:   Can a moderator please remove the tag from these questions so that it can get cleaned up? Is there a more appropriate way to flag these questions for attention than bringing it up on Meta?  Or is this such an edge case that it's just easier to bring it up here instead of doing something silly like flagging some other question and then including your request in the "Other" notes?


Im using ajax to render a table on my page. In the last row of the table Im trying to display a button which is handling my "edit" function like so: $(".editPersonnel").on("click", function () { $("#editPersonnelModal").modal("show"); $tr = $(this).closest("tr");  var data = $tr   .children("td")   .map(function () {     return $(this).text();   })   .get();  $("#idPer").val(data[0]); $("#updateLastName").val(data[1]); $("#updateFirstName").val(data[2]); $("#updateJobTitle").val(data[3]); $("#updateEmail").val(data[4]); $("#updateDepartment").val(data[5]); $("#updateLocation").val(data[6]); console.log(data);  }); Im trying to render that button using jQuery but when I do this:  $("<td>").html(              '<td><button class="btn btn-info editPersonnel">Edit</button>'             )  the button shows on the page but doesn't work. Can anyone help me to solve this problem? Im still such a newbie... Thanks!


How vulnerable are my PHP parameters when used within HTTP GET?

I'm creating a login system for my online game and am using MySQL to manage users. In order to verify login data against the stored data in the database i'm using the following php script:  <?php function mysqli_result($res, $row, $field=0) {      $res->data_seek($row);      $datarow = $res->fetch_array();      return $datarow[$field];  }  $dbhost = 'host'; $dbuser = 'user'; $dbpass = 'pass'; $conn = mysqli_connect($dbhost, $dbuser, $dbpass, 'my_db');  if(! $conn ) {   die('Could not connect: ' . mysql_error()); } //First, get the login details from the URL $username = $_GET["username"]; $password = $_GET["password"];  //Now fetch the password that is on record for that account $sql = "SELECT DISTINCT acc_password FROM users WHERE acc_username = '$username'";  $result = mysqli_query($conn, $sql) or die(mysqli_error($conn)); $p_hash_store = mysqli_result($result, 0);  if (password_verify($password, $p_hash_store)) {     echo "true"; } else {     echo "false"; } mysqli_close($conn);   Now here's the bit I'm worried about. In order to get the players username and password into that verify script I use a function in the game IDE that's the equivalent of a HTTP GET request, calling that verify script with the users raw username and password as parameters. It looks like this.  async_ini = http_get("http://www.website.com/script.php?username=" + obj_control_login.username + "&password=" + obj_control_login.password);   Since the verify script either echos true if the password matches the hash and false otherwise I can easily tell if the login details were correct. This system is all up and running fine.  My problem is that I don't like the fact that I'm sending the player's raw username and password off in a HTTP GET request hence the guts of my question: Are the parameters I pass in the php URL secure or are they open to prying eyes? If they are vulnerable is there anything I can do to fix that?  I'm a total novice at MySQL and php, this is literally the first thing I've done in them, so if the whole thing is laughable insecure please let me know; this is the only way I could think of integrating my game making software with MySQL and password hashing.


What is the carrier of push and pull force?

Suppose I push a book with my hand. I am applying force on it in the process. My question is: What is the carrier of the force I am applying?


secure dynamic parts of prepare statements

I am implementing prepared statements with dynamic parts like so   $stmt = $db->prepare("SELECT * FROM" .$table. "WHERE id=? AND name=?");   The "table" part is dynamic , is a variable that contains the name of the table. For now it is inserted by the code, but what if in the future I decide to have the user insert it?  How can I secure against injection a variable that is not part part of the WHERE part of the statement?   Thanks


How can I get sound working on Bootcamp + Windows 8.1?

Windows 8.1 isn't playing back audio on my 13" mid-2012 Macbook Pro.  I only have a speaker with an x on my notifications bar.  When I click on it, I get the usual "detecting problems" garbage.  Unfortunately, every "solution" I've found seems to work for everyone else, but not for me.    Device Manager  Windows shows a High Definition Audio Controller listed under System.  Its properties state that it has a Code 10 - "This device cannot start", along with "The requested operation was unsuccessful."  This is the only notion of an audio device listed in Device Manager.  Most solutions I've found say drivers need to be reinstalled (downloaded from the internet or simpliy re-run from the Bootcamp support drivers) and I've currently tried the following:   Bootcamp setup.exe (No errors are reported, 5.0.5033 "installs" a variety of sound drivers) Cirrus Audio (Both CirrusAudiox64.exe and a manual .inf installation) Realtek (I've tried nearly every link I've found)  Intel Graphics 4000 (apparently it does audio too)   Every executable runs and reports success, however, I don't see any sign of a change apart from the Realtek driver copying files somewhere in Program Files, and the Intel driver blanking the screen a few times.    Cirrus Audio  I've tried manually installing the Cirrus Audio driver by performing the following:   Select High Definition Audio Controller from Device Manager Click on Driver -> Update Driver Select "Browse my computer for driver " Select "Let me pick from a list of device drivers" Click "Have Disk..." and navigate to the .inf file   At this point windows complains that the driver does not support Windows x64, despite having "x64" written all over it.  "The folder you specified doesn't contain a compatible software driver for your device. If the folder contains a driver, make sure it is designed to work with Windows for x64-based systems."  If I skip #'s 4 and 5, and browse directly for the driver files, Windows reports that the Driver software is already up to date.  "Windows has determined the driver software for your device is up to date."  This makes me believe that Windows 8.1 might have an issue with certain drivers, deeming them unusable in some way.  It's possible that windows is denying the .exe installers' drivers, Realtek, and Cirrus behind the scenes, without letting them install anything.  Maybe they report success and silently fail?    Setup  It's worth mentioning that my Bootcamp setup isn't typical.  I've partitioned the hard drive and installed windows manually, alongside Arch Linux.  (I've triple booted this thing, and windows audio is the final hurdle.)  I'm also using the refind efi bootloader to boot the system.  For the windows boot option, I point refind to /EFI/Microsoft/bootmgfw.efi, without any options. I'm thinking that Bootcamp might do more than partition and install, and that I'm supposed to do more to inform windows about the macbook hardware at this stage.  Is this the case?  Did I miss something critical about Bootcamp?    If anyone can help me solve this, I will be eternally grateful.  Thanks.  P.S. I'm a linux user, so windows drivers aren't exactly my forte.  If I'm doing something totally wrong, please let me know.


How to fix a runtime "Null Pointer Exception" of a generic type parameter

I have two different classes with a method inside each. Classes are 'DBConnect' and 'Controller'. Since I try to build an fx application I have a combobox named as 'privilageBox' and a generic type named 'privilageList' for its choices (inside Controller class).   ObservableList<String> privilageList = FXCollections.observableArrayList("Admin","Employee");   There is a function called 'login' inside the same class and there is some coding inside it. I have an if statement as well and what I am trying to do inside the requirements section is I try to call 'checkUser' method that is located inside the DBConnect class and set its parameters.  DBConnect lg = new DBConnect(); if(lg.checkUser(textField1.getText(),passwordField1.getText(),(privilageBox.getValue()).toString()))   This is where I get the NullPointerException. I am setting the paremeters wrong and I ran out of solutions.  Here is the checkUser function's parameters inside DBConnect class:  public boolean checkUser(String username, String password,String privilage) throws SQLException   I have tried to set the parameters for 'checkUser' and if statement inside 'login' as below:  public boolean checkUser(String username, String password,ObservableList privilage) throws SQLException  if(lg.checkUser(textField1.getText(),passwordField1.getText(),privilageList.toString))   It did not work also. By the way, this is a runtime error. I get no errors at compile time. Error message (discarded unnecessary parts):  Caused by: java.lang.NullPointerException at sample.DBConnect.checkUser(DBConnect.java:70) at sample.Controller.login(Controller.java:44)


If $a_1$ is positive integer and $a_{n+1} =  a_n + \frac {1}{a_n}$ , how can I prove ${a_n}$ diverges to $\infty$ ?


"cat" command: how to automatically escape everything that might be a violation?

If you copy the contents of   httpd.conf   and then paste it into a cat command.. such as this one..  #!/bin/bash cat > /test << EOF pasted here.. EOF   you run into this error:  -bash: command substitution: line 1: unexpected EOF while looking for matching `'' -bash: command substitution: line 4: syntax error: unexpected end of file   perhaps the solution is to escape the dollar signs and maybe even quotes and so on..  but given that this is such a large file.. can dollar signs be automatically be escaped ?  is my only option to escape them via another program and then give it to the cat command ?


My book of physics (I won't uote it here, since it is in Catalan) says that in the 1887 Michelson - Morley experiment, after getting the transversal and longitudinal phase shifts, they claim that the number of fringer observed will belong to the number of times that both phase shifts contains 2 pi because that is the phase two maximums repeat. My question is: why is here said that waves should form maximums? Because as I understand it, the expected result was to obtain a destructive interference whose phase shift could be used to determine Earth's velocity. If they were expecting a destructive interference, shouldn't the book use the phase two minimums repeat instead of using the interval when twho maximums do?


How to recover deleted directories "/home/pi"

I just deleted my /home/pi directory while I was trying to remove the directory under /home/pi which was /home/pi/nmap. So, is there anyway to recover /home/pi directory as I have other important directories under it. I use the commmand:    rm -rf /home/pi


$$\int \frac{dx}{(x^2+1)^2}$$   How should I approach this? Is there a general approach when the degree of the denominator>>numerator in this case $x^4>>1$?


Why is energy calculated with respect to distance and not time?

Okay, so looking at the basic definition of energy the force is summed over the distance it is applied. Why exactly is it taken over the distance applied and not the time applied? I understand that the impulse and hence the change in momentum is what we call this summation over time, but it's not exactly clear to me why we chose to do it the way we did.   Side note - I've seen the examples where there's an object at rest and if you took the force over time you would get infinite energy, but if you took the sum of the force (both holding it up and pushing it down (gravity) you would get 0, and thus an integral over the net force would be 0, right? Thanks   -edit  Okay, so really the crux of what I'm getting at that I can't seem to find an answer for is: Why did we choose to do it this way? What experiment or thought experiment led us to believe that momentum isn't in fact energy, but a separate quantity? The problem I keep having is that when you want to sum up this quantity we know as force, you have two options, sum it over the time its applied or the distance. I just don't understand the idea behind choosing one over the other.


I don't understand the truth table for logical consequence $(a \rightarrow b)$

When I take a look at the truth table for implification, I don't get the logic:  a     b       a --> b ---------------------- 1     1         1 1     0         0 0     1         1 0     0         1   I understand implication $a \rightarrow b$ means that $a$ becomes $b$ or I understand this wrong now? Because if I compare what I said with the table, it seems contradicting... My understanding works for all lines except for the last one where we have 0 0 1..  Anyone could please explain me?


I'm trying to validate a postcode in the format 'LLNN NLL'. L for letter and N for number. I think I have to use re.match () but I'm not entirely sure. Thanks


Computing the binomial series: $\binom{n}{2}\cdot2^2+\binom{n}{4}\cdot2^4+\binom{n}{6}\cdot2^6+\cdots+ \binom{n}{n}\cdot2^n$

How to find the tight bound for the binomial series $\binom{n}{2}\cdot2^2+\binom{n}{4}\cdot2^4+\binom{n}{6}\cdot2^6\ldots,+ \binom{n}{n}\cdot2^n$ I have found $3^n$ for series $(1+2)^n=1+\binom{n}{1}\cdot2^1+\binom{n}{2}\cdot2^2+\binom{n}{3}\cdot2^3+\cdots+ \binom{n}{n}\cdot2^n$ Is there any way to prove the bound of above series.


What happened to not a real question close vote

I have seen new options for close vote screen:   I can't see not a real question and too localized here any more.  In many of question we have sen that "not a real question" will be the option in case user have not shown any research in his question. I have been using this option much during my close votes. But It's no more there. So What now?


Why do harmonics occur when you pluck a string?

When you energise a taut string, the following resonant modes of vibration occur:    Plotting on the frequency domain, you can see their corresponding frequencies:    But what is the underlying physical principle? Why does this happen?  Is there any way of explaining it that could be understood by a smart 15 year old?  EDIT: I'm going to give my best attempt so far. Here goes:   We can start with sympathetic resonance. Sounding a particular frequency, a pure sinewave.  And noticing the string resonates sympathetically at the frequency of each harmonic. Say this is explained and understood. Now imagine that plucking a string is equivalent to a burst of white noise, which contains frequencies all the way through the spectrum. This could be approached backwards, by starting with random frequencies and noticing that resultant wave produced looks like white noise.   If the above is scientifically correct, then it restricts the domain of the question.  I would really like to be able to understand it scientifically and also be able to explain it intuitively.  PS Images from


Test the convergence of the series with alternating signs

The series is given by ($a>0$) $$\frac{1}{a} +\frac{1}{a+1} - \frac{1}{a+2} +\frac{1}{a+3} +\frac{1}{a+4} -\frac{1}{a+5} +\cdots$$ So how can I move forward? I  can not find the general term  of the series. If someone can give the general term then I can go further.


mtcars=data.frame(mtcars) m=glm(vs~mpg+cyl+disp+hp+drat,family="binomial",data=mtcars) m=glm(vs~wt,family="binomial",data=mtcars)   I seek to estimate pseudo-r-squared that is adjusted for number of predict values however I have not seen such a resource.  Is there a way to do so?


What happens to AirDropped files on the iPad that do not prompt the user to open an app?

When I AirDrop a file to my iPad, with no app installed to open the file type, the prompt still appears on the iPad that the file is being transferred. After the transfer completes, nothing happens.  Where does the file go? Is it stored on the iPad? Is it deleted on the spot? If not, how do I locate and delete it?


how to load the QGIS openlayers_plugin in standalone python script (not the QGIS embedded python console)

if I try to load the openlayers plugin in a standalone application it always fails with False, although paths are set, and plugin shows available.  (tested on Ubuntu 14.04, QGIS 2.4, python-2.7)  #!/usr/bin/python # -*- coding: utf-8 -*-  import sys, os  import qgis import qgis.gui, qgis.utils from qgis.core import * from PyQt4 import QtGui   # open an app app = QtGui.QApplication(sys.argv) # supply path to where is your qgis installed QgsApplication.setPrefixPath(u'/usr', True) # load providers QgsApplication.initQgis()  # set up the plugins qgis.utils.plugin_paths = \     ['/usr/share/qgis/python/plugins',     os.path.expanduser('~/.qgis2/python/plugins'),] qgis.utils.updateAvailablePlugins() print qgis.utils.available_plugins print "...load:", qgis.utils.loadPlugin(u'openlayers_plugin') print "...start:", qgis.utils.startPlugin(u'openlayers_plugin') print "active:\n",qgis.utils.active_plugins  canvas = qgis.gui.QgsMapCanvas() canvas.show()   what is the issue here ? post  refers to the embedded python console, where the plugin was magically available before.  thanks!


Whats is the best user to manage webserver?

In Apache webserver I have user www-data, and all files in /var/www are owned by www-data. Isn't that for security? Sometimes I need to upload files via FTP to /var/www/*, but with my own user I don't have write permission to it.   Let's say I use WordPress which recommends the permission to be 644 for files and 755 for folders. What is the best way to do this securely? I need still be able to upload file via FTP.


sudo apt-get update not working ,,showing error

it shows error E: Type 'sudo' is not known on line 2 in source list /etc/apt/sources.list.d/google-chrome.list E: The list of sources could not be read. tried to install google chrome ans it lead me here


calculating micro controller power consumption

I have searched and looked through the data sheet and I can't find the information I am looking for.   I am designing a circuit that uses an ATtiny45-20PU operating at 5V. I will be using three digital (high/low) inputs and driving one output that will draw 22mA when driven high (a PLC relay, APAN3105).  I am trying to figure out how to calculate the power consumption both when the output is low and when the output is high.  The datasheet I am looking at is here:   The power consumption when the output is low is important because the power supply is a battery.  The power consumption when the output is high is important so I can chose an appropriately rated voltage regulator.  I do understand that the operating speed chosen during programming will effect power consumption. High speed operation is not critical here as all of the inputs are electromechanical in nature and require a physical (human interface) input, so I plan to use as low of a speed as possible.  I don't want anyone to spoon feed me the answer here. I just need help figuring out how to get to the answer. Is there a more detailed datasheet that I am not finding? I searched the Atmel website and got lost in a web of links for hours and didn't find anything helpful.


I know that artificial light (i.e. lights generated by lamps, torches, et cetear)  but I'm not sure if this applies to natural light (light generated by the sun) as well.  Does natural light affect sneaking?


Sending Data from Activity to Fragment using Bundle Giving Null Pointer Exception

Scenario is :   I Have a MainActivity(MainActivity.java) with pager making Fragment(MyFragment.java) in it.   I have one more activity called Main2Activity(Main2activity.java).  I want to send Data from Main2Activity to MyFragment.  Main2Activity.java:    public class Main2Activity extends AppCompatActivity{    private String myString = "hello";    @Override    protected void onCreate(Bundle savedInstanceState) {    super.onCreate(savedInstanceState);    setContentView(R.layout.activity_main2);              Bundle bundle = new Bundle();             bundle.putString("path1", "Hey Brother");              MyFragment frgmentObj = new MyFragment ();             frgmentObj.setArguments(bundle);     }   MyFragment.java :     public class MyFragment extends android.support.v4.app.Fragment{    @Override   public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {  String brother = getArguments().getString("path1");   // Here showing NPE   return view; } }   But its giving me Null pointer exception       java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String android.os.Bundle.getString(java.lang.String)' on a null object reference   please help me out package is same Thanks


Divisibility Proof $8\mid (x^2 - y^2)$ for $x$ and $y$ odd

$x,y \in\Bbb Z$. Prove that if $x$ and $y$ are both odd, then $8\mid (x^2 - y^2)$.  My Proof Starts:  Assume $x$ and $y$ are both odd. So, $x = 2k + 1$ and $y = 2l +1$ for some integers $k$ and $l$. Thus, \begin{align} x^2 - y^2 &= (2k + 1)^2 - (2l + 1)^2 \\ &= 4k^2 + 4k + 1 - (4l^2 + 4l + 1) \\ &= 4k^2 + 4k - 4l^2 - 4l \end{align}    My two concerns:  1) Is this correct so far?  2) How would I deal with the “$8\;\mid$” part?


I want to calculate the area of the largest square which can be inscribed in a triangle of sides $a, b, c$ . The "square" which I will refer to, from now on, has all its four vertices on the sides of the triangle, and of course is completely inscribed within the triangle, and by "largest square", with the maximum area of such squares.   I did some research. I found that in the case of right triangles, there seemed to be only two kinds of squares being formed. One with a side of $\frac{ab}{a+b}$ and the other of $\frac{abc}{c^2 + ab}$, $c$ being the hypotenuse.   After some time, I realized that there was a common formula for all triangles. And that is:  $$side = \frac{ch}{c+h}$$       or $$\frac{1}{side} = \frac{1}{c} + \frac{1}{h}$$ where, $h$ is height on base $c$, or $$h = \frac{2\sqrt{(s(s-a)(s-b)(s-c))}}{c}$$    I achieved the above results using similar triangles, and have added a figure, to make the point clear. But that is all, I can prove. I tested for many triangles, and found that the smaller side always yields the larger square, but I am not able to prove it. For example, I can say that the largest square of a $4,7,10$ triangle, has area of approximately $\fraq{16}{3}$. I also want to make another conjecture (with an intuitive proof) that any triangle will give at most three squares.  So I want to ask you, are my calculations, proofs ... correct? Have I got them right? And those predictions? Are they right, and if so, proofs? Conclusively, do we have a sure-fire formula to get the area of the largest square?


If $P \leq G$, $Q\leq G$, are $P\cap Q$ and $P\cup Q$ subgroups of $G$?

$P$ and $Q$ are subgroups of a group $G$. How can we prove that $P\cap Q$ is a subgroup of $G$? Is $P \cup Q$ a subgroup of $G$?   Reference: Fraleigh p. 59 Question 5.54 in A First Course in Abstract Algebra.


How to call a async method in c# and display the output?

I am trying to run the _Main method and display the output in the console.But it is not showing the output. Can u tell me where is the problem?  {      public View_files()     {         InitializeComponent();     }     static async Task _Main()     {         List<string> fList = new List<string>();         IMongoClient client = new MongoClient("mongodb://localhost:27017/");         IMongoDatabase database = client.GetDatabase("mymongodb");         IMongoCollection<BsonDocument> collection =          database.GetCollection<BsonDocument>("store");         BsonDocument filter = new BsonDocument();         filter.Add("UserID", "abc");         using (var cursor = await collection.FindAsync(filter))         {             while (await cursor.MoveNextAsync())             {                 var batch = cursor.Current;                 foreach (BsonDocument document in batch)                {                     Console.WriteLine(document.GetElement("FileID"));                  }                 Console.Read();                            }         }     }     private void button1_Click(object sender, EventArgs e)     {         _Main().Wait();     }   }


My script in pyqgis run (grass7:I.pca) runs fine but output folder empties

this is my PyQGIS scrpit (QGIS 3.10).  this code runs fine but the output folder doesn't show results.  the MyFeedBack function shows me that it runs correctly and matches the Registry that is generated when the action is performed from the Grass7 i.pca module.  please i need help i don't know what else to try  import os import sys import gdal  path=r'D:\ESCUELA\clip_L8' output= r'D:/ESCUELA/PCA'  bandList = [band for band in os.listdir(path)if band[-4:]=='.tif'] input = [os.path.join(path,band) for band in bandList] print(input)   class MyFeedBack(QgsProcessingFeedback):    def setProgressText(self,text):        print(text)    def pushInfo(self,info):        print(info)    def pushCommandInfo(self,info):        print(info)    def pushDebugInfo(self,info):       print(info)    def pushConsoleInfo(self,info):       print(info)    def reportError(self,error, fatalError=False):       print(error)  def pca(input,output): params ={'input':input,\     'rescale':[0.300],\     'percent':99,\     '-n':True,\     '-f':False,\     'output':output,\     'GRASS_REGION_PARAMETER':None,\     'GRASS_REGION_CELLSIZE_PARAMETER':0} feedback = QgsProcessingFeedback() res = processing.run("grass7:i.pca",params,feedback=MyFeedBack()) print(res) return  pca(input,output)


Working around float or double numbers in C++. Errors of representation. Loss of decimal values

I heard that C/C++ has a problem with the management of the float point numbers. I've implemented a simple program to try it. It consists in a change machine: the user enter the quantity to charge and the quantity paid, and the program calculates the number of coins for each coin type to give as change.  Here is the code:   The thing is, when you insert a non-integer value, the program enter in a loop and never ends. I've printed the content of the variables to find out what's going on, and, somehow, from a 2 decimal value let's say: 0.10, the program changes its value to a 0.0999998. Then, the remaining change to be processed never is 0 and it enters in a infinite loop.  I've heard that this is due to the machine representation of the float point numbers. I've experimented the same either windows and Linux; and also programming it in Java, but I don't remember to have had the same issue in pascal.  Well, Now the question is: what is the best workaround for this? I've thought that one possible solution is using fixed point representation, via external libraries as:  or  . Other maybe is to use a precision arithmetic library as:


After hitting 80% LTV, my mortgage lender refuses to remove PMI. Any recourse?

I recently refinanced my home. At the time based on the appraisal vs. amortization I found I would be stuck with PMI (private mortgage insurance) for about 9 months.  I've paid extra on the mortgage each month and after 7 months I got my LTV (loan-to-value ratio) to be 79%. Yay! So I called Pacific Union and asked for PMI to be removed.  The woman said I'd need to fax in a written request. Then she added that my written request would likely be denied because my account had not been in good standing the last 12 months. I pointed out that I'd only had the loan for 7 months and had never been late, but that didn't seem to matter to her.  So I faxed in my written request. Then I read through all my documentation on my loan. Nowhere did it say that I needed to have the loan for 12 months.  After a week I called them back and they said it would be another week for a decision.  So, I waited another week and called. They now just had a recording saying they were too busy to take a call and I could leave a callback number. I did this and never heard back. I've now tried twice more to call them. Each time I leave a number and each time I don't hear back. So I've fired off a written request again.  At this point we've gone around the horn to the next month and in two short days I'll be paying PMI on March's payment.  Do they have any grounds to not remove PMI? Isn't it federally mandated that PMI must be removed at 80%? Any recourse anyone can think of?  [EDIT] - I heard back from Pacific Union. They state that I did not sign anything agreeing to these terms which is what I was certain of. They state these terms are simply automatic with Fannie Mai backed loans and it doesn't matter if I was informed or not about these terms. They also chose not to hide behind the "no late payments" clause and instead said they were requiring an appraisal to remove PMI. Of course an appraisal is $400 and I'll hit 78% LTV before I would pay that much extra in PMI. I have now contacted a lawyer. I'll update again with whatever opinion the lawyer has and whether I proceed or not.  [EDIT] - I filed a BBB complaint. They waited 30+ days to respond. In their response they indicate that the first woman (and some SE users below) are wrong. The loan does NOT have to be in good standing for 12 months. The loan simply needs no late payments within 12 months. They then hide behind the request for another appraisal as the sole reason to not remove it. I checked with Fannie Mae who backs the loan and was told this is optional per the lender, however the lender can force it and I have no recourse. Additionally, they could have asked for a Broker's Price Option (BPO) or a certificate of value which would cost me hundreds less.   At this point I cannot continue to fight them because the amount of PMI I'll pay until 78% LTV is equal to or less than the appraisal cost of $400.  [EDIT] As of August 2015 I've hit 78% LTV. I called Pacific Union to ensure that the automatic cancellation of PMI had happened. They said no, I'd need to request that in writing. This is a violation of federal law as it's supposed to be automatic. They also said they would still deny it because now they want 24 months of good history. I've sent a threatening letter off and am waiting for a reply. If any lawyers come along and read this I'd sure like to hire you.  [EDIT] After my letter they said they would remove PMI. They did not and I was charged again in September. I called them yet again and complained. They said PMI was going to be removed. They then charged my again in October! I called again. I called again and went berserk on the phone. PMI was finally removed for November 2015. First month without it.


How do I run a 12V 450mA DC motor using a 12V 1A DC adapter? It is for a small water pump for one of those decoration waterfalls. Should I simply add a (R=V/I) resistor? If so, what is the approximate R value I should go for? Also, where should I put the resistor in the circuit?


Running Win32 program from Bash for Windows 10

I got the latest update from Windows that adds bash, and I was trying to script the execution of an Android emulator through this; however the Path variables of Windows are not taken into account for bash.  Plus I tried executing adb manually and I got:  andtest@DESKTOP:/mnt/c/Android/sdk/platform-tools$ exec ./adb.exe bash: /mnt/c/Android/sdk/platform-tools/adb.exe: cannot execute binary file: Exec format error   Is there something I'm missing here? I want to use this Windows computer as a test server for Android.


Is it possible to trigger an email using microsoft flow when a date in a field of a sharepoint list item is nearby?

I want to build a flow to trigger an email when a date in one of the fields is nearing. I have a field named Payment due date. is it possible to trigger an email 2 days prior to the Payment due date. So that I don't miss the payment due date and payment is not delayed. I tried using schedule in power automate. but what should I use while giving the path to the sharepoint list and selecting the sharepoint, I think if I use "when an item is created/modified" it will only trigger when an item is created/modified.   Thank you very much in advance!


Whenever  i clipping mask any image it takes extra invisible space... And it causes problem when i mock it. Is there any way to get rid of that extra space in bounding box? I want image 1 to get the same bounding box like image 2.


Why might it be advisable to keep student debt vs. paying it off quickly?

As of a couple weeks ago, I paid off all of my student debt. Hooray...  But I have a friend named A who has a friend named B who is a financial advisor (a young so therefore perhaps ignorantly malicious one). B has convinced A that he should take a very long time to pay off his student loans.   This makes no sense to me. Even if your money can be invested to produce value faster than your debt will accrue interest, there are still obvious problems. For example, if you lose your job, you're potentially in trouble. Any financial setback could turn into a terrible credit score.   Is there some reason somebody would and should willingly take a long time to pay off student debt and why?


How To Create a Matte Car Paint Material?

This is something that has been irking me for a while, as I've been working on a car project. I'm trying to create a paint (in cycles) similar to the the material in this image:    The problem is, whenever I try to make it, it always comes out looking to diffused or too sharp.  Here's my node setup:    And here's the render:


What is the equation for an ARIMA(1, 1, 0) Model?    Please note that I fit the model to a time series in R and received an "ar1" coefficient of 0.6017 and that was the only coefficient estimate provided by R.


NullPointerException where there's no possibility for one

I'm trying to find a solution for a programme which I'm writing. The problem occurs even though I tried to prevent it and I don't seem to be able to find a mistake. This is the ''problematic'' part of my code:   if (this.s != null) {         if (s.s != null && s.s.sta.length != 0) {             for (int n = x; n < s.s.sta.length + x; n++) {                     this.sos[n] = s.s.sta[n-x];             }             x = x + s.s.sta.length;         } }   I have an array STA which I'm using and a method which gives me the ''s'' neighbour of an object, so s.s is a neighbour of a neighbour.. What I'm trying to do is copy the objects from more than one specific neighbour into one array with many different if sentences. This one is an example but it doesn't work.  Thank you and I really hope I get some info because I'm completely lost.


Image of dual map is annihilator of kernel

Suppose $T:V\to W$ and that $V$ is finite-dimensional.  I want to prove that $$\text{Im }T'=(\ker T)^0$$ where $T'$ is the dual/transpose map and $(\ker T)^0$ is the annihilator of the kernel.  I know that $\phi \in V'$ is an annihilator of $\ker T$ if and only if $$\phi(v)=0 \space \forall v\in \ker T$$ if and only if $$\phi(v)=0 \space \forall v \in V \text{ such that } T(v)=0$$  Now I also know that $\phi \in \text{Im }T'\subset V'$ if and only if $$\phi = f \circ T \text{ for some } f \in W'$$ I can see that if $v\in \ker T$, then this implies $\phi(v) = f(T(v)) = 0$, so $\phi \in (\ker T)^0.$  However, I'm having trouble showing the other way, that if $\phi \in (\ker T)^0$, then $\phi \in \text{Im }T'.$  Could anybody help?


Historical grammatically of “Do not go gentle into that good night”?

I am not by any means a poetry expert, but I know a bit about grammar and writing. Ergo, I can say that in Dylan Thomas’s most famous poem, , the refrain that the poem takes its name from is ungrammatical. The grammatically correct way to write (or say) this would be “Do not go gently into that good night.” What I want to know is as follows:   a) Is there a historical usage of “gentle” as an adverb and b) if there isn’t, why did Thomas determine that it was okay to use an adjective adverbially? Or is there some poetry-grammar exception that I am unaware of?


Why am I getting an undefined control sequence?

Sorry if this is very basic but I really cannot figure out why I am getting this error. I checked all my commands and they seem correct. I attached my attempt along with what I am supposed to be typesetting.Thanks!


I want to prove that with $z_0$ a root of $1+z^n$, I have  $$ z^n - z^n_0 = (z-z_0)\sum_0^{n-1} z^kz_0^{n-1-k}$$


self-adjoint operator, such that $T^2=T^3,$ is orthogonal projection.

Let $T$ be a self-adjoint operator on a Hilbert space $H$, such that $T^2=T^3.$   Prove that $T$ is an orthogonal projection. Is that true if we had $T^4=T^3$?   Thank you for the help.


Is it possible to filter questions by reputation of the author? Just Something like [favtag] [rep<5] to show all the newcommer questions.


I am trying to use bibtex for the first time. I am on windows 7, using TeXstudio. I am trying to follow the steps of .  I have created a .bib file, put it in the right directory and written the code in my .tex file. However, I do not know how to compile bibtex with TeXstudio (I looked around in the menus but didn't find it).   Most tutorials I found don't explain how to do it, or say to run a command, which I'm not sure how to do.  Any help much appreciated!


OS X El Capitan downloading froze and now it won't let me download?

I was trying to upgrade to OS X El Capitan when my screensaver kicked in or something and froze the download. But now the App Store shows it "download" as apposed to "downloading" when I try and download it. And nothing happens vs before when the screen turned into an iPad screen. Not sure if there is a file to delete of what?


I am having the same problem discussed at .  I don't know what I did but my attribute table is now lurking somewhere but I can't find it. I use only one monitor. The previous question was resolved by right clicking on the taskbar and selecting "show windows stacked." However, I have tried right-clicking everywhere and I haven't seen an option for "show windows stacked."  I've tried quitting ArcMap but nothing changed. I do not want to have to reinstall ArcGIS Desktop nor do I want to have to change the registry.


Second Monitor does not detect on Ubuntu 14.04.1 LTS but detects on Windows 8.1

I just installed Ubuntu 14.04.01 LTS on my secondary partition on my Solid State Drive. I noticed that when I went into System Settings --> Displays --> Detect Displays, my system is not detecting the second Acer monitor I have set up.   Other details that my be relevant is that I have a Nvidia GTX 750 TI and the Dell monitor is connected to the video card via DVI and the Acer monitor that is not detecting is connected to the video card through HDMI cable cord.   Please let me know if there is anything I can do to trouble shoot this. I'm sure it is not a hardware issue because the dual monitor set up works on my windows 8.1 OS partition. Happy holidays!


What happens when a devil fruit eater is asleep?

In One Piece, I know that when a Devil Fruit eater is unconscious the people that were affected by the fruit are then returned to normal, like in Sugar's situation for example. And I was thinking, being asleep is also a state of being unconscious.  So does Sugar ever sleep or is being asleep a different story?


What's with this Adobe logo? I don't use Adobe Flex, I use Flex, the fast lexer, and I've had to add a million tags to my ignored list to try (unsuccessfully) to filter out the questions about this Adobe Flex business to get to the (few) questions about Lex and Yacc. And now this?  I suppose this is some kind of promotion sponsored by Adobe. How long will it last? When can I go back to trying to forget that a company I don't like has a product with the same name as a common tool that helps write compilers?


I wrote a code linking my sql database with project. I have been attempting to create an ATM with graphics. i have the following tables in the database: table userinfo: accno(P key), name,  balance table pin: accno(foreign key from userinfo), pin I wrote the following code, however on running it shows nullpointer exception which I am unable to fix. I tried to find the point where the exception occurs by writing system.out.println("world"); in order to check which part of the code is wrong. I found that my try block is not working and I am unable to fix this. Please help me. my code:  public void actionPerformed(ActionEvent evt) {  try{      System.out.println("world4");  PreparedStatement ps=con.prepareStatement("Select * from pin where accno=? AND pin=?");            System.out.println("world5");   l1=Long.parseLong(acc);         l2=Integer.parseInt(pin);   ps.setLong(1,l1);  ps.setInt(2,l2);                 System.out.println("world7");   r=ps.executeQuery();  PreparedStatement ps1=con.prepareStatement("Select * from pin where accno=?");  ps1.setLong(1,Long.parseLong(tfnumber.getText()));  r1=ps1.executeQuery();  if(r.next())  {      m=new menu();      setVisible(false);      System.out.println("world1");  }  else if(r1.next())          {   System.out.println("world2");              lblerr=new Label("INVALID PIN!");              lblerr.setBounds(470,400,80,30);              img.add(lblerr);              lblerr1.setVisible(false);              lblerr.setVisible(true);          }  else  {      System.out.println("world3");     lblerr1=new Label("ACCOUNT NOT FOUND");      lblerr1.setBounds(370,300,80,30);          img.add(lblerr1);          lblerr.setVisible(false);          lblerr1.setVisible(true);    }  } catch(Exception excp) {      System.out.println("world6");      System.out.println(excp);  }   here WORLD4,WORLD6 are printed on the screen, however, WORLD5&WORLD7 were not printed, indicating the non functional tryblock.


Find the limit of $\frac{n^{x}}{(1 + x)^{n}}$

Let $x>0$. Find $$\lim_{n\to\infty}\frac{n^{x}}{(1 + x)^{n}}.$$   What I was thinking involved an inequality, by reason of considering the fact that  $$(1 + x)^{n} > C(n, k) x^{k}$$ for some $k$ such that $n>k$. Expanding the binomial coefficient and taking the $n$ common from each bracket, we have something like $$(1 + x)^{n} > C(n, k) x^{n} > \frac {x^{k}n^{k}}{k! 2^{k}}.$$ But now, I am totally clueless. By intuition, I know that the limit has to be zero, so I just want to prove using the concept of inequalities that what I thought was the right approach (being the sandwich theorem). Any help would be appreciated!


I was wonderwing about a matrix equation (in some way similar to a very well known theorem :P).  Find all positive integers $n,m$ such that there exists $X$, $Y$, $Z$ matrices $n\times n$, non-singular, such that: $$X^m+Y^m=Z^m$$  Disclaimer: $X$, $Y$, $Z$ must have integer entries. Also, they may have an inverse which is not necessarily in $\mathbb{Z}^{n\times n}$.  I made some approachs (I don't know how to spoil, so if you want to think it yourself stop reading):  As my intuition says to me that there will always be solutions for $n>1$, then, it suffices to show there will be solutions for $n=2$ and $n=3$ (because then you can form a matrix composed by matrices $2\times 2$ and $3\times 3$ in its diagonal).  I showed that for all $m$ odd, and $n=2$ there is a solution.   Can someone give me a hand with the other cases? I would be very grateful.


How do you install chntpw on Ubuntu 17.04?

I downloaded the tar.gz off of the Ubuntu Package website and have tried following 3 different tutorials, and every time I try to do something terminal tells me I can't. I haven't made any progress.


Querying multiple post types ensure 1 of each type

If I'm querying more than 1 post type, is it possible to ensure that I will always get at least 1 of each type?  $args = array(     'post_type' => array( 'post', 'project' ),     'posts_per_page' => 3,     'ignore_sticky_posts' => true, );  $recent_posts = new WP_Query( $args );   In this example, I'd like to ensure that I always have at least 1 post in the 3 posts that are returned.  I dislike how sticky posts behave as it ends up returning more than the 3 items requested and will impact other parts of my site.


Hydrogen radial wave function infinity at $r=0$

When trying to solve the Schrödinger equation for hydrogen, one usually splits up the wave function into two parts: $$\psi(r,\phi,\theta)= R(r)Y_{\ell,m}(\phi,\theta).$$ I understand that the radial part usually has a singularity for the $1s$ state at $r=0$ and this is why you remove it by writing: $$R(r) = \frac{u(r)}{r}$$ But what is the physical meaning of $$R(r=0) = \infty~?$$ Wouldn't this mean that the electron cloud is only at the centre of the atomic nucleus?


Uncountable set with exactly one limit point

Is there any uncountable subset of $\mathbb{C}$ with exactly one limit point?


loss of precision when using sqrtl() with long long int  I need to use a variable to store the value since I would expect the user to type in their own value in range 0 to 10^18, so it makes sense to use long long int in this situation. But this is where the error occurs which I could not solve it properly.  unsigned long long int a = 999999999999999999; cout << fixed; cout << (floor(sqrtl(999999999999999999)) == sqrtl(999999999999999999)) << endl; cout << floor(sqrtl(999999999999999999)) << endl; cout << (sqrtl(999999999999999999)) << endl;  cout << a << endl; cout << (floor(sqrtl(a)) == sqrtl(a)) << endl; cout << floor(sqrtl(a)) << endl; cout << (sqrtl(a)) << endl;   In my machine, the output is  0 999999999.000000 1000000000.000000 999999999999999999 1 1000000000.000000 1000000000.000000   which shows the loss precision when using sqrtl(a) compare to sqrtl(999999999999999999)  I want to be able to get the correct value while using the variable


Is a Riemann-integrable function always differentiable?

Let $f:[a,b]\to\mathbb{R}$ be Riemann-integrable and $F(x)=\int_a^xf(t)dt$. Is this function $F$ always differentiable? Because the antiderivative is defined as $F'=f$ right, so you would think that it always holds.


How to calculate the square root of a number?

By searching I found few  but all of them involve guessing which is not what I want.  I need to know how to calculate the square root using a formula or something. In other words how does the calculator calculate the square root?


How to solve null pointer exception when working with Firebase

I am getting a null pointer exception while trying to retrieve data using Firebase.  The following is a description of my error:-  The error was pointing on myRef = mfirebaseDatabase.getReference();  This is my full error:-   java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.vignanstudent/com.example.vignanstudent.v_b_d}: java.lang.NullPointerException: Attempt to invoke virtual method 'com.google.firebase.database.DatabaseReference com.google.firebase.database.FirebaseDatabase.getReference()' on a null object reference         at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3335)         at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3474)         at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:83)         at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)         at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)         at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2081)         at android.os.Handler.dispatchMessage(Handler.java:107)         at android.os.Looper.loop(Looper.java:214)         at android.app.ActivityThread.main(ActivityThread.java:7643)         at java.lang.reflect.Method.invoke(Native Method)         at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:516)         at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:950)      Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'com.google.firebase.database.DatabaseReference com.google.firebase.database.FirebaseDatabase.getReference()' on a null object reference         at com.example.vignanstudent.v_b_d.onCreate(v_b_d.java:39)         at android.app.Activity.performCreate(Activity.java:7815)         at android.app.Activity.performCreate(Activity.java:7804)         at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1318)         at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3310)         at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3474)          at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:83)          at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)          at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)          at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2081)          at android.os.Handler.dispatchMessage(Handler.java:107)          at android.os.Looper.loop(Looper.java:214)          at android.app.ActivityThread.main(ActivityThread.java:7643)          at java.lang.reflect.Method.invoke(Native Method)          at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:516)          at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:950)


Ubuntu 19.04 Software Center - which apps are official / legitimate?

I've just installed Ubuntu 19.04 and I'm installing all my normal sofware.  I've noticed that many apps have mutilple versions/sources.  How would I tell which ones are official?  Some are from ubuntu-disco-universe and others from Snap Store.  Some have a developer listed and others don't.  Some packages have different developers for each version.  For example I have these two options for kdenlive:  kdenlive   - Version: 16.12   - Developer: j-b-m   - Source: Snap Store   kdenlive  - Version: 4:18.12.3a-0ubuntu1  - Developer: ...BLANK...  - Source: ubuntu-disco-universe   Edit:  I'm specifically trying to avoid potential malware or trusted software.


Can we do residual analysis for random forest classification model that gives out probability instead of class label?

My colleague introduced me to this idea that we can do residual analysis for random forest classification problem that spits out probabilities instead of the class label for a binary classification problem. This claim has surprised me. I am under the assumption that residual analysis can only be done for a regression problem. I cannot find relevant literature to rebuttal the arguments of my co-worker. May I know if anyone of you has come across this idea before, or you have a proof for why this claim might be wrong. In addition, will a residual plot have any meaning in this regard?


Understanding Pantheon Workflows and Best Practices for Deployment to an Active Site

I've currently moved an active user site over to Pantheon. It's structured and themed extensively using Panels Everywhere, Panels, Views, and Display Suite.  What I would love to do now, is on the Dev/Test version is to revamp the site structure and display. But while that work is being done, every day new users are interacting with site changing its content, uploading files, etc...  From this previous post...        I understand that the following is a best practice...   code should go from dev -> test -> live  database should go from live -> test -> dev   My question is in this scenario, how can I work on my site (ala Panels, Views, Display Suite) in a Development environment and then push those changes to the Live environment?  There seems to be no way to do this purely in Pantheon since a large majority of the site changes will be on the DB, and if I push that to the Live environment, it will override all the new and changed user content.  Can someone point me in the right direction on this? I seem to be chasing my own tail about how I should be going about this in a sustainable fashion.


In which part of the history the man jumped from the intuitive concepts to the most complex ones?

This question explains better what this one tried:      In the history mathematics we always see how the numbers were created and for what purpose. Like ordering, calculation of areas and taxes. This is the most common approach on documentaries and so in the math books.  It's always easy to understand the basics: Add, subtract, multiply and divide. The reason it is easy is that it is intuitive. We can imagine those things happening in our minds through visual representations.  I'm digging these documentaries looking for the part where we jumped from these basic operations to the complex ones. At least to me, the complexity starts when we add negative numbers. For example, in this simple operation:   $1 + (-1) = 0$  It's easy to understand how to apply and use the provided logic of signs. But to me it is not easy to imagine what is really happening here. And when I say "happening", I mean that I can't create any object visualization of that operations, like the ones we learn on high school:  "Imagine that you have two breads. You have eat one. Now how many do you have?"  On that kind of visualization you can imagine the two objects and then you can take off one and see how it looks like. This can be done for all the basic four operations on small scales.  You could say that the operation above is the same as $1 - 1 = 0$ But that's not the case. Doing so you are omitting the signs part and using it just as predefined formula.  The main question is about when in the history and for what reason the man came out with the signs and that kind of operation. In other words: Which was the first step given after these basic and very intuitive operations? And which was the necessities that leverage these discoveries? Like the need to have a convention where plus and minus become minus.  It is easy to think of debts. In that case, can you provide a simple visualization like the mentioned above for the product of two negative numbers?


How do you databind to a System.Windows.Forms.Treeview control?

I'm looking at this control, and it seems to be lacking the standard .net "datasource" and "datamember" properties for databinding.  Is this control not bindable?  I can write some custom function that populates the treeview from a given data source, I suppose, and embed data objects as necessary, but is that the 'best practice'?  Or does everyone simply use a 3rd party treeview control?


What makes RAW formats better for manipulation than JPEGs or PNGs

So I've seen everyone saying that RAW format is much better for manipulation in photo editing applications like Lightroom than JPEGs or PNGs. While I read some posts here like  and , I'm  still wondering why is that.   Is it because of better dynamic range? Or because of the bit depth which is 12/14 bits in RAW compared to only 8bit in JPEGs?.  To clarify my question further... By format I mean how the file written, it's a purely technical question... What make those shadow recoveries, and such great dynamic range possible?


Should I really have been awarded mortarboard on a Per-site meta?

The  caused me to win , yey!  But wait.     [Mortarboard] Hit the daily reputation cap for the first time   Per-site metas don't have any reputation... I am confused :-)  I know why I got the badge. Should I have?  Let me rephrase. Is this behavior desirable?


count(*) vs count(column-name) - which is more correct?

Does it make a difference if you do count(*) vs count(column-name) as in these two examples?  I have a tendency to always write count(*) because it seems to fit better in my mind with the notion of it being an aggregate function, if that makes sense.   But I'm not sure if it's technically best as I tend to see example code written without the * more often than not.  count(*):  select customerid, count(*), sum(price)  from items_ordered group by customerid having count(*) > 1;   vs. count(column-name):  SELECT customerid, count(customerid), sum(price) FROM items_ordered GROUP BY customerid HAVING count(customerid) > 1;


How to root a xperia mini device? is it safe? Am i need a program or an app? is there an open source or private application  for this procedure?


Given: a = 1 b = 10 c = 100  How do I display a leading zero for all numbers with less than two digits? This is the output I'm expecting: 01 10 100


How to calculate the confidence interval of the mean of means?

Imagine that you repeat an experiment three times. In each experiment, you collect triplicate measurements. The triplicates tend to be fairly close together, compared to the differences among the three experimental means. Computing the grand mean is pretty easy. But how can one compute a confidence interval for the grand mean?  Sample data:  Experiment 1:   34, 41, 39  Experiment 2:   45, 51, 52  Experiment 3:   29, 31, 35  Assume that the replicate values within an experiment follow a Gaussian distribution, as does the mean values of each experiment. The SD of variation within an experiment is smaller than the SD among experimental means. Assume also that there is no ordering of the three values in each experiment. The left-to-right order of the three values in each row is entirely arbitrary.  The simple approach is to first compute the mean of each experiment: 38.0, 49.3, and 31.7, and then compute the mean, and its 95% confidence interval, of those three values. Using this method, the grand mean is 39.7 with the 95% confidence interval ranging from 17.4 to 61.9.   The problem with that approach is that it totally ignores the variation among triplicates. I wonder if there isn't a good way to account for that variation.


New to Java HTTP requests, and can't sort out how to decode the input stream.  It's a simple GET, so as per the advice here, I'm using the following code:  public void setupIPCheck() throws IOException {     URLConnection connection = new URL("http://freegeoip.net/json/").openConnection();     InputStream response = connection.getInputStream();     Log.d("IPcheck", response.toString()); }   I'm expecting a JSON blob - do I have to read every byte from the stream manually?  I'm developing for android, so I can't use IOUtils.


Add separation of numbers to view counter?

For usability reasons, for example in , the 'viewed' counter should show as  ...instead of... . It's much harder to decipher that there are a million views on the question just by looking at it.  Some people in the comments pointed out internationalization concerns with it. I do think that since there might be a problem with it, that spaces would probably be a better idea.


Slope analysis from NED data gives crazy histogram?

I'm attempting a simple slope analysis in QGIS2 using the plugin at Raster -> Terrain Analysis -> Slope. The slope output layer has a very strange histogram, basically spikes at 0 and at 89.9098 with one big valley in the middle:    Here's the initial DEM:    And the resulting slope layer (note that Contrast Enhancement is already at 'stretch to minmax'):    The place I got the DEM is the NED. I tried the gridfloat format, and the arcgrid format, and the IMG format. I downloaded from nationalmap and also from atlas.ca.gov - all seem to have the same resulting histogram.  The procedure I used to make the slope layer was Raster -> Terrain Analysis -> Slope, GeoTIFF, Z factor = 1.0 (what does that do anyway?)  Seems like simple pilot error; however: I found  online (for QGIS 1.something) that comes with a sample DEM, and it worked just fine using the same procedure. So, it's not a fundamental QGIS2 bug.  So, it must be slightly more complex pilot error: there must be a conversion step or something I'm missing?


Does someone know how to make one preg replace from this two? It should cut off: https://, http://, ., . or only www.  preg_replace("/^www\./", "", preg_replace("/https?:\/\/(www\.)?/", "", $hostname, 1), 1);


Relationship between Gamma and chi squared distributions

What is the relationship between the Gamma distribution and the chi-squared distribution?


A bounded net with a unique limit point must be convergent

Let $(x_i) _{i \in I}$ be a net in a compact Hausdorff space X, with the property that every convergent subnet has the same limit $x$. Does this imply that $(x_i) _{i \in I}$ converges?  If I try to proceed by contradiction, I do not how to rule out the possibility of having subnets that do not converge at all. (Of course, by compactness each such subnet should have at least a subnet convergent to $x$, but this does not help me.)  (If it helps, my compact space is in fact a weakly-compact subset in a locally-convex linear topological space space, obtained with Alaoglu's theorem.)


How many ways are there to split $10$ people into two groups of $5$?

In the example below I get the first part. May I know why they're dividing by 2 for the second part? I'm asking because I feel the answer for second part should also be $\binom{10}{5}$.   In the first part simply by choosing 5 people, we're already splitting the squad into two teams. So I don't really see a difference between parts 1 & 2. Help?  Example  There are ten people in a basketball squad. Find how many ways:   the starting five can be chosen from the squad the squad can be split into two teams of five.   Solution   There are $\binom{10}{5} = \frac{10\times9\times8\times7\times6}{5\times4\times3\times2\times1} = 252$ ways of chosing the starting five. The number of ways of dividing the squad into two teams of five is $\frac{252}{2} = 126$.


I have a loop that is doing some error checking in my PHP code. Originally it looked something like this...  foreach($results as $result) {     if (!$condition) {         $halt = true;         ErrorHandler::addErrorToStack('Unexpected result.');     }      doSomething();  }  if (!$halt) {     // do what I want cos I know there was no error }   This works all well and good, but it is still looping through despite after one error it needn't. Is there a way to escape the loop?


How do I generate GUID in apex class in salesforce in the following format mentioned(16 bytes or 128 bits)?  BA8D6569-9208-4DBB-9357-A4500838101E  Any suggestions will be appreciated. Thanks in advance


I have the following question that I attached in png format.   I have done part (a), but I am having difficulties in part (b) when I proceed according to the book. I have non zero tension at equilibrium length. I reached that conclusion by taking the derivate of entropy with respect to L and n at the same time. What is the physical principle underlying this?


How can give me two or three examples about Banach spaces which it is not Hilbert spaces with proof ( I mean why it isn't Hilbert spaces ) ?


Delay of 15 hours in Air India Flight from New York to Delhi

I am supposed to travel by Air India International flight from New York to Delhi on 7th July (Departure time 12:05 pm)  but i have received a mail from them saying that now the flight has been rescheduled for 8th July (Departure time 03:45 am) and the delay is for than 15 hours. Kindly let me know what steps can i take to get refunfd from them regarding hotel and food as all my bookings were till 7th July only.


Changing the default decoder aac(native) into aac(libfdk_aac) or aac(libfaac)

Is is posible to change default decorder of ffmpeg? If I use  ffmpeg -i pipe_video.fifo -i pipe_audio.fifo -c:v copy -f flv file.flv   ffmpeg automatically changes aac(native) into (mp3)libmp3lame (!!!!). I just wanna copy the stream automatically. No more. input pipe_audio.fifo is adts (libfaac)


Delete all contacts in Marketing Cloud to delete all duplicates

We have duplicates in our all contacts in Marketing Cloud. To solve this, we want to delete all contacts (audience builder).   We use the Marketing Cloud connector, and send emails to synchronized data extensions. Because of this connector the all contacts will be filled with fresh data after 15 minutes right?  Is there any reason not to do this? What can go wrong?


I have written an algoritm to resolve a collision between two balls with conservation of momentum. It looks to work exactly as expected in my simulations. Here is the code:  public void Resolve() {   var r = 0.5; // coefficient of restitution   var m = Ball1.Mass + Ball2.Mass;   var ua = Ball1.Velocity.Magnitude * Math.Cos(Ball1.Velocity.Angle(Normal));   var ub = Ball2.Velocity.Magnitude * Math.Cos(Ball2.Velocity.Angle(Normal));   var va = (r * Ball2.Mass * (ub - ua) + Ball1.Mass * ua + Ball2.Mass * ub) / m;   var vb = (r * Ball1.Mass * (ua - ub) + Ball1.Mass * ua + Ball2.Mass * ub) / m;   Ball1.Velocity -= Normal * (ua - va);   Ball2.Velocity -= Normal * (ub - vb); }   Now I also want to make this work for more than two balls colliding at the exact same moment. My initial thought was that I could just solve this equation several times for each contact between balls. When I have a situation like a "Newton's cradle" where the balls is in contact in a "serial" way it's easy to just solve each collision on at a time and without moving the balls just go ahead and calculate the next and the next etc until reaching the last ball which will end up with all energy not lost along the way. This works fine also, albeit not very fast.  But what about for instance a case where three balls are in contact in a V-shape and the bottom ball is the one with a velocity (up in this case)? I mean how now do I distribute the energy between the other two balls? The equation I have only works for two balls and now I don't see how I can calculate this iteratively anymore. Can you help guide me in how I should think with this? Can I modify my Resolve-function to work with any number of balls? I mean with a set of $N$ balls with connecting surfaces and initial velocity vectors, what will the outcome velocities be? Is there a well known general solution for this?  Note:  I have tried out the method currently marked as the answer but I have unfortunately got a bit weird results in some setups. Be warned. I will probably revert back to resolving one collision at a time again. I will update this info when I have tried this more.


$\Gamma \subset \mathbb{R}^{+}$ is uncountable. Can we choose a sequence from $\Gamma$ of which the sum is $\infty$

If $\Gamma$ is a set of uncountably many different positive real numbers, can we choose a sequence of pairwise different positive numbers from $\Gamma$, say $\{a_n\}$, such that $\sum a_n = \infty$ ?   I am considering such problem and I think the answer should be yes. But what's the rigorous way to prove it? Please give me some hints and I will appreciate any help :-)


How to make user automatically log in in Lubuntu 16.04?

How do I make a user automatically log in in Lubuntu 16.04?


Prove that $3^n>n^2$ for any positive integer n>2  Let $n=1$ $$3^1>1^2$$ Let $n=2$ $$3^2>2^2$$ Assume P holds for n=k $$3^k>k^2$$ Let $n=k+1$ $$ \begin{align} 3^{k+1}>(k+1)^2 \\3\times3^k>(k+1)^2 \end{align}$$ From here I can not find where to go to finish the proof.   The main part of the question is the proof, however; I would like to also know if using $n=k+1$ is always the way to go? I have only done a few proofs by induction and so far to my understanding is that the whole point is to prove the function, series or statement for all positive integers. Is there a special way to go about these types of problems when only given an inequality or a single statement? In comparison to being give a sequence and told what that sequence as a function is, i.e $1+2+3+...+n=\frac{n(n+1)}{2}$ as an example as an easy sequence to prove with $n=k+1$


Windows 7 indicates "you need permission to perform this action" (deleting file)

I'm logged in as an Administrator on Windows 7.  When I try to delete a folder (which shows Security settings indicating that Administrators have FULL access) I get a message that :  You require permission from SYSTEM to make changes to this file.  I don't have any other user accounts on this computer.  What's up with this?


How many different ways are there to write $2016$ as the difference of two squares?  So the question is asking for the integer solutions for $2016 = x^2-y^2$. The prime factorization of $2016$ is $2016=2^5\cdot3^2\cdot 7^1$. I’m not sure how should I continue from here, what would be the proper way?


Regex matching across multiple lines with 3 values

I've seen a few examples of this, but I can't seem to get it to work in my particular situation.  Lets say there is the below file.  foo line 1 line 2 line 3 bar junk junk foo line 1 line 2 baz line 4 bar   I'm trying to catch everything between 'foo' and 'bar' as long as it contains 'baz' with a one liner.  Everything I've found so far is great for finding everything between foo and bar, but nothing seems to be good for only finding it if it contains baz.  Edit:  The below works for me:  sed -n '/foo/{:a;N;/bar/!ba; /baz/p}' input.txt


What is the Linux equivalent to Windows' Program Files?

Under Windows, most applications and application data are stored in a special directory known as C:\Program Files (and occasionally C:\Program Files (x86)). What is the Ubuntu/Linux equivalent to this path? Is there even one?


Operate on all files under a folder that are larger than some size

I'm working with some PhotoRec output files, and I'm only interested in files that are larger than a certain size threshold let's say 10M. I've found ways to sort recursively in other posts () but I couldn't quite figure out let's say move all of these files to a different location. Right now the structure of the folders looks something like this:  parent folder  re1 re2 re...