I have a valid B1 visa until 2020 and recently my Indian passport got damaged on the front and back, applied for a new passport.   My visa is in a very good condition and passport is also in good condition. Can you please tell me whether I can travel on the visa or should I apply for a new visa?


How to transfer thousands of dollars ($7000) to a friend?

If a friend wants to transfer $7000 to me, what is the best way to do it, especially if we don't share the same banks? We could do wire transfer, but that comes with its own fees. Could we also do direct deposit? Paypal doesn't allow such large lump sum transfers.  This would be US-to-US transfer.


Is Mana Weaving ok if it's followed by a thorough shuffle?

My friends and I are relatively new to MtG. At some point, one of them introduced us to the idea of mana weaving, and we'd do this to declump our decks prior to a very thorough shuffling. However, at the Theros pre-release, one of us was asked not to do this, and we learned it was frowned upon and ceased to do it.  I just now came across , and it sounds like mana weaving's only bad if you use it to leave your deck in an even distribution, and it's OK if your deck is then thoroughly shuffled. In hindsight, the judge may have simply thought my friend wouldn't have shuffled afterwards, but at the time I came under the impression it was frowned upon even if you did shuffle afterwards.  So: is mana weaving my deck OK, if I shuffle it very thoroughly afterwards?


How to see photos taken from iPhone 6+ in photo stream on my mac w/10.10.2

I have photo stream turned on, on my iPhone 6+, iPad 2 and my Mac with 10.10.2  I just took some photos with my iPhone, to share via an email.  I sat down at my Mac to type the email and attach the pictures within mac mail.  But they are not showing up in the photo stream when I click on 'Photos' under media.  I see things from yesterday, but none I've taken so far today show up.  Is there a way to 'refresh' photostram for iPhoto on my mac?  Michelle


France Schengen Visa; Want to Travel to Italy Next Month

I was recently issued a France Schengen Visa (multiple entries); however, I want to travel to Italy next month...will I need to apply for a Spanish Schengen Visa or can I use the France Visa to go to Italy?


What negatives can occur when installing mismatched memory?

Specifically, if I have a machine spec'd for 1.5V and I install 1.3V RAM modules, what side effects can occur?


Spam email addresses hiding in iPhone calendar sharing

I got some spam events in my Apple iCloud calendar events and have been able to delete them by deleting the calendars. However, when I make a new calendar, I am finding it's being shared with two Chinese fake emails. It only shows in the iPhone calendar app.    In the App, I click Calendars at the bottom to show them all - in the iCloud if I press the i button at the right side of the relevant calender, it says "shared with/add person" - when I click this it has my own iCloud email address and two Chinese spam email addresses. These two reappear with every iPhone iCloud calendar I make and I can't delete them. clicking on them just brings up a "new email" to that email address.  I cant find anything on Google about this, just how to block/remove events. How do I get rid of these spam email addresses sharing my iCloud iPhone calendars?  This is not about how to remove the events but finding that my calendar has been shared with two spam email addresses (probably appeared since the event hacking) that I now cannot remove.  I'd do a screen shot if I could share it.


I need to drive several indicator LEDs at <2mA.  Each LED has a nominal Vf between 3.2V and 3.3V (Vf max up to 4V).  In the past I've had the luxury of (a) current-limiting resistors or (b) constant-current power supplies.    But what do I do when my entire circuit has to run off a single 3.3V SMPS, and the microprocessor outputs are limited to 25mA? Here solution A isn't applicable, and the budget doesn't allow solution B (unless maybe all the LEDs can share a single current-limited supply--they don't all have to be on at the same time--and yet I still get to control the LEDs from a microprocessor directly, without external transistors.)  Background:     I have a microprocessor with a few PWM outputs, but not enough for every LEDs.  (yes, multiplexing is possible) This is an ultra-low-power, portable application. BOM cost has to be low, low, low.


The verb 'TRY': Transitive or Intransitive

Consider these sentences, please:  Try to complete the examination  He tried to climb a cliff.   Are the to-infinitives the objects of the verb try Or are they infinitives of purpose?


Is there any required amount of variance captured by PCA in order to do later analyses?

I have a dataset with 11 variables and PCA (orthogonal) was done to reduce the data. Deciding on the number of components to keep it was evident for me from my knowledge about the subject and the scree plot (see below) that two principal components (PCs) were enough to explain the data and the remaining components were only less informative.   Scree plot with parallel analysis:  observed eigenvalues (green) and simulated eigenvalues based on 100 simulations (red). Scree plot suggests 3 PCs, whereas parallel test suggests only the first two PCs.      As you can see only 48% of the variance could be captured by the first two PCs.    Plotting observations on the first plane made by the first 2 PCs revealed three different clusters using hierarchical agglomerative clustering (HAC) and K-means clustering. These  3 clusters turned out to be very relevant to the problem in question and were consistent with other findings as well. So except the fact that only 48% of variance was captured everything else was tremendously fine.      One of my two reviewers said: one cannot rely much on these findings as only 48% of variance could be explained and it is less than required.      Question Is there any required value of how much variance should be captured by PCA to be valid? Is it not dependent on the domain knowledge and methodology in use? Can anybody judge on the merit of the whole analysis just based on the mere value of the explained variance?    Notes     Data are 11 variables of genes measured by a very sensitive methodology in molecular biology called Real-Time Quantitative Polymerase Chain Reaction (RT-qPCR).   Analyses were done using R.   Answers from data analysts based on their personal experience working on real-life problems in the fields of microarray analysis, chemometrics, spectometric analyses or alike are much appreciated.   Please consider supporting you answer with references as much as possible.


How to delete rows that has multiple values and pick only 1 row

Please let me know if there's a query for this case: I want to delete multiple rows based on spesific column  id    | date       |   user    | item  |      material      | Text | Description | ------+------------+-----------+-------+--------------------+------+-------------+ 12345 | 31.03.2015 | Starbucks | 00010 | 000000001011000106 | abcd |  something  |  null  | 31.03.2015 | Starbucks | 00010 | 000000001011000106 | abcd |  something  |  54321 | 31.03.2015 |   Burger  | 00010 | 000000001011000106 | abcd |  something  | 11111 | 31.03.2015 |   Burger  | 00010 | 000000001011000106 | abcd |  something  |   Let say I want to delete multiple rows that contains user "Starbucks" more than 1, I want to delete the one that has id null. But if there's no id that contains null, like "Burger", I just want to delete one, and pick 1 whatever it is. So, it should be like this :  id    | date       |   user    | item  |      material      | Text | Description | ------+------------+-----------+-------+--------------------+------+-------------+ 12345 | 31.03.2015 | Starbucks | 00010 | 000000001011000106 | abcd |  something  |  54321 | 31.03.2015 |   Burger  | 00010 | 000000001011000106 | abcd |  something  |   Can I?


Comments saying "thank you" remind OP to accept answer

A lot of times I will answer a question, OP will post "Thanks very much!" And then leave, not accepting the answer that fixed their problem. I know I can just give them a gentle reminder (asking them to consider accepting), and on most occasions I do and they do end up accepting, but the site should be intuitive enough for them to do this by themselves. So when they post "Thank you" or "Thanks" the site could display a tool tip saying to "accept the answer if it helped best".    The message on the image could be changed to be less forceful I guess.


Everyone of us know about the . But I wonder, how the formula of $AB\sin\theta$ has been derived? Can anyone help?


I bought my laptop from at an action and it has a admin password and since I don't know who the original owner is I can't get the help I need from dell so can anyone tell me how to get past the administrative password and reset it


How to extract Object[] and get it into query using preparedstatement setObject()?

might be a silly question but I cant get the query running. This is my code:  ArrayList<Attraction> getAttraction(Object[] obj) throws SQLException {      Connection connection = facade.getConnection();      ArrayList<Attraction> attractions = new ArrayList<>();      // Check obj value     System.out.println(java.util.Arrays.toString(obj));      PreparedStatement ps = connection.prepareStatement("SELECT DISTINCT attra.attractid,attractname,x,y,z,age,weight,"             + "height,duration,price,status FROM attraction attra "             + "INNER JOIN attrib_bridge ab ON attra.attractId = ab.attractId "             + "INNER JOIN attribute attri ON ab.attributeId = attri.attributeid"             + "WHERE attri.attributename IN ?");      ps.setString(1, java.util.Arrays.toString(obj));      ResultSet rs = ps.executeQuery();       while(rs.next()){          // Initialize attraction object         Attraction attraction = new Attraction();          attraction.setAttractionId(rs.getInt(1));         attraction.setAttractionName(rs.getString(2));         attraction.setxLocation(rs.getInt(3));         attraction.setyLocation(rs.getInt(4));         attraction.setzLocation(rs.getInt(5));         attraction.setMinAge(rs.getInt(6));         attraction.setMaxWeight(rs.getInt(7));         attraction.setMinHeight(rs.getInt(8));          attraction.setRideDuration(rs.getInt(9));         attraction.setPriceRide(rs.getInt(10));         attraction.setStatus(rs.getString(11));          // Add new object to to movies         attractions.add(attraction);     }      return attractions; }   And this is the error I get :     [Gentle rides, Thrill rides, Transport rides]   com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: You have an error in >your SQL syntax; check the manual that corresponds to your MySQL server version >for the right syntax to use near 'attri.attributename IN '[Gentle rides, Thrill >rides, Transport rides]'' at line 1      at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)     at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source)     at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source)       at java.lang.reflect.Constructor.newInstance(Unknown Source)       at com.mysql.jdbc.Util.handleNewInstance(Util.java:411)       at com.mysql.jdbc.Util.getInstance(Util.java:386)       at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:1052)       at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3609)       at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3541)       at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:2002)       at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2163)       at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2624)       at com.mysql.jdbc.PreparedStatement.executeInternal(PreparedStatement.java:2127)       at com.mysql.jdbc.PreparedStatement.executeQuery(PreparedStatement.java:2293)       at com.ThemeParkG02.rs.control.manager.ManageAttraction.getAttraction(ManageAttraction.java:123)       at com.ThemeParkG02.rs.control.manager.Facade.getAttraction(Facade.java:85)       at com.ThemeParkG02.rs.control.listener.ViewAttractionListListener.run(ViewAttractionListListener.java:32)     I'm really dizzy right now. The values is out but I the query is not working. The '[' and ']' really blocking my goal. Any input guys?   Thanks in advance.


In the following sentence construct:     [...], together with [...], make [...]   Would "make" be considered singular (and thus take an s), or plural?


Find $\displaystyle \int_{0}^{\frac{\pi}{2}} \dfrac{\sin^n(x)}{\sin^n(x)+\cos^n(x)} dx$.   I was told to switch the limits of integration then add them. How can I do that here?


USA Tourist Visa Extension due to Covid-19 also Airlift for Indian nationals in the US details

Given the current covid-19 situation where the home country (India) has stopped all international flights, how can one (65+ year old) extend their B2 visa or stay after I-94 extension? Any help is appreciated.  I called up USCIS regarding the same and they told me it usually takes around 6 months to process these applications. My main concern is what if the application is rejected and the applicant has already overstayed their original VISA expiry date, will it be considered illegal? What happens if it is considered illegal?  The BringIndiaHome Initiative, is an initiative by Indian and American Indian lawyers to assist stranded Indian citizens to return to India. The petition seeks the relief of directing the Government to formulate a scheme to identify Indian Nationals in distress in the US and airlift them, specially in view of the WHO travel advisory which advised nation States not to impose disproportionate and excessive travel bans.If anyone interested please mail :  or fill up this form :   P.S. Please don't remove the Airlift details I have added here, last time someone edited my posting and removed those details.It's an important info, don't delete it.


What UML (Unified Modelling Language) tools are available?

I just can't find a decent (and free) one. What can I use?


Comparing CPU across different generations

So. My friend asked me to just improve performance of his computer, but I found a little issue. I found out that CPU is the bottlenecker, when I was about to order better CPU (3rd gen - the same gen as previous, but higher clock and i5), I found less powerful i5, but it was 8th gen. The difference is not as big, but I'm curious, how can I compare those?


Why does iid (independent and identically distributed) have same probability distribution. What does it implies.


Is there a way to grep for a regular expression on an Ubuntu server and then find and replace it with another string? I am using the following command right now, but it doesn't account for actually changing the grepped string:   grep --recursive --ignore-case “string”   If I use awk or sed how would I write it to replace for instance "wavbyte" with "gitship" for all instances where "wavbyte" occurs for my entire server?


I want to expand a function $\arctan(x)$ as a polynomial form. I know that I can use Taylor expansion in the case of x <1. But in my case, the x can be pretty large. Is there any way to expand or approximate arctan function?


Do We Need the Axiom of Choice for Finite Sets?

So I am relatively familiar with the Axiom of Choice and a few of its equivalent forms (Zorn's Lemma, Surjective implies right invertible, etc.) but I have never actually taken a set theory course.  I know there are times when an explicit way of choosing some elements may not be provided, and instead we call upon the Axiom of Choice to do it for us. But one thing has always bothered me.  I have heard that for a finite set we do not need the Axiom of Choice to choose an element. I find this a little confusing. How is choosing an element from a finite set any different than choosing from an infinite set? I have heard before "since the set it finite, there are finitely many orders, so order the set and choose the first element in the order." But how does one choose what order to use? This involves picking an element from a finite set, i.e. it presumes the conclusion.  I'm guessing there is a good reason why everyone keeps insisting that the Axiom of Choice in not needed to choose from finite sets, so could someone please explain it to me?  Edit: There seems to be confusion on what exactly I am asking. I know that we need the Axiom of Choice, sometimes, to make infinitely many choices, from finite or infinite sets. This is not what is confusing me. Allow me to be more precise:     Suppose $S$ is a nonempty finite set. I want to pick one element from $S$. Does choosing one element from $S$ require the Axiom of Choice? If not, how can the choice be made without the Axiom of Choice?   Saying $S$ is not empty, therefore there is an $x \in S$, does not suffice. How do I choose such an $x$? There is one, but how do I describe it without any information about the set, other than the fact that it nonempty and finite?  Another clarification: I am not asking about using "Let ... be given" as a proof technique.


How should get the expectation value of $1/r$ in the hydrogen atom?

I have a question of quantum mechanics. I want to calculate \begin{align}\left\langle \frac{1}{r} \right\rangle \end{align} in the state $n, l$ of the hydrogen atom. In the textbook I have, the wavefunction is given as \begin{align} \psi_{nlm} = \sqrt{\left(\frac{2Z}{na_0}\right)^3\frac{(n-l-1)!}{2n[(n+l)!]^3}} e^{-Zr/na_{0}}\left(\frac{Zr}{na_{0}}\right)^{l}L^{2l+1}_{n+l}\left(\frac{2Z}{na_{0}}r\right)Y^{m}_{l}(\theta, \phi)\end{align} Though I referred , the index of the associated Laguerre polynomial and the normalization coefficient are quite different hence I cannot get an idea how to simplify the result. How can I calculate the expectation of \begin{align}\left\langle \frac{1}{r}\right\rangle?\end{align}


Do we use another "the" if a proper noun already begins with one?

The lowest in-game rank of authority is that of the Baron – variations are Timariot, Shaman, Mayor, Bishop, Patrician – of which only Patrician is a playable rank if the player owns the The Republic DLC.  Is "the The" correct in the sentence, or should it just be "The"? DLC stands for downloadable content (in this case, a new place) in a game. It is the same idea as the following.   The New York Times is a good newspaper. We read the The New York Times.


Number of roots of differentiable function

I have two related problems that are causing me big trouble:  Let $\;a_1,...,a_n\in\Bbb R\;,\;\;a_i\neq 0\;\;\forall\;i\;$ , and let $\;b_1,...,b_n\in\Bbb R\;,\;\;b_i\neq b_j\;\;\forall\,i\neq j\;$ .  (1) Prove that the equation  $$a_1x^{b_1}+\ldots+a_nx^{b_n}=0$$  has at most $\;n-1\;$ different zeros in $\;(0,\infty)\;$ (Hint: Use induction)  (2) Prove that the equation  $$a_1e^{b_1x}+\ldots+a_ne^{b_nx}=0$$  has at most $\;n-1\;$ different zeros in $\;\Bbb R\;$ .  Now, the following is what I've done so far: for a differentiable function $\;f\;$ ,  I can prove that if $\;f'(x)=0\;$ has $\;n-1\;$ different zeros, then $\;f(x)\;$ has at most $\;n\;$ different zeros, using the mean value theorem, say.  But I can't see how to use induction in this case: if I differentiate in the first problem, I get $$0=f'(x)=a_1b_1x^{b_1-1}+\ldots +a_nb_nx^{b_n-1}=\frac1x\sum_{i=1}^na_ib_ix^{b_i}$$  ...and now?! How does induction kick in here? I though perhap something like: if we suppose WLOG $\;b_1<b_2<...<b_n\;$ , then perhaps inducting on $\;\lfloor b_n\rfloor\;$, but it gets messy and blurry if $\;b_n<0\;$...  Any help, hints are very much appreciated.


Calculating the sum of a binomial coefficient series

Calculate this:  $$\bigl(\begin{smallmatrix} 80 \\0 \end {smallmatrix}\bigr)-\bigl(\begin{smallmatrix} 80 \\1 \end {smallmatrix}\bigr)+\bigl(\begin{smallmatrix} 80 \\2 \end {smallmatrix}\bigr)-\bigl(\begin{smallmatrix} 80 \\3 \end {smallmatrix}\bigr)+...-\bigl(\begin{smallmatrix} 80 \\79 \end {smallmatrix}\bigr)+\bigl(\begin{smallmatrix} 80 \\80 \end {smallmatrix}\bigr)$$  Can I get hints/suggestions for this?  All I know is that: $\bigl(\begin{smallmatrix} 80 \\0 \end {smallmatrix}\bigr)$ and $\bigl(\begin{smallmatrix} 80 \\80 \end {smallmatrix}\bigr)$ must be equal to 1, right?  I know there must be some kind of trick but I just can't find it.  Thanks


The Runnable run() method executes synchronously while the Callable call() method executes asynchronously.?

Difference between submitting Runnable and Callable tasks for execution using ManangedExecutorServices?


Chi Square Tests throws varying p-value results

Suppose I have a random number generator and I want to check with a Chi Square Test whether its pdf is uniform or no. I can write a script that does that and I will run it several times. To my surprise, I get completely different results each times. Sometimes I will get a p-value of 0.3, sometimes 0.987 and other times 0.003. Which is the number I should take? Should I try to get an average of the p-values I get? How do I decide if this generator passes the test or not?  So what I try next is using a random number generator that I already "know" to be uniform and I run the test on that. And I keep getting absolutely varying results. Even if I increase the number of samples, it keeps varying a lot! From what I understad, the probability if seeing a very low p-value when drawing random samples from a uniform distribution should be low, and the probability of seeing a high p-value should be high. But this doesn't seem to happen.  How should I interpret the results I get from this test?  This is the Python script I am using:  import numpy as np from scipy.stats import chisquare  bins=256 x = np.random.randint(bins, size=bins*100)  h = []; for i in range(bins):   h.append(0);  for n in range(0, len(x)):   h[x[n]] += 1;  print(chisquare(h))   and this are the results I get:  Power_divergenceResult(statistic=303.19999999999999, pvalue=0.020572599306529871) Power_divergenceResult(statistic=211.06, pvalue=0.97933788750272888) Power_divergenceResult(statistic=289.66000000000003, pvalue=0.066874498546635575) Power_divergenceResult(statistic=275.63999999999999, pvalue=0.17885688588645363) Power_divergenceResult(statistic=257.86000000000001, pvalue=0.43814613213884313) Power_divergenceResult(statistic=217.07999999999998, pvalue=0.95911527563656596)   Even more, I did a histogram of the p-values I got and it looks pretty uniform. If I know the samples I have are drawn from a uniform distribution, shouldn't I get most of the times a high p-value?


Force Alt+Tab show only active desktop apps in gnome-shell

I'm using Gnome Shell.  Alt+Tab shows all opened application windows from all virtual desktops. It becomes impossible to use when many windows are opened. Is it possible to show only these apps which are on active desktop?


An inequality involving 4 real or complex numbers

Let a,b,c,d be real or complex numbers with absolute value less than $1$. Is the following true:  $$|ab-cd| \leq |a-c| +|b-d|?$$


I just found a good question via Google. There is  answer which links to a self-made project by the user. It has awarded a bounty worth 50 rep by the Community ♦ user.  But how can this user award bounties? How is this possible that, or when does, this bot award bounties?


make copy of file and place in new directory using relative path

i have been stuck on this question for my lab for linux class


Feature Selection Packages in R, which do both regression and classification

I am very new to R. I am learning machine learning right now. Very sorry, if this question appears to be very basic.  I am trying to find a good feature selection package in R.  I went through Boruta package. It is a good package but I read that it is only useful for classification.  I want to do implement feature selection in R for regression tasks. I went through the caret package documentation but for my level, it is very difficult to understand.  Can any one please point me to a good tutorial or list any good packages or most frequently used packages in R for feature selection.  Any help would be appreciated. Thanks in advance.


I'm completing the Stanford's "Introduction to Logic" course, and I'm having issues with the following exercise:  "Consider a language with object constants a and b, binary function constant c, and unary relation constants m and p and q. The definitions for the relations are shown below. Relation m is true of a and only a. Relation p is true of a structured object if and only if it is a linear list (as defined in Chapter 7) with a top-level element that satisfies m. Relation q is true of a structured object if and only if there is an element anywhere in the structure that satisfies m.  Your job is to show that any object that satisfies p also satisfies q. Starting with the axioms, use Fitch with Structural Induction to prove ∀x.(p(x) ⇒ q(x)). Beware: The proof requires more than 50 steps (including the premises)."  I think I'm getting there, but I've been stuck in step 24 for days now.    How can I go on? Thanks


C++ / How can someone that asks questions like this have 3500+ reputation?

Also see:   Response:      Is this really an exact duplicate, and so deserving to be closed?  It may lead to an ultimately similar discourse, but Rich B's request for a specific and precise remedy of the reputation scoring system isn't the same as my question.       My question is abstract and somewhat subjective, what is reputation in regards question-asking, what will happen to SO if it incentivises noise? I think I've developed the question sufficiently for it to be different to the linked question.      Is that not the true meaning of meta?  In the generic, what is the nature of reputation?        Is the question "Shall we go for lunch?" an exact duplicate of "Why do I feel hungry at lunchtime?"  It would depend what you assume is in the mind of the asker of the 2nd question (you might assume they are saying hinting to go to lunch), but that is highly subjective.   I'm not complaining about the user asking the questions - but the points system seems to reward some participants to ask low quality questions.  Is an answer not its own reward?  This is an example user that I've seen asking a spate of C++ questions over the last few days.  Some of the questions have since been re-edited, with the most egregious errors removed.  But I can't understand given that C++ is what he mentions on his profile that he can possibly have gotten to 3500 on the back of his lack of knowledge on the subject.    What can you say?      pair<const char*, const char*> as a map key?   To ask whether assigning to a std::string alter its memory address such that a reference that is taken to it will alter?  the map value type parameter is a reference type?     How on earth can someone get to 3500 on the back of such nonunderstanding of the programming language?  I really don't see the point in bothering on this website when the competition is volume over quality.   Surely an answer is its own reward.  Basically anyone with a large collection of points has no claim to particular merit, if a situation persists where the non-experts can rack up the points through the tedium of asking questions.  I know this user didn't get all his points asking C++ questions.  But he has got, say about half of them.  Can you get a silver badge in C++ for just asking questions like:   "When should I use a ThreadLocal variable?  How is it used?"  (+11 votes)  "Should C++ eliminate header files?"  (+14 votes)   "When should I use private inheritance?"  (+8 votes)   How is that 330 points of contribution?  Part of the motivation to participate in answering to some degree is that it's a game and people like to score points.  That seems to be undermined when you have people equally rewarded for asking dozens of very average questions.    There's nothing wrong with not knowing and asking.  There something wrong when people rack up points for asking questions which are pre-university level.  It is a rewarded behaviour, at the cost of question answerers.   The balance of any rewards system should be to encourage the knowledgeable to participate.  There is natural motivation for people to ask questions and need answers.  The website will otherwise run the risk of being deluged by the ill-informed with no real knowledge that are perversely incentivised to spam away.    I see evidence this is already in play.


PHP Override function inside class from outside

Is there a way to override a function inside a class without touching the class coding?  We have the class, let's say it's located in foo.php:  class WPSEO_Frontend {       public function head() {             echo '<!-- / ', $this->head_product_name(), ". -->\n\n";             return;       } }   So without modifying this class above, is there a way to remove this echo from the outside of the class, like (I know the below example isn't going to work):  bar.php  class WPSEO_Frontend overrides head {       echo '';       return; }


Relation between Variance of one variable and variance of two independent variable

Is the following statement correct?   If $X$ and $Y$ are independent then $\operatorname{Var}(X)\lt \operatorname{Var}(XY)$ and $\operatorname{Var}(Y)\lt \operatorname{Var}(XY).$


We are planning a trip with a bike rack attached to our trailer hitch. What is the best way to lock the bikes while the vehicle is unattended? I see some racks have locks on the knobs but they don't seem very strong.   What do you suggest?


If $id:(X,d_1)\to (X,d_2)$ is continuous then what will be $X$?

Let, $id:(X,d_1)\to (X,d_2)$ is continuous. Then which is(/are) TRUE ?  (A) $X$ must be singleton.  (B) $X$ can be any finite set.  (C) $X$ can NOT be infinite  (D) $X$ may be infinite but NOT uncountable.  My Thought :  If $X$ is singleton then the function is continuous trivially but the condition is not necessary. So (A) is FALSE. If $X$ is finite then $d_1$ and $d_2$ are equivalent and so the function is continuous. So, (B) is TRUE. If $X=\mathbb R$ and $d_1$ is discrete metric and $d_2$ is any metric then then the function is continuous. So (C) and (D) are FALSE.  Am I right or wrong ? If I am wrong then where my fallacy ?


Apache2 mod_rewrite redirect all except one folder

I need to redirect the requests for my old website (www.old.com) to the new domain (www.new.com) but I would like to keep the old content available in a different folder (www.old.com/oldsite). I've got the rule to redirect all requests but the folder exception doesn't seem to be working:  RewriteCond  %{HTTP_HOST} www.old.com RewriteRule ^/old_website/(.*) $1 RewriteRule (.*) http://www.new.com/new_site_is_here.php   Thanks!


Upgraded to macOS Catalina and now cannot install latest version of SQLDeveloper.app

I am getting the error: “SQLDeveloper.app” can’t be opened because Apple cannot check it for malicious software.


How to change initial login screen background?

I want to set the background of my initial login screen to black. The problem is, everytime I turn on my laptop and login, it sets it to this blurry image of a beach.     So I tried setting my ubuntu.css file to use only black and its still using the beach background.    How do I change the initial login screen background to black?  UBUNTU 18 LTS


I'm trying to create a buffer around a feature in a polygon in QGIS. Trying to do 100m buffer, but when I run it, I just get a huge circle around what my shapefile was showing originally.  I have tried changing CRSs on the layer, and the project a million times. I always try to find one that uses meters (+vunits=m right?). I've saved the layer and opened it fresh to make sure the project  had the same CRS and it keeps doing the same thing. Is there something obvious I'm doing wrong?


Do I need a Transit Visa for a layover in Shengen zone, I am a Cameroonian and Permanent resident of Canada

As a Cameroonian and permanent resident of Canada,  do I need a transit Visa for a layover in the Schengen zone?


How would I prove the following problem on modular arithmetic?

Let $a > 2$ and $n ≥ 1$ be any integers. Prove that $a − 1 ∣ a^n − 1$.  Is this a problem involving induction or on using mods? I  thought it was induction but would I need to have two base cases, ($a=3$ and $n=1$). If I do, how would I proceed with more than one base case? Or is it not related to induction at all and there is some other way?  Any help would be highly appreciated!


To use Windows and Ubuntu on one computer, which should I install first?

I understand it's possible to  or to , but assuming I have the freedom to do either, which is the better, easier, and more reliable installation order?


Understanding scipy Kolmogorov-Smirnov test

I'm trying to understand the Kolmogorov-Smirnov test using a very simple example. I generate a set of random, uniform values between 0 and 1.0. I then test that these values are from a uniform distribution by using the . I'm expecing a very small D value and a pvalue close to 1.0, but instead I get wildly varying pvalues every time I run the code. What am I missing?  import numpy as np import scipy a = np.random.uniform(size=4999) print(scipy.stats.kstest(a, 'uniform'))   Here are the outputs of a few consecutive runs:  (0.0075523161200627964, 0.93798952050647577) (0.013787195268362473, 0.29799260741344774) (0.014359046616557847, 0.25402403230845855) (0.012521820948675988, 0.41329007558099806) (0.011159003477582918, 0.56216895575676396)


Brand New to Linux - Where should I start?

I'm brand new to Linux. I just installed Ubuntu as a dual boot system on my HP Pavilion laptop.  Where should I start? I've tried to play around with Terminal over the last hour or so, but I'm probably not helping myself out. Any suggestions are welcome!


Quantum Mechanic: Sperically symmetric finite well

Consider the following 3D potential: $$V(r)=\begin{cases}-V_0 \ \ \ \ \ \ & r \leq a\\ 0 &r > a\end{cases}$$ we want to find the eigenfunctions for $\ell=0$, in particular we are interested in the bounded states. Of course we get: $$\left[\frac{p_r}{2m}+V(r)\right]R(r)=ER(r)$$ and so with: $$u(r):=rR(r)$$ $$-\frac{\hbar ^2}{2m}u(r)+V(r)u(r)=Eu(r)$$ so for bounded states we get: $$u(x)=\begin{cases}A\sin{\alpha r}+B\cos{\alpha r} \ \ \ \ \ \ & r \leq a\\Ce^{-\beta r} & r > a\end{cases}$$ I kind of breeze trough this introductory part, I hope it's all clear. Now I have a problem: I would like to impose continuity and continuity of the derivative in $a$, to get more information about the shape and the energy of the solution, in particular I would like to find the number of bounded state in function of the value of $V_0$; but the calculation that derives from this procedure seems pretty hard. But: looking for the resolution for this exercise I found out that $u(r)$ must be $0$ in $r=0$, and this of course implies that in the first region the function becomes a $\sin$. $$u(x)=\begin{cases}A'\sin{\alpha r} \ \ \ \ \ \ & r \leq a\\Ce^{-\beta r} & r > a\end{cases}$$ and this, other than being the correct system of equations, greatly simplify the calculations. However: I don't understand why $u(r)$ must be zero in $r=0$. So my question is: Why must $u(r)$ be zero in $r=0$?


Proof of $\gcd(a,b)=ax+by\ $ [Bezout's identity]

Here is my proof of $\gcd(a,b)=ax+by$ for $a, b, x, y \in \mathbb{Z}$. Am I doing something wrong? Are there easier proofs?  $a,b \in \mathbb{Z}, g=\gcd(a,b)$ and suppose $g \neq ax + by$. Let $c$ be a common divisor of $a$ and $b$. Then   $$\forall x', y' \in \mathbb{Z}: c | ax' + by'\Longrightarrow\exists q_1, q_2 \in \mathbb{Z}\,\,\, s.t.\,\,\, c q_1 = ax' + by'\,\,,\,\,cq_2 = g$$   So   $$gcd(a, b)=g=c q_2 = c q_1 \frac{q_2}{q_1} = \left(\frac{q_2}{q_1}x'\right)a + \left(\frac{q_2}{q_1}y'\right)b$$ So if we have $q_1|q_2$ then we found $\gcd(a,b)=ax'+by'$ for all $x', y' \in \mathbb{Z}$.  Now   $$\frac{q_1}{q_2}=\frac{c q_1}{c q_2} = \frac{ax'+by'}{g}$$ but $g|a$ and $g|b$ so $\exists q_3 \in \mathbb{Z}: \frac{q_1}{q_2}=q_3 \Rightarrow q_1=q_2 q_3 \Rightarrow q_1 | q_2\,$ . QED.


Getting the default text editor used in system

I have used select-editor and I note that I am using /usr/bin/nano. Is this the default text editor I am using?  When I open text files, It opens with gedit  What command in terminal must be specified to get the default text editor that I am using, and have it returned to e in terminal?


Infinite partition of $\mathbb N$ by infinite subsets

I am looking for an explicit partition of $\mathbb N$ with the following condition: $$\mathbb N=\bigsqcup_{i\in\mathbb N}A_i$$ where all the $A_i$'s are infinite. What I mean by explicit is a formula for each $A_i$ (I will have to do computation with the elements of $A_i$). So, I can not use the choice axiom.  If someone has an idea to build such a partition...


Understanding tuple output from groups() method after re.match()

I am working with regular expressions and am struggling to understand a particular output.  Case 1:  >>> m = re.match("(abc)+", "abc") >>> m.groups() ('abc',)   Case 2:  >>> m = re.match("([abc])+", "abc") >>> m.groups() ('c',)   In Case 1 above, I do understand how m.groups() returns ('abc',) (a tuple with the matched string for group 1, the only group in the RE).  However, in Case 2 above, where I put 'abc' in the RE inside a character class as [abc], I do not understand why does m.groups() return ('c',). I would have still expected the same tuple returned as Case 1, i.e. ('abc',)  Could anyone please help me understand why does m.groups() return ('c',) in Case 2.


List of equations, including equation contents and caption

I would like to automatically generate a list of equations present in the document, which includes the equation itself. Here is a MWE:   \documentclass{article} \def\caption#1{} \begin{document} First Euler observed that \begin{equation} 1 + e^{i \Pi} = 0. \caption{Euler's equation tying together the five fundamental constants of mathematics} \end{equation}  Then, Gauss discovered the normal distribution: \begin{equation} P(x) = \frac{1}{{\sigma \sqrt {2\pi } }}e^{{{ - \left( {x - \mu } \right)^2 } \mathord{\left/ {\vphantom {{ - \left( {x - \mu } \right)^2 } {2\sigma ^2 }}} \right. \kern-\nulldelimiterspace} {2\sigma ^2 }}} \caption{Normal distribution} \end{equation}  Finally, Einstein proclaimed:  \begin{equation} E = m C^2 \caption{Equivalence of mass and energy} \end{equation}  \end{document}   Here is an example of how the output might look, but any other format may be fine; it would of course be nice to have hyperref links, page numbers, etc, but these are not essential.    \section*{List of equations} \begin{enumerate}   \item Euler's equation tying together the five fundamental constants of mathematics         \[           1 + e^{i \Pi} = 0.         \]   \item Normal distribution:         \[           P(x) = \frac{1}{{\sigma \sqrt {2\pi } }}e^{{{ - \left( {x - \mu } \right)^2 } \mathord{\left/ {\vphantom {{ - \left( {x - \mu } \right)^2 } {2\sigma ^2 }}} \right. \kern-\nulldelimiterspace} {2\sigma ^2 }}}         \]   \item Equivalence of mass and energy         \[           E = m C^2         \] \end{enumerate}


Why the direct product does not form a ring?

Prove the direct product of rings never form a ring.  And be the direct product $A\times B$: $+$: $(x,y) + (z,t) = (x+z,y+t)$ $*$: $(x,y) * (z,t) = (x*z, y*t)$ $x,z\in A$. If we define $A$ and $B$ both commutative rings, with units and inverses itself (So $A$ and $B$ are fields). Now, $A\times B$ is commutative, it is a ring, there is a unity element. And since $A$ and $B$ have inverses, the inverse of each element in $A\times B$ $(x,y)$ is just $(x^{-1},y^{-1})$, being $x^{-1}$ the inverse of $x$ in $A$, and so to $y$ in $B$. So $$(x,y) * (x^{-1},y^{-1}) = (e_{a},e_{b})$$ Defining the unity of $A\times B$ as $(e_{a},e_{b})$ I can't see the error in my writings.


VirtualBox '/etc/init.d/vboxdrv setup' issue

I have installed VirtualBox through the software centre, but when I try to start a VM, I get the following error:     Kernel driver not installed (rc=-1908)      The VirtualBox Linux kernel driver (vboxdrv) is either not loaded or   there is a permission problem with /dev/vboxdrv. Please reinstall the   kernel module by executing      '/etc/init.d/vboxdrv setup'      as root. If it is available in your distribution, you should install   the DKMS package first. This package keeps track of Linux kernel   changes and recompiles the vboxdrv kernel module if necessary.   I already updated my dkms and installed linux-headers, but this /etc/init.d/vboxdrv doesn't exist.  I have been googling but I can't find an answer.


Show that $n$ does not divide $2^n - 1$ where $n$ is an integer greater than $1$?  Clearly $2^n - 1$ is an odd integer, therefore, let $n$ be an odd integer and it divides $2^n - 1$. We can write $2^n - 1 = (2-1)(2^{n-1} + \cdots \cdots + 1) = (2^{n-1} + \cdots \cdots + 1)$ From here on I don't know how to proceed?


Why is the image of a homomorphism a subgroup of the codomain?

Why is an image of a homomorphism a subgroup of the codomain? I know that the image of any function is a subset of the domain, but I don't know how to proceed with the former statement.


Difference between and usage of "Them" and "These/those"

What is the difference between them and these/those? What is the usage of them and these/those?   Example sentence -        Some of these are insured by govt...      But I think "Some of them" is more common. But again there is nothing wrong with the quoted sentence.


Why do elementary matrix operations not affect the row space of a given matrix?

I have shown that two of the three elementary operations will not change the image of the row space of the matrix: given a row vector $\vec{v}$, $k\vec{v}$ will span the same (scalar multiplication), and switching the order of the rows won't change anything because the span of the row vectors will be the same (vectors will be in a different order). However, how would one show that adding/subtracting vectors does not change the row space?


Today I heard a sentence:     Do you want more potatoes peeled.   But I have always used it as:     Do you want having more potatoes peeled.   Which one is grammartical? Please explain with examples.  Thanks in advance.


Algorithm for randomly generating reachable platforms

I want to randomly generate reachable platforms on the fly for a 2D game.  Right now, I am just creating platforms at random x,y positions.  Only 4 platforms can exist at once, so once the 5th one is generated the 1st one is removed (fifo).  So, I want to ensure that the player can jump from his current platform to at least one other at any given time.  I was thinking of using some variant of the distance formula to calculate the location of the next platform being generated.  I was hoping someone could help me out with the formula for calculating the next platforms possible x,y positions.  The player variables I am assuming will be important are speedX, speedY, and gravity.  From here, I should be able to calculate the maximum distance to plug into the distance formula.    However, I am thinking that some variation of the distance formula that contains a variable for slope would be better in my case.  I want to ensure that the player will never get stuck on a platform with no where it can jump.  Also, I want to ensure that platforms aren't generated on top of each other.  Formulas/images/code are a huge plus.  Here is how jumping is currently working.  Field speedY:Float = 4 Field GRAVITY:Float = .05  Method Update:Void()     If KeyDown(KEY_SPACE) And not jumping Then         dy=-speedY         jumping = true     EndIf       If jumping         dy += GRAVITY         local tempY:Float = y + dy         y = tempy     Endif End Method   Edit: I now understand that the formula is just the displacement of basic projectile motion.     Except, in my case, we don't care about cos/sin because the angle will always be the same.


Where can I get replacement parts for Canon cameras?

My son accidentally cracked a glass on the back of the camera. It is not an LCD itself, but rather a protective cover over the LCD. I took the camera to photo store and they said they can order the part and fix it but for nearly $130, most of which is labor. Where can I order the part? I'm pretty certain I can handle the replacement myself?


I know I can use the macros \TeX and \LaTeX for typesetting the names of TeX and LaTeX (including the necessary vertical alignment trick).  But how am I supposed to typeset "TikZ"? (I am asking because I'd like to mention TikZ in the Colophon of a book).


search a particular string and remove all the remaining after that string

This is the file.  scr  PI Name: RRC Access Failures due to UU, Value: 0.13394141 prog PI Name: RRC Access Failures due to UU, Value: 0.16077702 sch PI Name: RRC Access Failures due to UU, Value: 0.11781933   I want to search Failures and remove the remaining strings in that line.  My output should be,  scr  PI Name: RRC Access Failures prog PI Name: RRC Access Failures sch PI Name: RRC Access Failures   I tried sed command, but it is deleting entire line.  Any suggestions?


How can I change Excel 2007 shortcuts from foreign to English?

I have a copy of Excel 2007 that happens to be in Brazilian Portuguese. For me it's great since I'm in Brazil but there is a catch.  All the English shortcuts I'm used to, like Ctrl+S for saving, Ctrl-B for bold etc. are also translated.  When I press Ctrl-S it thinks I want to underline the text.  How do I change the shortcuts to the English default?


I have on a few occasions in the past, downvoted a question and then after re-evaluation thought that it shouldn’t have been.  When trying to cancel the downvote or changing it to an upvote, I find that I cannot do that unless an edit is made.  Why is that?


Confused about the definition of a group as a groupoid with one object.

A groupoid is defined to be a category where every morphism is an isomorphism. So sometimes a group is said to just be a groupoid with one object.   When I try to make sense of this, I denote the single object as $G$. I view the morphisms as the analogue of "elements." The identity $1_G$ is the analogue of the usual identity $e$, we can compose any two morphisms since they are all arrows on $G$, and for any arrow $f$, we have some $f^{-1}$ such that $f\circ f^{-1}=f^{-1}\circ f=1_G$, so the idea of inverses is still there.  So I informally associate the elements of the group in the usual definition to be the arrows in the groupoid. But what does the sole object $G$ in the groupoid "correspond to" if I were to try to informally make sense of a group in the usual sense? Does it even correspond to anything?


How can I check dependency list for a deb package. I am running Ubuntu 11.10 and I have backed up all deb packages from var/cache/apt/archives. I want to format my pc and re-install selected applications only. Also how can I get the list of installed packages and dependencies.


Linux: How to find the device driver used for a device?

If my target has one device connected and many drivers for that device loaded, how can I understand what device is using which driver?


I'm asked to state whether or not $(X, d_u)$ and $(X, d_L)$ are complete where $d_u$ is the uniform metric and $d_L$ is the $L^1$ metric. All I need is to give the name of a supporting theorem or counterexample. $X$ is taken to be the space of continuous real-valued functions over the interval $[0, 1]$.   My thoughts are   if I can show compactness then this holds (using perhaps heine-borel) arzela-ascoli directly completeness directly   But since all I'm required is a theorem name - I'm supposing that it should be obvious. So how would one go about showing completeness or lack of for these metric spaces?


Should I file Form 1040 or Form 1040 NR?

I am currently on H1 B (since October 1, 2017). Last year when on F1 OPT, I had filed Form 1040 NR for my taxes. Which form is advisable for 2017, considering I am on H1 B now. What options do I have?


Tesla Inc. (TSLA) recently announced a 5-for-1 stock split. The split takes effect on August 31 for each shareholder of record on August 21. So, what happens to people that buy shares of Tesla after the 21st? Do they not get the 5-for-1 split? I am interested in learning about this process but have not come across what happens to shareholders after the date of record for the split.


"-ic versus -ical" what's the difference in meaning between adjectives ending in -ic or -ical?

Possible Duplicate:                   What's the difference for instance between ironic/ironical, rhythmic/rhythmical, historic/historical, comic/comical, economic/economical? If these adjectives are identical in meaning why the need for the different endings?


Various errors when adding new row or horizontal line to table

I'm trying to replicate the table from Annex A of the ISO/IEC 27001 standard:    Here is my MWE:  \usepackage{array,longtable} \begin{longtable}{| l | >{\raggedright}p{0.2\textwidth} | >{\raggedright}p{0.7\textwidth} |}     \hline     \multicolumn{3}{|>{\raggedright}p{\textwidth}|}{\textbf{Text text text}} \\                \hline     Lorem & ipsum & text \\ \end{longtable}   However, adding almost anything between the 'Lorem ipsum' row and the \end{longtable} causes compilation to fail, but in different ways.  Adding another row of cells containing text causes the following:  ! Extra alignment tab has been changed to \cr. <recently read> \endtemplate   l.195                       Lorem2 &                         ipsum2 & text2 \\   Adding \hline causes the following:  ! Misplaced \noalign. \hline ->\noalign                    {\ifnum 0=`}\fi \hrule \@height \arrayrulewidth \futurelet... l.195                       \hline   And adding \cline{1-3} causes the following:  ! Misplaced \omit. \@cline #1-#2\@nil ->\omit                             \@multicnt #1\advance \@multispan \m@ne \ifnum \@... l.195                       \cline{1-3}   This happens whether I use the longtable or tabular environment.  The only thing that I can add that won't break it is a single text cell, e.g.:      Lorem & ipsum & text \\     adsfdsfdsf \end{longtable}   I am at a complete loss as to what is wrong here. Every other question I can find with the same error is using different packages or nesting things in a way I am not.  The fact that compilation fails no matter what I add makes me think the actual error messages are red herrings, but I have no idea how to debug whatever the underlying issue may be without that information.


Filling in the date gaps mysql query for ajax call

What is the best way to include empty dates for a time series graph generated from a mysql db.  If I run a query to get say all of the red cars sold on a particular day I could run :  SELECT count(car_sale_order) as 'count', DATE(sale_date) as 'sale_date' FROM car_sales WHERE colour = "red";   but the results could have date holes in them i.e.   ------------------ count | sale_date ------------------ 2     | 2017-09-03 10    | 2017-09-04 1     | 2017-09-07 23    | 2017-09-09 45    | 2017-09-10 2     | 2017-09-11 21    | 2017-09-12   when what id really like is :  ------------------ count | sale_date  ------------------ 2     | 2017-09-03 10    | 2017-09-04 0     | 2017-09-05 0     | 2017-09-06 1     | 2017-09-07 0     | 2017-09-08 23    | 2017-09-09 45    | 2017-09-10 2     | 2017-09-11 21    | 2017-09-12   I use PHP so know that i could generate this stuff at that side but it would be really handy to just have the result set include this from the get go....    This isn't the same as   I'm looking for a MySQL only result


I have a folder called CSV, in it there are several CSV files with coordinates and attributes.   I want to convert all files in a CSV folder into shapefiles New created shapefiles should have original CSV file name All newly created shapefiles should be placed in another folder called SHP. Once all shapefiles created, merge all shapefiles into one (could go over a GB)   For this, I tried to play around with ogr2ogr, had a bit of success but could’t go further.  For example, one web page shows to create (1) Create a dbf file (2) Create a vrt file (3) Create the shapefile by using ogr2ogr.  I can recreate what it says but I can’t workout how to point a folder i.e. CSV and convert all files in that into shapefiles.  Once I could accomplish above then, I would like a simple ogr2oge like command to merge all shapefiles into one shapefile.  Another point: Is there any way to use just text.bat file for above processes instead of OSGeo4W shell?


Is there a 'at the bottom here!' float specifier?

For specification of the placement of a float (like a figure or table), one can use 'h' meaning 'here', 't' for 'somewhere at the top of a page' and 'b' for 'somewhere at the bottom of a page'. Is there a way to force a float to be placed 'here, but at the bottom of this page'? A sort of h!b combination.


Add brackets([ ..,.. ]) before and after braces in C#

How can I add open bracket([) before first open paranthesis({) and close bracket(]) last close paranthesis(}) in the below string : res.data = "{\"id\":\"97\",\"studentName\":\"#28 McCarran Center, LC\",\"email\":\"\",\"inactive\":false},{\"id\":\"98\",\"studentName\":\"+Pura\",\"email\":\"dc@maspura-gt.com\",\"inactive\":false}"  I needs to make it as : res.data = "[{\"id\":\"97\",\"studentName\":\"#28 McCarran Center, LC\",\"email\":\"\",\"inactive\":false},{\"id\":\"98\",\"studentName\":\"+Pura\",\"email\":\"dc@maspura-gt.com\",\"inactive\":false}]"  res.data =  res.Content.Insert(1, "[");  This made me to add "[" for the first. But how can I add to the last closed parenthesis one ?


How do I make buttons function on the cursors click in roblox studio?

I would just like to know how to add buttons in roblox studio because when I play roblox and see all those great games with buttons that I can click! How do I make a button, and how do I make it work?


Proving a statement about the determinant of tridiagonal matrix

The statement of the question is given below:        In order to understand the meaning of tridiagonal, I tried to calculate the $4 \times 4$ matrix of the above description and I get the following matrix:  $$ \begin{vmatrix} 1&1&0&0\\ 1&1&1&0\\ 0&1&1&1\\ 0&0&1&1 \end{vmatrix} $$   Also, I tried to calculate the $3 \times 3$ matrix of the above description and I get the following matrix:  $$ \begin{vmatrix} 1&1&0\\ 1&1&1\\ 0&1&1\\ \end{vmatrix} $$  So I can see why it is called tridiagonal matrix. And I know that the definition of the determinant of a matrix is as follows:            But I still did not know how to prove the question, shall I prove it by induction on $k$? if so, how I can deal with proving the case of $k = n+1$? could anyone help me please?   **My idea:*  I think I can change the given matrix to an upper triangular matrix ? can this work?


Throughout the books we are told that      there is no safer place than Gringotts... Except hogwarts.   But is it really safe?  I mean, the trio managed to get to the Lestrange vault by using just the Imperius curse.  Look at how easy it was. Clearly any wizard who knows how to cast Imperius might force a goblin to open any vault.  Has this been clarified or explained by J.K.R or mentioned in any of the books?


1960s Moon short story, man activated a time machine and a disruptor weapon which eventually shrinks the moon

I can only remember part of this short story, which I believe is from the '60s.  A lunar base has been set up to study an installation abandoned by technologically advanced aliens eons before. I can't remember how, but the main character - who was some kind of screw-up - activates two pieces of alien technology which he cannot control. The first is a time machine that keeps shifting him from the far future to the far past - the other is a small rod, a disruptor weapon.  He drops the disruptor, which burns all the way down to the lunar core, and when he is shifted into the distant future he finds himself drifting in space because the disruptor has been working all that time and the moon is about the size of a football.  Then he is shifted back to the time of the aliens - one of them sees him and picks him up. The end.


Did the Marauder's Map show other animals besides Mrs. Norris the cat?

According to , Harry sees  on  in chapter 10 of Prisoner of Azkaban. She's a normal cat, not an animagus, as far as we know.  Why does the map show her if she is just an animal?  Does the map show other animals? (e.g. - Crookshanks, owls, Fluffy, Buckbeak, Nagini, Thestrals, etc...)  Please provide answers based on canon sources. I prefer canon sources over speculative answers. (And if somebody has a copy of the book, please confirm this citation from chapter 10. I don't have a copy with me.)


What flash slaves can be used with a Canon Speedlite 600EX-RT?

My current flash setup is a standard shoe mount but I've been thinking about getting a remote.  I've been drooling over the Speedlite 600EX-RT. It uses radio to control slaves, which is nice (longer distance, doesn't require line of sight, etc.).  One thing I don't understand: do slaves also have to be 600EX-RTs or do other flash units use radio to communicate already? Can any (cheap?) flash slaves can be used with a Canon Speedlite 600EX-RT or do I need to buy the 600EX and a ST-E3-RT transmitter in order (or multiple 600EX-RTs) to have a radio-controlled remote flash setup?


For quite some time, I've been trying to prove Raabe's Formula, or in other words:     $$\int_a^{a+1} \ln\bigg(\Gamma(t)\bigg)dt=\dfrac{1}{2}\ln(2\pi)+a\ln(a)-a$$   This is how I tried: $$I(s)=\int_a^{a+1}\ln\bigg(s\Gamma(t)\bigg)dt$$Differentiating with respect to $s,$ $$I'(s)=\int_a^{a+1}\dfrac{\Gamma(t)}{s\Gamma(t)}dt=\int_a^{a+1} \dfrac{dt}{s}$$ However, at this point I stopped thinking I must have made a mistake because I was told that proving Raabe's Formula was really difficult, and this seemed too simple a method to prove Raabe's Formula. $$$$ I would be grateful if somebody would be so kind as to tell me how to prove this result, as well as what went wrong with my method. Many, many thanks in advance!


How do I make a command that triggers when I step on a block?

I have been looking this up and watching videos on it for a week now. Nothing has helped! Please, does anyone know how I can do it?


Short story about a scientist trying to prove faster-than-light travel with a billiard ball

A short story about a scientist trying to prove faster than light travel. He uses a billiard ball for the demonstration. It works but the billiard ball passes through a rival scientist, killing said rival.


we were trying to find the username of a mercurial url:  default = ssh://someone@acme.com//srv/hg/repo   Suppose that there's always a username, I came up with:  tmp=${a#*//} user=${tmp%%@*}   Is there a way to do this in one line?


Why did Dumbledore's wand connect with Voldemort's?

At the Battle at the Ministry of Magic, Dumbledore and Voldemort's wands connect (Priori Incantatem) but as far as I'm aware, the Priori Incantatem only happens when two wands share the same core  Voldemort's wand has phoenix core and Dumbledore (the Elder wand) has a Thestral core.  Can someone explain to me why the wands connected?


questions about extremal epimorphisms in category theory

let $K$ be a category with equalizers, show that every extremal epimorphism is epic. for composable morphisms $f: A \rightarrow B $ and $g: B \rightarrow C$ in $K$, show that if $gf$ is an extremal epimorphism, then $g$ is an extremal epimorphism. let $K$ be a category with pullbacks.  For composable morphisms $f$ and $g$ as given in #2, show that if $g$ and $f$ are extremal epimorphisms, then $gf$ is an extremal epimorphism. show that if an extremal epimorphism is monic, then it is an isomorphism.   here is what I know:  In any category $K$, an arrow $f: A \rightarrow B$     is called an isomorphism if there is an arrow $g: B \rightarrow A$ in $K$ such that $ g \circ f = I_{A} $ and $ f \circ g = I_{B}$ is called a monomorphism, if given any $g,h : C \rightarrow A, fg=fh$ implies $g=h$ is called an epimorphism, if given any $i,j: B \rightarrow D, if = jf$ implies $i=j$ is an extremal epimorphism, if for each commutative diagram, $f = mh$ where if $m$ is monic, then $m$ is an isomorphism   I have tried to answer #2:     since $gf$ is an extremal epimorphism, then $gf = mh$ where $m$ is monic and an isomorphism. now let $g = nk$ where $n$ is monic.     I now need to show that $n$ is an isomorphism.  my problem is how do I do this?  I'm trying to visualise things using diagrams, but I'm lost.  Here is what I have so far for #1:  let $f: A \rightarrow B$ be and extremal epimorphism.  consider $ g,h: B \rightarrow C$ such that $gf=hf$ so I need to prove $g=h$  let $e: E \rightarrow B$ be the equaliser of $g, h$  now I don't know where to go from here to prove $g=h$.    I know that $f$ factors through the equaliser.  since $e$ is an equaliser, there is a unique morphism  $\varphi : A \rightarrow E$ therefore I now have $f=e \varphi$   which means that $e$ is now isomorphic since $f$ is an extremal epimorphism.    So can I now conclude $g=h$ ?


Correlation between dichotomous and continuous variable

I am trying to find the correlation between a dichotomous and a continuous variable.  From my ground work on this I found that I have to use independent t-test and the precondition for it is that the distribution of the variable has to be normal.  I performed Kolmogorov-Smirnov test for testing the normality and found that the continuous variable is non-normal and is skewed (for about 4,000 data points).   I did the Kolmogorov-Smirnov test for the entire range of variables. Should I split them into groups and do the test? I.e., say if I have risk level (0 = Not risky, 1 = Risky) and cholesterol levels, then should I:    Divide them into two groups, like  Risk level =0 (Cholestrol level) -> Apply KS Risk level =1 (Cholestrol level) -> Apply KS  Take them together and apply the test? (I performed it on the whole dataset only.)   After that, what test should I do if it is still non-normal?    EDIT: The above scenario was just a description I tried to provide for my problem. I have a dataset which contains more than 1000 variables and about 4000 samples. They are either continuous or categorical in nature. My task is to predict a dichotomous variable based on these variables (maybe come up with a logistic regression model). So I thought the initial investigation would involve finding the correlation between dichotomous and a continuous variable.  I was trying to see how the distribution of the variables are and hence tried to go to t-test. Here I found the normality as an issue. The  Kolmogorov-Smirnov test gave a significance value of 0.00 in most of these variables.  Should I assume normality here? The skewness and kurtosis of these variables also show that the data is skewed (>0) in almost all cases.  As per the note given below I will investigate the point-biserial correlation further. But about the distribution of variables I am still unsure.


How to increase the signal power of a wi-fi card?

I use an atheros card that requires ath9k driver. Are there any tools that can be used to increase the signal power of the wi-fi card?


Studies showing the impact of response time variability on user experience

Have there been any studies, or results, focusing on the impact of variability in latency of response times on the overall user experience?   I'm aware of the research on the "generally accepted" recommendations (100ms for instant, progress indicators for 1s+, etc.). However, what I'm curious to know is specifically the perceived performance difference (if any) between cases like:   consistent 500ms response time for all interactions average 300ms response time with +/- 200ms variability   Is (1) preferable to (2), vice versa? If either, in all cases? Etc. Of course, 500ms and 300+/-200ms are arbitrary stand-in values.


How to have Google Chrome Canary on Ubuntu?


I have the following in a script  for server in ${servers[@]}; do     echo ${server}     ssh user@${server} "for i in /tmp/foo* ; do echo ${i}; done" done   But it doesn't work. Weird thing, I see $I amount of return lines. So if I have ten files, I see ten blank lines.


If a group is of order $m$ and $n$ divides $m$, must the group contain an element of order $n$? Say we have a group of order $120$. Must the group contain an element with order $12$? If not, are there any theorems that tell us what order elements of a group must contain?


Where can I post a home-brew classes for peer review in the interest of balance?

I've created a new partial caster class that focuses on using spell slots solely for the purposes of suppressing magic in the world. I'm calling it the Void Mage. I've done my best to make it balanced using the guidelines from . I've also had the players I regularly play with contribute to balancing as well.   Now I feel like I should have it reviewed by someone outside of our circle in order to have a more unbiased opinion. Where can I upload my home-brew class so that others may comment and critique my work?


I'm getting the following output when the mount command is executed.  [root@]# mount /dev/sda2 on / type ext4 (rw) proc on /proc type proc (rw) sysfs on /sys type sysfs (rw) devpts on /dev/pts type devpts (rw,gid=5,mode=620) tmpfs on /dev/shm type tmpfs (rw) /dev/sda1 on /boot type ext4 (rw) /dev/sda3 on /home type ext4 (rw) none on /proc/sys/fs/binfmt_misc type binfmt_misc (rw) sunrpc on /var/lib/nfs/rpc_pipefs type rpc_pipefs (rw) gvfs-fuse-daemon on /root/.gvfs type fuse.gvfs-fuse-daemon (rw,nosuid,nodev)   I'm not able to understand the output of this command. Can anyone give the explanation for this output?


Android Device Manager password reset doesn't work

I accidentally forgot the password for my Galaxy S3 Neo (i9301i). People suggested I make a new one by locking it from Android Device Manager. However, when I send a new password to my device, the Samsung logo appears, similar to booting but faster. After that when I try to use the new password it rejects it. How should I proceed (I'm not rooted btw)?


“Have you heard?” vs “Did you hear?” and “Sally broke/has broken her leg”

Earlier today I had a private lesson with an Italian student—intermediate level, who has been studying the present perfect vs. past simple tense. His teacher had given him an exercise where a list of Italian phrases had to be translated into English. One of the sentences was the following:      Hai sentito che Sally si è rotta una gamba?   It looks deceivingly simple to translate (for a native speaker) but I found myself with five versions, all of which I am certain are idiomatic and grammatical.   Have you heard that Sally broke her leg? Have you heard that Sally's broken her leg? Have you heard about Sally breaking her leg?   Did you hear that Sally broke her leg? Did you hear that Sally's broken her leg?   The actual moment when Sally broke her leg happened at a specific time in the past, hence the past simple seems to me appropriate but we also say, Sally's broken her leg  to express an action that occurred in the past but whose consequences are still felt in the present so...     Which sentence tells the reader that Sally's leg is still broken?  Which tense is more appropriate; the present perfect, Have you heard?  Or the past simple Did you hear? Both sound acceptable to me. How is the meaning affected? Is it preferable for both verbs to be in the same tense? Why or why not? Ignoring the Italian translation and focussing on the five sentences, how would you interpret each one? Do they mean the same?     EDIT (updated September 1 2014) Let me explain, more fully, why I posted this question. There was an Italian phrase which had to be translated (the first line in a short exchange) the rest of the dialogue was easy enough for my student and I to translate but he had difficulties with this first line.   In the exchange we learn that Sally broke her leg while skiing.   A: Have you heard/Did you hear... etc. B: How did it happen? A: She was skiing when she fell.  When I thought carefully about how the first sentence could be translated, I came up with five versions. I had a problem explaining to myself why they all sounded equally valid to me, in fairness sentence number 3 sounded the weakest candidate to me because it seems that the news of Sally's accident is very recent and conveys greater intensity.   As I tried to explain earlier, I was wondering how switching the past simple with the present perfect might change the meaning of the first line. If I say: Sally broke her leg,  I might be thinking about the precise moment when this accident occurred. The event is established in the past and cannot be repeated. If I say: Sally has broken her leg it is plausible that her leg is still broken, seeing as a broken leg takes about a month to heal, and I am concerned with the results of that action which are felt in the present i.e. Sally now has her leg in a plaster/She cannot walk properly/She is currently injured, etc.   If the first verb is in the past simple, Did you hear...? does it affect how I write the rest of the sentence? Is Have you heard...? more colloquial?   Finally, I am NOT asking about translation, nor how to use the present perfect or the past simple.


Any element $x \in D_{2n}$, represented as $rx=xr^{-1}$.

I am working through  problems in Dummit and Foote and am having a hard time interpreting this question.  Use the generators and relations to shat if if $x$ is any element in $D_{2n}$, which is not of power $r$, then $rx=xr^{-1}$  I thought this relation was already given in presentation of $D_{2n}$. How do I interpret this problem?  $D_{2n}= < r,s | r^n=s^2=1, \hspace{2mm} \underline{rs=sr^{-1} } >$


How to customize the default search block form template?

How can I customize the default search block form template, I now use below template to display a search form block, but this code doesn't allow me to edit and customize each part of this form separately and doesn't have any flexibility.  form--search-block-form.html.twig  <form{{ attributes.addClass('search-form', 'search-block-form') }}>   {{ children }} </form>   and then print in my theme by below code:  {{ page.search_box }}   Is there any better template name suggestion with more variables and flexibility in customization?


.addEventListener() not working to an element

So I'm new to javascript and I am trying to make a basic appointment sort of app. So my project contains 2 phases: 1 is to add an entry and 2 is to remove an entry Everything is working fine till phase 1, but I can't add the event listener to initiate phase 2 Here's my code:   const list = document.getElementById('app-list'); const form = document.querySelector('form');  form.addEventListener('submit', formSubmit);  function formSubmit(e) {   e.preventDefault();   let name = document.getElementById('name').value;   let date = document.getElementById('date').value;   // Now that we have the data Submitted, let's make the element!   let entry = document.createElement("tr");   entry.innerHTML = `<td>${name}</td><td>${date}</td><td><div class="red-box"><h1>X</h1></div>`;   list.appendChild(entry); } var removebtn = document.getElementsByClassName('red-box');  for (i = 0; i < removebtn.length; i++) {   removebtn[i].addEventListener('click', removeEntry, false); }  // Adding Event listner to the removeBTN function removeEntry(e) {   console.log('hello World'); }
   <form>
       Appointment Name
       <input id="name" type="text" name="name" placeholder="Appointment name.." required>

       <lable for="date">Appointment Date</lable>
       <input id="date" type="date" name="date" placeholder="Appointment Date.." required>

       <input type='submit' value="add">
   </form>

         Name	         Date


When you show the info of a badge by hovering the mouse over it, e.g. for the nice/good/great question it shows:   bronze badge: Question score of 10 or more silver badge:: Question score of 25 or more gold badge:: Question score of 100 or more   The :: is a typo for all silver/gold badges.


there is a discrepancy between the viewport hair ( how I intend it to be) and the render in Cycles  What's the reason for this difference


This question is out of Rudin Functional analysis, but only attention was really brought to part (b) on this site, my apologizes if this is considered a re-post. I was just hoping for some assistance. I added what I have so far in my proof.   Let $L^1$ and $L^2$ be the usual Lebegue space on the unit interval. Prove that $L^2$ is of the first catagory in $L^1$, by the following.  Show that $\{f:\int |f|^2 \leq n\}$ is closed in $L^1$ but has empty interior.  proof:  Let $f \in L^2$ be arbitrary. Then $\int |f|^2 d \mu \leq n$, for some finite $n$. Observe that $|f g| \leq \frac{|f^2 + g^2|}{2}$. Suppose that $g = 1$. Then $$ \int |fg| d\mu = \int |f| d \mu \leq \frac{1}{2}\int |f^2 + 1| d\mu \leq \frac{1}{2}\int |f|^2 d\mu + \frac{1}{2} \int d \mu \leq \frac{1}{2}(n + 1) $$ Hence $f \in L^1$ $f$ arbitary and closed in $L^2$ implies that $L^2$ is closed in $L^1$.   I'm really struggling with showing that the interior is empty, and not sure how to make the argument.


"Value was fetched successfully" or "Value is fetched successfully"?

In an application I'm developing, a user is allowed to fetch a value using a button. Upon the value being successfully fetched, I need to notify the user. I used the following sentence.  The value was fetched successfully.  Upon reviewing it, my co-worker suggested the following sentence, which doesn't sound right to my ear.  The value is fetched successfully.  Appreciate if someone can clear up the difference between these two sentences. Are both grammatically correct? If so, which is more appropriate to use for this case?


I have a B1/B2 US visa valid from 18 Nov'14 - 16 Nov'19, however, have not visited the US during this period and do not foresee visiting by the 16th November this year.  There were several changes in my circumstances (family, finances, etc.) over the past few years that did not enable me to visit. I wish to extend my visa for future visits, hopefully, next summer. Will this be ok? Kindly advise. Thank you.


How to add a dash character in between numbers expression?

Trying to format the numbers expression of [0-9]{2}[-]{1}[0-9]{2}[-]{1}[1-9]{4} so that the users input have to be of the format XX-XX-XXXX. Is the following expression above the correct way to do just so?    try {     int datum = Integer.parseInt(s);         if (!strPersnr.matches("[0-9]{2}[-]{1}[0-9]{2}[-]{1}[1-9]{4}")) {          throw new IllegalArgumentException("You printed wrong format, try again");                     }                     System.out.println("Processsing...");                  } catch (IllegalArgumentException e) {                     System.out.println(e.getMessage());                     valid = false;                 }   } while (!valid);


Disclaimer:  I am in no way part of any under-represented group, quite the contrary, so if anyone feels that I am out of place with this suggestion please let me know.    Of what we can piece together from the mess that unfolded the last few days one of the reasons for this all is an upcoming change to the Code of Conduct (CoC). This change supposedly resolves around using correct pronouns (not necessarily those indicated by the gender you are born with, but those you feel comfortable with as a person).  To be clear: I personally have no problems whatsoever with using any pronoun. However, I sense there are users, within the Network at large, that have (religious) objections to using pronouns that are not those that one is "born with".   One of the arguments many have voiced is that we are a Q&A site, questions and answers, nothing more nothing less. This seems to deny the notion that we, users are human beings, with human needs of confirmation. So for any that seek that: It is okay to be YOU, whoever you are!. Another point is that whilst we are strictly about questions and answers we also have comments. Comments don't always tend to be nice and can make this place less than welcoming. Of course, we have moderat(ing/ors) for troubling comments, but I can read my notification a lot quicker than anyone else can flag that obscene comment, and any moderator can resolve that. Hence the damage is done almost immediately when a comment is written. This also includes misgendering any user when writing a comment.  A second scenario where the use of pronouns can be needed is the interaction between moderators/staff and users. Also in this case misgendering is hurtful, as it always is. Avoiding pronouns in a message altogether is also not desirable, it just makes for an awkward message.  The third scenario is chat. A place where we let go of the reigns a bit more. Resulting in rooms needing to be locked every now and then, and locking doesn't happen because there is a peaceful tea-party going on. I'll just leave it at that.  Now to summarize:   Pronouns are a thing we need in communication. We hurt users by misgendering them, something we should definitely strive to avoid. There are users with objections to using pronouns other than those of your sex at birth indicate.   As we want to be an inclusive community we should welcome everyone to participate and be a part of the network. Therefore I wonder if we can't just Live and let Live. To me, that would mean using ONE, and only ONE pronoun, singular they. In this way, we don't single out any group.  Now, these are my two cents. I'd love to hear yours. So to conclude:  Are there any objections to using singular they for everyone?    Conclusion: Yes, there are plenty objections from all sorts of angles. I am pleased by all the feedback written in polite ways.


Here is my error message:   Round 0 of The War  Player 0: Exception in thread "main" java.lang.NullPointerException     at WAR1.printHand(WAR1.java:113)     at WAR1.main(WAR1.java:93)   This is the code:  import java.util.Scanner;   public class WAR1 {      private int cardNum;     final static String[] suits = {"Spades", "Hearts", "Diamonds", "Clubs"};     final static String[] ranks = {"2", "3","4","5","6","7","8", "9","10", "Jack", "Queen", "King", "Ace"};      WAR1 (int theCardNum) {         setCardNum (theCardNum);     }      public void setCardNum (int theCard) {         cardNum = (theCard >= 0 && theCard <= 51)? theCard: 0;     }      public int getCardNum() {         return cardNum;     }      public String toString() {         return ranks[cardNum%13] + " of " + suits[cardNum/13];     }      public String getSuit() {         return suits[cardNum/13];     }      public String getRank() {         return ranks[cardNum%13];     }      public int getValue() {         return cardNum%13;     }         private WAR1[] deck = new WAR1[52];     private int topCard;      WAR1() {          topCard = 0;          for (int i = 0; i < deck.length; i++)             deck[i] = new WAR1();      }      public void shuffle() {          topCard = 0;          for (int i = 0; i < 1000; i++) {             int j = (int)(Math.random()*52);             int k = (int)(Math.random()*52);             WAR1 tmpCard = deck[j];             deck[j] = deck[k];             deck[k] = tmpCard;         }     }      public WAR1 dealCard() {         WAR1 theCard;         if (topCard < deck.length) {             theCard = deck[topCard];             topCard++;         }         else             theCard = null;          return theCard;     }        public static void main(String[] args) {          WAR1[][] hands = new WAR1[2][1];          Deck myDeck = new Deck();          for (int i = 0; i < 26; i++) {             System.out.printf("\n Round %s of The War \n", i);                   for (int player = 0; player < hands.length; player++)                     hands[player][0] = myDeck.dealCard();              for (int player = 0; player < hands.length; player++) {                 System.out.printf("Player %d: ", player);                 printHand(hands[player]);             }              int player1 = hands[0][0].getValue();              int player2 = hands[1][0].getValue();              if (player1 > player2)                 System.out.println("Player One Wins The War");             else if (player2 > player1)                 System.out.println("Player Two Wins The War");             else                 System.out.println("The War Is A Tie");          }     }       public static void printHand(WAR1[] hand) {          for (int card = 0; card < hand.length; card++)             System.out.printf("%s", hand[card].toString());          System.out.println();      }  }   What am i doing wrong??


Inputs a string or list of int, returns a list with no duplicates next to each other

Input: a string of characters or a list of integers Output: a list of elements with no repeats next to each other in the same order as input  i.e. ('aabbcccdddaaa') = ('a','b','c','d','a')  def no_near_dups(a):     L = []     i = 0     while i < len(str(a)):         if a[i] == a[i+1]:             i += 1             continue         L.append(a[i])         i += 1     L.append(a[i])     return L   I am receiving the error: IndexError: string index out of range


Finite parallel impedance network general solution

Does anyone know if a finite number of parallel-series impedance has a general solution?  I am trying to model a network flow problem that can be described in electrical terms and represented as a finite discrete transmission line with arbitrary impedance.  While it is not difficult to write the equations down for a small number of terms, I'm curious if there are some general solutions or insights into the problem.  It looks like  ----Z1---+----Z3---+----Z5---+---...---+          |         |         |         |          Z2        Z4        Z6        ZN          |         |         |         | ---------+---------+---------+---...---+   All the Z's are, in general, different.  I'll need to know the "current" and/or "voltage" at every branch. In this case the bottom is grounded.  What would be cool is to be able to know the voltage and/or current in terms of i, the ith position (the top +).  Any ideas?


When you write a join statement, and just use 'join' does that default to any join? Or is join also a type of join statement? select * from a join b on a.c = b.c


def fib_memo(n, memo={}):     if n == 0 or n == 1:         return 0     try:         return memo[n]     except KeyError:         result = fib_memo(n-1, memo) + fib_memo(n-2, memo)         memo[n] = result         return result  for i in range(121):     print('fib', str(i),fib_memo(i))  Returning the following output fib 0 0 fib 1 0 fib 2 0 fib 3 0 fib 4 0 fib 5 0 fib 6 0 fib 7 0 fib 8 0 fib 9 0 fib 10 0


how to read all recurrance events from sp calendar list in SP hosted app

I am trying to create one SP hosted app which will read all events (includes recurring) from SharePoint calendar list. I tried but am enable to reach to it.  my code is as below.  function retrieveListItems() {         var appContextSite;         ListName = "MyList";         web = context.get_web();         context.load(web);         var myList = web.get_lists().getByTitle(ListName);        var query = new SP.CamlQuery();       query.set_viewXml(      "<ViewFields>"      "<FieldRef Name='EventDate' />"+      "<FieldRef Name='EndDate' />"+      "<FieldRef Name='RecurrenceData' />"+      "<FieldRef Name='fRecurrence' />"+      "</ViewFields>"+      "<Query><Where>" +     "<DateRangesOverlap>" +     "<FieldRef Name='EventDate' />" +      "<FieldRef Name='EndDate' />" +      "<FieldRef Name='RecurrenceID' />" +      "<Value  Type='DateTime'>" + currentDate + "</Value>" +      "</DateRangesOverlap>" +      "</Where>" +      "<queryOptions>" +      " <QueryOptions>" +      "<ExpandRecurrence>TRUE</ExpandRecurrence>" +      "</QueryOptions>" +      " <QueryOptions>" +      "<CalendarDate>" + currentDate + "</CalendarDate>" +      "<RecurrencePatternXMLVersion>v3</RecurrencePatternXMLVersion>" +      "</QueryOptions>" +      "</queryOptions>" +      "<OrderBy>" +      "<FieldRef Name='EventDate' Ascending='True' />" +      "</OrderBy></Query>");     var items = myList.getItems(query);     context.load(items);     debugger;    context.executeQueryAsync(Function.createDelegate(this, this.onQuerySucceeded), Function.createDelegate(this, this.onQueryFailed));      function onQuerySucceeded(sender, args) {      var listItemInfo = '';      var listItemEnumerator = collListItem.getEnumerator();      while (listItemEnumerator.moveNext()) {         var oListItem = listItemEnumerator.get_current();         listItemInfo += '\nID: ' + oListItem.get_id() +              '\nTitle: ' + oListItem.get_item('Title') +              '\nBody: ' + oListItem.get_item('Body');     }      alert(listItemInfo.toString()); }  function onQueryFailed(sender, args) {      alert('Request failed. ' + args.get_message() + '\n' + args.get_stackTrace()); }  }


Problem evaluating $ \int_{0}^{\pi/2}\frac{x}{\tan x}dx $

I am trying to evaluate  $\int_0^{\pi/2}\frac{x}{\tan x} \, dx$. This is how I started: $$  \int_0^{\pi/2} x\cot x \, dx$$ Integrating by parts we get: $$x\ln\left|\sin x\right| - \int_0^{\pi/2}\ln\left|\sin x\right| \, dx $$ Since $x$ is between $0$ and $\pi/2$, we can drop the absolute value. $$x\ln \sin x - \int_0^{\pi/2}\ln \sin x \, dx $$ Integrating the second integral again by parts we get:  $$x\ln \sin x - x\ln \sin x - \int_0^{\pi/2}\frac{x}{\tan x} \, dx$$  Now we take the last integral to the other side to get $$2\int_0^{\pi/2}\frac{x}{\tan x} \, dx = 0$$ and therefore $\int_0^{\pi/2} \frac{x}{\tan x} \, dx = 0$. However, when I checked the memo, it said the answer was $\frac{\pi}{2} \ln2$. What is wrong with my solution? Please help me find where I went wrong.


Understanding Join Attributes by Location in QGIS?

I wonder if there is somewhere an explanation for the parameters that can be set when running the Algorithm "Join Attributes by Location" in QGIS 2.18.  I had a look here:       but there is no explanation. Any hints?


Where can I get information on freighter travel?

I want to go from New York City to any destination in Europe on a freighter.  The only place I've found information for doing this requires a round trip.  I don't want to go round trip.  I want to spend some months in Europe and I don't care where in Europe I start.


Does vapor latent heat depend on temperature?

Adding energy to water makes it's temperature increase. This continues until it reaches 100 °C (at 1 atm) when it turns to vapor with a vaporization energy of 2257 kJ/kg. But if we lower the pressure on the water, it can start boiling at lower temperatures. In this case, would it's vaporization latent heat still be 2257 kJ/kg?   If not, how does the latent heat of water depends on boiling temperature or vapor pressure?


I’m trying to install a chain with a snap on master link, but I can’t figure out how. I’ve tried twisting the chain as suggested by other questions to get it into place, but that doesn’t help. How do you do this? What’s the secret?    It’s a Shimano 8S CN-HG40 chain.


Why can't I edit a post with pending/suggested edits even though I have enough rep?

If a post has a pending edit (like  did for a bit) then it gets stuck in the review queue, requiring multiple approvals.  However, if it didn't have that pending edit, I could simply edit it and save it without any review/approval process.  So, why I can't I make edits to a post with pending edits and just save them?  Or conversely, if I have enough rep to edit without review, why shouldn't I be able to approve edits myself?


Is it possible to create a table with two entries in one cell separated by 45 degree line?

I want to create a table like the below picture in LaTeX.  Does anyone tried this before? Can you introduce how to create such  a table?  The problem is that I don't know to how create the slash line separating "Name" and "Group" fields.


I Know that $\sum_{n=1}^\infty \frac{1}{n}$ Diverges, but what is $\sum_{n=1}^{\infty} \frac{(-1)^{n+1}}{n}$

We know that $\sum_{n=1}^\infty \frac{1}{n}$ diverges since it is a harmonic series. However, I was recently working on a homework problem where I was given to find if $\sum_{n=1}^{\infty} \frac{(-1)^{n+1}}{n}$ converges. I found that it does converge, but I wanted to go further than just this. I was attempting to find what this sum was. I rechecked my work multiple times, and I know for sure that the sum does converge. How would I go about finding what the sum is for: $$\sum_{n=1}^{\infty} \frac{(-1)^{n+1}}{n}$$


I am very new to regex and learning by practice. I wrote the following regex for finding a number inside a string of characters, however, it returns nothing. Why is that?   string = "hello world & bello stack 12456";  findObj = re.match(r'[0-9]+',string,re.I);  if findObj:     print findObj.group(); else:     print "nothing matched"   Regards


Is there a faster way to find any name in namesArray?

Can I find a required name without loop through each array item?  Is there any faster way to do the same assuming that I have a very big array length, because if I have an array of 10000 items and the name doesn't exist in it, it will be a waste of time and assuming that we don't have inclouds function     $(document).ready(function() {   function binarySearch(names, requiredName) {     for (var i = 0; i < names.length; i++) {       if (names[i] === requiredName) {         return true;       }     }     return false;   }   console.log(binarySearch(['ola', 'amer', 'anwar', 'mamon'], 'hadeel')); }); <script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>


Is it okay to repost a reformulated question that is closed (or on hold)?

If you    Formulate a question vaguely It gets closed / put on hold for this You take the comments to heart and reformulate it It no longer gets attention but you have not enough reputation to trigger a reopen.   Then is there anything you can do? Is closing the question and stating it as a new question a legitimate solution? I have the feeling it is not, but did not find any info here on meta.


Showing only point markers when labels are shown in QGIS?

Is there a chance to define a QGIS style rule to just show point markers when their label is shown?   My aim is to exclude all points which are not labeled because of collision between labels.  Example:


Facebook notification style (3), etc. in the window title

Facebook puts a little (1) in the page title whenever you have a comment, etc. I find this really handy when I have a bunch of tabs open, and it would be great on Stack Overflow too. So, could we get the development team to add this in? To clarify, when a notification or comment is received and shown as a number in a red/blue circle next to the Stack Exchange logo in the top bar, I think it would be a good idea to mirror that number in the page title, similar to the way Facebook does.


I'm trying to switch over to U from windows. All of this is new to me. I just installed U14.04 on my laptop. I want to be wireless. I have downloaded wifi-radar 2.0.s05-1.1.deb How do I install it? Because it recommended i also downloaded Aptitude_0.4.11.11.orig. How do I get it to install?


Diamond is not shown for mod name under wiki posts

If a diamond mod is an author of a wiki post then the diamond is not displayed besides the mod name. E.g. :        Even when the name refers to the user profile page (in case of more then one author) like in :        Is it intentional or a bug?


How to un-auto-award a bounty to an answer that didn't solve my problem?

I recently received a message telling me "Your bounty on question "" has expired - answer auto-selected."  But how can that be? None of the answers truly solved my problem, especially because I had to develop a workaround to finally have what I wanted.  And now 25 points have been given to an answer that didn't serve my purpose? Seriously?!  How do I undo this?


Blog posts look like Meta Stack Exchange posts; mistakenly display "Meta Stack Exchange" in the icon tooltip

On Music, I saw this little bar on the right:    This is weird. I don't read things closely and thus didn't see "Blog", so I clicked on it thinking "hmm, is this some very unusual announcement?" based on it having the blue-and-white Meta logo.  I found this:    That's no Meta!! This is a leftover icon from the thing where non-Meta sites would show Meta posts on the right; . Can this be changed to the Stack Overflow logo or something to make it clear that these are SO blog posts?


How to erase .lof file (and other auxiliary files) in Overleaf?

I am working on the  collaborative platform. I am facing the following error code :  ./main.lof:18:  Missing $ inserted.  <inserted text> $  l.18 ...some figure_name}}{23}{figure.17}   The thing is, even after correcting/deleting the figure that causes this error, the compilation will always stop on this.  From my understanding, I would need to erase the .lof file to avoid this error again but I do not know how to access it on the overleaf platform.  Do you think I undersand well the situation? Do you know how to access the .lof file?


Prove that $n!$ can never be a perfect square for $n>1$   I have no idea on how to begin this problem.(I don't want to use Bertrand's theorem as it is beyond the level of the exam I have to take now.)


Is it imbalancing to have unarmed strikes count as weapons?

Unarmed strikes already count as "attacks", "melee attacks", and even "melee weapon attacks" as the , version 2.3, states this on page 11:     For example, an unarmed strike counts as a melee weapon attack, even though the attacker’s body isn’t considered a weapon...   I was wondering if there are unforeseen consequences of letting unarmed strikes simply count as weapons in general.


Option to view entire markdown source text in suggested edit review

I recently encountered a suggested edit which replaced the display text of several links (the text in square brackets) which were using the "URL is in footnote" markdown. I couldn't see the URLs because they were in the "n identical lines skipped" section, so I couldn't really judge whether the edited text matches the URL.  Would it be possible to add a third button alongside the existing rendered output and markdown which would show the complete markdown (not skipping identical lines), something like full markdown? I can imagine other cases where this would be useful.  I know there are workarounds - using Improve or, in this particular case of URLs, hovering the mouse in the rendered output view the URL. Still, I believe it would be useful to have the option to view the markdown unabridged.


The difference between "char* variable" and "char *variable" in C

I'm learning C and I'm wondering about the difference between writing type* variable and type *variable.


How is a ROCAUC=1.0 possible with imperfect accuracy?

I used sklearn to compute roc_auc_score for a dataset of 72 instances. The accuracy was at 97% (2 misclassifications), but the ROC AUC score was 1.0. How is this possible? I would think that even one misclassification should have dropped the score to slightly below 1.0.  # Python 3.6.4 # numpy==1.14.3 # scikit-learn==0.19.1 # scipy==1.1.0  from sklearn import metrics import numpy as np  y_true = np.array([0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 1.0, 1.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 1.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 1.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 1.0, 0.0, 0.0, 1.0, 0.0, 0.0, 0.0]) y_prob = np.array([0.0, 0.1, 0.0, 0.0, 0.0, 0.0, 0.1, 0.0, 0.1, 0.0, 0.0, 0.0, 0.0, 0.7, 0.5, 0.0, 0.0, 0.0, 0.0, 0.0, 0.1, 0.1, 0.0, 0.0, 0.9, 0.0, 0.0, 0.0, 0.0, 0.1, 0.0, 0.0, 0.0, 0.1, 0.1, 0.0, 0.0, 0.7, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.1, 0.0, 0.0, 0.0, 0.0, 0.1, 0.0, 0.0, 0.1, 0.1, 0.0, 0.9, 0.0, 0.0, 0.4, 0.0, 0.0, 0.0])  # Show which actuals do not match their expected probabilities for index, (actual, predicted_prob) in enumerate(zip(y_true, y_prob)):   if (actual == 1 and predicted_prob <= 0.5) or (actual == 0 and predicted_prob > 0.5):     print (f'Mismatch at index {index}. Actual={actual}, predicted_prob={predicted_prob}')   rocauc = metrics.roc_auc_score(y_true, y_prob)     print (f'ROCAUC: {rocauc}')  # Outputs: # Mismatch at index 14. Actual=1.0, predicted_prob=0.5 # Mismatch at index 68. Actual=1.0, predicted_prob=0.4 # ROCAUC: 1.0   Then I debugged the score computation itself and looked at the coordinate ROC output.  # In sklearn/metrics/ranking.py, line 271: --> 271         fpr, tpr, tresholds = roc_curve(y_true, y_score,     272                                         sample_weight=sample_weight)  ipdb> fpr array([0.        , 0.        , 0.        , 0.18181818, 1.        ]) ipdb> tpr array([0.33333333, 0.66666667, 1.        , 1.        , 1.        ]) ipdb> tresholds array([0.9, 0.7, 0.4, 0.1, 0. ])  # coords = [] # for x, y in zip(fpr, tpr): #   coords.append((x, y))  ipdb> pp coords [(0.0, 0.3333333333333333),  (0.0, 0.6666666666666666),  (0.0, 1.0),  (0.18181818181818182, 1.0),  (1.0, 1.0)]   All of those coordinates are on x=0 or y=1, meaning ROCAUC is showing 1.0. The only plausible explanation I can think of is that if the alg had more fpr/tpr points, it would show a very tight curve that never reaches x,y = (0, 1), and the ROCAUC would be close to 1, but not exactly 1. Is that a reasonable interpretation or am I missing something?


Calculate $ \lim_{\left(x,y\right)\to\left(0,0\right)}\frac{xy^{2}}{x^{4}+y^{2}} $

Im trying to calculate (or prove that the limit dosent exists) $ \lim_{\left(x,y\right)\to\left(0,0\right)}\frac{xy^{2}}{x^{4}+y^{2}} $ Wolfram says the limit does not exists, but for every path I choose the limit ends up being 0. If someone can tell if the limit exists or not, it would be helpful. Thanks in advance


How do I graph a 30-petal rhodonea curve (rose)?

A rose of the form $r = \cos(c\theta)$ normally has $2c$ petals when $c$ is even and $c$ petals when $c$ is odd. A rose may also have $4c$ petals when $c$ can be expressed as $Z + \frac{1}{2}$ where $Z$ is an integer. A rose may also have $12c$ petals when $c$ can be expressed as $Z \pm \frac{1}{6}$.  A rose may also have as many petals as one with $3c$ when $c$ can be expressed as $\frac{Q}{3}$ but not as $Z$ where $Q$ is either $Z$ or $\frac{Q}{3}$. How is a rose with 30 petals graphed (in the form shown above)?


What are the different skins in Agar.io?

I've noticed in  there are a number of different skins when you choose specific usernames.  For example, entering Moon, Earth or Mars shows you as that particular celestial body.  Is there a list of the rest?