I would like to apply for following PhD studies in the Nordic countries, particularly in the field of Computer Science. The problem that I found is that it says in the admission procedure that "before applying one should get a Professor or Researcher that agrees to supervise the applicant".   I have checked up the personal webpages of the Professors and I have found their topics of interests, publications and so on. I like a lot of the topics in which they make research, but I do not really know how to address an email to them asking if they would agree to supervise me. Particularly I have the following doubts:   Should I make a small research article putting my ideas about one research interest of them? The problem here is that I believe I would not have the enough time to go through a lot of papers made on their reseach groups. What can I do if do not have the enough background? Time is running fast for submitting the application and I do not believe I would have enough time to study in deep their research. Should I send my CV and ask to a specific Professor that I have interest in following PhD studies under their supervision, and if it would be possible if he or she to send me some open question or open research task so that they could see that I will manage to do it well on his or her research group?   I will transcribe what the ad specifically says:        You must do your best to find a suitable supervisor at the department who agrees to supervise you. Please see the research pages   of the department, and especially the descriptions of the research   groups.   You must agree on a study plan, a research plan and a financing plan together with your (found) supervisor,  and submit an application   to the steering committee of the department's doctoral programme.      also about the supervisor it says:     A student who wants to become a PhD student should start the   application process by finding a supervisor at the department, who   works in the field of interest of the student and who is willing to   supervise the student. If the student is unsure of which supervisor to   contact, he or she may first contact the research coordinator of the   department who will steer the student in the right direction.   Generally, a supervisor is a professor and/or principal investigator   employed by the department.   For what I read it seems, at least to me, that one should really have in mind a good research proposal before applying, am I wrong? or only with an email will suffice to contact the potential supervisor?  What should I do in this situation?  Thanks

I know many master's students who get an opportunity to talk to their potential PhD advisors well before applying. In most cases this opportunity is available by the professors with whom they worked for their master's. Moreover, there are many others who establish a contact with professors by mailing them and enquiring about PhD vacancies.   My questions are:   How important is knowing an advisor prior to applying for PhD?  Does an email interaction play a vital role when the department makes its admit decisions? If email contact is important, can a student send out mails to 2-3 professors (working in the same area) in case one of them does not bother to reply? To sum up, is applying of any use (especially in top universities) when you have no contacts and only your credentials to bank on?


I have a few hundred image files. This consist of files of multiple type like 1.png 2.jpg 3.png and so on. I want to create a PDF from these images without changing the order of pages. The number in the image name must be used to preserve the order of pages.

I have a bunch of text files, images and pdf files which I want to convert into a single pdf file. How do I do it?


I wrote a simple python script that outputs a bunch of linux commands for a custom image manipulation command-line tool. As an example, here is what the python script creates: img_dae_create /d /t /19 "file1.jpg" -output "heavy" -t /mnt/img/output/ img_dae_create /d /t /7 "file2.jpg" -output "light" -t /mnt/img/output/ img_dae_create /d /t /8 "file3.jpg" -output "ex" -t /mnt/img/output/  Normally, I just copy and paste them to my Ubuntu command line and run one by one. Each command can take from 1 minute to 15+ minutes to execute. But sometimes, the python script will generate 100s of these, and it is very tedious to copy and paste each one. So I was wondering what would be the best command line operator to use in this case? Would ; be better than && given that:  The time it takes for each command to run could be between 1 and 15 minutes.  The outcome of the command does not matter, if it fails, then the command line tool records that in a log file and can be dealt with later.   Thanks!

In tutorials and how-to's I often see commands combined. For instance,  sudo apt-get update && sudo apt-get install pyrenamer   There seem to be four possible connectors: &, &&, || and ;. Though the &  connector is clear to me (it sends a process to the background and leaves the terminal available), it is not clear what the difference is between && and ;. And I did not know of || until Kaya's comment.  The following questions deal with the difference between the two connectors, but do so mostly in the comments:        So here are a number of related questions:   What is the difference between ; and &&?  When should you use them respectively? It would be nice to see some use cases: if I want to run a command and then after it shutdown my computer, which connector should I choose? What are their advantages and dangers?  mentions in a comment to  that a command like cd /somewhere_else; rm -Rf * can have destructive consequences if the first element in the command chain fails, for instance. If relevant, where do they come from?


$\lim_{n\to \infty} \frac{1}{2^n}\sum_{k=1}^n \frac{1}{\sqrt k}\binom{n}{k}$  Could it have a connection to Euler summability?

Find $$\lim_{n \to \infty} \frac {1}{2^n} \sum_{k=1}^n \frac{1}{\sqrt{k}} \binom{n}{k}.$$  First time I thought about Stirling's approximation but didn't get anything by applying it. I would also think about a Riemann Sum, but no idea how to rewrite...  The answer is $0$.


Let $A=3^{105} + 4^{105}$. Show that $7\mid A$.  My attempt-   I tried to convert $3^{105}$ like this: $3^{105}\equiv 3\cdot(3^2)^{52}\equiv 3\cdot 9^{52}\equiv 3\cdot2^{52} \pmod 7$. And for $4^{105}$ I tried the same way to convert it into $4\cdot 2^{52}$ but that's not possible and I'm getting $4^{79}\cdot 2^{52} \pmod 7$. I had the idea of doing it in $3^{105} + 4^{105}\equiv 3\cdot2^{52}+4\cdot 2^{52}\equiv 7\cdot2^{52}\equiv 0 \pmod 7$.  But I'm getting $4^{79}$ making it complex.  Can anyone suggest me some easier method? Please.

I read somewhere that     $(a^n - b^n)$         It is always divisible by $a-b$.   When $n$ is even it is also divisible by $a+b$.   When $n$ is odd it is not divisible by $a+b$.      and     $(a^n + b^n)$         It is never divisible by $a-b$.   When $n$ is odd it is divisible by $a+b$.   When $n$ is even it is not divisible by $a+b$.      I wonder what's the proof for this.  First postulate is clear. $(a-b)$ would or would not be a factor. Any light on others?


I am running a kstest on MATLAB. When I take the data directly,  i.e. kstest(data), the result says that my data is non normal. However, if I use kstest((data-mean(data))/std(data)) it would come out as normal distribution.   What is the correct way of testing normality?

We know that the original KS-test has a limitation, requiring the Null hypothesis testing underlying distribution to be fully specified, rather than estimated. But in practice, we usually need to test goodness of fit for the fitted distribution.  It is suggested to conduct a Monte Carlo Simulation by . But there are very few limited literature review about such simulation. There are several ideas come up in my mind.    Approach 1  It seems that the reason why original KS-test is no longer valid for testing estimated distribution, is that we need a smaller critical threshold KS Distance (d value) to reject the null hypothesis underlying distribution, as it is fitted around the data.  The  solves such problem. Although it is only for Normal distribution, we can extend its method.   Find the KS Distance ($D_{0}$) between the data (n data points) and the estimated underlying distribution, like original KS-test. Generate n data points by the estimated underlying distribution for M times (around millions), find their KS Distance $D_{m}$ set = {$D_{1}$, $D_{2}$, $D_{3}$, ..., $D_{M}$} for each time. Compare the $D_{0}$ value and the percentile of $D_{m}$ set as the p-value.   $P(>D_{0}|Null Hypothesis Distribution)$    Approach 2  Some post said that the original KS-test can not be applied to estimated distribution, because it does not take into account the standard error of estimation (or fitting).  So they suggest bootstrap from raw data as a simulation, but they have not described the details. I think the approach can be as follow.   Find the KS Distance ($D_{0}$) between the data (n data points) and the estimated underlying distribution A, like original KS-test. Bootstrap from raw data and fit distribution again, getting a new fitted distribution B. Find the KS Distance ($D_{1}$) between this new raw sample and new distribution B. Repeat step 2 for M time, getting their KS Distance $D_{m}$ set = {$D_{1}$, $D_{2}$, $D_{3}$, ..., $D_{M}$} for each time. Compare the $D_{0}$ value and the percentile of $D_{m}$ set, to see whether it is out of the 95% empirical interval.   It seems that this takes into account the estimated error (or confidence interval) about the estimation, which affecting the original KS-test. But it seems that this approach does not follow the p-value definition, or hypothesis definition, assuming Null hypothesis and find the sample statistics probability.    Approach 3  My fellow also comes up an idea, like the approach 2.   Find the KS Distance ($D_{0}$) between the data (n data points) and the estimated underlying distribution A, like original KS-test. Set the Null hypothesis that the data is from the distribution in question (A). Generate n points from the distribution in question (A) and fit the same distribution to this new sample which gives parameter set B. Measure the KS distance $D_{1}$ between this sample and the distribution in question with parameter set B.  Repeat step 3 a large number of times (M) which gives a distribution of KS distances $D_{m}$ assuming the actual data is from the distribution in question using our fitting method. If distance $D_{0}$ is greater than 95% of the distances calculated in 4 then reject the Null hypothesis that the data is from the distribution in question with parameter set A.   It seems that it is something parametric bootstrap from approach 2. But it appear strange to generate such sample and fit data again. And it seems still not following the hypothesis definition.    Do you have any idea about these three approaches? or any modification?  Or do you find any formal literature saying simulation details for KS-test for estimated distribution?  I only find  with details about this. But sorry I can not find the full text about this book. Does anyone have any other electronic version of similar details about simulation KS-test?  Does Anderson-Darling test also suffer from this estimated parameter issue?  Any ideas or discussion are highly appreciated.  Thank you.


How does the astronaut in the following video do what he is doing ?  This question is kind of a follow up to  I was under the impression that linear motion and rotational motion were analogous with displacement, velocity, acceleration, mass, momentum, force being analogous with angular displacement, angular velocity, angular acceleration, moment of inertia, angular momentum and torque respectively. We all know that an astronaut in space cannot undergo any linear displacement without having some external force ( the most he can do is throw objects, or gases in one direction and move in opposite direction , but even then the Center of mass of the man + object system will stay right where it was ) . In short, the center of mass should wind up back where it started. So, how come in case of rotational motion, the astronaut is able to undergo angular displacement without any external torque ? He is facing one way and at the end he has rotated and is facing another way, without there being any external torque during the process. What is the physics i am getting wrong here ? Whatever he does, should he not wind up back where he started ?

We know that if an imaginary astronaut is in the intergalactic (no external forces) and has an initial velocity zero, then he has is no way to change the position of his center of mass. The law of momentum conservation says: $$ 0=\overrightarrow{F}_{ext}=\frac{d\overrightarrow{p}}{dt}=m\frac{d\overrightarrow{v}_{c.m.}}{dt}$$  But I don't see an immediate proof, that the astronaut can't change his orientation in the space. The proof is immediate for a rigid body (from the law of conservation of angular momentum). But the astronaut is not a rigid body.   The question is: can the astronaut after a certain sequence of motions come back to the initial position but be oriented differently (change "his angle")? If yes, then how?


If 20 students can clean 5 classrooms in 4 hours, so in how many hours can 40 students clean 40 classrooms?

I came across the following question:     If 3 boys can paint a fence in 2 days what part of the job can     be completed by two boys in 1 day?   The answer to this problem is $\frac13$.  I can't manage to tackle this problem. Could anyone tell me what would be the quickest way to solve this problem (This question is a standardized test based question). Any help would be appreciated.


I have a dynamic Soql in which I want to pass a set.  I get an error:     System.QueryException: expecting a colon, found '{'   Anonymous window  Set<Id> idSet = new Set<Id> (); idSet.add('xxxxx00000xxxxAAAR'); RS.GetOrder('xxxxx00000xxxxAAAR', idSet);   Class   public class RS {     ..       public static LIST<Order__c> GetOrder(string idField, Set<Id> idSet) {     ..             String where_clause = '';             if (idField != null && idSet == null) { where_clause = ' WHERE Id =\'' + idField + '\'';     }               String where_in_clause = '';             if (idField != null && idSet != null) { where_in_clause = ' WHERE ' + idField + ' IN ' + idSet;           }              String soqlSo = 'SELECT' + cFieldsSo ' FROM order__c' + where_clause + where_in_clause;             system.debug('soqlSo: ' + soqlSo);             List<sObject> sobjSoList = Database.query(soqlSo);     }   Debug  ...FROM Staging_order__c WHERE xxxxx00000xxxxAAAR IN {a1x2o00000xxxxAAAR}   When I add a colon  where_in_clause = ' WHERE ' + idField + ' IN :' + idSet;   I get the error      System.QueryException: unexpected token: '{'

When I have a Set of Id's and I want to do a dynamic SOQL query that I want to use it in for an IN comparison, I have to convert the Set to string in the format of:  ('id1','id2',id3',...)   The way I do it works, but is not particularly elegant, so I'm wondering if anyone has come up with a better way. Am I missing something? Is there something out there that can just turn a set or list into the properly formatted string?   Here's my code (yes, my example isn't dynamic SOQL, but I've used this several times in dynamic SOQL):   Map<Id,Account> accts = new Map<Id,Account>([select Id from Account]);  String idString = '(\''; for (Id thisId : accts.keyset()) {     idString += thisId + '\',\''; } idString = idString.substring(0,idString.length()-2); //<--this is the bit I hate doing idString += ')';  String q = 'select id from Contact where AccountId in ' + idString;  List<Contact> cts = Database.query(q);


I made a PayPal account 8 months ago and signed up with another nationality mistakenly (choosing nationality before the sign up page at the time wasn't clear and many cities all over the world share my city name; I'm not sure how I signed up but I ended up with US nationality) and I linked a MasterCard. When I received a payment from a freelancing site about a couple weeks ago, I tried taking the money on the MasterCard and it didn't work. So I tried linking my Visa with the same billing address as the MasterCard and it isn't the right address so it gives me errors. I can't add the right address as the nationality is set to US. So   I can't receive the money on a card I can't accept the money on the account and use to buy any product online as I don't have any document to prove I'm a resident of the US  I can't send the money to a new account I made linked with a Visa   Will the money will be in waiting status forever? Can I do anything about it?

Is there any way to change one's nationality in a PayPal account without having to open a new one?


What is the origin of the electric charge? In order to explain mass we had to postulate the existence of a quantum field (Higgs field), and we say that elementary particles get their mass by interacting with this field.   But where does electric charge come from? Is electric charge the result of particles interacting with some field or is it just a property of some fields (e.g. electron field)?

Baryons have charges that are the result of a polynomial calculation of their building blocks (quarks)'s fractional charges. But what gives these quarks electric charges? What interactions do they have with photons? And what about leptons, like muons and electrons? How do they get their -1 charge? And then, how do positrons and anti-muons get +1 charge? Same goes for quarks: how does up-antiquarks get -2/3 charge? Or I may want to formulate my question this way:  How does any elementary particle interact with the EM-Force to get an electric charge?


I need my formula to increase by "1" for every "25".  I wrote the following formula, but it does not work:  =SUM( IF(O11<25,0, IF(O11<50>21,1, IF(O11<75>51,2, IF(O11<100>76,3, IF(O11<125>101,4))))))


I saw a curious behavior working with QList. Follows the code:  QList<int> returnListTest() {     QList<int> a;     a.append(52);     a.append(77);     if (false) {        return a;     } }   Notice, there is no return, because never enter in the "if (false)". But when I call this function:   QList<int> r = returnListTest(); foreach (int a, r) {     qDebug() << "return item" << a; }   I have:  "return item 52" "return item 77". Does anyone know why this happens?

Yesterday, I found myself writing code like this:  SomeStruct getSomeStruct() {     SomeStruct input;      cin >> input.x;     cin >> input.y; }   Of course forgetting to actually return the struct I just created.  Oddly enough, the values in the struct that was returned by this function got initialized to zero (when compiled using g++ that is).  Is this just a coincidence or did another SomeStruct get created and initialized somewhere implicitly?


I proved that $\{1,\sqrt 2\}$ and $\{1,\sqrt 3\}$ are respective bases of $\mathbb Q(\sqrt 2)$ and $\mathbb Q(\sqrt 3)$ over $\mathbb Q$. I want to show in some sense that since $\sqrt 2,\sqrt 3$ are Linearly Independent over $\mathbb Q$, that the product of the bases $\{1,\sqrt 2\}$ and $\{1,\sqrt 3\} =\{1,\sqrt 2,\sqrt 3, \sqrt 6\}$ is exactly a base $\mathbb Q(\sqrt 2,\sqrt 3)$  Can this make sense?

Is $\mathbf{Q}(\sqrt{2},\sqrt{3}) = \mathbf{Q}(\sqrt{6})$?   If $\mathbf{Q}(\sqrt{2},\sqrt{3})=\{a+b\sqrt{2}+c\sqrt{3}+d\sqrt{6}\mid a,b,c,d\in\mathbf{Q}\}$ and $\mathbf{Q}(\sqrt{6})= \{a+b\sqrt{6} | a,b \in \mathbf{Q}\}$  Assume an element in $\mathbf{Q}(\sqrt{6})$ , then obviously it is also in $\mathbf{Q}(\sqrt{2},\sqrt{3})$.   Assume an element in $\mathbf{Q}(\sqrt{2},\sqrt{3})$ , because we can write: $\sqrt{6} = \sqrt{3} \cdot \sqrt{2} $ and $\sqrt{6} = \sqrt{2} \cdot \sqrt{3}$ the sum of $b\sqrt{3} + c\sqrt{2}$ is equal to a fraction of $\sqrt{6}$.   So $\mathbf{Q}(\sqrt{2},\sqrt{3}) = \mathbf{Q}(\sqrt{6})$.


let result= str.match( /i/g ); //it works and returns all occurrence of i   but i tried the below statements it didnt work when i pass a dynamic variable which has the same input 'i' as the above statement. what is wrong in the below syntax. let result= str.match( /arr[i]/g ); let result= str.match( '/'+arr[i]+'/g ');

I would like to create a String.replaceAll() method in JavaScript and I'm thinking that using a regex would be most terse way to do it.  However, I can't figure out how to pass a variable in to a regex.  I can do this already which will replace all the instances of "B" with "A".  "ABABAB".replace(/B/g, "A");   But I want to do something like this:  String.prototype.replaceAll = function(replaceThis, withThis) {     this.replace(/replaceThis/g, withThis); };   But obviously this will only replace the text "replaceThis"...so how do I pass this variable in to my regex string?


I'm trying to read/write INI files in VISUAL C++ 6.0 (with MFC) I tried to load registry.hpp and CINIfiles and a few more but they don't exist in this version(because of constraints in the workplace I can't use the BOOST library). So which way should work with INI files?

I'm trying to parse an INI file using C++. Any tips on what is the best way to achieve this? Should I use the Windows API tools for INI file processing (with which I am totally unfamiliar), an open-source solution or attempt to parse it manually?


I am confused about the amount of work done when lifting an object at a constant speed. If you find the work done by you on the object and the work done by gravity on the object and add them the net work would be 0. How is there an increase in Potential Energy if the net work done on the object is 0? I was told that 0 was the incorrect answer and the net work should be equal to the potential energy. Which answer is correct?

A previous post () defines work qualitatively as "a process in which energy is transformed from one form to another form". And mathematically, work is defined as: $$\Delta KE=\int_{C} \vec{F}\cdot\mathrm d\vec{r}$$ But if you imagine lifting up a rock from the ground at constant speed, am I not doing work on the rock by converting the chemical energy stored in my muscles into the potential energy of the rock? I am confused because the kinetic energy of the rock does not change and yet I am still converting energy from one form to another, which is the qualitative definition of work. What's the right way to think about this and the concept of work in general?


There is a text with IP addresses on each line as well arbitrary ones with digits/dots. How can I match only lines that are not IP addresses?  10.123.34.12   asdADSas 3242 .  10.123.34.12   Empty lines are OK.  How do I solve this problem?

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


Can I make money from taking out a loan from a country with a low interest rate (such as Switzerland, that has an interest rate for loans from 4.9%) and put it into a fixed savings deposit account in a country with a high interest rate (the Ukraine, for example, where the interest rate has been said to be around 20%).  What would be all the possible drawbacks. This case of making money of a loan with a savings account(mentioned above) seems to be to black and white(obvious).   I know Ukraine is an unstable country and there is a higher risk of course of losing my money. but apart from that, what else should one look out for?

If I live in the US, for example, where current interest rates are practically nil, how can I take advantage of the fact that ?


I searched a lot regarding my question, but I never found the exact piece of information explaning how to implement rel="prev" and rel="next" inside the code of a certain site?  I'll be very greatful if some could give me good imformation on this matter.

How rel="next" and rel="prev" helps in SEO, if used for pagination? Is it really required ?  i.e. imagine you're on page 2:  <link rel="prev" href="http://www.example.com/article-part1.html"> <link rel="next" href="http://www.example.com/article-part3.html">


Given a dictionary d where the key values pair consist of a string as key and an integer as value, I want to print the key string where the value is the maximum.  Of course I can loop over d.items(), store the maximum and its key and output the latter after the for loop. But is there a more "pythonic" way just using just a max function construct like  print max(...)

I have a dictionary: keys are strings, values are integers.  Example:   stats = {'a':1000, 'b':3000, 'c': 100}   I'd like to get 'b' as an answer, since it's the key with a higher value.  I did the following, using an intermediate list with reversed key-value tuples:  inverse = [(value, key) for key, value in stats.items()] print max(inverse)[1]   Is that one the better (or even more elegant) approach?


Not sure if this is a closed or open question. But the question is suppose $f[f(x)]=x^2+1$ then what is $f(x)$? Though the question does not refer to the domain let us suppose it is defined on $\Bbb R$.  Thanks.

There are some math quizzes like: find a function $\phi:\mathbb{R}\rightarrow\mathbb{R}$  such that $\phi(\phi(x)) = f(x) \equiv x^2 + 1.$  If such $\phi$ exists (it does in this example), $\phi$ can be viewed as a "square root" of $f$ in the sense of function composition because $\phi\circ\phi = f$.  Is there a general theory on the mathematical properties of this kind of square roots? (For instance, for what $f$ will a real analytic $\phi$ exist?)


I am starting a small company and wanted to have an email address that isn't g*mail etc. In the past I have been able to achieve my own custom email by using a domain of co.cc (there have been others also but it was many years ago). I've been trying to look around at free webhosts (I already see Dot TK for the free domain as example). Of course, once I've set it up fully, purchasing a .com domain will not be much of a problem. However, all the webhosts I found don't give a free email. And I really cannot afford a monthly fee right now. Again, many years ago I ran my own website using something called 'WAMPServer'. Thing is I am really busy and sadly not earning enough to even pay for hosting service. I don't have much time to waste hence I am asking here for advice. If WAMPserver or similar is capable of doing the job, I only really need that confirmed. I can then go and learn the steps to set it up by myself. The thing I am trying to avoid is going down a long rabbit-hole with something like WAMPserver only to find I cannot do what I need. What is the best way in this day and age to set this up? Thanks for your help.

This is a "catch-all" question designed to serve as an answer for all questions about choosing web hosting.  Pro Webmasters no longer accepts new questions about how to choose hosting.  All future questions pertaining to finding web hosting should be closed as a duplicate of this question. For more information about this policy please see .    How to find web hosting that meets my requirements?  What we're looking for in answers to this question are the basics about web hosting:   What is web hosting? What is the difference between shared, VPS, and dedicated hosting? How does a content delivery network relate to web hosting? Anything else you feel is helpful in finding a web host.   What we do not want is:   Endorsements or recommendations for specific web hosts We do not want your experience or other subjective information (just the facts please)


CentOS 5.x  I'm trying to confirm which specific rule in my iptables config is allowing return UDP traffic from my DNS server. I THINK, it's this one:   -A RH-Firewall-1-INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT     If I take off RELATED and bounce iptables, DNS queries on the server still work.   If I comment out the line entirely, and bounce iptables, DNS queries start failing.    So by that logic, it seems reasonable to me that iptables is considering the return UDP packet to be part of an ESTABLISHED connection state.  Why does it think that though?   I get that it sees the response coming back to a port pertaining to an open query but the man page for iptables defines ESTABLISHED state as "the packet is associated with a connection which has seen packets in both directions".  In this case, only one UDP packet would have been sent out and presumably only one would be coming back.  Where did the connection previously seen "packets in both directions"?   Apologies in advance if I'm over-thinking this.

let's look at these two iptables rules which are often used to allow outgoing DNS:  iptables -A OUTPUT -p udp --sport 1024:65535 --dport 53     -m state --state NEW,ESTABLISHED -j ACCEPT  iptables -A INPUT -p udp --sport 53 --dport 1024:65535    -m state --state ESTABLISHED -j ACCEPT   My question is: How exactly should I understand the ESTABLISHED state in UDP? UDP is stateless.  Here is my intuition - I'd like to know, if or where this is incorrect:  The man page tells me this:     state   This module, when combined with connection tracking, allows access to the connection tracking state for this packet.    --state ...    So, iptables basically remembers the port number that was used for the outgoing packet (what else could it remember for a UDP packet?), and then allows the first incoming packet that is sent back within a short timeframe? An attacker would have to guess the port number (would that really be too hard?)  About avoiding conflicts:  The kernel keeps track of which ports are blocked (either by other services, or by previous outgoing UDP packets), so that these ports will not be used for new outgoing DNS packets within the timeframe? (What would happen, if I accidentally tried to start a service on that port within the timeframe - would that attempt be denied/blocked?)  Please find all errors in the above text :-) Thanks,  Chris


Recently, on math.stackexchange.com, some people posted problems from an active contest. Is there a way I can "flag" the questions to get them deleted?

Suppose I want to have someone with moderator abilities review a post. What would be the best way to flag this?    Is there already some standard way to do this that I don't know about?     For more information, see "" in the .


I have a 20-year-old daughter, born in the US to military British parents. She has dual nationality / both birth certificates.  Her US passport is expired and Social Security number misplaced. She needs to travel to the USA as soon as possible.  Can she travel on her British passport with an ESTA? She can't wait for 8 weeks to get new Social Security number, and then three more weeks for a new US passport.  Will she be okay with her British passport with an ESTA?

I am a dual citizen. I have both a US passport and a non-US passport. I live in the US. My US passport is currently being processed for renewal. I am unsure whether I will receive my passport in time for a trip that I have scheduled. Could I use my non-US passport to leave the US and return? I have never entered the US with my non-US passport. There is no immigration leaving the US but I still need to scan my passport for ticketing. Will the airline refuse me a ticket? I know that in this situation returning with a non-US passport can be problematic as well, but will I be able to leave at all? Note that I am traveling to a country which neither of my passports are from.


I have old speakers and decided to make them useful again by making then battery powered but I am new to this so I'm not 100% sure on what to do. In the speakers there is a small transformer which converts the 230 volts to 12 volts and 1.2 amps but I have two 12 volt 4.5 amp batteries which I am going to use in parrellel so that I get a longer battery life. This means I will have 9 amps coming from the batteries but I don't know how to reduce the amps without interfering with the voltage. Thank you in advance.

Power supplies are available in a wide range of voltage and current ratings.  If I have a device that has specific voltage and current ratings, how do those relate to the power ratings I need to specify?  What if I don't know the device's specs, but am replacing a previous power supply with particular ratings?  Is it OK to go lower voltage, or should it always be higher?  What about current?  I don't want a 10 A supply to damage my 1 A device.


The perfect question for my problem is erroneously closed as a duplicate. The one answer doesn't work; in fact, it's an answer to the (allegedly) duplicated question. Maybe that (and the fact that the answer was, at one point, accepted) is part of the problem.    I've done   to get it reopened:   I commented on the question itself I commented on the unsatisfactory answer I carefully examined the alleged duplicate to make sure it was different I edited the question to highlight the differences I flagged it for moderator attention ... twice, or tried to, anyway - see below I'm asking about it on Meta

I asked a question regarding a very specific feature of a program and whether or not it works with a larger program.  Within hours someone had marked it with "This question may already have an answer here of a similar question, but not related to my question.  The question I asked IS NOT ADDRESSED in the referred-to question. It's frustrating to spend half an hour putting together an intelligent and specific question, and then have someone mark it as a duplicate (or possible duplicate), which apparently causes people to skip over my question. I haven't received any more responses since the question was flagged.   Two questions:  (1) How do I get this flagging removed and (2) what's the best way to prevent these "helpful" flaggings in the future?


Does anybody have experience enter and exit on expired National Identity Card for Overseas Pakistanis (NICOP) + renewal Slip? Already ask PIA, they will let me board but question is   Can we come back to Canada same way with expired NICOP and renewal slip?    Toronto Consulate have no idea about coming back on renewal slip.

According to the Federal Immigration Authority Pakistan, it's possible for dual citizens to travel to Pakistan with an expired NICOP.    I've already booked my ticket with PIA. Anyone here who has traveled under similar circumstances? I just want to be sure that I will be allowed to board.


For example I have 3 calls of one method (always 3 calls) and I need to pass 1 to method for the first call 2 for the second and 3 for the third. I can solve that Problem in 2 ways. Either make 3 calls with 1, 2, 3 or use a for loop.  call(1); call(2); call(3);  for (int i = 1; i <= 3; i++) {     call(i); }   The question is what will run faster. As I know this depends completly on the Java Compiler, because it could make optimizations on the for loop.  In plain C the redundant way would be a little bit faster I guess, because there is no counter needed to increment and compare.

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


How do I iterate over all pair combination in a list, like:  list = [1,2,3,4]   Output:  1,2 1,3 1,4 2,3 2,4 3,4   Thanks!

I have a list with 15 numbers in, and I need to write some code that produces all 32,768 combinations of those numbers.   I've found  (by Googling) that apparently does what I'm looking for, but I found the code fairly opaque and am wary of using it. Plus I have a feeling there must be a more elegant solution.  The only thing that occurs to me would be to just loop through the decimal integers 1–32768 and convert those to binary, and use the binary representation as a filter to pick out the appropriate numbers.   Does anyone know of a better way? Using map(), maybe?


This is my code:  private <T,L extends ArrayList<? extends T>> L Foo(L<T> list1) {     L list2 = new ArrayList<T>();      //more code  }   I'm using IDEA and get the following error message for the method parameter:  Type 'L' does not have type parameters  and the following error message for creating the ArrayList:  Incompatible types.
Required: L
 Found: java.utils.ArrayList<T>;   Why does this happen? L extends ArrayList so it should have the same type parameters right?

I read about Java's type erasure .  When does type erasure occur? At compile time or runtime? When the class is loaded? When the class is instantiated?  A lot of sites (including the official tutorial mentioned above) say type erasure occurs at compile time. If the type information is completely removed at compile time, how does the JDK check type compatibility when a method using generics is invoked with no type information or wrong type information?  Consider the following example: Say class A has a method, empty(Box<? extends Number> b). We compile A.java and get the class file A.class.  public class A {     public static void empty(Box<? extends Number> b) {} }     public class Box<T> {}   Now we create another class B which invokes the method empty with a non-parameterized argument (raw type): empty(new Box()). If we compile B.java with A.class in the classpath, javac is smart enough to raise a warning. So A.class has some type information stored in it.  public class B {     public static void invoke() {         // java: unchecked method invocation:         //  method empty in class A is applied to given types         //  required: Box<? extends java.lang.Number>         //  found:    Box         // java: unchecked conversion         //  required: Box<? extends java.lang.Number>         //  found:    Box         A.empty(new Box());     } }   My guess would be that type erasure occurs when the class is loaded, but it is just a guess. So when does it happen?


I compiled and installed vim 7.4 in Ubuntu 12.04. I want to set gvim as the default application for all text and C/C++ files.   I tried : Right click > Open With Other Application. But couldn't find Gvim in that list. I also can't find Gvim in the launcher.    $which gvim /usr/bin/gvim   Currently, I have to launch gvim from command line only.   $gvim filename &   How can I make gvim as the default editor when I open any text/ C/C++ files from file explorer?

While trying to make vim default instead of gedit, I found this could be done two ways:  Use defaults.list and make text/plain (and others) point to vim.desktop (what is the format for creating .desktop files?)  Use update-alternatives and change gnome-text-editor (right now it has only one alternative, so I guess I have to install one more. How to do that?)  and which is the better way to do it?


My school textbook says that we don't need to use unit vectors (i ,j,k) to represent the direction of vectors in 1D motion as + and - sign indicate direction. But that is creating a lot of confusion like this: Suppose a question for one dimensional motion is like this: a body is thrown vertically upwards with a speed of 10 m/s. Here if we consider upward direction as positive, then I have seen information written like this: v= + 10 m/s a=-g=-9.8 m/s^2 But I don't agree with the way it is written. I am relating it with vectors. Firstly, why are they not using vector symbol when it has both magnitude and direction ( with + or - indicating direction). Secondly, a should represent the magnitude of acceleration vector but magnitude can't be negative. So why it is written like this? Rather I think they should write like this: v=+10 m/s a=-9.8 m/s^2 Am I right? Note: bold letters here represent the symbol of vectors.

In my textbook instantaneous velocity and acceleration are wrote only as $v$ and $a$ in the chapter of One dimensional motion. Instead, in two dimensional motion chapter they are written with the "arrow" symbol upon them, $\vec{v}$ and $\vec{a}$.  Why if they are both vectors they don't have an arrow in that particular chapter? I just can't get it.


I have a multiple regression model with 4 independent variable. I want to test heteroscedasticity with the Breusch-Pagan test. If I do a studentized BP test the p-value is 0,173, with a non-studentized test, it is 0,89.

Using R on some data and trying to see whether or not my data is heteroscedastic, I've found two implementations of the Breusch-Pagan test,  (package lmtest) and  (package car). However, these produce different results. What is the difference between the two? When should you choose to use one or the other?  > model <- lm(y ~ x) > bp <- bptest(model) > bp studentized Breusch-Pagan test  data:  model  BP = 3.3596, df = 1, p-value = 0.06681  > ncvTest(model) Non-constant Variance Score Test  Variance formula: ~ fitted.values  Chisquare = 3.858704    Df = 1     p = 0.04948855    These example shows that according to the tests, my data is in one case heteroscedastic and in the other case homoscedastic. I did find  so bptest might be studentized and ncvTest might not be, however, what does this mean then?


Is it possible to make the ‘tip box’ in the photograph below using the tcolorbox package (or any other way for that matter)? My abilities in tcolorbox are severely lacking, so any help is greatly appreciated.  Thank you in advance for any assistance.

I was wondering how to create a theorem environment similar to the following example:   Specifically, the environment should resemble the box that contains "Claim -- The function g is linear".  This comes from a , who has his style files uploaded  I have tried to mimic what I believed to be the relevant code (as there's a lot of stuff there that isn't related to this), to no avail. I have attached my attempt below, but it may be better to ignore it.  \usepackage{amsmath} \usepackage{amsthm} \usepackage{mdframed} \usepackage{thmtools} \usepackage{tikz} \usepackage{xcolor} \usepackage[framemethod=TikZ]{mdframed}     \mdfdefinestyle{mdgreenbox}{%         linewidth=0.5pt,         skipabove=12pt,         frametitleaboveskip=5pt,         frametitlebelowskip=0pt,         skipbelow=2pt,         frametitlefont=\bfseries,         innertopmargin=4pt,         innerbottommargin=8pt,         nobreak=true,         backgroundcolor=SpringGreen!15,         rightline=false,         leftline=false,         topline=false,         bottomline=false,         linecolor=green,     }     \declaretheoremstyle[         headfont=\bfseries\color{OliveGreen},         mdframed={style=mdgreenbox},         headpunct={\\[3pt]},         postheadspace={0pt},     ]{thmgreenbox} \declaretheorem[style=thmgreenbox]{thrm1}   This returns an error, one for xcolor not recognizing the colors, and the following.  l.17        \mdfdefinestyle                       {mdgreenbox}{% The package mdframed has already been loaded with options:   [] There has now been an attempt to load it with options   [framemethod=TikZ] Adding the global options:   ,framemethod=TikZ to your \documentclass declaration may fix this. Try typing  <return>  to proceed.  Package thmtools Info: Key `mdframed' (with value `style=mdgreenbox') (thmtools)             is not a known style key. (thmtools)             Will pass this to every \declaretheorem (thmtools)             that uses `style=thmgreenbox' on input line 39. Package thmtools Info: Automatically pulling in `thmdef-mdframed' on input line 40. (/usr/local/texlive/2017/texmf-dist/tex/latex/thmtools/thmdef-mdframed.sty Package: thmdef-mdframed 2014/04/21 v66 ) \c@thrm1=\count282 (/compile/output.aux) \openout1 = `output.aux'.   I am looking for a way to mimic the environment more than to fix my methods.  Thank you in advance!


Find all solutions of the equality $y^2=x^3+23$ for integers $x,y$   I guess, that x cannot be even. because we can apply mod 4 test  say $x=2k$ then $y^2=8k^3+23\equiv3\mod(4)$   but, this is not possible, since the square of an integer is congruent to $0$ or $1$ $\mod (4)$  so $x$ is of the form $4k+3$ or $4k+1$  $x=4k+3$ is also not possible for the same reason but for the last case the test fails.  any hints ?

As the title stated, I am wondering the integers $x,y$ that satisfy the equation $x^2-y^3 = 23$.


I'm trying to subtract to floating point numbers in python. I've values   a = 1460356156116843.000000, b = 2301.93138123  When I try to print a-b, it's resulting the value 1460356156114541.000000 contrary to the actual value 1460356156114541.06861877.  What are the limitations in python while doing floating point arithmetic. Is there any way in python through which I can get the actual result of this subtraction?

Consider the following code:   0.1 + 0.2 == 0.3  ->  false   0.1 + 0.2         ->  0.30000000000000004   Why do these inaccuracies happen?


Why is inner_LOAD_ATOM(buffer, ATOM_MAX) converted to scanf("%" "ATOM_MAX" "s", x) but the wrapped version isnt? I would expect ATOM_MAX(identifier) to be replaced by 10 before it is "passed" to inner_LOAD_ATOM or LOAD_LINE and making the wrapper useless. More elaborated answer why the wrapper is necessary would be very appreciated.  #include <stdio.h>  #define ATOM_MAX 10 #define inner_LOAD_ATOM(x, y) scanf("%" #y "s", x)      /* inner part */ #define LOAD_ATOM(x, y) inner_LOAD_ATOM(x, y)           /* wrapper of inner_LOAD_ATOM */   int main(void) {     char buffer[ATOM_MAX] = {0, };      /* wrapped works fine */     LOAD_ATOM(buffer, ATOM_MAX);              /* [Warning] unknown conversion     type character 'A' in format [-Wformat=] */     inner_LOAD_ATOM(buffer, ATOM_MAX);      printf("%s\n", buffer);       return 0; }

For example, how to avoid writing the 'func_name' twice?  #ifndef TEST_FUN #  define TEST_FUN func_name #  define TEST_FUN_NAME "func_name" #endif   I'd like to follow the  rule.  Version of C preprocessor:  $ cpp --version cpp (GCC) 4.1.2 20070626 (Red Hat 4.1.2-14)


Finite group $G$ contains elements $g_1,g_2,...,g_n$. Show $g_1g,g_2g,...,g_ng$ contains each element of G exactly once.  I know that by definition $g_ig$ is an element of group $G$. How can I prove by contradiction that $g_ig$ does not equal $g_jg$?

Finite group $G$ contains elements $g_1,g_2,...,g_n$. Show that $g_1g,g_2g,...,g_ng$ consists of every element from $G$, where $g\in G$.  I know that the operation of a finite group gives back each element of the group once, but how can I prove this? I know I have to show that some $g_ig$ is in the group and some $g_ig$ does not equal some $g_jg$


I tried with a few algebraic manipulations with no success. for the system:  $$ \begin{pmatrix} x_1' \\ x_2' \end{pmatrix} = \begin{pmatrix} 4 & -5 \\ -7 & -3 \end{pmatrix}\begin{pmatrix} x_1 \\ x_2 \end{pmatrix} $$  Tried  $x_{1}'=x_{2}$ thus from first equation I get $x_{2}=4x_{1}-5x_{2}$ and then replacing the $x_{2}$ in second equation with $\frac{2}{3}x_{1}$ and the result become $y''=-9y$.  This is not the final answer for some reason, They didn't do any example in class and my logic isn't working here...

So I have two equations   $X' = aX + bY$  $Y' = cX + dY$  I want to convert it back to a second order equation with the form   $X'' + \alpha X' + \beta X$ with $\alpha,\beta$ in terms of a,b,c,d.   I have been racking my brain for hours trying to go backwards from a reduction of order, but just can't seem to figure it out. Any help would be much appreciated!


This was an exercise on a course on abstract algebra at the University of Groningen. I have been working on this for ages, but I can't seem to figure it out.  Problem  Let $R$ be a ring with $\forall x \in R: x^3 = x$.  Prove that $x+x+x+x+x+x=0$.  Tried  If $x=0$, the statement is of course trivial.  If $x \neq 0$, we have $x(x^2-1)=0=(x^2-1)x$, so either $x^2 = 1$, so $x$ is a unit, or $x^2-1$ and $x$ are zero-divisors.  And this is as far as I get... Any help would be appreciated! :)  Edit: guide to answer  The following hint was provided by Abel:  $$\begin{align} x \in R &\implies x+x \in R\\ &\implies x+x=(x+x)^3 \end{align}$$  If you then work out all the terms, the answer will follow quickly.

Let $R$ be a ring with unity where  $$x^3=x,\;\;\; \forall x \in R$$  How do I prove that $$x+x+x+x+x+x=0$$


Couldn’t find my Google account that’s what it says when I try logging in

I have forgotten the password or username for my Google account, or I'm unable to access my account for other reasons.  How can I recover my account?  (This Q&A is meant as a general description for all Google and Gmail username/password questions. See: )


I have a point layer and I want to create polygons arround points which are in distance of 10 meters.  I did create a grid vector of 10m but it doesn't group as well as they have to be.  I did create a buffer arround my points in arcgis, as you know arcgis buffer tool gives you the posiibility to choose a dissolve type yet in the merged buffers I can have also a point which is in a distance of 20m.  I'm wondering if there is a possibility, using ArcGIS Desktop, to select from the same layer the features within a distance of  10m  and create a polygon around.

I have a project in ArcGIS (ArcMap 10.2) where I want to identify naturally occurring dense spots of points and then form groups in that dense area, where points are within 45 miles of each other. This would mean that not so dense areas will be left out and not become part of any group?   I don't have access to Point Density tool. I run Python code for Grouping Analysis but I get errors due to Python or GIS version mismatch.


When a star dies it explodes in a supernova. This happens when heavier elements like iron is fused in the core of the star. Then the star collapses under its own gravity. This leaves a black hole behind. Now in order to conserve momentum the star must spin. So does a black hole spin? If so at what speed does a black hole spin?

My question is in the title: Do black holes have a moment of inertia?  I would say that it is: $$I ~\propto~ M R_S^2,$$ where $R_S$ is the Schwarzschild radius, but I cannot find anything in the literature.


It was posited in answers/comments to "  " that somehow, Harry is being protected from harm in general (post-GoF) by the fact that - as per HP7 - Voldemort took Harry's blood and thus with his blood took inside him the protection that Lily's sacrifice bestowed on Harry.  However, I think that this protection (both Lily's original protection in Harry's blood, and the part of it that got transferred to Voldemort) is VERY VERY specific and is only against harm done directly by Voldemort. This means that Harry is still subject to non-Voldemort harm, for example he could have been easily killed by Basilisk fang's bite in HP2 or by FiendFyre started by Crabbe in HP7 in Room of Hidden Things.  Is there good in-Universe or JKR information  to support or reject my theory that the protection is only against harm directly done by Voldemort?

If Quirrell got burnt when he wanted to hurt Harry, why didn’t others? I mean, was this power Harry had from his mother mentioned in any other situation? Or did Lily's sacrifice just work for Voldemort and Quirrell died because of Voldemort?


I would like to use this special character - a 'bullet' '•', but LaTeX won't let me. Does anyone know how to use this in LaTeX?

I know what my symbol or character looks like, but I don't know what the command is or which math alphabet it came from. How do I go about finding this out?


I want to store multiple functions inside an array and execute one function when i call array[index] to be executed and not all the functions inside the array, how to do it in python?  Example:       array = [  function2(1, 2), function3(2, 3)]      array[0] #Execute array[0] and not all the functions inside array

How can I bind arguments to a Python method to store a nullary functor for later invocation?  Similar to C++'s boost::bind.  For example:  def add(x, y):     return x + y  add_5 = magic_function(add, 5) assert add_5(3) == 8


I just installed VSCode on macOS latest (Mojave 10.14.5) and every time I open it I get a popup saying:     “Visual Studio Code” is an app downloaded from the Internet. Are you sure you want to open it?   This app was downloaded from the internet and it is installed in my Applications folder. I have clicked the 'Open' button every time and still it pops up like this.   Is there a way to not have that happen? I followed the regular install instructions and I don't have this problem on my other Macbook Pro ... not sure what is going on.

This is not a question on how to disable the warning when opening files or apps downloaded from the internet but instead it is about Xcode Projects.  New with Xcode 7.3 released yesterday whenever a project is opened for the first time that was downloaded from the internet a warning pops up asking      “ProjectName” is a project downloaded from the Internet. Are you sure   you want to open it?   How do I disable this warning from popping up?


I'm new to Ubuntu 13.04. I want a 'refresh' option, like in Windows when you right click on desktop. Can anyone help me to get that option in Ubuntu?

I'd like to have an option on the right-click menu to refresh Nautilus.  How can I achieve that?


New with 10.9 is the ability to easily create a bootable drive from the installer that is downloaded from the App Store, with a single command createinstallmedia in the Terminal.   has details.  I encountered a problem with this, with an Error -9999 when trying to erase the USB drive I had inserted.  The error occurred while booted into 10.6.8; but since that particular computer also has a 10.8 partition, I booted from it and tried the same command with the same USB drive.  It was able to erase and create the boot drive successfully.  Don't know how widespread this problem is; but, if this occurs to someone else who does not have the newer OS available to boot into, I'm wondering if there is any other way to fix the error; or if the Disk Utility methods of creating the boot drive will need to be used.

Does anyone have a Terminal command-line recipe for making a new bootable USB flash drive for one of the new MacBook Air's?  Is there a way to dd copy the USB boot device that comes in the box and make the new copy bootable?  I'd like to make a new backup copy of the USB rescue device for my MBA, preferably on a much larger flash drive with room for a backup of some of my working directories.  Added:  And is it possible to make, not just a rescue drive, but a bootable USB drive that will boot a fully updated version of the OS (say 10.6.8 or later)?  If so how on a MacBook Air 11, and how big a USB stick will this require?


I have experienced this kind of error ever since it had a server error. Can someone explain me to this and help me resolve this problem? Thanks!  Error on updating Ubuntu:

How do I select which server Ubuntu will get it's software and updates from? I know how to find the  on the web, but not how to use them.


I am developing a php application with laravel. In my application I need to do some data fetching from a number of servers. In order to speedup the results I have to send those requests in the same time. I've found laravel queue but the problem is that the I need to get information back from the queue. Another solution is php pthreads but I'm having a very hard time installing it. Is there any way (multithreading / multiprocessing) to do seprate jobs async.

Is there a realistic way of implementing a multi-threaded model in PHP whether truly, or just simulating it. Some time back it was suggested that you could force the operating system to load another instance of the PHP executable and handle other simultaneous processes.  The problem with this is that when the PHP code finished executing the PHP instance remains in memory because there is no way to kill it from within PHP.  So if you are simulating several threads you can imagine whats going to happen.  So I am still looking for a way multi-threading can be done or simulated effectively from within PHP. Any ideas?


So to start off, the goal of this function below is to read each line in the text file (TitanData.txt). Each line has 3 pieces of information: Age, Passenger Class, and if the passenger survived (saved as "TRUE" or "FALSE") in order. I've created 3 vectors: vector Age, vector PassengerClass, vector Survived. The issue seems to be that the push_back functions aren't working properly. I've been looking for solutions for hours and I have yet to come across one so hopefully I can get an answer here. The function is below: void ReadFromFile(vector<int> Age, vector<string> PassengerClass, vector<bool> Survived) {     bool survived;     int age;     string Passenger_Class;      string val1, val2, val3;     ifstream infile;     infile.open("TitanicData.txt");     if (infile)     {         while (infile >> val1 >> val2 >> val3)         {             age = stoi(val1);             Age.push_back(age);               Passenger_Class = val2;             PassengerClass.push_back(val2);               if (val3 == "TRUE")             {                 survived = true;                 Survived.push_back(true);             }             if (val3 == "FALSE")             {                 survived = false;                 Survived.push_back(false);             }         }         infile.close();     } }

What is the difference between    a parameter passed by reference a parameter passed by value?   Could you give me some examples, please?


I'm doing principal component analysis (PCA) on my nutrition data. Basically, I want to condense 43 food groups into fewer groups (aka, I want to define 2-3 patterns based on the 43 food groups). The problem is, my Kaiser-Meyer-Olkin (KMO) measure is very low (~0.35) but my Barlett's test for sphericity remains significant (<0.0001). Could I still proceed with PCA or do I have to delete a few food groups based on the Anti-image correlation matrix?

I have a dataset that contains data from $307$ subjects and nine variables for each subject. I would like to run a PCA. My problem is that I get a Kaiser-Meyer-Olkin (KMO) value of $0.06$.  Can it be due to the fact that within every subject the variables add up to $1$? Is there another way to test whether it is okay to run PCA on my data?


I developed colour negative film for the first time yesterday and I have two problems. Firstly many of the pictures have these stains like circles on them and I cannot understand what caused them and how to clean them. And also the pictures came out looking way too magenta/ purplish which is bizarre because the film I used is supposed to come out more to the greenish side rather than the magenta side. Any ideas about how I could clean the stains or what could have gone wrong? :))

This is my first roll of Tri-X 400, developed with D76 using Massive Dev's chart in this order:   developer  stop bath (tap water) fixer  tap water (quick 1 minute wash) Photo Flo (2 minutes) tap water (final wash, 11 minutes)   then off to the scanner the next day (V500 flatbed) for scanning.  There are some weird effects going on however in most of the frames, as well as the usual pixelated look I've grown accustomed to with flatbed scanning 35mm.  I've highlighted the spots in the photos below:      I am wondering what this is and how I can fix it. Using distilled water maybe?


What things responsible for android update. . Means if i have a android phone which will not upgrade my os version . In this scenario , why it is not upgradable ?.. what factor make it .?  Any hardware problem or  any other ?

I never dealt with Android devices before so I'm completely newbie at it, please comment if something is too simple.  Say I purchase , that has got Android Froyo 2.2 installed in it.  If there is a new version of Android released tomorrow or next month, will I be able to update it (like I will be able to update my iPod Touch 4 to iOS 5)?


I'm trying to root my Galaxy Note 4 and I see the above terms being used everywhere. What do each of them mean? I have a vague idea about each of them, but I'm still confused about some of them. A brief description about each would be enough. Thanks in advance.

What is the difference between:   Unlocking the bootloader (prerequisite for doing many, though not all, other things below) Rooting Jailbreaking ROM NAND and Nandroid Operating System Mod (e.g. CyanogenMod) Recovery (ClockworkMod, Amon Ra) Custom Kernel (e.g. LeshaK's kernel) Firmware Driver Over The Air (OTA) update Fastboot SIM unlocking Flashing SPL (Second Program Loader)   (any other often-confused terms that I've missed?)


Knowing AC = BC, find x.    I tried to solve the question and found many angles.    And x + k = 110, x + y = 140, k + z = 130, z + y = 160.  But I still can't find x. Is this problem uniquely solvable?  The book answer is x = 30°.

Given :  Angle ABE = 50, Angle DAC = 20, Angle BAD = 60, Angle ACB = 20 and Side CD = Side DA.Unit of angle values given is degree.  Find : Angle ADE.    I'm stuck and I need help here.


I recently installed two of the same pcie wireless LAN cards into my HP 2710p computer with Kali Linux 2 installed. I can use one of the cards, but the second card is not available. I cannot find a second wireless LAN entry within my file system nor within the interface selection for Wireshark. Why is the second card not available?

I am noticing a bunch of a half-PCI Express Centrino chipsets that say "not for Lenovo/HP", what's the reason for this? Technically, PCI-Express is standardized. What could possibly be different?  Here is  and , and .


I've asked this question almost a dozen times and it seems to stump everyone.  I've come a little closer - but still not close enough to the solution.  I want to recursively convert .mp4 to .png (1 frame only).  I'm able to do the conversion - although it's not recursive.  Here is the script I'm using:  how do I make this recursive?  for i in *.mp4;   do name=`echo "$i" | cut -d'.' -f1`   echo "$name"   ffmpeg -i "$i" -r 0.0033 -vf scale=-1:1024 -vcodec png "${name}.png" done   This post relates to:

How can I use the following script to recursively convert a directory containing .mp4 to .png (1 frame only).  Right now it only converts the directory.  It's not recursive.  for i in *.mp4 do name=`echo "$i" | cut -d'.' -f1` echo "$name" ffmpeg -i "$i" -r 0.0033 -vf scale=-1:1024 -vcodec png "${name}.png" done


I am still stuck with the same problem. CKeditor doenot work, instead the plain text editor gets open. I tried everything from re-installing ckeditor to updating drupal to newer version.when I open any heading and try to open the edit option, it runs very slow. then when it gets open the data is visible in the form of plain text(no ckeditor), i checked the console it shows this error Synchronous XMLHttpRequest on the main thread is deprecated because of its detrimental effects to the end user's experience in drupal Please can anybody help

I have designed a website on Drupal. It was working fine but now when I tried to update a link (by adding any name under any option) it does not show the rich text editor. Instead it shows the plain html body.  This way :  <ul> Assignemnt UID </ul>   I mean switch to plain text editor is not working. This way I am not able to update any file or link.  How I can make this to work?    I am still stuck with the same problem. CKeditor does not work, instead the plain text editor gets opened. I tried everything from re-installing CKeditor to updating Drupal to newer version. When I open any heading and try to open the edit option, it runs very slow. Then when it gets open the data is visible in the form of plain text(no CKeditor). I checked the console it shows this error:     Synchronous XMLHttpRequest on the main thread is deprecated because of its detrimental effects to the end user's experience in drupal   Any help?


I am using Ubuntu 14 (with UI) and I was trying to find a shortcut key to SELECT ALL text in the Terminal  Currently I have to click on EDIT > SELECT ALL and this bothers me a lot :P

In (X)Ubuntu 14.04, I was able to perform a Select All operation via keyboard, in Gnome Terminal, invoking the menu (Alt-E -> A).  With more recent versions of (X)Ubuntu, I've noticed that the shortcuts for the menu bar are not available anymore.  For some operations, it's possible to set a direct shortcut (eg. Reset and clear terminal), but not for Select All.  Is there a way I can perform this operation via keyboard?  Note: I refer strictly to Gnome Terminal, not other terminal applications.


I've created a partition of 50GB to my Ubuntu on my SSD (using Win10 with 200GB), I want to expand my Ubuntu's space by say, 20GB. So I've de-allocated that space from my /sda2 (ntfs) partition.  Now I would like to merge the unallocated space with /dev/sda5 which is an extended partition.  I've tried using AOEI software on win10 but it said it doesn't take care of extended paritions. Tried to unmount sda5 (with --force or -f too, and with -l too), and it just made my system laggy, couldn't do anything and had to restart, and eventually the key stayed.  I guess the steps should be to unlock the extended parition and then move the unallocated space down, and then I would be able to extend my Ubuntu's space, but I'm not able to do it.   I've also read many posts and watched some YouTube videos which didn't help me before asking here. Any help is highly appreciated, I need that space :(

Previously, I have installed Windows 7 on my 320 GB laptop with three partitions 173, 84 and 63 GB each. The 63 GB partition was where the Windows was installed. The rest were for file containers.  Now I changed my OS to Ubuntu 12.04 LTS. I installed Ubuntu by replacing the entire Windows 7 on the 63 GB partition. The rest of the partitions remain as an NTFS Windows partition and I can still access them both (the 173 and 84 GB partitions).  Now I want to change the two partitions of Windows into an Ubuntu format partitions plus most importantly, I want to extend the 63 GB partition to more than a 100 GB because at the moment I am running out of disk space. Whenever I try to install any application, especially using wine, it always complains for a shortage of disk space.  How do I do the extending activity before I entirely format my laptop again and lose all the important files on my partitions?


I'm trying to make a model for a mod and i'm not 100% sure how to export it with texture. I have searched all over the internet for tutorials but keep on failing. I know it probably me and you are annoyed that you keep on seeing this question.

I used node textures in a mesh I exported to .FBX.  I then imported it into Unreal Engine 4 and it didn't import any textures; I clicked the Upload Textures option in Unreal Engine.  Is there something I'm doing wrong or is it Blender?


I am developing an application that will be embedded inside an iframe in another domain so I do not have any access to the iframe element that the app will be embedded in.  I cannot use the following method, since my application will be embedded in another domain: var frame = window.frameElement();  if (frame) {   // do something } else {   // do something else }  However, I do not need to have access to the full iframe element, I just need to know whether or not my app is embedded.  Is there a way of just determining whether or not the app is embedded in this situation?

I am writing an iframe based facebook app. Now I want to use the same html page to render the normal website as well as the canvas page within facebook. I want to know if I can determine whether the page has been loaded inside the iframe or directly in the browser?


As the question states, I'm interested in the difference between CIs, SEM, and SD, explained in plain words (so as to be able to communicate it to people without maths/stats background).  My current understanding (mainly gained through Googling around) is that:   CIs indicate the reliability of a measurement SEM reflects the uncertainty in the (sample?) mean and its dependency on the sample size SD informs us about the spread of the population (i.e. SD reflects the variation of the data)   Is that correct?

I'm struggling to understand the difference between the standard error and the standard deviation. How are they different and why do you need to measure the standard error?


$cat contents.txt  cat-1.15  cat-1.15  cat-1.15 cat-1.18   The above output has blank lines  $cat contents.txt | grep cat results in the word cat being highlighted, but the resultant text is also merged, eliminating blank lines  cat-1.15 cat-1.15 cat-1.15 cat-1.18   How can I grep to highlight without grep affecting the text structure, so that the only difference is the grep term being highlighted ?

Say I have the following file:  $ cat test  test line 1 test line 2 line without the search word another line without it test line 3 with two test words test line 4   By default, grep returns each line that contains the search term:  $ grep test test  test line 1 test line 2 test line 3 with two test words test line 4   Passing the --color parameter to grep will make it highlight the portion of the line that matches the search expression, but it still only returns lines that contain the expression. Is there a way to get grep to output every line in the source file, but highlight the matches?  My current terrible hack to accomplish this (at least on files that don't have 10000+ consecutive lines with no matches) is:  $ grep -B 9999 -A 9999 test test     If grep can't accomplish this, is there another command-line tool that offers the same functionality? I've fiddled with , but it doesn't seem to have an option for it either.


I am attempting to give a Banner object with a custom name of 'Keycard2'. The command I'm using is: /give @p banner 1 11 {display:{Name:"Keycard2"}}   The error I'm getting is:  Line 1, Column 2 Missing '}' or object member name  What am I doing wrong? Bear in mind that this is Bedrock edition, but as far as I can tell this command should work.

This question was recently split into different questions for each workaround. See   meta posts for more information.   Can you use NBT tags in commands? I’ve tried commands that normally work in Java Edition like: give @s minecraft:planks 30 1 {display:{Lore:["Wooden planks"]}} give @s stone_pickaxe{Unbreakable:1b} give @s item_frame{EntityTag:{Invisible:1b}} summon villager ~ ~ ~ {Offers:{Recipes:[{buy:{id:"emerald",Count:5b},sell:{id:"diamond_sword"}}]}} summon tnt ~ ~ ~ {Fuse:20s}


So I'm getting this warning whenever I typeset a document which is using the subfiles package for modular documents. The warning occurs both when running the master file as well as the individual parts.   /usr/local/texlive/2014/texmf-dist/tex/latex/oberdiek/auxhook.sty: Package auxhook Warning: Cannot patch \document,(auxhook)                using \AtBeginDocument instead.   It's just a warning, and it doesn't seem to change anything at all. Everything looks good. It's just that I prefer not to have warnings...  Any ideas?

I'm using subfiles within my report (written on sharelatex), when I compile a subfile it produces a warning. Am I doing something wrong or is this normal?  Example  \documentclass[report.tex]{subfiles} % \usepackage{acronym} \begin{document}  some text  \end{document}   Error     /usr/local/texlive/2015/texmf-dist/tex/latex/oberdiek/auxhook.sty   Package auxhook Warning: Cannot patch \document, using \AtBeginDocument instead.   When I compile the main document it does not produce this warning.  The raw log file produces this warning     ......   Package: auxhook 2011/03/04 v1.3 Hooks for auxiliary files (HO)   Package auxhook Warning: Cannot patch \document,   (auxhook)                using \AtBeginDocument instead.   ) (/usr/local/texlive/2015/texmf-dist/tex/latex/oberdiek/kvoptions.sty   Package: kvoptions 2011/06/30 v3.11 Key value format for package options (HO)   ....    Packages  I'm using the following packages:    \documentclass[whitelogo]{tudelft-report}   % Used for referencing   \usepackage{natbib}   % For writing remarks in the text (is this going to be used?)   \usepackage{changes}   % used to write and render different subfiles   \usepackage{subfiles}   % used to draw boxed problems   \usepackage{mdframed}   % for subcaptions in combined figures   \usepackage{subcaption}    % used for Epigraphs of course   \usepackage{epigraph}   % Makes weblinks clickable   \usepackage{hyperref}   % used to display pictures   \usepackage{graphicx}   % used to add urls with strange symbols   \usepackage{grffile}   % used for H command in figures   \usepackage{float}   % used for tickz pictures (Causes a warning)   %\usepackage{pgfplots}   %used for the acronym page [printonlyused,withpage] are options   \usepackage{acronym}    % ######################### open section for code appendix #######################   \usepackage[utf8]{inputenc}   \usepackage{listings}   \usepackage{color}   \definecolor{codegreen}{rgb}{0,0.6,0}   \definecolor{codegray}{rgb}{0.5,0.5,0.5}   \definecolor{codepurple}{rgb}{0.58,0,0.82}   \definecolor{backcolour}{rgb}{0.95,0.95,0.92}


Well, I am a freelancer and not a native English speaker.  I am taking a look at job requirement what my client sent to me.  Here is what I am asking.  "We want this product built OFF of XXX platform".  Client brought XXX from a marketing site.  As seen above, OFF is being with upper-case letter that seems like my client is going to emphasize something that is most important.  I can't understand what is client's need really and exactly.

What is the meaning of "build off of"? I Googled it, but can't find any definition!  I encountered it in the sentence in a technical book. The sentence is:     For the application we will build, the todos example is the closest   fit, so we'll go ahead and build off of that example.   There is a link related to it I found by Google, But it didn't give the definition!


Considering $A^b$, we have a nice definition and properties when $A$ is a matrix and $b$ is a real (or field) value.  We also have a fairly useful definition for $e^B$, where $B$ is a matrix and $e$ is the Naperian base.  I imagine this can be extended to an arbitrary base using logarithms.  My question is whether there is a general definition for $A^B$ with $A$ and $B$ as matrices with some suitable properties.  Some properties might be:   $A^b$ and $e^B$ are special cases of the definition of $A^B$ $A^I = A$ $A^{B + C} = A^BA^C \text{ under suitable conditions }$ $(A^B)^C = A^{BC} \text{ under suitable conditions }$   Is any such definition known?  Can computations be done with it?  What properties do we get and under what conditions?  Thank you, this is for my own curiosity.    Edit : Fly by Night found this previous question: , but it doesn't really address the properties that I was asking about.  The real usefulness in a definition is in what you can infer from it, so I want to keep this question open.

I was wondering if there is such a valid operation as raising a matrix to the power of a matrix, e.g. vaguely, if $M$ is a matrix, is $$ M^N $$ valid, or is there at least something similar?  Would it be the components of the matrix raised to each component of the matrix it's raised to, resulting in again, another matrix?  Thanks,


$X$ is said to have a Cauchy distribution iff $X$ has a probability distribution of the form:  $$f(x)= \begin{cases}  \frac{a}{\pi(ax^2+x^2)} & \text{,$x>0$} \\ \ \ \ \ 0 & \text {,otherwise} \end{cases}$$ where $a>0$  How can I show that $X$ has no mean?

Why is the mean of a Cauchy distribution undefined? Surely, it should be $0$ by symmetry? $$\int_{-\infty}^{\infty} {\frac{x}{\pi (1+x^2)}} dx =0?$$


I have a Mimo monitor and it runs USB. I tried and failed and I don't know what to do......All i get from the USB screen is just a green screen. Anyone could help me?

I have a DisplayLink-based external USB monitor, which has both power and data over USB, and seems to work perfectly under Windows 7, but only can display a text console under Ubuntu 10.10, and that I can only use when I am actually switched to it. So the only Use I can have so far is to have some text-based monitoring or console that I can watch while working on the graphic display.   I know there are some development done for DisplayLink, but I never could get it to actually run properly.   Yes, I tried the detailed setup described in other , but they did not work, and instead crashed my X that I had to restore.   Merci :-)


I'm looking to send a chat to someone that conveys this message/thought but I simply cannot, for the life of me, remember what word I used to use for this. The message I'm looking to send goes along the lines of, in a positive light,  I have been able to free up more time recently due to workflow efficiency improvements but for ________ sake I would like to stick to our original terms, which is X days to complete Y milestone. Her company gave her a generous Christmas bonus and she can return what she owes you immediately. However, in the name of ________, she wants to follow your original amortization terms.  I was thinking of the word "formality" but in the second example, it may have been a simple, informal oral agreement between the two of them. I'm looking for a word that's sort of the antonym of "indecisiveness" and "turncoat". Edit: I failed to make it clear before. The context is between two/a few parties. The answers and  holds the agreement to widely-accepted societal morals and standards, which may not necessarily be the case for the agreement the parties might have entered into. What I was looking for, after additional thought, is  Her company gave her a generous Christmas bonus and she can return what she owes you immediately. However, in the name of [the agreement between them, or something that conveys this thought], she wants to follow your original amortization terms.  This would work for me:  Her company gave her a generous Christmas bonus and she can return what she owes you immediately. However, [in the name of commitment/for the sake of the commitment between the two of you (non-one word)], she wants to follow your original amortization terms.

I'm looking for a good word to express the concept of "the right thing being done" but avoiding the connotations of the two most obvious words:   Justice - has too much of a connotation of being legalistic or enforced by the police. Morality - has too much of a connotation of "traditional values" and puritanism.   Is there a better word?


I need to validate phone number that allows numeric and symbols + - ()  how can i do so in asp.net?  <asp:TextBox ID="TxtNo" runat="server"></asp:TextBox>     <asp:RegularExpressionValidator ID="RegularExpressionValidator2" runat="server" ErrorMessage="Enter valid Phone number" ControlToValidate="TxtNo" ></asp:RegularExpressionValidator>

I'm trying to put together a comprehensive regex to validate phone numbers. Ideally it would handle international formats, but it must handle US formats, including the following:   1-234-567-8901 1-234-567-8901 x1234 1-234-567-8901 ext1234 1 (234) 567-8901 1.234.567.8901 1/234/567/8901 12345678901   I'll answer with my current attempt, but I'm hoping somebody has something better and/or more elegant.


Is it possible to output positive numbers in c# with the plus sign '+', without writing a char code like this?:  Console.WriteLine("+" + 5);   This is what I mean: For example, n = 5: I want the algorithm to output +5 like this:    Thanks for your help.

Is there any way I can specify a standard or custom numeric format string to always output the sign, be it +ve or -ve (although what it should do for zero, I'm not sure!)


If $$\cos x + \cos y - \cos(x+y) = \frac{3}{2}$$ then         (a) $x + y = 0$   (b) $x = 2 y$   (c) $x = y$   (d) $2 x = y$      It is problem of trigonometry, and I have the solution of the problem. However, after seeing the solution, I don't quite understand how is one supposed to know how to approach this problem. My request is:     Don't just solve the problem, but also tell me from where do you come to know which approach would work. (Tell me from where do you come to know which trick or approach to be used to solution this problem.)   Thanks in advance.

If $0\leq x,y\leq\frac{\pi}{2}$ and $\cos x +\cos y -\cos(x+y)=\frac{3}{2}$, then how can I prove that $x=y=\frac{\pi}{3}$? Your help is appreciated.I tried various formulas but nothing is working.


I've recently been having difficulty in Minecraft. It's a modded creative, but sometimes, I can break blocks but not place them in creative mode. I switched over to a server that used the same mod I was playing and I couldn't place on there either.   When I play a non-modded game (typically 1.8.8) it works fine.  My internet is at 5 full bars (4 sometimes) and runs very smoothly. It also mostly only occurs after I make a new world and play on it shortly after making it (and, I have a load of worlds.)  EDIT: It now happens mid-game too. It happened with any mod I used, same or different, and does not occur in vanilla Minecraft. I use Forge 1.7.10.

I'm playing on a Survival world with cheats on, "easy" difficulty, and at night in-game. I didn't have a sword or anything to make a sword with, and I was starving, so I switched to Creative to give myself a stack of food and a bed to set my spawn point. When I switched back to Survival, I couldn't destroy or place blocks. I'm on single player, and my Internet is fine, and I can destroy blocks still if I switch to creative. I've tried resetting the button one, and reloading the map, and it still doesn't work. I've even tried deleting everything I gave myself in Creative. This happened before on a different world and I ended up deleting it.  This only happens on this world. How do I fix it?  If I know I'm in the correct game mode, what else can cause this?  Are there different causes in multiplayer?


It seems that there is no way to search file content using regex by spotlight. Is it so? Thanks.

Possible Duplicate:          How could I use spotlight to search for example for files that end with jar or files that end with doc and at the same time contains "Hello" in it's name?


I've been playing Minecraft for years now, however I ran into a problem I haven't before: when I opened Minecraft I only had version 1.16.2 and a couple of modded versions. I remember adding some vanilla versions but I just assumed it was nothing. I went to installation to get a new 1.8.9 (I wanted to test some old worlds), went to versions and there was only version 1.16.2 and a couple of modded versions. I went to make sure that snapshot and historical boxes were checked and they were, I closed the browser down and opened it again still happened. I went in the .minecraft folder, saved all the important stuff, uninstalled the game and installed it again but now I can only go on Minecraft 1.16.2. To fix this I cant get the other versions simply cause it wont let me.

How do I downgrade Minecraft to play on a server running an older version?


I am trying to calculate the point from a given lat/long, a bearing, and a distance.  This is for plotting weather given a aeronautical way point.   For example:  Given a waypoint with a known lat/long (LAX airport control tower), with a bearing of North by Northwest and a distance of 45 nautical miles, where is the point?  I could treat the world as flat, but I think the resulting calculations would be inaccurate the further north the point is since longitudes get more narrow near the poles.  I am mainly interested in plotting these points in the US.  Is there a projection that would help me do this?  This is for a Python application I'm writing, and the libraries I have access to are GDAL and Proj4 for projections. So no fancy tools like ArcGIS are available to me.  Ultimately I want to combine 4 or these calculated points to form a polygon that should roughly be about 100-200 miles in width and height.  Thanks!

There are several algorithms to calculate distance between two latitude/longitude points.     Hubeny     But there are not so many algorithms (actually I can't finally find it) which can calculate latitude/longitude of point B from another latitude/longitude point A with bearing and distance.      I'm glad to know if there are any algorithms which is lesser accurate, but faster than Vincenty's formulae.


I have a large MySQL table on 5.6.35-81.0 Percona Server with gaps in the PRIMARY key. The table has around 53 Million records and the auto-increment key is now at around 370 million. The table is a list of phone numbers and users add/delete the numbers very frequently hence the PRIMARY key which is BIGINT has gaps inside.  The problem I am facing now is that when I do a simple SELECT * FROM table, MySQL does not used the PRIMARY key to sort the results by default. It uses the phone number field from the table to sort the data and because of this the data is SELECTed as sequential instead of the way it's saved in the DB.   Offcourse SELECT with ORDER BY id takes a very long time. The other solution is to copy all the data to another table but that would require application downtime. How can I fix this or to avoid such in the future?  CREATE TABLE `contacts` (   `id` bigint(20) NOT NULL AUTO_INCREMENT,   `phonebook_id` int(11) NOT NULL,   `campaign_id` int(11) DEFAULT NULL,   `contact` varchar(45) NOT NULL,   `status` tinyint(1) unsigned NOT NULL DEFAULT '1',   `admin` tinyint(1) unsigned NOT NULL DEFAULT '0',   `call_status` tinyint(1) unsigned NOT NULL DEFAULT '1',   `active_call` tinyint(1) unsigned NOT NULL DEFAULT '0',   `test_call` tinyint(1) unsigned NOT NULL DEFAULT '0',   `dnc_contact` tinyint(1) unsigned NOT NULL DEFAULT '0',   `v_node_name` varchar(45) DEFAULT NULL,   `timezone` varchar(4) DEFAULT NULL,   `updated_date` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,   `created_date` timestamp NULL DEFAULT NULL,   `contact_name` varchar(45) DEFAULT NULL,   PRIMARY KEY (`id`),   UNIQUE KEY `phonebook_id` (`phonebook_id`,`contact`),   KEY `idx_001` (`active_call`,`campaign_id`,`test_call`),   KEY `idx_002` (`phonebook_id`,`call_status`,`test_call`,`campaign_id`,`active_call`,`dnc_contact`),   KEY `idx_003` (`phonebook_id`,`test_call`,`call_status`,`dnc_contact`),   KEY `FK_campaign_id_idx` (`campaign_id`),   KEY `idx_testcall` (`test_call`),   KEY `idx_004` (`campaign_id`,`call_status`,`test_call`),   KEY `idx_active_call` (`active_call`) ) ENGINE=InnoDB AUTO_INCREMENT=2369201 DEFAULT CHARSET=latin1;

Suppose you have the following table and data:  create table t (     k int,     v int,     index k(k)     ) engine=memory;  insert into t (k, v) values (10, 1),        (10, 2),        (10, 3);   When issuing select * from t where k = 10 with no order by clause, how does MySQL sort the records by default?


I just buy new iPhone. I want to transfer only Whatsapp chat history, and none of all the other apps. I want to start with clean slate. I don't want to going through each app to delete them one by one on the new iPhone. But I still need all the Whatsapp chat history. How can I do that using  Finder? I presume I have to use the backup on Finder to backup just the selected app (Whatsapp), and then use the backup to restore on the new iPhone. But how do I do that (backup just the selected app)? I don't see any selection on the Finder iPhone management to do that. Only "Back Up Now" button.

I just got a new iPhone, and wanted to start "fresh", that is, only installing the app I actually use - not the full pile of junk that was lying around on my old iPhone. Therefore, I opted not to set up the new iPhone from the old one's backup, but instead, downloaded what I wanted from the App Store.  Now I see that one of the apps on the old phone is subscription based, so that I need a password to use it. The password is stored, so I don't have to enter it on my old phone.  But I do not know that password, and for various reasons, I'm unable to use the app's forgotten password function.  So I would like to transfer that single app, including its data (password) to my new phone. How can I do that?


I'm stuck in the proof of the following theorem of complex analysis:  There is a $R\in\mathbb{R}_{0}^{+}\cup\{\infty\}$ s.t.: (i) $\sum_{k=0}^{\infty} a_k (z-z_0)^k$ converges absolutely and locally uniformly (i.e. every point has a ngbh. in which the convergence is uniformly) on $D_R(z_0)=\{z\in\mathbb{C}\mid\lvert z-z_0\rvert< R\}$ (ii) The power series diverges on $\mathbb{C}\backslash\{\overline{D_{R}(z_0)}\}$. The Cauchy-Hadamard Theorem holds: $$R=\frac{1}{\limsup\limits_{n\rightarrow\infty}\sqrt[n]{\lvert a_n\rvert}}$$  The proof starts as follows:  General idea: majorizing by the Geometric Series Let $0<r_0<r_1<R$. If $R=0$ consider (ii). We want to show absolut and uniform convergence on $D_{r_0}(z_0)$; this implies the theorem. [...]  Here I'm stuck. Why does this imply the theorem? I don't have any counterexample but have even less a clue to show this implication. In the proof there is no further explanation given why this implication holds. Could anyone please proof this implication or refer to some open resource? Many thanks in advance!

$\sum_0^\infty a_nz^n$ , $z\in \mathbb{C}$, a power series with $R:=\sup \{ t\ge0 : a_n t^n$ is bounded $\}$ as its convergence radius. I wish to prove that $\sum_0^\infty a_nz^n$ is locally normally convergent over $B(0,R)$.  What I did so far:   Let $r_1 <r_2<R$ , then for all $z\in B(0,r_1)$ :  $$\sum_0^\infty|a_nz^n| = \sum _0^\infty|a_n|\frac{r_2^n}{r_2^n}|z|^n \le \sum _0^\infty|a_n|r_2^n(\frac{r_1}{r_2})^n .$$  Now, because $r_2<R$ , $|a_n|r_2^n <M$ , so: $$\sum _0^\infty|a_n|r_2^n(\frac{r_1}{r_2})^n \le M\sum _0^\infty(\frac{r_1}{r_2})^n ,$$ which converges as a geometric series when $r_1<r_2$. So any power series for $z\in B(0,r_1)$ is mutually bounded by $M\sum_0^\infty(\frac{r_1}{r_2})^n$.   Yet I don't succeed to make the next step, and show that  any $z\in B(0,r_1)$ has a neighborhood $U_z$ such that $\sum_0^\infty \sup_{U_z} |a_n z^n|$ converges.


After making index for my local repository, I get this error while updating.  E: Encountered a section with no Package: header E: Problem with MergeList /var/lib/apt/lists/_home_soroush_repository_dists_precise_local_binary-amd64_Packages E: The package lists or status file could not be parsed or opened. E: _cache->open() failed, please report.   Then no package manager works. I know that there is a problem with index file generated by dpkg-scan-packages but can't find it.  I maintain my repo using this script and it worked properly for a long time:  #!/bin/bash for dist in "precise" #"oneiric" do     for component in "local"     do         for architecture in "amd64" # "i386" "all"          do             echo "Generating package index for $dist $component $architecture..."              dpkg-scanpackages -a $architecture pool/local /dev/null | gzip -9c > dists/$dist/local/binary-$architecture/Packages         done     echo "Generating source index for $dist $component $architecture..."      dpkg-scansources pool/local > dists/$dist/local/sources/Sources     done done   My question is how can I find which package is causing problem in index file? There should be some sort of parser for that...

The computer gave me this output in a window:  E: Encountered a section with no Package: header E: Problem with MergeList /var/lib/apt/lists/archive.ubuntu.com_ubuntu_dists_natty_main_binary-i386_Packages E: The package lists or status file could not be parsed or opened.   How can I fix this?


Unpopular would not be the word I am looking for. Something may be popular but only among a small group of people. For example, classical music: here in India, not many people like it but there are some who do. Therefore, I cannot say classical music is unpopular in India. Is there a word that means liked only by a few?

Is there some way to describe something that the average person doesn't know about but is still not obscure? Such as a musician who doesn't get much radio play but still has thousands or even millions of fans, or how an independent movie that does well at a festival like Sundance but doesn't get a major release.


I have looked around the internet for methods of having big redstone delays (Up to 5 or 7 minutes), and multiple of these delays in a row, each delay sending a redstone signal to a command block then activating another long redstone delay (Not a loop).  The problem is that I don't want to use a whole lot of repeaters connected between different command blocks, as this would take too long and take up a lot of space. The amount of time also does not need to be too accurate.  What I have found is that many of the solutions I have tried to find are loops (Like Etho's Hopper Timer), and instead of a constant loop I want a redstone delay, like a bunch of repeaters, but more compact.  Anything easy to set up via redstone is preferred but I'm open to using scoreboards.  Edit: I slightly edited Yeet's suggestion so that the command kills the minecart, sand, and also gives an output.

I tried:  /tp @e[type=ArmorStand,T=100] ~ ~1 ~   Then:  /tp @e[type=ArmorStand,Time=100] ~ ~1 ~   I'm stuck.  I am looking for a command-block only solution.


I have a list of strings such as this :   ['z+2-44', '4+55+z+88']   How can I split this strings in the list such that it would be something like  [['z','+','2','-','44'],['4','+','55','+','z','+','88']]   I have tried using the split method already however that splits the 44 into 4 and 4, and am not sure what else to try.

I don't really understand regular expressions.  Can you explain them to me in an easy-to-follow manner?  If there are any online tools or books, could you also link to them?


Here's the situation: I want to bring my girlfriend over here to Portugal for the holidays. She's Venezuelan but is in Trinidad and Tobago right now. My plan is to save money by buying 2 different plane tickets, one from Trinidad to Miami, and another one from Miami to Portugal. My question is, does she need a visa to stay in the US for 3 hours to catch another flight?

In Europe usually you don't need to go through immigration to change planes (unless you are entering/exiting Schengen). Is it the case in the US as well? May I catch a connecting flight on one of the US airports if I don't have US visa?


Couldn't find solution to my problem so making a new thread. My controller can't work unless plugged in ps/pc It works perfectly fine on cable but as soon as I unplug it it just turns off. Also can't be turned on/no led light without being plugged. I tried resetting it Then check the battery with multimeter- holds normal amount of charge. No issues with the usb port, no issue with ps button or the conductive mat under all buttons Tried resetting connections with PS+share Tried different cables/ports Tried restarting the ps There is no obvious sign of damage on the motherboard. And I have no idea what could be the problem. Any ideas?

I was playing my PS4 two days ago and then packed it up with two controllers that were both connected to this PS4.   I got to where I was going, set everything up and now the controllers won't connect. They show pulsing orange when they plug in, but when I hit the PS Button to connect, it blinks white 1-2 times and goes back to orange.   I have tried resetting them both.  Can anyone help?


I have about 1700 rep on SO, meaning I can retag questions without review, but I cannot edit, yet.  I have problem with one specific question (and some other earlier, but I have not reported the problem then):   I click the Edit link, change the tags, click the Save Edits, but I get an error message for the main "question" input box, saying:     Edits must be at least 6 characters; is there something else to improve in this post?   and another for the Edit Summary, saying:     Your edit summary must be at least 10 characters   It would make sense, if I made a small edit inadvertedly in the post. But I did not. I've tried like dozen times. Both in full and mobile version of SO. No luck.  If I specify Edit Summary, I get rid of the latter error message. But I cannot get rid of the first.  I'm not getting the problem, when re-tagging with other questions.

Now that the retag feture has been merged with the edit feature tag edits also have to be over 6 characters? A question can legitimately have only one character in tags? Is this an intended side effect of the change? For  if I click the edit link, then remove  I get the error edits must be at least 6 charicters. My browser is Safari on iOS 6.0.


I read different articles including .   Why is bias term not included in regularization, in general? I see some of the algorithms such as LinearSVC includes bias term in regularization. Also, is bias term used for only predicting minimum value possible when all weights are zero? What is its significance exactly?

According to , weight decay (regularization) is not usually applied to the bias terms b why?  What is significance (intuition) behind it?