Work done by kinetic friction on a block modelled as a system

Let's consider a setup consisting of a table with friction, and a block on top of it. Suppose we drag the block across the table with a constant speed. The applied force $f_{app}$ acting through a distance $d$ does a work $f_{app}d$. The frictional force $\mu N$ is equal to $f_{app}$ since there is no acceleration. So the total work done on the block by these external forces will be $\Sigma W = W_{app} + W_{friction} = F_{app}d - f_{Kinetic Friction}d = 0$  According to law of conservation of energy, if there is an energy change in the system , it is because the energy is being transferred across the system boundary by a transfer mechanism (work, heat, mechanical waves, matter transfer, electromagnetic radiation etc.) So, $\Delta E_{system} = \Sigma T$, where $\Delta E_{system} = \Delta K + \Delta U + \Delta E_{internal}$ and  $\Sigma T$ is an energy transfer mechanism.  In our case, we have $ W_{app} + W_{friction} = \Delta K + \Delta E_{internal} $, $\Delta K = 0$ as there is no change in speed, then $ W_{app} + W_{friction} = \Delta E_{internal} $ , but as $ W_{app} + W_{friction} = 0 \Longrightarrow \Delta E_{internal} = 0$ So that means there is no increase in the internal energy, but clearly the block heats up. Can anyone explain to me what's happening here?


How do I improve my ability to get loans to use as leverage for my business?

Relating to Europe, but an US-focused answer is also welcome.  Plan:  I have a small stain on my credit history due to a tax issue. I am otherwise financially sound.  I am not big enough for a bank to give me loans for certain things. I had recently took a loan out to purchase a bulk of products that I later re-sold. The type of loan was "personal" and I only specified it was for personal needs. It was for 3 months and I paid it in 3 months.  I didn't need the loan; I simply wanted to see if the bank would approve a small-medium sized loan to me. The deal worked for me better because of the smaller risk posed by 3 payments instead of a bigger one.  After it was all done, it occurred to me that this could be used to boost my financial reputation in terms of someone who'd need a loan / credit later on.  Assume the numbers:  I take a loan for $10,000 for 12 months.  I'd have to pay $1,100 monthly for these 12 months. Instead, because I'm well off and just needed this to lessen my personal risk, I pay it all off in 3 months.  In my humble opinion, I just hopefully traded $1,100 now for trust and a bigger leverage in the future.  Does paying off such loans earlier than anticipated improve the metrics the bank would use to evaluate me for future loans?  As such, do these actions of paying upfront, paying full upfront help me in any way or measure to raise my trust within the system?  My end goal is to have the ability to take out larger or longer term loans in the future.


Let $(X,d)$ be a metric space and fix some $y \in X.$ Show that the function $f: X \to \Bbb R $ defined by $f(x) = d(x,y)$ is Lipschitz continuous.  Let $x, z \in X$. Using the triangle inequality one has $$f(x) = d(x,y) \leqslant d(x,z)+d(z,y ) =d(x,z) +f(z)$$ and $$f(z) = d(z,y) \leqslant d(z,x)+d(x,y) = d(x,z)+f(x).$$ Now I was trying to combining these to bound $|f(x)-f(z)|$ somehow, but this doesn't seem to work like I thought. I get that $|f(x)-f(z)| \leqslant |d(x,z)+f(z)-(d(x,z)+f(x))| =d(x,z) +f(z) +d(x,z)+f(x) = 2(d(x,z)) + f(x)+f(z)$, which doesn't help at all. What am I missing here?


Validation set after hyperparameter tuning

Let's say I'm comparing few models, and for my dataset I'm using train/validation/test split, and not cross validation. Let's say I'm completely done with parameter tuning for one of them and want to evaluate on the test set. Will I train a new model, on both the training and the validation datasets combined with the best configuration, or will I just run the same model on the test data?


String in Java is object, so it should be reference?

I am a beginner in Java, recently faced such an interview question on Java String concept:  public class Test1 {      public static void changeStr(String str){         str="welcome";     }      public static void main(String[] args) {         String str="1234";         changeStr(str);         System.out.println(str);      } }   I think the output should be "welcome", however, I tested it in Eclipse, it showed "1234", isn't Java string is a reference, so the Java string "str" references gets changed to "welcome" in method changeStr?  Pardon me for the beginner question!


Does electric field rotates with moving electron, due to spin? Does spin influence on electric field at all?

When electron moves, its electric field contracts, and becomes asymmetric. If spin means that electron rotates around itself, does the electric field rotates too?  Does spin influence on electric field at all?


Replace specific character from an array of pointers

I'm self-learning C from a book and currently studying pointers and arrays.  #include <stdio.h> #include <string.h> #define LINES 5 void main() {     char* str[LINES];     str[0] = "hola";     str[1] = "mundo";     *(*(str + 0) + 1) = 'Z';     printf("%c", *(*(str + 0) + 1)); }   Here I want to replace 'o' of "hola" with 'Z' but it's not working. if i remove:      ((str + 0) + 1) = 'Z'; I get 'o' in the output but how do i replace the character of the string?


How to delete/remove manually apt added repositories?

Please help me: I added this repositories manually and i cant remove them  echo 'deb http://download.opensuse.org/repositories/home:/Horst3180/Debian_8.0/ /' > /etc/apt/sources.list.d/vertex-theme.list  wget http://download.opensuse.org/repositories/home:Horst3180/Debian_8.0/Release.key   I tried to use removing the key using apt-key list and then removing using the id, it successfully removed the key but when i use apt update i get this output:  W: GPG error: http://download.opensuse.org/repositories/home:/Horst3180/Debian_8.0  Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 5A7D1D38BEB6D886 E: The repository 'http://download.opensuse.org/repositories/home:/Horst3180/Debian_8.0  Release' is not signed. N: Updating from such a repository can't be done securely, and is therefore disabled by default. N: See apt-secure(8) manpage for repository creation and user configuration details.   I just want to be able to run apt update normally like when a fresh OS install was made


Japanese version of Stack Overflow not working in Opera Mini browser

I am unable to use the Japanese version of Stack Overflow.  I have an account on .  The problem I am facing is this: Whenever I try to upvote/downvote or post questions/answers, I get an error:     Bad request-invalid url      Http 400 error: the requested url is invalid     How can I fix the issue?


How to completely remove ubuntu (18.04 Gnome) dock on apps screen

I removed standard ubuntu dock, and i want to delete this dock, when using "win" key and i see all running apps (dock on left side):  Is it possible to remove it? (Because i do not using it, and that dock is just interferes :c) P.S Sorry for bad english. Thanks!


American English. Please help me identify the correct form of 'become' in the following sentence:

I'm sure we'd all rather I became a bit more self-sufficient.   Using became feels right, but I would appreciate anyone who could explain what's going on grammatically here. I think become is in the subjunctive, so maybe most correctly I should say     I'm sure we'd all rather that I become a bit more self-sufficient.   Is that strictly necessary? And regarding my original construction: am I wrong to feel so right?


Changing a person's name into an adjective

What do you call it when a person's name or group's name is changed into a adjective? Is it "conversion" or "functional shift"?  For instance, saying a band's music is "Beatlesque" or that someone's singing will be "Aguilerian" (implying she will be singing with some gusto).


I am looking for an example where you have $P(n)$ implying $P(n+1)$. However there is no base case. For which there is therefore no solution at all for the induction problem even though the inductive step itself works.


Humorous story about toilet paper perforations leading to the creation "Nothing" - an unbreakable, invisible material

In this short story, a scientist/engineer discovers that the perforations on toilet paper are the strongest part.  He reasons that more perforations will make it even stronger.  He makes a material that is so perforated that it consists of nearly nothing (hence the name, "Nothing"), and is invisible and impenetrable.


This thread is not a duplicate to  because   the file /etc/locale.gen has uncommented the line en_US.UTF-8 UTF-8 which should sufficient  no localepurge is installed   I get strange perl: warning: Setting locale failed in all Linux kernel things etc  masi@raspberrypi:~ $ sudo a2enmod rewrite && a2enmod headers && a2enmod ssl perl: warning: Setting locale failed. perl: warning: Please check that your locale settings:     LANGUAGE = (unset),     LC_ALL = (unset),     LC_PAPER = "en_US.UTF-8",     LC_ADDRESS = "en_US.UTF-8",     LC_MONETARY = "en_US.UTF-8",     LC_NUMERIC = "en_US.UTF-8",     LC_TELEPHONE = "en_US.UTF-8",     LC_IDENTIFICATION = "en_US.UTF-8",     LC_MEASUREMENT = "en_US.UTF-8",     LC_TIME = "en_US.UTF-8",     LC_NAME = "en_US.UTF-8",     LANG = "en_US.UTF-8"     are supported and installed on your system. perl: warning: Falling back to the standard locale ("C"). Module rewrite already enabled  # https://unix.stackexchange.com/a/287622/16920 masi@raspberrypi:~ $ sudo deluser -remove-home pi perl: warning: Setting locale failed. perl: warning: Please check that your locale settings:     LANGUAGE = (unset),     LC_ALL = "en_US.UTF-8",     LC_PAPER = "fi_FI.UTF-8",     LC_ADDRESS = "fi_FI.UTF-8",     LC_MONETARY = "fi_FI.UTF-8",     LC_NUMERIC = "fi_FI.UTF-8",     LC_TELEPHONE = "fi_FI.UTF-8",     LC_IDENTIFICATION = "fi_FI.UTF-8",     LC_MEASUREMENT = "fi_FI.UTF-8",     LC_TIME = "fi_FI.UTF-8",     LC_NAME = "fi_FI.UTF-8",     LANG = "en_US.UTF-8"     are supported and installed on your system. perl: warning: Falling back to the standard locale ("C"). /usr/sbin/deluser: The user `pi' does not exist.   Solution  I had en_GB.UTF-8 UTF-8 only enabled in /etc/locale.gen. I should have there only enabled en_US.UTF-8 UTF-8 because of other commands run for it. So I uncommended GB and added US and everything work now  masi@raspberrypi:~ $ sudo vim /etc/locale.gen  masi@raspberrypi:~ $ sudo locale-gen  Generating locales (this might take a while)...   en_US.UTF-8... done Generation complete.  masi@raspberrypi:~ $ sudo a2enmod rewrite && a2enmod headers && a2enmod ssl Module rewrite already enabled Module headers already enabled Considering dependency setenvif for ssl: Module setenvif already enabled Considering dependency mime for ssl: Module mime already enabled Considering dependency socache_shmcb for ssl: Module socache_shmcb already enabled Module ssl already enabled   System: Raspbian Jessie Hardware: Raspberry Pi 3 b


What would happen if a show would remove its disclaimer?

What would happen if shows like South Park would remove their introductory disclaimer like message like 'all celebrities are impersonated...poorly'etc. before the show stars. What could happen to them legally? Would they be allowed to and how bad would it be?


Googling my name reveals silly things from when I was younger. I am embarassed. How will this affect me in my future academic career?

I am a masters student at one of the top two universities in the UK and will be applying for PhD positions soon. When I google my (unique) name, the first few results are what you'd expect, my LinkedIn, Twitter, Facebook, and some university web pages.   However if you keep scrolling and go through the pages of Google's search results, you see some silly forum posts from when I was 12-14 years old, and some poorly written Yahoo Answers questions from the same time. I am now 22 so this was almost 10 years ago.  I know it's stupid but when I was that age no one really taught me how to use the internet properly and so ended up using my full name in a number of places.  I've not written anything offensive and my name isn't on anything objectively bad, but it's just childish silliness (memes, poorly written stories, Yahoo Answers nonsense, and just weird forum posts) and I'm a bit embarrassed to be honest. I feel like as I continue to progress academically, it will become more likely that people will Google me and see all this which might make it likely that I will be judged. Again, it's nothing offensive or objectionable just old young teenager stuff. Benign but embarrassing.  Should I just ignore it and hope that as my career develops these old results get pushed further back in Google's search results? Should I try to remove this stuff from the internet (very difficult as I have lost all these old accounts)?  The stuff I posted back then has little to nothing to do with who I am now professionally, and I would hate for people to think it is. Having a unique name does seem like a curse sometimes and I have made it worse by being extra foolish when I was young.


Will 'Install Ubuntu alongside' choose unallocated space?

I currently have a C: drive with Windows, that I'd like to leave untouched and a D: drive with ~130GB of free space and some music/movies.   If I shrink the D: drive in Windows and leave, lets say, 60GB unallocated, will choosing the 'Install Ubuntu alongside Windows 7' grab this unallocated space and install everything that is needed there?   Do I have to create those swap and root partitions I keep reading about manually? If so, when and how?  Thank you.


How I can create a graph of acceleration and speed - tikz?

How can I create a graph of acceleration and speed like the one in the picture. Knowing that they are each other's consequence?    \documentclass{article} \usepackage{tikz}  \begin{document}  \begin{tikzpicture}               \end{tikzpicture} \end{document}


Showing $\lim_{n\to\infty} \left( \frac{n}{n^2+1^2} + \frac{n}{n^2+2^2} + \cdots + \frac{n}{n^2+n^2} \right) = \frac{\pi}{4}$

How could I go about proving the following limit:  $$ \lim_{n\to\infty} \left( \frac{n}{n^2+1^2} + \frac{n}{n^2+2^2} + \cdots + \frac{n}{n^2+n^2} \right) = \frac{\pi}{4} $$


Movie where a creature (monster) wears a wedding dress

I watched this movie around 80s to 90s.  I remember the part about a monster creature, who wore a wedding dress and was about to marry the kid's dad. She changed her skin from a kind of green lizard-like or alligator-like but little creepy into human skin. Some kids found out this woman is not human; he tried to tell his father about it but he don't believe him.  Some kids went to the cave to free some people whom she had kidnapped.


How are second order nonlinear ordinary differential equations solved?

I conceived the following second order nonlinear ordinary differential equation:  $$\frac{d^2y(x)}{dx^2}=\frac{k}{(y(x))^2}$$  I can tell it's nonlinear because of the $\frac{k}{(y(x))^2}$ term and second order because of the second order derivative.   Also, I did some research and concluded that it is of the type "missing x". In this category we use the relation,  :  $$\frac{d^2y(x)}{dx^2}=v\frac{dv}{dy} (1)$$  by making v equal to $$\frac{dy(x)}{dx} (2)$$ and then, using the chain rule, simplify to obtain equation (1).  Despite all that, I can't seem to find a logical solution to my ODE. I would appreciate any help or clue! Thanks!


Local versus global conformal groups/algebras

I am reading  and I am somewhat puzzled by the use of global and local. Specifically, I understand that the generators of two-dimensional conformal transformations are not globally defined on the Riemann sphere $C \cup \infty$, and the only globally defined Virasoro generators are $\{l_0, l_1, l_{-1}\}$ (and the corresponding antiholomorphic versions).  But at later stage (page 9) he says      Strictly speaking the only true conformal group in two dimensions is the projective (global) conformal group, since the remaining conformal transformations of (1.5) do not have global inverses on $C \cup \infty$.   What does he mean by "projective (global) conformal group"?


If $[K(\alpha):K]=p\neq q=[K(\beta):K]$ then $[K(\alpha+\beta):K]=pq$

I am having some trouble with the following problem:     Let $K\subseteq L$ be fields. Suppose $\alpha,\beta\in L$ are algebraic elements over $K$ of degrees $p,q$ respectively, where $p$ and $q$ are distinct primes. Show that $\alpha+\beta$ is algebraic over $K$ with degree $pq$.   I have shown that $\alpha+\beta$ is algebraic over $K$, but I am having trouble showing that the degree is $pq$. I have previously shown that $[K(\alpha,\beta):K]=pq$, so I have been trying to use this result. I thought that if I could show that $K(\alpha,\beta)=K(\alpha+\beta)$ then I'd be done. To show this I first noted that clearly $K(\alpha+\beta)\subseteq K(\alpha,\beta)$. Then we have $$pq=[K(\alpha,\beta):K]=[K(\alpha,\beta):K(\alpha+\beta)][K(\alpha+\beta):K]$$ so that $[K(\alpha+\beta):K]=1,p,q,pq$. I tried looking at the cases when it is equal to $1,p,q$ and deriving a contradiction, but have been unsuccessful.   Another way I thought of solving this is to show that $\alpha,\beta\in K(\alpha+\beta)$, which would allow me to conclude that $K(\alpha+\beta)=K(\alpha,\beta)$, but I am not sure how to complete this either.    I am looking for some assistance to show that $[K(\alpha+\beta):K]\neq 1,p,q$, or that $\alpha,\beta\in K(\alpha,\beta)$. If you have any other solutions to this problem I would like to see those too.


Solving quadratic Diophantine equations: $5n^2+2n+1=y^2$

I hope it's not inappropriate asking this here.  I stumbled upon this site recently while researching a Project Euler problem, now I figure I'd use it to ask about a recurring theme in these problems: quadratic Diophantine equations.  I've recently boiled down another Project Euler problem (I won't say which, it should be unrecognizable from the original problem and should probably be kept that way) to the following Diophantine equation:  $$5n^2+2n+1=y^2$$  I've been trying to use  as a reference, but I seem to get lost in a sea of constants.  And the steps that program on the bottom of that page takes don't seem to match what he says to do.  I'd rather be able to understand the steps I'm taking anyway rather than just copying a method.  I'm interested in all positive integer values of n and I'm more or less given a solution exists with n=2.  How would I go about finding the rest of the solutions?  And how would I solve these kinds of equations in general?  If that last part is too complex a question to be handled here, is there any other resource that might help?  As far as my current level of math, I have a degree in engineering (and helped a math major with some courses I never took myself) and I've already worked on Project Euler problems involving Pell's equations and continued fraction expansions of square roots.


What is this sequence of all permutations with gaps permissible

Let there be a sequence $a_1, a_2, a_3,...,a_n$ that represent some actions that you know are required to solve a problem. However, you do not know what order these actions need to be taken to solve that problem, but you know that all of them are required at some point. What is the shortest such sequence $S$ of actions with length $m$ in terms of $n$ such that all permutations of the actions are contained within $S$ with gaps and overlaps permissible?  Example:  Let's say you know that 3 steps are required to fix your computer, but you don't know in what order:   Restarting a program. Installing a different program. Run antivirus.   So one sequence containing all permutations $(123,132,213,231,312,321)$ guaranteed would be $S=123\ 123\ 123$ (meaning $m$ has a guaranteed upper bound of $n^2$ if we extrapolate) but a shorter sequence would be $S=1231231$ (which I am not sure is of minimum length). How can we generate this minimum sequence?


In Outlook, how do I give one instance of a recurring meeting to someone else?

I have a weekly meeting at which I am the only attendee. It represents something that has to be done at a particular time every Tuesday. When I am out of town and can't do it, I can invite someone else to that instance, which succeeds in getting it on their calendar. However I don't seem to be able to get it off my calendar, which messes up my view of all the things I am doing out of town.    Even though I am the organizer, and do not want to be removed from all the other instances of the meeting, can I somehow be removed from just this one? Failing that, can I arrange for this instance not to appear on my calendar, to make more room for other things?


What ways are there to show two analytical methods are equivalent?

I have two different analytical methods that can measure the concentration of a particular molecule in a matrix (for instance measure the amount of salt in water)  The two methods are different, and each has it's own error.  What ways exist to show the two methods are equivalent (or not).  I'm thinking that plotting the results from a number of samples measured by both methods on a scatter graph is a good first step, but are there any good statistical methods ?


Use of SqlParameter in SQL LIKE clause not working

I have the following code:  const string Sql =      @"select distinct [name]        from tblCustomers        left outer join tblCustomerInfo on tblCustomers.Id = tblCustomerInfo.CustomerId         where (tblCustomer.Name LIKE '%@SEARCH%' OR tblCustomerInfo.Info LIKE '%@SEARCH%');";  using (var command = new SqlCommand(Sql, Connection)) {            command.Parameters.AddWithValue("@SEARCH", searchString);     ... }   This does not work, I tried this as well:  const string Sql =      @"select distinct [name]       from tblCustomers       left outer join tblCustomerInfo on tblCustomers.Id = tblCustomerInfo.CustomerId        where (tblCustomer.Name LIKE @SEARCH OR tblCustomerInfo.Info LIKE @SEARCH );";  using (var command = new SqlCommand(Sql, Connection)) {            command.Parameters.AddWithValue("@SEARCH", "'%" + searchString + "%'");     ... }   but this does not work as well. What is going wrong? Any suggestions?


I'm designing a board that can be powered either by USB or an ATX power supply.  They can both be plugged in at the same time, independently.  I'd like the ATX to provide 5V if its plugged in, but fall back to the USB if possible.  The chips in the circuit will all be running at 5V.  Any ideas?


I am trying to install Sublime through the following command. But it returns error.   sudo apt-get install sublime-text-2   but it returns   Reading package lists... Done Building dependency tree        Reading state information... Done E: Unable to locate package sublime-text-2   Any helps I have not found any similar question and solution for this problem.  And Also 2 is the recent one or version 3 is available.


Force and Torque being applied off-center due to magnetic forces

Say that I have two magnetic dipoles, one of which is rigidly attached to a freely movable inflexible body at some point that is not at the body's center of mass, while the other is fixed in space.  Now I already know how to compute both the force and torque that the dipoles exert directly upon eachother per the , and I can calculate the net force and torque that is exerted on the body due to said force between them, per the answer to , but the answer to that question does not address how to also calculate any additional force and torque on the body due to any torque that is exerted on an off-center point.  This question is admittedly highly similar to , but I do not believe it is identical.   They differ in that the other question was asking about computing effective torque and force on the center of mass from a force being applied off-center, while I am asking about applying both force and torque through an off-center point, and computing the effective force and torque on the center of mass from that.   As I said, I already am aware of how to calculate the net force and torque on the rigid body due to just the force that exists between the two points, but how do add in the issue of torque between them?   Edit:  This is for 3d.  Although I know that torque does not any any additional force when applied to the object's center of mass.  If I twist an object around a point that is not at the object's center, however, in addition to the object starting to spin, the object's center of mass will be moved, and it will spin as if a force and torque HAD been applied to the object's center of mass.  What is that force and torque?  Edit: I do not understand how this question is answered by the one that has been alleged to already answer it, nor do I understand what anyone is thinking I was actually asking about to suggest that the answer to that question would answer mine.   They seem entirely different to me.


How could I detect with command blocks when a mob is at a certain health or percentage?

I am building a boss fight with multiple waves of enemies. I am trying to figure out how to detect whether an entity (in this case wither) so when it's at 2/3 and 1/3 health it spawns more entities such as angry zombie pigmen, blaze, wither skeleton, etc. Is there a way to do this on Minecraft Bedrock or is it really only possible on the Java edition on Minecraft? From what I know you can only use "dummy" scoreboard objectives on Bedrock. All others are only available on Java (please correct me if I'm wrong).


Limit as $z$ approaches $0$ for $e^{1/z^4}$

I want to work out if the limit as $z$ approaches $0$ for $e^{1/z^4}$ exists and if not then why. I worked out that the left and right sided limits both equal to +∞ so I thought that was enough to conclude that the limit therefore existed.   But when I checked the solutions it said that the limit did not exist, because you get different limits when you approach ($0,0$) along different rays, ($x,y$) = ($at,bt$) as $t$ $\rightarrow$ $0$.  I don't understand this though can anybody help explain? What does it mean by the rays? Like gradients?   Edit $z$ is a complex number


In The Flash 4x04 “Elongated Journey Into Night”, there is a scene in the final act when Joe arrives at Star Labs and shows a box of cigars to Team Flash, handing them out to everyone. The scene is silent except for some music, so we can’t hear anybody. However, they seem super excited in a way that I wouldn’t expect for people who don’t appear to be smokers.  Why did Joe give cigars to the team? And why were they so happy about it?


Subdomain or New domain for new company division - SEO

Someone has asked me about developing a site for a new division that this company is expanding to include in their services.  They have purchased a domain for this new service, but I was wondering:  Since they already have an established domain with a Pagerank (3), would they be better suited with a subdomain (specialty.domain.com), redirected to from their new domain?  Any SEO benefit here?


How do I enable Firefox check spelling on single line text-boxes forever?

As you know, we can enable the spell checker on single line text boxes in the following way:    We have to enable it every time for checking words.  How can we enable it forever, so it doesn't need to be enabled each time?


Why can't I upload pics on certain sites

I can't upload pictures on sites from my iPad 2 . I was trying to upload a picture of a part that I needed and it would let me .


Can I connect a capacitor in parallels to power supply of a router

In the building where I live, because of older wiring, the mains voltage frequently drops for a fraction of a second and this restarts my wifi router. I am planning to solder a capacitor in parallel to either input or output of the 9V power supply.  Would this work, and would it cause any problems?


Ubuntu keeps telling me there is a system error and won't send updater to updates site.  this line keeps comming up:   E:Line 1 too long in source list /etc/apt/sources.list.d/medibuntu.list.    How do I fix this?


First things first: I'm using MS SQL Server 2008 with a database at compatibility level 80, and connecting to it with .Net's System.Data.SqlClient.SqlConnection.  For performance reasons I've created an indexed view. As a result, updates to tables referenced in the view need to be done with ARITHABORT ON. However, the profiler shows that SqlClient is connecting with ARITHABORT OFF, so updates to those tables are failing.  Is there a central configuration setting to make SqlClient use ARITHABORT ON? The best I've been able to find is to manually execute that each time a connection is opened, but updating the existing code base to do this would be a fairly large task so I'm keen to find a better way.


Using Kubuntu 16.04, I'm trying to use Google Hangouts via Chrome. Webcam works fine, however no one can hear me.   Using Blue's Snowball which works fine in Skype and Audacity.   Someone suggested I need to disable the linein, not sure how to do that.  Any help would be much appreciated.


Analysis- subspaces from $\mathbb{R}^{n}$

Let $E\subset \mathbb{R}^n$ a vector subspace such that $E\neq \mathbb{R}^n$. Show that $\text{int}(E)=\emptyset$, where $E$ is a closed and connected set.   I don't know how to solve, someone can help me, any tips?


Largest integer that can't be represented as a non-negative linear combination of $m, n = mn - m - n$? Why?

This seemingly simple question has really stumped me: How do I prove that the largest integer that can't be represented with a non-negative linear combination of the integers $m, n$ is $mn - m - n$, assuming $m,n$ are coprime? I got as far as this, but now I can't figure out where to go:  $mx + ny = k$, where $k = mn - m - n + c$, for some $c > 0$ $\Rightarrow m(x + 1) + n(y + 1) = mn + c$  If I could only prove this must have a non-negative solution for $x$ and $y$, I'd be done... but I'm kind of stuck. Any ideas?


I have xml which have different nodes. I want to build decision tree logic using xml.  Is there any js library to parse xml?


Rear wheel is moving from side to side anyone have any ideas what might be the problem thanks


I'm following Miguel Grinberg's Flask Megatutorial. He defines the configuration class of the app as:  class Config(object):     SECRET_KEY = os.environ.get('SECRET_KEY') or 'you-will-never-guess'   What is te meaning of object? why is it passed to the classs? to my understanding, passing an argument when defining a class means inheritance so, why is Config inheriting form object and in what other cases should I do the same?


Use a lemma to prove that $A_4$ has no subgroup of order $6$.


ubuntu 18.04, nm(Network Manager) is not able to manage network devices

I am playing around with networking component of latest Ubuntu. I faced the above issue when I tried to manage networking devices with NM.  The command line output is  root@sankar:~# nmcli d s DEVICE  TYPE      STATE      CONNECTION eth0    ethernet  unmanaged  -- eth1    ethernet  unmanaged  -- eth2    ethernet  unmanaged  -- lo      loopback  unmanaged  --   I tried couple of solutions(comment #36 and #30) given in .  Any help is highly appreciated


Immigration officer placed a standard Leave to Enter stamp when I have Indefinite Leave to Remain. What do I do?

I travel on a NZ passport and have lived in the UK since 2006. I travelled to Canada in June 2016 to begin a 2 year Canadian working visa but on a trip back to the UK in July I received a 6 month visa stamp in my passport despite having an Indefinite Leave To Remain Visa in my old passport (I haven't got a biometric card yet but plan to apply for one before I return to the UK to live. What should I do about this?


I'm trying to find a specific episode of an old sci-fi show I watched decades ago. It involved two planets that were originally at war with each other, but the wars became too costly, and both planets agreed to do simulated war, where imaginary missiles would detonate (in a simulator) over real towns.  The inhabitants of the town were then "registered", and then had a day to say their goodbyes and then go into a room that vaporized them, sending the kill count to the other planet to make sure both sides were honoring the rules of the "war". The protagonist "saves the day" by damaging the simulator, causing the two planets to think the other side reneged on the war pact, and actually resumes a real war with real weapons.


Can I ride a motorcycle in the US with a Pakistan license?

I'll be traveling to the US (California) soon and would like to ride a  bike that my friend owns.  I have a valid driving license from Pakistan (valid for both car and motorcycle). I understand that I can rent and drive a car in the US without the need for an IDP.   Does the same apply to motorcycles? Do I need some special kind of insurance coverage? I already have travel insurance.


Problem with integrating $\int_0^{\pi/2}\frac{\cos^6x}{\cos^6x+\sin^6x}dx$

Someone told me there is an equation $$\int_0^{\pi/2}f(sinx)dx=\int_0^{\pi/2}f(cosx)dx$$ With this equation, it's easy to get the answer$\frac{\pi}{4}$. What I want to know is why we have this equation, and if there is an alternative way to integrate it?


Prove the limit as $n$ tends to infinity for a bounded monotonic sequence $u_{n+1} = \sqrt{u_n + 1}$.

Saw this problem in my textbook the other day, and since I'm not very familiar with bounded monotic sequences, I've been struggling with it.      If $u_{n+1} = \sqrt{u_n + 1}$ and $u_1 = 1$, prove that $\lim_{n \to \infty} u = 1/2(1 + \sqrt{5})$.   Since I'm not that good with sequences yet, and I'm new on this site, I'd like to request that whoever's answering try to simplify things a bit more. Thanks!


Ramanujan's $\sqrt{\frac{\pi e}{2}}$ formula

The following identity : $$\DeclareMathOperator{\k}{\vphantom{\sum}\vcenter{\LARGE K}} \sqrt{\frac{\pi e}{2}}=\frac{1}{1+\k_{n=1}^\infty \frac{n}{1}}+\sum_{n=0}^\infty\frac{1}{(2n+1)!!}$$ or $$\sqrt{\frac{\pi e}{2}}=\frac{1}{1+\frac{1}{1+\frac{2}{1+\frac{3}{\vdots}}}}+1+\frac{1}{1\cdot 3}+\frac{1}{1\cdot 3\cdot 5}+\cdots $$ I'm interested in the proof of this identity, but I couldn't manage to find any reference except for the linked page.


How many non-isomorphic Abelian groups of order $2^7 3^4 5^2$ are? How to find?


Physical intuition of solid angle of a closed surface

It is mathematically proven that the solid angle of any closed surface which does not contain the origin, is zero.  Following the definition of solid angle, the total projection of the surface upon a sphere with radius one is zero. Does it not mean if someone was standing on the sphere, they wouldn't see the surface? Is my intuition right? How does it apply to real life then? I'm sure it is way more complicated than that. I will be glad for some physical intuition of how is it possible.


How to display the word "AMS-LaTeX" in LaTeX?

How do I display the word "AMS-LaTeX" properly in LaTeX like in the image below?  Is there a command for the "AMS" part similar to \LaTeX?


where does Microsoft Store put Start Menu entries?

I have several Microsoft Store programs installed.  For example, MineSweeper is installed via Microsoft Store. Looking my Start Menu, I can see those installed programs, including MineSweeper which is in the M section of the Start Menu. However, using Explorer, I cannot find the MineSweeper.lnk shortcut file. I searched well known paths:  %ProgramData%/Microsoft/Windows/Start Menu/Programs (C:\ProgramData\Microsoft\Windows\Start Menu\Programs) (also accessible via [Environment]::GetFolderPath('CommonStartMenu') %APPDATA%/Microsoft/Windows/Start Menu/Programs (C:\Users\user1\AppData\Roaming\Microsoft\Windows\Start Menu\Programs) (also accessible via [Environment]::GetFolderPath('StartMenu')  and less well known Start Menu paths:  %APPDATA%/Local/Packages/Microsoft.549981C3F5F10_8wekyb3d8bbwe/LocalCache/Roaming/Microsoft/Windows/Start Menu %APPDATA%/Local/Packages/Microsoft.DesktopAppInstaller_8wekyb3d8bbwe/LocalCache/Roaming/Microsoft/Windows/Start Menu  Explorer has View → Hidden items checked. Since MineSweeper is installed via Microsoft Store, a right-click on the Start Menu entry MineSweeper does not display the Open file location option. What is the path where Microsoft Store saves the .lnk shortcut files that appear as Start Menu entries?  Using Windows 10 Pro.


User is serially voting for me.. What to do?

Let me explain. There is a user with just 20 rep voting on every answer/comment I post on Stack Overflow. In my reputation overview I can see I'm not earning any rep anymore after just a few votes by this user, but my concern of getting banned/losing my rep because of this user made me post this question.  Is there any way to block a user or something? Hope someone has some good advice in this matter.


Recover files from hard drive that has been formatted thrice

I have a situation.  I got married 6 months ago and stored some very important pictures on my laptop which was running Linux. Later I formatted the whole hard drive, installed Windows and a hacked version of Mac (just to play around) and I have been using the laptop for last 8 months or so after that.  Is there any software that can recover the files for me? I am happy to pay money!


Is $\sqrt1+\sqrt2+\dots+\sqrt n$ ever an integer?

Related:    Except for the obvious cases $n=0,1$, are there any values of $n$ such that $\sum_{k=1}^n\sqrt k$ is an integer? How does one even approach such a problem? (This is not homework - just a problem I thought up.)


Resolving a Git conflict with binary files

I've been using Git on Windows (msysgit) to track changes for some design work I've been doing.  Today I've been working on a different PC (with remote repo brian) and I'm now trying to merge the edits done today back into my regular local version on my laptop.  On my laptop, I've used git pull brian master to pull the changes into my local version. Everything was fine apart from the main InDesign document - this shows as a conflict.  The version on the PC (brian) is the latest one that I want to keep but I don't know what commands tells the repo to use this one.   I tried directly copying the file across onto my laptop but this seems to break the whole merge process.  Can anyone point me in the right direction?


how to use a static variable in a static functions of a struct

following compiles fine with g++:  struct acounter {    long static counter;    void static create() {  //reset or create the counter     counter=0;   }    void static count() {   //the counter changes its internal value.     counter=counter + 1;   }     };   int main(int   argc,  char *argv[] ){    //compiles and executes!   //do some random stuff...   return 0; }   The problem is: as soon as I add "acounter::create();" or "acounter::count();" to the main loop, I get an error:      undefined reference to `acounter::counter'   But I defined "counter" and even initialize it. What is the problem?  (P.S. I can only use static functions as I have to deal with callbacks later - the idea is to use the whole struct only on its global scope without creating instances.)


Is CPU required for gaming with Direct Storage?

If I have a GPU like a RTX 3070 (that has a feature like RTXIO) does that mean that the only thing that matters or that can cause bottle neck is the storage and it does't matter what CPU (e.g. single core vs 8 core or 1GHz vs 4GHz) or RAM (e.g. 4GB vs 16GB ) or Motherboard is. Also, are there other dependencies for this, like Operating System (e.g. will Windows 7 work with this feature) and Application support (e.g. will old games work with this) required or it is independent of them? Lastly, can Linux send data directly to the GPU if the GPU can directly process them?


Why is everything floating in space so cold?

Of course there is pretty hot stuff too. For example Suns.  But isn't the vacuum of space the perfect containment for heat? And shouldn't the rare collision with particles even heat up an object that floats around in space?  Why aren't they hot from time to time? Is it because they loose their heat by radiant heat?  And if so does radiant heat emission always occur until the object is the same temperature as the surrounding or does it depend on other factors?


Where can I find examples of Mindmap diagrams like that of the attached figure? Thanks a lot. No need for complete solution just some guidelines.    found . Thanks in advance!


Question about a nested radical identity of Ramanujan involving $\sqrt 5$

Ramanujan stated this radical in his lost notebook:  $$\sqrt{5+\sqrt{5+\sqrt{5-\sqrt{5+\sqrt{5+\sqrt{5+\sqrt{5-\cdots}}}}}}} = \frac{2+\sqrt 5 +\sqrt{15-6\sqrt 5}}{2}$$  Where the pattern of the signs is $++-+++-++++-+++++-\cdots$  I do not have access to his lost notebook. I wonder how we can prove this.  For periodic sign changes this kind of question is easy but for nonperiodic Im clueless.


What is the importance of the Poincaré conjecture?

The Poincaré conjecture is listed as one of the Millennium Prize Problems and has received significant attention from the media a few years ago when Grigori Perelman presented a proof of this conjecture. But why is this interesting at all? What practical and interesting questions can be answered now that this conjecture is proven?


Couldn't Kabuto have un-summoned Itachi?

I know that the Kotoamatsukami rendered Itachi free of Kabuto's control over his will. But he was still bound to the Edo Tensei, since he was released when the technique was cancelled.  So, couldn't Kabuto simply have un-summoned Itachi?    We have, in other situations (namely in chapter 514, with Deidara), seen that Kabuto can un-summon shinobi at will, an empty coffin appearing and 'reclaiming' the summoned. Were these other situations somewhat different from the situations with Itachi? Or did Kabuto have to completely undo the technique, even if he just wanted to un-summon a single shinobi?


Repeated division - Converting from base 10 to another base

I am teaching how to convert from one base to another base, however, I can't find a way to do something like this:    I know little about Tikz, the only thing I have been able to produce is a simple square with a couple of lines over it, so I don't even know where to start. Any suggestions? I don't mind typing all the numbers, what I want to do is to automatize the process of creating the lines.


Prove that ln(n) is not a Cauchy Sequence?

Show from the definition of a Cauchy Sequence that Xn=ln(n) is not a Cauchy Series


Disallow closing of questions with a certain number of question / answer upvotes

With reference to this currently open question   At the time of writing, it has 3 close votes yet has 7 question upvotes and the single answerer (11 upvotes) will have been awarded the enlightened badge (silver).  Therefore in the opinion of many (i) the question adds value and (ii) the answer adds value.  As a staring point for discussion, I suggest that 5 net question upvotes (and perhaps 5 answer net upvotes) should be enough to keep a question permanently open. Let's haggle over the numbers though. Thoughts?


What is the template syntax for an arbitrary container of doubles?

I have a function that rounds a value according to a policy  double round(double f, Policy p);   What I want to do now is to build a version of this that can be applied only to a container of doubles (there's no point in having a container of any other type due to the way the rounding works).  template <class Iterable> Iterable<double> round(     Iterable<double> y, Policy p){     for (auto&& e : y){         e = round(e, p);     }     return y; }   I know my template syntax is not correct, but what should it be?


I'm planning on selling a USB external hard drive that currently contains an old Ubuntu installation with stored passwords and banking information.  How can I securely erase the drive before selling it?


Why does Root refer to the Machine as "She", not "He"?

about Person of Interest already asked why everyone else but Root called the Machine "she" rather than "it". But in this question I'm more concerned about why Root actually calls it a "she", rather than a "he". I am asking about Root because she started calling it "She" and others have simply followed the trend, as indicated by the answers to the previous question.  I understand that Root considers the Machine an intelligent being, even superior to humans. Later, she says she has an intimate relationship with the Machine. So, that helps me understand why she doesn't refer to it as "IT". Still why simply not refer to it as "He"?


Is it appropriate to put a comma before "which"?

On Server Fault, we were discussing  in chat. There are non-native speakers in the chat and somehow we got on the topic of grammar and proper use of commas.   The sentence of interest:     I have just got a new Ubuntu LAMP VPS server, which I am trying to configure.   Some people thought that the comma was superfluous. Others did not.   When is it appropriate for a comma to preceed the word which, and is the example sentence above correct?    Also, before you vote to close this question as a dupe of , please consider the differences between the two questions and ignore the similarity of the titles. The OP's example sentence was restructured in that question instead of addressing the proper use of commas.


Impact of denied entry to Croatia on trying to enter a Schengen country with a valid visa

Last year I was not allowed to continue my trip to Croatia due to having only single entry Schengen visa. However when I was refused entry to Croatia the border guard from the Croatia side did not stamp anything nor give me a letter. I was however not allowed to go in, and they just asked me to go back to Slovenia and enjoy my holiday elsewhere in a Schengen  country.   Question is now I got a valid multiple entry Schengen visa from the Spanish embassy in Buenos Aires will I be turned away at the border?  My concern is due to being denied entry from Croatia will I be recorded in the sis system? Even though at that time the Croatian  border guard did not stamp any cancellation stamp, or ask me to sign any letter. The guard even said to just apply for a Croatian visa in Ljubljana if you wish or travel to Venice since it is in the Schengen area.   My concern was not allowed to enter Spain despite valid visa due to being denied entry from Croatia in last years trip.


Word for feeling one gets when someone else gets just punisment

asks for an idiom for someone getting what they deserve. But what about the feeling one gets when someone else gets "what they deserve"? Is there a specific word or expression for the good feeling you get when justice is served?


Query works in phpmyadmin but not in PHP

Ok so i have this kind of query  SELECT * FROM table WHERE column LIKE 'Blahblahblah Blah - Blah (Blah-Blah)'   (Yep, column values are 20-30 characters long) And it works in phpmyadmin and returns ~ 100 results. But whn i try it in PHP framework CI (CodeIgniter) It is not returning any values. My code looks like:  $sql = "SELECT * FROM table WHERE column LIKE '$val' ORDER BY column ASC"; $sql = $this->db->query($sql); return $sql->result();   So how do i get this to work?


Find with two grep (contains AND not contains) and one awk

I would like to store in file all path files with a specific extract of file content where file contains AAA but NOT BBB.  I tried so many things but this try is close to my goal :  find /data/my_project -type f -name "*.php" -exec grep -q "AAA" {} \; -exec grep -L "BBB" {} \; -exec awk '/AAA/{print $NF}'> /tmp/tables_names.txt {} \;  -print > /tmp/class_list.txt   But... Result contains file with sometimes AAA only, AAA AND BBB..  EDIT :  This is pretty same question as  but where there's no answer validated it was really difficult to read. 75 % of my answer was in fact there sorry...  But, I would like to return not only matched files paths but an extract (piece of text) of this matched file !


I have a maps where i want to show 6 different sites around europe. Instead of creating 6 different maps, i want to use the atlas generator.  I'm using QGIS 2.18.3 (Las Palmas).  I have made a coverage.shp including 6 polygons to show the extent of my different maps. Also, i set visibility presets (always showing 2 Layers: one is my backround google satellite image and one is always my vector shape). I have consulted a previous question:  ().  The Problem I have is that i want each map to have a different scale. I added an attribute to my coverage layer with the scale of my choice (eg. 30000, 16000...etc.). In the Print composer I went to the scale of the Map, data defined override > Edit, and set the scale of my attribute table. This is however not working.  where am I going wrong?


What's the easiest way to download all albums from Google Photos?

I have around 950 albums at Google Photos.      I want to back them up now, but organised by albums, not by date.   Whenever I create a backup from within Google Photos, the backup splits my photos by date and adds metadata here and there.  What I am doing now is to click on every album, and choose "Download all". But this will take me ages.  Is there a way through Google Drive or another app to have a easier job?


Simple self oscillating flyback converter

Please am studying about switching power supplies, starting from the simple ones. I've just concluded on joule thief and blocking oscillator, now am progressing to Self oscillating flyback converter(or RCC) and am finding a bit difficulty on how the transistor switches OFF. It seems the transistor switch off concept is quite complex than the switch ON process. Some say the operating principle is very much the same to that of blocking oscillator, but i think the are some contrast.  Here I only understand that a small current flows through the startup resistor to the base of the transistor, to initiate the turn on process. As the transistor is partially ON(active region), collector current will flow and energize the primary winding, as a result, a same polarity voltage will be induce in the feedback winding which will create a positive regenerative feedback and conduct more current to the base of the transistor, and the transistor turn on fully(saturation). That's all I know. I don't know how the transistor will switch OFF. I might make some assumptions based on my knowledge of the joule thief circuit, but am not sure. I don't also know how RC circuit can affect the switching frequency.


What's the difference between asymptotic unbiasedness and consistency?

Does each imply the other? If not, does one imply the other? Why/why not?  This issue came up in response to a comment on an answer I posted .  Although google searching the relevant terms didn't produce anything that seemed particularly useful, I did notice  on the math stackexchange. However, I thought that this question was appropriate for this site too.  EDIT after reading the comments  Relative to the math.stackexchange answer I was after something more in depth, covering some of the issues dealt with in . Also, as I see it the math.stackexchange question shows that consistency doesn't imply asymptotically unbiasedness but doesn't explain much if anything about why. The OP there also takes for granted that asymptotic unbiasedness doesn't imply consistency, and thus the sole answerer so far doesn't address why this is.


What’s the consensus on signaling the open/close state for an accordion menu?

Should the caret point down when the menu is down, or point up? See example.


Should "it/this" always refer to a specific noun?

I have a paragraph starting with the below sentence. "it" is not referring to any specific noun. Is there any problem with that?  It  has been estimated that health care costs accounted for 11.6% of Canada’s GDP in 2019, the majority of which were spent in hospitals.  Best, Amir


Uniform continuity of $\sin(x\sin x )$ for all $x\in (0,\infty)$

I want to prove or disprove that $f(x)=\sin(x\sin x)$ for all $x\in (0,\infty)$ is uniformly continuous.  We know that $g(x)=x\sin x$ is not uniformly continuous on $(0,\infty)$. But what about $f$? I am not getting any hint. Any help is appreciated.


is $\sigma$-algebra $\mathcal{F}_1 =$ {$X \subset \mathbb{R}: X \textrm{ or } \mathbb{R} \setminus X \textrm{ is countable}$ } countably generated?

Given that we have a $\sigma$-algebra $\mathcal{F}_1$ such that $\mathcal{F}_1 =$ {$X \subset \mathbb{R}: X \textrm{ or }   \mathbb{R} \setminus X \textrm{ is countable}$ } Is $\mathcal{F}_1$ countably generated? If it is not countably generated, how can I show it? Thanks,


BlockingQueue can't read String from JTextField

I am having an issue creating a custom console, on the following code: public class UserConsole {      protected static BlockingQueue<String> inputData;      private final static JTextArea textArea = new JTextArea();     private static JTextField textField = new JTextField("");  private void createGUI() {      final KeyListener returnAction = new KeyAdapter() {             @Override             public void keyPressed(KeyEvent e) {                 if (e.getKeyChar() == '\n') {                     returnInput();                    }             }};     }  private void returnInput() {   //Here is the problem, the BlockingQueue throws a NullPointerException, which is strange, because the... //...right after "System.out.println(textField.getText());" works perfectly fine.    inputData.offer(textField.getText());         System.setOut(userStream);         System.out.println(textField.getText());         textField.setText("");         System.setOut(nebulaStream);            } }  I tried searching online, but didn't find anything, also tried adding .toString() but it does not work as well. As far as I know, a BlockingQueue cannot be initialized... So my final question is. Why is the BlockingQueue not reading the JTextField's string, and how can it be solved? I hope it is not something obvious that I missed, every help is appreciated!


I may be stupid but I can't find my terminal window, I just installed version 12.04.3, Help

I can't find my terminal window, I just installed version 12.04.3, Help..


how to update kernel when I can't install kmod?

I have a problem..  I want to update my kernel, but I have a notice when I install the new kernel like this please install the kmod first.  so I install kmod, but when I install the kmod, my terminal say  Reading package lists... Done Building dependency tree        Reading state information... Done Package kmod is not available, but is referred to by another package. This may mean that the package is missing, has been obsoleted, or is only available from another source  E: Package 'kmod' has no installation candidate   why?? and when I check dpkg -l kmod i have this   ||/ Name           Version        Description +++-==============-==============-============================================ in  kmod           <none>         (no description available)   can you help me to update my kernel, my friend? I'm newbie ubuntu user. My kernel 3.5.0-23-generic .. Thank You ..


Solving $\sin x\cos3x+\cos x\sin3x=\sqrt{3}/2$ in the interval $[0,2\pi]$

Solve the following trig equation: $$\sin(x)\cos(3x)+\cos(x)\sin(3x)=\frac{\sqrt{3}}{2}$$ in the interval $[0,2\pi]$.  Using trig identities, it is now at $$\sin(x+3x)=\sqrt{3}/2 \tag{1}$$ Next, it has become $$\sin(x+3x)=\sin 60^\circ \tag{2}$$ leading to $$\sin(x+3x)-\sin60^\circ=0 \tag{3}$$ From there, it is unclear what to do.


Is the TSA Lock acceptable in European Airports?

I understand if you travelling in or to the US, you can lock your luggage using the TSA Luggage Lock. (Immigration is still able to open your luggage using their own special keys)  How about Europe? Especially Heathrow + Charles de Gaulle?    If the TSA Lock is not acceptable in Europe, are there any other alternative precautions I could use instead?  (FYI, information about the )


How to prove wave nature of large object?

In double slit experiment only small sized particles were used. however if we use large objects such as a tennis ball, the expected pattern is not observed.   Why the wave nature is not visible for large objects in double slit experiment ? How do I then prove that large objects also have wave nature?


How does one derive these solutions to the cubic equation?

In the first major studies into the magical properties of the complex number and the application to solving the cubic equation, Cardano did the following in around 1539:  He reduced the cubic equation  $ax^3+bx^2+cx+d$  to the form  $x^3=3px+2q$  where $p$ and $q$ are real numbers.   (1). How did Cardano get to this?  There was also another solution to the cubic, discovered before 1926, and it is often referred to as the (del Ferro-)Cardano solution, and is perhaps where Cardano went from in his first reduction. This solution is:  $x=(q+w)^{1/3}+(q-w)^{1/3}$  where $w=\sqrt{(q^2-p^3)}$.  (2). How is the del Ferro-Cardano solution derived?


UFW blocking connection every minute at home

I'm using a router to connect to the internet at home. I used a long password with WPA2/AES, changed the SSID and changed the default password.  But strangely, even if I disconnect the router from the internet, I'm still getting UFW blocks (It's every minute, as I'm showing below)  Apr 12 10:59:59 nori-hidamari kernel: [  773.060910] [UFW BLOCK] IN=wlan0 OUT= MAC=fc:f8:ae:3d:f9:b9:3c:1e:04:7e:3d:32:08:00 SRC=192.168.0.1 DST=224.0.0.1 LEN=32 TOS=0x00 PREC=0x00 TTL=1 ID=19836 PROTO=2  Apr 12 11:00:59 nori-hidamari kernel: [  833.031904] [UFW BLOCK] IN=wlan0 OUT= MAC=fc:f8:ae:3d:f9:b9:3c:1e:04:7e:3d:32:08:00 SRC=192.168.0.1 DST=224.0.0.1 LEN=32 TOS=0x00 PREC=0x00 TTL=1 ID=19838 PROTO=2  Apr 12 11:01:59 nori-hidamari kernel: [  892.812248] [UFW BLOCK] IN=wlan0 OUT= MAC=fc:f8:ae:3d:f9:b9:3c:1e:04:7e:3d:32:08:00 SRC=192.168.0.1 DST=224.0.0.1 LEN=32 TOS=0x00 PREC=0x00 TTL=1 ID=19840 PROTO=2  Apr 12 11:02:59 nori-hidamari kernel: [  952.666473] [UFW BLOCK] IN=wlan0 OUT= MAC=fc:f8:ae:3d:f9:b9:3c:1e:04:7e:3d:32:08:00 SRC=192.168.0.1 DST=224.0.0.1 LEN=32 TOS=0x00 PREC=0x00 TTL=1 ID=19842 PROTO=2  Apr 12 11:03:59 nori-hidamari kernel: [ 1012.649716] [UFW BLOCK] IN=wlan0 OUT= MAC=fc:f8:ae:3d:f9:b9:3c:1e:04:7e:3d:32:08:00 SRC=192.168.0.1 DST=224.0.0.1 LEN=32 TOS=0x00 PREC=0x00 TTL=1 ID=19852 PROTO=2  Apr 12 11:04:59 nori-hidamari kernel: [ 1072.520670] [UFW BLOCK] IN=wlan0 OUT= MAC=fc:f8:ae:3d:f9:b9:3c:1e:04:7e:3d:32:08:00 SRC=192.168.0.1 DST=224.0.0.1 LEN=32 TOS=0x00 PREC=0x00 TTL=1 ID=19854 PROTO=2  Apr 12 11:05:59 nori-hidamari kernel: [ 1132.392421] [UFW BLOCK] IN=wlan0 OUT= MAC=fc:f8:ae:3d:f9:b9:3c:1e:04:7e:3d:32:08:00 SRC=192.168.0.1 DST=224.0.0.1 LEN=32 TOS=0x00 PREC=0x00 TTL=1 ID=19856 PROTO=2  Apr 12 11:06:59 nori-hidamari kernel: [ 1192.248521] [UFW BLOCK] IN=wlan0 OUT= MAC=fc:f8:ae:3d:f9:b9:3c:1e:04:7e:3d:32:08:00 SRC=192.168.0.1 DST=224.0.0.1 LEN=32 TOS=0x00 PREC=0x00 TTL=1 ID=19910 PROTO=2  Apr 12 11:07:59 nori-hidamari kernel: [ 1252.057452] [UFW BLOCK] IN=wlan0 OUT= MAC=fc:f8:ae:3d:f9:b9:3c:1e:04:7e:3d:32:08:00 SRC=192.168.0.1 DST=224.0.0.1 LEN=32 TOS=0x00 PREC=0x00 TTL=1 ID=20730 PROTO=2  Apr 12 11:08:59 nori-hidamari kernel: [ 1312.009383] [UFW BLOCK] IN=wlan0 OUT= MAC=fc:f8:ae:3d:f9:b9:3c:1e:04:7e:3d:32:08:00 SRC=192.168.0.1 DST=224.0.0.1 LEN=32 TOS=0x00 PREC=0x00 TTL=1 ID=21310 PROTO=2  Apr 12 11:09:59 nori-hidamari kernel: [ 1371.882191] [UFW BLOCK] IN=wlan0 OUT= MAC=fc:f8:ae:3d:f9:b9:3c:1e:04:7e:3d:32:08:00 SRC=192.168.0.1 DST=224.0.0.1 LEN=32 TOS=0x00 PREC=0x00 TTL=1 ID=21856 PROTO=2  Apr 12 11:10:58 nori-hidamari kernel: [ 1431.752999] [UFW BLOCK] IN=wlan0 OUT= MAC=fc:f8:ae:3d:f9:b9:3c:1e:04:7e:3d:32:08:00 SRC=192.168.0.1 DST=224.0.0.1 LEN=32 TOS=0x00 PREC=0x00 TTL=1 ID=22388 PROTO=2  Apr 12 11:11:58 nori-hidamari kernel: [ 1491.624027] [UFW BLOCK] IN=wlan0 OUT= MAC=fc:f8:ae:3d:f9:b9:3c:1e:04:7e:3d:32:08:00 SRC=192.168.0.1 DST=224.0.0.1 LEN=32 TOS=0x00 PREC=0x00 TTL=1 ID=22798 PROTO=2  Apr 12 11:12:58 nori-hidamari kernel: [ 1551.442926] [UFW BLOCK] IN=wlan0 OUT= MAC=fc:f8:ae:3d:f9:b9:3c:1e:04:7e:3d:32:08:00 SRC=192.168.0.1 DST=224.0.0.1 LEN=32 TOS=0x00 PREC=0x00 TTL=1 ID=22838 PROTO=2  Apr 12 11:13:58 nori-hidamari kernel: [ 1611.367003] [UFW BLOCK] IN=wlan0 OUT= MAC=fc:f8:ae:3d:f9:b9:3c:1e:04:7e:3d:32:08:00 SRC=192.168.0.1 DST=224.0.0.1 LEN=32 TOS=0x00 PREC=0x00 TTL=1 ID=22860 PROTO=2  Apr 12 11:14:58 nori-hidamari kernel: [ 1671.238148] [UFW BLOCK] IN=wlan0 OUT= MAC=fc:f8:ae:3d:f9:b9:3c:1e:04:7e:3d:32:08:00 SRC=192.168.0.1 DST=224.0.0.1 LEN=32 TOS=0x00 PREC=0x00 TTL=1 ID=22862 PROTO=2    Ubuntu 14.04 is also updated. Is the problem from the router or from the OS? (I already checked that I'm the only person in the network, but still getting UFW blocks is really strange)  Thank you guys for helping me.


prove the equation by generating functions

Im studying a book about stochastic processes and it is mentioned in the book that the equation below is true and we can obtain it by generating functions can anyone prove it. Thanks a lot. $$\sum_{m=0}^{\infty}\binom{2m}{m}p^m = (1 - 4p)^{-1/2}$$


Keyword-based spam detection to keep spam questions out of the network

Over the course of the Winter Bash, I have encountered a lot of spam questions here on MSE, the common pattern among them being the keyword "keto diet" or simply "keto".  No doubt they are deleted as soon as they are posted (thanks to the active community), but isn't there a method already in place which helps prevent such cases? If not, is there a plan to introduce/try one?  To begin with, one can check the user's history of questions to see if they have been asking questions with similar keywords earlier, and whether those questions were closed/deleted. This can then be expanded to consider posts made by that user across the SE network to prevent spam.  Thoughts?


I am having a problem with my references, the error message is       Bibliography not compatible with author-year citations.    I have stripped down all tex and references files however I still have the same problem.  I have tried the following:   Delete all the temp file. I am using WinEdt8  I have year in my reference  Using \citet instead of \cite Try \usepackage[square,sort,comma,numbers]{natbib}   It will be much help you can help point out where did I went wrong :(  Here are the content of the files   .tex file:  \documentclass[english]{article} \usepackage[T1]{fontenc} \usepackage[latin9]{inputenc} \usepackage{babel} \usepackage[authoryear]{natbib} \begin{document} Text here  \citet{Ioannou2001}  \bibliographystyle{IEEEtran} \bibliography{reference}  \end{document}   .bib file (with only one record)      @ARTICLE{Ioannou2001,       author = {Ioannou, G and Kritikos, M and Prastacos, G},       title = {A greedy look-ahead heuristic for the vehicle routing problem with   time windows},       journal = {J Oper Res Soc},       year = {2001},       volume = {52},       pages = {523--537},       number = {5},       month = apr,       __markedentry = {[duongh:6]},       issn = {0160-5682},       owner = {d},       publisher = {Palgrave Publishers Ltd},       timestamp = {2013.03.29},       url = {http://dx.doi.org/10.1057/palgrave.jors.2601113}     }


Server error after switching from mobile to full site

Being on mobile web and trying to post an answer with empty body properly shows me an error:        This looks fine and friendly, until you switch to the full site from the bottom link on this page. This leads to a server error:


Valid US visa on old passport has a different given name while new passport has a corrected given name, will this be an issue?

The old passport with a still valid US visa on it has Given Names: XXX YYY and Surname: YYY  Due to this my visa has the same combination i.e. full name reading XXX YYY YYY (surname twice at the end).   On my new passport this was corrected to Given Name: XXX Surname: YYY  Will this cause an issue during travel? The new passport has the old passport number officially recorded in the alterations page.   I would like to clarify that the name change in the new passport was correcting the old mistake (a clerical error). It is not an official name change with legal documents to back it.


Have any of the lesser rings made by the Elves, beside the 20 Rings of Power, been shown or named?

The lesser rings were forged by the elves as essays in the craft of ring making. These rings were made sometime between S.A. 1200, when Sauron came in disguise to Eregion, and 1500, when they began crafting the greater Rings of Power.  Tolkien's essay "Of the Rings of Power and the Third Age" in The Silmarillion gives the background of the making of the rings. Midway through the Second Age Sauron came in disguise as Annatar ("Lord of Gifts") to the Elven smiths of Eregion, who were led by Celebrimbor, and taught them the craft of forging magic rings. Tolkien writes that the Elves made many lesser rings as essays in the craft, but eventually with Sauron's assistance they forged the Seven and the Nine. The Three were made by Celebrimbor himself without Sauron's assistance; they remained unsullied by his touch.  What became of these lesser 'essay' rings?


how to upgrade my Debian package with minor changes

I created a .deb which installs some features and copies some library to /usr/lib/ location.  Now that if I have changed  one of the .so file in the package and want to update the same to Debian package, what could be the scenario.   Simply how can i update files after installing the package. In windows the same is achieved by .MSP files to corresponding .MSI . How can I do the same in ubuntu?  Any help is appreciated.Thanks in advance.


A question about circles and their tangents.

The question is: Find the range of parameter 'a' for which the variable line $y = 2x + a $ lies between the circles $(x-1)^2+(y-1)^2$=1 and $(x-8)^2+(y-1)^2=4$ without intersecting or touching other circle. Now, how I solved it was realising the line has a positive slope of $+2$ and thus if it's a tangent to circle #1 then it's intercept should be negative and so using the condition of tangency, $a^2= m^2(r_1)^2+(r_1)^2= 4+1 $ And thus, as $a$ can only be negative (otherwise a positive value of $a$ will make the line intersect the circle) Thus, making the lower bound of $a> √5$ Similarly for the bigger circle $a<{√20=√[(2^2)(2^2)+(2^2)] }$ Hence I find that the solution should be $(√5,√20)$ but the actual solution is$ (2√5-15,-√5-1)$


Definition of "kissing cousins"— Are the dictionaries wrong/incomplete?

With relatives in the US south, I always thought that the definition of "kissing cousin" was a second cousin (or more distant) whom you could kiss and subsequently marry (FWIW I never did either!).  However, a number of dictionaries have a very different definition: namely, a relation close enough to kiss on meeting (sort of like a hug, I gather).  I never heard the term used this way.  Is it a recent "invention"?    Example:        noun   1. A relative close enough to be kissed in salutation, hence anyone with whom a person is fairly intimate:   The two species will often prove to be kissing cousins, for they'll crossbreed.   You guys talk like kissing cousins    and  confirm The Dictionary of American Slang's definition.  The closest reference I found to the idea I mentioned was the discussing of  in Wikepedia.  Has any else heard the term used to refer to cousins who can be married?


In SO, while hover over the drop down menu,  It shows there are 168 Communities In SE main, when hover over the drop down menu,  It shows there are 170 communities In the content of SE main,  It shows there are 167 communities Actually there are 168 communities


Often while playing Pathfinder, my group will run into problems where rules for 3-dimensional play simply don't exist, so far as we can find. Arguments will come up over things like carrying-capacity, movement speed, area-effects, and a variety of other things.  Simply put, are there rules for 3D play for Pathfinder, and if so where can I find them?


Installed ubuntu for dual boot with windows 7, want to use windows bootmanager instead of grub

Installed ubuntu recently on to the same disk with windows 7.  Currently, grub loads and I've made windows the first choice so it loads into windows.  However, I want to use the windows bootmanager instead of grub.  I went into BIOS and changed the boot order, but that didn't seem to have any effect.  Where does one go to make this change?  Thanks in advance.


What is meant by the standard error of a maximum likelihood estimate?

I'm a mathematician self-studying statistics and struggling especially with the language.   In the book I'm using, there is the following problem:  A random variable $X$ is given as $\text{Pareto}(\alpha,60)$-distributed with $\alpha>0$. (Of course, you could take any distribution depending on one parameter for the sake of this question.) Then a sample of five values $14$, $21$, $6$, $32$, $2$ is given.   First part: "Using the method of maximum likelihood, find an estimate $\hat{\alpha}$ of $\alpha$ based on [the sample]." This was no problem. The answer is $\hat{\alpha}\approx 4.6931$.  But then: "Give an estimate for the standard error of $\hat{\alpha}$."  What is meant by this? Since $\hat{\alpha}$ is just a fixed real number, I don't see in what way it could have a standard error. Am I to determine the standard deviation of $\text{Pareto}(\hat{\alpha},60)$?  If you think the question is not clear, this information would help me as well.


I know it is possible to add new CSS classes definitions at runtime through JavaScript. But... How to change/remove CSS classes definitions at runtime? For instance, supose a I have the class below: <style> .menu { font-size: 12px; } </style>  What I want is, at runtime, change the font-size rule of the .menu class, so that every element in the page who uses this class will be affected. And, I also want to know how to remove the .menu class definition.


Can I choose to fail the ability check for Dispel Magic?

Suppose I want to cast Dispel Magic (at 3rd level) on a target that has one beneficial spell on it and one harmful spell on it. I only want to dispel the harmful spell and leave the beneficial spell intact. Clearly, if the beneficial spell is 3rd level or lower, I am out of luck, since it is dispelled automatically. However, if the beneficial spell is of a higher level, it is only dispelled with a successful spellcasting ability check. Can I choose to fail this check on purpose to ensure that the beneficial spell is not dispelled while still attempting to dispel the harmful spell?  Another less likely context where this might come up would be if I was being forced under duress to dispel a spell, and I wanted to pretend to try and fail. This seems somewhat similar to  about destroying a spell scroll by intentionally misreading it, but it also seems different enough that I can't quite tell how to apply that answer here.


Why do metal objects in microwaves spark?

I heard that electrons accumulate at points on metals, and this clearly explains the arcing phenomenon, but how does a microwave make an electron imbalance on the fork?


I search for: title:change - I get results I search for: title:chang* - No results I search for: chang* - I get results (body & title)  Wildcard searches in the title should work or the text of  info page should be changed.


What is the safest way to pack syrup on a long-haul flight?

I would like to bring some homemade syrup on a long-haul flight which requires a flight transfer. I am thinking of putting it into some empty 500ml plastic mineral water bottles. How to make sure it arrives intact at its destination?


Slope of geometry as `fac` input for cycles material

I have a terrain with two materials going into a Mix Shader, I want the fac input to be the slope of the terrain. Steep parts should be one color, flat part another.


Compute the limit of $\sqrt{1-a}\sum\limits_{n=0}^{+\infty} a^{n^2}$ when $a\to1^-$

I need some suggestions, hints for the limit when $a \to 1^{-}$ of $$\sqrt{\,1 - a\,}\,\sum_{n = 0}^{\infty}a^{n^{2}}.$$


How to get accurate co-ordinates from mouse clicks in javascript

I'm trying to teach myself how to get the x and y co-ordinates clicked in a canvas to write games with. The code I've written has a subtle bug I can't figure out. When you click on the canvas, the ball moves roughly to where you clicked. But I want it centred on where I click. Instead that point is in the upper left corner of the new ball.  (I've edited the code to work correctly by using subtracting canvas.offsetLeft from the returned event.clientX and canvas.offsetTop from event.clientY, two properties I wasn't aware of until pointed to a similar post.)    var canvas, context, ball_pos;  var BALL_RADIUS = 15;  function start() {     'use strict';     canvas = document.getElementById('c');     context = canvas.getContext('2d');     ball_pos = [canvas.width / 2, canvas.height / 2]; }  function draw() {     'use strict';      // draw background     context.fillStyle = "rgb(248,248,248)"; // off white     context.fillRect(0, 0, canvas.width, canvas.height);      // draw ball     context.strokeStyle = 'black';     context.lineWidth = 1;     context.fillStyle = 'red';     context.beginPath();     context.arc(ball_pos[0], ball_pos[1], BALL_RADIUS, 0, Math.PI * 2, true);     context.closePath();     context.fill();     context.stroke(); }  function animate() {     'use strict';     window.requestAnimationFrame(animate);     draw(); }  function click(evt) {   ball_pos[0] = evt.clientX - canvas.offsetLeft;   ball_pos[1] = evt.clientY - canvas.offsetTop; }  // register event handlers window.onclick = click;  start(); animate(); <!DOCTYPE HTML> <html> <head>   <meta charset="utf-8"> </head> <body>   <canvas id="c" width="600" height="400"></canvas> </body> </html>


I keep stumbling on the format specifiers for the printf() family of functions.  What I want is to be able to print a double (or float) with a maximum given number of digits after the decimal point.  If I use:  printf("%1.3f", 359.01335); printf("%1.3f", 359.00999);   I get  359.013 359.010   Instead of the desired  359.013 359.01   Can anybody help me?


For an $R$-module $M$ I have the following definition for a submodule $N\subset M$ to be $\mathfrak{p}$-primary: this is the case when $\text{Ass}(M/N) = \{\mathfrak{p}\}$, that is, $M/N$ is coprimary or $(0)$ is a primary submodule.  Now for an ideal $\mathfrak{q} \subset R$ this definition gives that $\mathfrak{q}$ is $\mathfrak{p}$-primary iff $\text{Ass}(R/\mathfrak{q}) = \{\mathfrak{p}\}$. It can be shown that this is equivalent with $\mathfrak{p}^n \subset \mathfrak{q}$ for some $n\in \mathbb{N}$ and the condition \begin{align*} \forall r,s \in R: rs \in \mathfrak{q}, r\not\in \mathfrak{p}\Rightarrow s \in \mathfrak{q}. \end{align*}     Now I suspect that if $R$ is Noetherian, and if $\mathfrak{q}$ is $\mathfrak{p}$-primary, then we have $\sqrt{\mathfrak{q}} = \mathfrak{p}$. I have shown this for PID's, but does this generaly hold?    And if so, is every ideal $\mathfrak{q}\subset R$ then $\sqrt{\mathfrak{q}}$-primary?   Many thanks.


How does a Venturi Injector comply with energy conservation?

How does a  Injector comply with energy conservation?    When the water flow enters the narrower cross section its velocity increases and its pressure decreases. When the pressure gets lower than ambient atmospheric pressure the atmosphere is pushing air or liquid through the injection tube into the main line.  The particles in the injection tube get accelerated. Following conservation of energy, where does the kinetic energy come from? Please notice that I am not asking whether the kinetic energy of the flow at the exit is equal to the entry (it is not because of inelastic losses in the mixing process), but: when a fluid is pushed or sucked in from the side, where does the energy come from to accelerate it?


I need help for my friend whenever he saves his video as mp4, it saves it as a "File" as its file type

So whenever my friend saves his file as mp4, it keeps saving the video as "file" and it doesn't play on any player but the windows media player. And another problem is that it glitches or it's distorted whenever he plays it in windows media player.  He tried to render the video a bunch of times already, but it always came out like that from what he said. Whenever he tries to open it like just double clicking it, it wanted him to find apps that could play it...


SF novel where body swapping/modification is widespread

I read this in the early 1990s when I was a teenager and I have no idea whether it was old or new at the time.  Changing your body involves going in to a tank of liquid. People wear bodies of many and various different types (probably chosen mainly for fashion reasons) but certain body types are prohibited although I don't really remember any of the reasons why.  The main character is persuaded by someone to change his body to an illegal type. Perhaps he becomes involved in some kind of secret underground organization. The new body is of a type that he has never seen before. The main thing that I remember about it is that it has a panel of lights built into the chest and after he has learned how to he is able to communicate with other people in bodies of this type at incredible speed by flashing these lights.  I've spent considerable time web searching with no joy whatsoever. I'd love to re-read this book... the image of the flashing-chest-array communication has been stuck in my head ever since I read it but I can't remember whether anything else about it was noteworthy.


Why don’t numbers with a difference of 2 have any common factors beside 1 and possibly 2?

For example, if x is odd, that means x-1 and x+1 are both even.  And from what I’ve seen, because x+1 and x-1 have a difference of 2, they have no other common factors beside 1 and because they are both even, 2.  If x is even, then x+1 and x-1 are both odd and therefore have only 1 as a common factor.  My questions are:   Is this true in all cases? If so, why is this true?


python passing positional arguments to another function call

Can someone please explain to me how the below works:  class Memoize:     def __init__(self, f):         self.f = f         self.memo = {}     def __call__(self, *args):         if not args in self.memo:             self.memo[args] = self.f(*args)         return self.memo[args]   Then:  def factorial(k):     if k < 2: return 1     return k * factorial(k - 1)  factorial = Memoize(factorial)   This is taken from . I would like to understand how does self.f(*args) work. args is a tuple of positional arguments. When I try to do:  *(1,2,3)   I get syntax error. I thought it's some kind on unpacking operator or something like that. Does asterisk with a tuple mean anything independently or does it exist only in the context of a function call? Thank you for any explanations.


is it ok to use a lower wattage dc adaptor?

I have a Samsung TV, with the following specifications:   The AC/DC adapter broke and I need to buy a new one but I haven't found any adapter with 66W, the closest one was 65W. So I want to know:   1 - Is it ok to use a 65W dc once the TV says 66W? 2 - What does it means the "Typical power"?


Prove that square root of 2 is irrational using the principle of Mathematical Induction

How do I prove that the square root of 2 is irrational using the principle of mathematical induction?


Determine all functions $f:\mathbb{N}\rightarrow\mathbb{N}$ such that $xf(y)+yf(x)=(x+y)f(x^2+y^2)$ for all $x,y\in\mathbb{N}$ (contest question)

The question below is from the 2002 Canada National Olympiad. I have found one family of functions but need help in finding (or proving the non-existence) of others. Suggestions on how to improve the solution method (especially rigour of arguments) would also be appreciated.     Let $\mathbb{N} = {0,1,2,\dots}$. Determine all functions $f : \mathbb{N} \rightarrow \mathbb{N}$ such that       $xf(y) + yf(x) = (x + y)f(x^2 + y^2) \tag{1}$      for all $x,y \in \mathbb{N}$.     Expressing $f$ as a power series:  $f(t) = a_0 + \displaystyle{\sum\limits_{k=1}^{\infty}{a_k x^k}} \tag{2}$  Assuming the power series is convergent, the general coefficient, $a_n$, is the same on both sides of equation (1). [I am not sure of this step].  So for $a_0$  $x(a_0) + y(a_0)=(x+y)(a_0)$  which is satisfied for all values of $a_0$. Hence $\boxed{f(t)=a_0,\:a_0\in\mathbb{N}}$ is a solution.  For any $n > 0$, we have  $\begin{align} x a_n y^n + y a_n x^n &= (x+y)a_n(x^2+y^2)^n \iff \\  a_n(xy^n+yx^n) &= a_n(x+y)(x^2+y^2)^n \end{align}$  and if this is true for fixed $n>0$ and all $x,y\ge0$ then $a_n=0$. So I am unable to find any other functions.


apt-get autoremove wants to remove linux headers

Today I ran apt-get autoremove to remove un-needed packages and it wants to remove linux-headers-3.2.0-37 and linux-headers-3.2.0-37-generic  Reading package lists... Done Building dependency tree        Reading state information... Done The following packages will be REMOVED: libglademm-2.4-1c2a linux-headers-3.2.0-37 linux-headers-3.2.0-37-generic ttf-umefont    ttf-unfonts-core 0 upgraded, 0 newly installed, 5 to remove and 0 not upgraded. After this operation, 67.6 MB disk space will be freed. Do you want to continue [Y/n]?    Is it safe to remove these? My installed kernel is a newer version than the headers that autoremove lists.  uname -r 3.2.0-38-generic


I'm a beginner to Ubuntu. Can anyone tell me how to edit a configuration file?  This is on Ubuntu 18.04 LTS. Thanks in advance.


Heteroskedasticity - residual plot interpretation

I am plotting a residual plot to test for heteroskedasticity. The Breusch-Pagan test is significant and therefore I am suspecting there is evidence on heteroskedasticity.  The question is:  (a) How can I interpret such graph? I know some points seem to be on top of each other etc. is it as simple as that?  (b) Also the data has a lot of binary dummy variables. Could this be the reason for heteroskedasticity?


Seeking India population by village, town and city for 1981, 1991, 2001 and 2011?

Trying to source population data for every village, town and city in India.  I have been able to extract data for 2001 & 2011 from the , but am having a tough time finding a reliable source for data from 1981 and 1991.    Any thoughts as to where this may be found?


In tennis if I serve the ball and it goes into the opposite service box, but hits the net on the way, it is a . Is there such a thing as a let in table tennis?


This is an example to illustrate the following theorem:  Let $a,b$ be integers and let $m,n$ be positive integers. The system \begin{eqnarray*} x&\equiv & a\pmod{m}\\ x&\equiv & b\pmod{n}\\ \end{eqnarray*} has solution if and only if $(m,n)\mid (a-b).$ In this case, the solution can be uniquely expressed modulo $[m,n]$  Determine the solutions to the following linear system of equations \begin{eqnarray*} x&\equiv & 5\pmod{6}\\ x&\equiv & 8\pmod{15}\\ \end{eqnarray*} The system will have a solution if $(15,6)\mid (5-8)$, wich is true, since $3\mid-3$. I have found that the solution of this system is $x\equiv 23\pmod{30}$, Which they argue as follows:  Since there is a solution, we express $-3$ as a linear combination of $6$ and $15$: $5-8= -3 = (-3)\cdot 6 + 1\cdot 15$, thus $x=8+15=23$.  In this step I am stuck, Is there another way to get to that 23?, if someone could explain in detail what was done in this step I would be very grateful.


header files c++ unresolved external symbol error

So im newbie and im doing a school project (got really strict rules about datatypes) need to use arrays instead of vectors. and stuff like that. So im basicaly storing every gamemap type as 10x10 array and showing only size depending on userconfig file.   template <class myType>   void printBoard(myType board[10][10], int size) {     for (int j = 0; j < size; j++) {         cout << endl;         if (j == 0) {             cout << "  ";             for (int jj = 1; jj <= size; jj++)                 cout << jj << " ";             cout << endl;         }         switch (j)         {         case 0: cout << "A "; break;         case 1: cout << "B "; break;         case 2: cout << "C "; break;         case 3: cout << "D "; break;         case 4: cout << "E "; break;         case 5: cout << "F "; break;         case 6: cout << "G "; break;         case 7: cout << "H "; break;         case 8: cout << "I "; break;         case 9: cout << "J "; break;         default:             break;         }         for (int i = 0; i < size; i++) {             cout << board[i][j] << " ";         }     }     cout << endl;     return; }`   Thats my function for printing arrays of different size and type. It works well! But when i try to move function to new cpp file. i get unresolved external symbol error  Im not really sure how i should construct my header file. Ive tried different methods without success.  HEADER:  #pragma once  template <typename myType> void printBoard(myType board[10][10],int size);   I think i need to read some more about this subject? Any help here?


$\prod_{n=2}^{\infty} \left(1- \dfrac1 {n^2}\right)= ?$   Attempt:   Simplified it to $\dfrac{(n-1)(n+1)}{n^2}$ , and then wrote some terms to observe the cancelllation pattern, but that didn't help, how to solve it then?


What do the + signs do in these DNS TXT records?

Is there a specific reason why some records contain the '+' sign and others do not?  Are these handled similar to a common search function where you can preface terms with + to include them, but it's usually redundant because they are included by default?  v=spf1 +a +mx +ip4:000.00.00.000 ~all  v=spf1 a mx ptr include:domain.com ~all


Vertex cover in a graph with maximum degree of 3 and average degree of 2.

Let $G$ be a graph with the same number of vertices and edges and maximum degree of 3.  For reasons that I will explain, I believe that a  minimum vertex cover has size at most $\frac{2}{3} |E(G)|$.   I might very well be wrong and if you have a counter example, that will solve it!  Note that G is not necessarly connected, otherwise we have $\tau (G) \leq \frac{1}{2} (|E(G)|+1)$ and this solves the problem.  My intuition comes from the following observations:  If all vertices are of degree $2$, then the worst case is if the graph is just a set of triangles, then we have exactly $\tau (G) = \frac{2}{3} |E(G)|$.   If there is no single edge in the graph, the results holds. (Any connected grah of size at least 4 has $\tau (G) \leq \frac{2}{3} |E(G)|$)   If there is a single edge, then we have two vertices of degree $1$ and also two vertices of degree $3$. Those two vertices of degree $3$ should help in maintaining the minimum vertex cover below a certain bound (this is the intuition part).  I tried to create some bad cases with graphs containing single edges. I believe that one of the worst case is if the graph has 2 single edges and a K4. Then  $|E(G)|=|V(G)|=8$ and $\tau (G)= \frac{5}{8} |E(G)|$, the result still holds.  I never really worked on vertex cover, so I am probably missing some important results that would help solving this problem. Also my intuition on this area is probably kind of weak.  Thanks a lot


difference in genetic instuctions between male and female

I'm a computer science graduate so please bear with me the following computer program : mov  ecx, -1 INC  ecx consist of 2 instructions (mov,inc) each working on specific data , can genetics instuctions be expressed in the same way ? if so what is the difference between male and female(humans) when it comes to the number of instructions and the difference if any (eg , n-instuctions being exclusive to female ... etc) ?  Edit#1 :what I mean by instructions is something like a computer program and a programming language commands.


Color all vowels differently in a LaTeX document

Is it possible to give the letters a,e,i,o,u,y a different color in a piece of text? For instance, color all the a's red, the e's blue, the i's green, etc.  EDIT: Without doing it manually of course.


Are user files still private when two sudo users exist in Ubuntu?

I am sharing my personal Ubuntu PC with one of my colleagues.   I created another user with a different password (he knows of course) and added it to the sudoer list.   Given that there are two sudo users in a single Ubuntu system:   Are the private files (specified by owners and permissions) of any of these users still private?  Can I modify my colleague's files via sudo command, even sudo su, or vice versa?


There is some historical usage of diacritics in English, like naïve, résumé or even façade. I've been once told that these are used to mark a different spelling, and it may be used like in coöperative instead of co-operative to split the 'oo'.  I've checked with Wikipedia:     The main use of diacritical marks in the Latin script is to change the sound-value of the letter to which they are added. Examples from English are the diaereses in naïve and Noël, which show that the vowel with the diaeresis mark is pronounced separately from the preceding vowel;   Such a situation frequently happens in word formation, where joining a prefix that ends with a vowel and a word that starts with one. For example: coinduction, preimage, prainvention, etc. Normally one could use a hyphen, but that might be undesirable, and without anything words like bioracle (joining bi- and -oracle, whatever that would mean) could be understood as bio-rackle (I'm sure there are better examples). For example, co-op is sometimes written coöp, stretching it, bioracle could be written biöracle (I admit, it does not look good).  I know this is not a real issue, as most prefixes are known and it is possible to recover the source given context. However, technically, is this correct? To give a more concrete motivation, would it be plausible that in some future version of English (e.g. in a novel) such use of diacritics would be more frequent?


How to Prove that if $A$ is bounded, then $A \cdot A$ is bounded?

Definition: Let $\varnothing$ $\neq$ $A,B$ be a subset of $\Bbb R$, then we define   $A \cdot B$ $:=$ $\lbrace$ $a\cdot b$ | $a \in A$ , $b \in B$ $\rbrace$     Let $\varnothing$ $\neq$ $A$ be a subset of $\Bbb R$.     Question: Prove or disprove the following statement: ''If $A$ is bounded, then $A \cdot A$ is bounded''.   Can someone help me with the proof?


I've stucked at the following problem:  Let $p$ be an odd prime number. Show that for all $a\in\mathbb{Z}$  $$a^p \equiv a\ (\mathrm{mod}\ 2p)$$  How can I prove it? I know within Fermat's theorem that $a^p \equiv a\ \mathrm{mod}\ p$.


I'm creating a html website using HTML, PHP and MySQL but on HTML appears some a diamond icon on characters with accent. There is some prints to help you out.  I set this meta too:  <meta http-equiv="Content-Type" content="text/html;charset=utf-8">   HTML Page:    PHPMyAdmin:   PS.: This question is not a replication of other question! If it is please tell me the link because I searched the same question and nothing found!!!


I've received an assignment to solve the following determinant for the matrix: A is an nxn matrix defined as follows:  Show that the determinant of A is equal to n+1. I've tried solving it and got stuck, so I checked the solution:  I'm just puzzled, how did the transition from the first determinant to the second happen? I thought maybe they added all the rows to the first one, but it doesn't make sense to me because they received the same result in every variable. Help would be much appreciated!


I want to list my references in a beamer presentation using thebibliography environment, with the nice little    book icon (\beamertemplatebookbibitems) and  article icon (\beamertemplatearticlebibitems)   in front of each source.  Is there an icon for websites too? something like \beamertemplatewebsitebibitems? If not, is there a way to implement this easily ?


I can't use the terminal while gedit command is running

I recently installed 12.04. When I try to edit a file with gedit, I can't use the terminal until I close the editing file or I have to open a new terminal. But I think I didn't have this problem with 11.04, however I'm not sure. Is there anyway to avoid this and to use same terminal while editing files.


First of all, this is not a duplicate... E.g., have a look at these posts:      Anytime people on those posts talked about the use of 'so...as...', they said either that it can be used 'only in negative context' or that it can be used 'only with negative comparatives'.   Well, it is not clear to me at all what is meant by 'negative context/comparatives'... I am quite sure there was something significant omitted in the explanations. E.g., look at the following sentences:     Like the coordinating conjunctions, it is perfectly fine to begin sentences with because, so long as you keep in mind that the goal is to avoid fragments.   (Source: ).  This sentence does not seem to contain any 'negative context/comparatives'.     So foolish, unreasonable, or out of place as to be amusing.   (Source: ).  This sentence does not seem to contain any 'negative context/comparatives' either.    And this post was not meant to be derogative in any way... I am sorry if anyone got offended.  I have also left the exact URLs of most of the websites I have linked to (without having used the hyperlink function) so as to let the users see some information about the links given before having them clicked on the link.   (additionally, is 'before having them clicked on the link' grammatical? I am not a native English speaker and I'm trying to get a hang of some more advanced kind of structures).  Some justifications of the uses of 'so...as...' in the two given sentences would be appreciated (as well as some other grammar corrections present in this post, if possible). Thanks!


(Basic question) normal distribution of error in predictive model

When I am developing a predictive statistical model, why do I need to ensure the error is normally distributed? (I have a very small statistical background, so I apologize in advance if this is a very, very basic question).


Show that if a normed space $X $ has a linearly independent subset of $n$ elements, so does the dual space $X'$ My attempt : $\text{Given that  a  normed space  $X$ has  a linearly indepenedent  susbset of  $n-$  element}\tag1$ let the subset be  $S=\{ e_1,e_2,e_3,....,e_n\}$ Define $e_i \in X$ by $f_j(e_i)= \delta_{ij} = \begin{cases} 1 & i=j \\0 , & i \neq j  \end{cases}$ where $1\le i\le n$ and $1\le j\le n$ From $(1)$ we have  $c_1e_1+...+c_ne_n=0\implies c_1f(e_1)+...+c_nf(e_n)=0$ After  that im not able to proceed further


What is "special" and what is "general" in Relativity?

Initially I thought in  the velocity was constant, whereas  allowed treatment of accelerated frames as well.  But now I have heard that SR is only valid locally?


Why don't authors include in their publications the duration of the research?

I've noticed that most papers do not say explicitly (or at all) how much time did the research take. This excludes certain types of studies, such as epidemiological studies that usually say that the study's cohort was followed for some-and-some months etc., but what I mean is that in most papers there is no actual indication of how much time the study\set of experiments took. I believe this type of information could be useful for readers, especially for readers that would like to perform similar experiments for their own research.  So why is this information not required from authors?  (I realize that it's sometimes hard to pinpoint the date when a person begins and finishes a research project, but it could still be useful to give an approximation in months. This way a reader could get a better estimation if such a project is reasonable for their own research, at least from time investment considerations.)


Can we mix tenses in the same paragraph?

From an Indian thriller TV show called Ssshhhh...Koi Hai     Ajinkya manages to find his mother but is shocked to know she had never transformed. He managed to kill Vikrant but that wouldn’t be the end of him. He enters Vayika’s body, who is injuired in a struggle and in order to finish Vikrant completely, ends up killing Vayika.   In this phrase taken from , does the bold part fit correctly with the rest?


I have an API I call to get a certain DateTime, the response I get however is a string and I don't know how to make the string into a DateTime. The string I get back is this "1388064600", I know it should represent "26/12/13 - Thursday 2:30PM CEST".   How can I convert this string into a DateTime object? Is this some known format?


Cannot boot after installing Ubuntu - Do not have access to any system

I installed Ubuntu after installing Windows 10 on my system. After the installation, my BIOS/UEFI can not boot. No boot device is found, although I loaded up the boot manager and selected the right drive.  I think that my problem is that I installed Ubuntu and Windows on the same drive and now my system does not know how to boot up. I cannot boot into any system. But if I try to install Ubuntu again, I can get to the the point where I have to create new partitions. It clearly says Windows 10 and Ubuntu, so why can I not boot? I do not have access to any OS.  Edit: I did some research and found out that my bootloader is probably corrupted. I am fairly new to OS-installation in general (I have found a different article regarding my problem, but could not figure out how to solve it).  Edit2: Your recommended software did not work for me.


Maybe there is the same question but I haven't found it.  I have following code:  class MBase {     public:         ~MBase() { cout << "Base destructor\n" << endl; } };  class MF: public MBase {     public:         ~MF() { cout << "MF Destructor" << endl; } };  class MS: public MBase {     public:         ~MS() { cout << "MS Destructor" << endl;} };  int main() {      unique_ptr<MBase> ptr1 = unique_ptr<MF>(new MF());     unique_ptr<MBase> ptr2 = unique_ptr<MS>(new MS());      return 0; }   And there is output   Base destructor  Base destructor   Isn't it right? Why derived destructors weren't called? What I have to do to fix that?


Transcribing long repeating phone numbers

I always have this problem of telling people my phone number which consists of a series of repeating numbers:     184 555 5555 (DO NOT CALL, this is just as an example)   I can tell people it is:   one eight four, five five five, five five five five, or; one eight four, five, double five, double five, double five, or; one eight four, five, triple five, triple five, or; one eight four, five, sextuple five.   Is there a prescribed way or a widely practised method of transcribing long repeating phone numbers?