Average answer count per question and comment count per question by week

I am trying to gather information on the number of answers per question by week for a user with fewer than 25 reputation points from the math.stackexchange site (and the comment count per question).  I have the following query but it has not worked  -- CTE with year, week and start of week dates with yw as ( select distinct     year(creationdate) as y   , datepart(week, creationdate) as w  -- http://stackoverflow.com/a/3936891/578411  , cast(      DATEADD(           day,            1 - DATEPART(dw, creationdate),            creationdate)        as date     ) as sdow from posts )  -- grouping over the union select sdow  , avg(answercount) as [answercount] from  ( --answercount from users with reputation < 25 select sdow    , count(*) as [answercount] from posts p inner join users u on u.id = p.owneruserid right outer join yw   on yw.y = year(p.creationdate)  and yw.w = datepart(week, p.creationdate)  where u.reputation < 25 -- rep group by sdow union ) as total


Special relativity: Two moving objects from different reference frames

Imagine a inertial frame of reference, in which two objects are moving with constant velocity in opposite directions. Object one is moving at $50$% the speed of light and object two has a velocity of $0.6c$. Now, one could think that from object one´s perspective, object two is moving with 110% the speed of light, which is obviously wrong, because nothing can go faster than c. But what is the velocity of object two in the reference frame of object one? My idea was that, since object one experiences time dilation and lenght contraction, these factors have to be included when determining object two´s velocity. So here are my calculations: Time gets dilated by $\frac{1}{γ}$. Since γ = $\sqrt{\frac{3}{4}}$ with v = $0.5c$, the time has to be multiplied by $\frac{2}{\sqrt{3}}$. Length gets contracted by γ. So the factor for length contraction is just the reciprocal of the factor for time dilation and vice versa. With those things in mind, I now calculated the velocity for object two. I started off by taking the "straightforward" velocity, $1.1c$ and modifying it by the above calculated factors. The factor I got for the velocity in the end was $γ^2$ = $\frac{3}{4}$, because the time dilation factor occurs in the denominator and is also the reciprocal of the length contraction factor and the reciprocal of the reciprocal is just the original value. So in the end, I got $1.1c \cdot 0.75 = 0.825 c = v_2$ Is that correct? And if not, where did I go wrong?


Is a visa to Poland required for a Russian spouse of a Polish citizen?

I am a holder of a Russian passport and my husband is a Polish citizen. We both live and work in the UK. I have received my family member of EEA national card, good for 5 years. We would like to travel to Poland together. On the website of the Polish embassy it clearly states that if we are traveling together, I do not require a visa, however in the embassy they were sure that I do need a visa. Could anyone please clarify?


Let $G$ be a group of order $125$. Which of the following statements are necessarily true?  $G$ has a non-trivial abelian subgroup.  The centre of $G$ is a proper subgroup.  The centre of $G$ has order $5$.  There is a subgroup of order $25$.    Solution(Partial):  Since $G$ has a subgroup of order $5$, $G$ has a non-trivial abelian subgroup. Hence (1) is true.  (*)I think (2) is not true, since $G$ can be abelian, then centre may not be proper subgroup.  Since (2) is not true it is not necessary to be centre of order $5$. Hence (3) is not true.  (4) is true for the fact that $125=5\times 25$.  Also see .    I think I need better explanation for (*). More generally is there any specific way to argue that ---- $\color{red}{\text{When we can say a group can not be abelian if we only know the order of the group?}}$


Let $R$ be a ring. Define a circle composition ◦ in R by $a ◦ b =a+b-ab$, $a, b ∈ R$.

For (b) the neutral element is $0$ since $a◦0 = a + 0-a0 = 0$ and $0◦a = 0 + a-0a = 0$, then element is invertible for all a in S must be $a◦ 1 = a + 1-a1 = 1$ and $1◦a = 1 + a-1a = 1$. I have not been able to prove the closure law of ◦, could someone help me? For Part (C), let $\phi :U(R)\rightarrow S$. $\phi$ is given by $a \mapsto a+x-ax$ ?


First recall some definitions :   Let $B$ be a Killing form on Lie algebra $\mathfrak{g}$ over ${\bf R}$ such that     $B(X,Y)\doteq Tr(ad_Xad_Y)$.   $\mathfrak{g}$ is semisimple if $B$ is non-degenerate.   Define $\partial \mathfrak{g} \doteq \{ D | D[X,Y]=[DX,Y] + [X,DY] \}$ Clearly it contains $ad(\mathfrak{g})\doteq \{ ad_X | X\in \mathfrak{g}\}$.   My question is about proof of $\partial \mathfrak{g}=ad(\mathfrak{g})$ :   I am reading Helgason's book. We can show that $ ad(\mathfrak{g}) = \mathfrak{g}$ easily.   I cannot proceed the proof since $B$ is defined on $\mathfrak{g}$ only.  How can I complete the proof ? Thank you in advance.


I have tried this problem but not able to find the answer. Could anybody help me in solving this. Is $(a+b)^p< a^p+b^p$ for all non-negative reals $a, b$ and $0<p<1?$


How can I make my animation play for longer than 250 Frames?

I'm trying to find the settings that allow me to see longer previews of my animations when I play the animation with ALTA.  The animations default to only 250 frames long, but I'd like them to be longer. What is the way to do this?


I once heard my mathematics teacher say that $\frac{0}{0} = \infty$ and she said proving this is difficult.      How would I prove this?    Then will $1 \times 0 = \infty$ as well or just $0$?


Consecutive Day count reset this morning

I have read a lot of the posts on here about consecutive days and how they are calculated, but I am not sure that I can explain this one...which is disappointing since I have been trying to get the consecutive days badges.  I logged in last night (SO) at 8/13/2010 @ 730P EST and my consecutive days count was somewhere in the teens (maybe 20's I don't remember).  I answered a question, browsed around for a bit longer and then went away.  This morning (8/14/2010 @ 815A EST), my consecutive days count is back to 1 (still on SO).    What is the exact method to calculate these?  Can anyone look to ensure that my days really should have been reset?  Its pretty crazy to attempt to go for a badge if when I log in twice within 11 hours I have my days reset.  And, just as an aside, its not so much about the badge as I do enjoy the site without the 'reward', but still would be nice to know why this reset occurred.


Solving the double precision issue for string representations of 0d and -.1d for cleaner UI

Not a duplicate of  If you take the time to read the question, I am looking for better ways of representing these floating point number in strings.  I have a numeric up/down control, essentially a normal textbox with up down buttons next to it that stores its value as a double. I have been running into an issue when cycling up and down, when the value is (or should be) 0 or -.1, the text box displays "1.38777878078145E-16" and "-0.0999999999999999" respectively (among others) and this makes the control feel messy.  I get that the floating point precision of double means that values get truncated and absolute precision for decimals longer than the doubles precision are lost. Precise representation of the actual value of -.1d is not as important to me as it's clean representation, meaning I would like -.1d (-0.0999999999999999) to simply display as "-.1".  Do not assume by my examples that all values are within one decimal, though precision is not terribly important granularity is.  Right now I am just catching the string in my double to string converter and handling it, but is there a better way to do this?  No I cannot use decimal due to its overhead.  [ValueConversion(typeof(Double), typeof(String))] public class DoubleToStringValueConverter : IValueConverter {     public object Convert(object value,                           Type targetType,                           object parameter,                           System.Globalization.CultureInfo culture)     {         string res = ((double)value).ToString(culture);         if (res == "1.38777878078145E-16") res = "0";         if (res == "-0.0999999999999999") res = "-0.1";         return res;     }      public object ConvertBack(object value,                               Type targetType,                               object parameter,                               System.Globalization.CultureInfo culture)     {         string val = value as string;         double res = 0d;         double.TryParse(val, System.Globalization.NumberStyles.Float, culture, out res);         return res;     }  }


There exists c such that $\int_0^1 x^2 \! f(x) \, \mathrm{d}x = 1/3 f(c)$

Let $f:[a,b]\rightarrow\mathbb{R}$ be a continuous function. Show that there exists $c\in[0,1]$ such that $$\int_0^1 x^2 \! f(x) \, \mathrm{d}x = \frac13f(c)$$  I am stuck with this one. $f$ is said to be continuous on $[a,b]$ so how can we conclude about $[0,1]$? Also can you please give me a clue about how to approach this problem? Integration by parts? Mean value theorem for integrals?


How can I know when my screen was locked last time?

Exist a log where I can look for that information? I want to know last days when my PC automatically locked the screen because was idle.


Visual Studio 2005/2012: How to keep first curly brace on same line?

Trying to get my css / C# functions to look like this:  body {     color:#222; }   instead of this:  body  {     color:#222; }   when I auto-format the code.


What is the use of abstract class that implements an interface

While reading Herbert Schildt I came across partial implementation where overriding is'nt mandatory , But I fail to understand why do we implement such an interface where we don't override its methods :  interface CallBack{   void callback(); }  abstract class Incomplete implements Callback {     //Legal void someMethod(); }   Is there any practical use of such a class or it's just theoretical ?


If a department places no limit to the number of recommendation letters, how many are appropriate?  Are 5 OK? Are 7 too many?  Of course this depends on how strong the letters are - but let's assume that all of them are equally strong.


Standard value of PATH variable Windows 10

After having poorly handled the PATH system variable (resulting in deletion), I'm now looking to reinstate the variable with the original value. I found answers like  about Windows 8 and below, but not for Windows 10. I guess values are virtually identical, but I'd like to know the exact string so I'm not missing anything. EDIT: Also, Regedit tree have changed and I'm not able to locate the variable


I have a file with multiple information in different columns to the same ID  first | x | y | z second | x | y third | x   I want something like this:   first | x first | y first | z second | x second | y third | x


Which camera is best in the beginning of photography?

I am going to start learning photography, can you please suggest which type of camera or phone camera i should buy on beginning of photography?


Strange math notation, vertical bar with parentheses.

So I was reading "Resistance Distance" (D. J. Klein, M. Randić) (Journal of Mathematical Chemistry 12(1993)81-95) when I came up with strange notation.  From the paper:  The graph adjacency matrix is defined as: $$A_{xy} = (x|A|y) =  \begin{cases} 1/r_{xy} & x \sim y \\ 0 & \text{otherwise}  \end{cases}$$  The graph degree matrix of a graph is defined as:  $$\Delta_{xy} = (x|\Delta|y) = \delta(x,y) \sum_{z}^{\sim x} 1/r_{xy}$$  $$ |\phi) \equiv \sum_x |x)  $$  My main question is what does the combination of the vertical bar parentheses mean. Thanks in advance.


iMac as external display for new MacBook Pro?

I've got an iMac from . Will I be able to use this as an external display for the new MacBook Pro? If yes, which adapters will I need? I'm not sure what to make of this info from  about the MacBook ports:     The USB-C port on your Mac notebook supports charging, data transfer, and other modes such as DisplayPort video. You can use a USB-C adapter to connect to HDMI and VGA displays or connect other standard USB devices. This includes devices like iPhones, iPads, and iPods for charging and syncing, and cameras, hard drives, and thumb drives for transferring data.   The USB-C port on your Mac notebook doesn't support Thunderbolt devices or displays.


Menu bar icons get hidden by long menu bar items

Sometimes on my Macbook Pro when I have a lot of icons in the menu bar, if I start an application which has a lot of menu items, some of these icons get automatically obscured by the menu items.  For example, when running iTunes, the Twitter icon gets obscured...    ...but if I switch to Finder (which has a fewer menu items) the icon then re-appears    Is there any way I can show or get to these obscured icons without having to switch to an application with a shorter menu bar?


Non significant intercept in linear model

I am a beginner in statistics so I would like some help with literature. I have a linear model $Y= b_0 + b_1 X^2$ Intercept $b_0$ is not significant (sig: 0,09 > 0,05) but $b_1$ is very significant. I cannot find any literature to support the fact that it is not a big problem for the intercept being zero and also I am not sure I am right.   I understand there's another similar question but I wonder if anyone has an official paper or book that, states the answer to my question. I haven't found something answering exactly that.


SQL Server 2008. Take info from two tables and concatenate row values.

I have looked at what was marked as the duplicate of this and it is not. I'm pulling from two tables, not one.  First, allow me to say I had nothing to do with the design of this database.  I have two tables that must be joined, and then an unknown amount of rows where the data must be concatenated into one giant string. They are joined by the Record ID.   Item table:  Item         RecordID --------------------- Car A        123 Car B        456 Car C        789   Yes, the words literally cut off in the middle. There should be nothing added between the values, and I also need to keep the commas and other special characters.  Details table:  RecordID     Details -------------------------------- 123          black pain 123          t, radials 123          , green le 123          ather, spo 123          rt steerin 123          g wheel, b 123          uilt-in GP 123          S 456          standard 789          black leat 789          her, teles 789          coping ste 789          ering whee 789          l, seven c 789         up holders 789         , heavy du 789         ty mudflap 789         s   What I want to end up with is this:  ItemID       RecordID     Details ---------------------------------------------------------------------------- Car A        123          black paint, radials, green leather, sport steering wheel, built-in GPS Car B        456          standard        Car C        789          black leather, telescoping steering wheel, seven cup holders, heavy duty mudflaps   I've looked at all the XML ones and can't figure out how to do this.  Thanks in advance.


In Sword Art Online, why do Kirito and Asuna never refer to each other as boyfriend and girlfriend?

I'm relying entirely on the English Dubbed version. As far as I know, they only refer to each other as friends when speaking to other people. Is there an explanation as to why?


I need to prove that $x^2\equiv -1\pmod p$ if $p=4n+1$.  ($p$ is prime of course...)  I need to use Wilson theorem.


How to interpret a negative adjusted R-squared

How do I interpret a linear multiple regression with a low positive R squared and a negative adjusted R squared?


Remove whitespace above and below itemize in a table

I have a table where some cells contain a bulleted list produced by itemize. I want to present these lists in a compact way. I use the enumitem package and \setlist[itemize]{nosep} (plus other parameters to reduce horizontal space but they're irrelevant here so I didn't include them in my MWE).  I'm still getting unwanted whitespace above and below the list, when it's the sole item in a cell (but not when there's text above/below). How can I get rid of this unwanted vertical space?  I'd like the first line of the list item to be aligned with the first line of a plain text cell in the same row of the table, or close enough.  Not acceptable: , because some items are multiline and I do want the indentation. I won't have nested lists, so redoing the bullets and the indentation of subsequent lines without invoking the itemize environment would be ok.    \documentclass{article} \usepackage{enumitem} \begin{document} \setlist[itemize]{nosep,topsep={0pt},partopsep={0pt}}  Too much space before and after \verb`itemize`:  \begin{tabular}{p{5em}p{15em}p{5em}}   \hline   wibble \par wobble \par wubble &   \begin{itemize}   \item something   \item something else, which can span multiple lines   \end{itemize} &   \begin{itemize}   \item hello   \item world   \item more   \end{itemize}   \\ \hline   wibble \par wobble \par wubble &   \begin{itemize}   \item something   \item something else, which can span multiple lines   \end{itemize} &   \begin{itemize}   \item hello   \item world   \item more   \end{itemize}   even more   \\ \hline \end{tabular}  \bigskip  Approximate desired visual effect:  \begin{tabular}{p{5em}p{15em}p{5em}}   \hline   wibble \par wobble \par wubble &   \vspace{-0.5\baselineskip}   \begin{itemize}   \item something   \item something else, which can span multiple lines   \end{itemize}   \vspace{-0.7\baselineskip}   &   \vspace{-0.5\baselineskip}   \begin{itemize}   \item hello   \item world   \item more   \end{itemize}   \vspace{-0.7\baselineskip}   \\ \hline \end{tabular} \end{document}


Is there an English dictionary that distinguishes words as either abstract or concrete?

The words that express the tangible and visible things of our experience, such as sand or sea, are all nouns, as are those expressing intangibles such as love or idealism.  Also, some nouns, like field or grain, can be imagined both as tangible and intangible.  People, generally, refer to these nouns with the terms concrete (tangible) and abstract (intangible).  That being said, my question is, is there an English dictionary that—as well as identifying a word as a noun—additionally identifies the noun as either “abstract” or “concrete”? Are there any other resources that do this?


Can I Claim Social Security If I Live Abroad?

Can I claim SS if I live abroad?  Specifically in France or Germany.  Does the answer depend on citizenship?  I am both a US and UK citizen at the moment. I currently reside in California.  I am eligible - I am 60 and have been paying the taxes since 1985.  I receive letters from the government every year or two telling me how much my monthly would be if I retire at 62, 65, etc.  I live in the US now and have done all the time I've been paying social security taxes.  In case it's not clear, I am referring in this question to the Social Security program of the US government intended to help older people that was started in F. D. Roosevelt's administration.  The duplicate pointed to by littleadv contains a link that does answer the question although the questions are not exact duplicates as one explicitly refers to non-citizens whereas this question refers to citizens.  Regardless, thanks for marking it as a duplicate as it led to the correct answer.


Best way to randomize an array with .NET

What is the best way to randomize an array of strings with .NET? My array contains about 500 strings and I'd like to create a new Array with the same strings but in a random order.  Please include a C# example in your answer.


Windows Server 2008 R2: User account set to not show on login

This afternoon I set up a Win Server 2008 R2 system for use with Team Foundation source code control. In order to give my team-mates the right to connect, I had to create a user account for each person, 10 in total. (I can't, and I don't want to create a domain).  Now, after doing this, all user accounts are displayed in the login screen.  What can I do so that all the accounts are not displayed there?


Is there a way to easily compute  (or the cumulative distribution function of the normal law) in LaTeX?  Currently, I use pgf to make computation, but I did not find a way to compute erf using pgf.  I would be happy to use any package that is available to compute erf, or any custom solution to compute that function.


is may you reply to my email grammatically correct?

I'm curious if "May you" + verb is grammatically correct - any comments?  Thank you.


I want to redirect all traffic from the root of my website to a subfolder on the same domain using .htaccess  Can someone help me out here?


I have an irritating friend of mine who has evil eye on my unlimited data plan. I have a few time asked him to do his own recharge but he tends not to. It's so irritating when he asks to tether.   Can I limit my download speed to 1 kbps? Or maybe 1/2?


f is differentiable, $f'$ is continuous, $f_n(x) = \frac{f(x+\frac{1}{n}) - f(x)}{\frac{1}{n}}$. Show that $f_n \rightrightarrows f'$

Let the function $f : \mathbb{R} \to \mathbb{R}$ be differentiable and let $f'$ be a uniformly continuous function. For each $n \in \mathbb{N}$, let the function $f_n : \mathbb{R} \to \mathbb{R}$ be defined by the formula: $$f_n(x) = \frac{f(x+\frac{1}{n}) - f(x)}{\frac{1}{n}}$$ Show that $f_n \rightrightarrows f'$. Give an example illustrating the necessity of the assumption of uniform continuity of the function $f'$. I see that the $f_n(x)$ formula is a formula for derivatives of $f$. If it's not tricky I think that I have no problem to show that pointwise. However, I don't know how to prove the uniform continuity using the definition with $\epsilon$.


Mouse-over truncated messages on star wall to see full message

Sometimes comments are too long to fit on the star wall, and are truncated with "...":    It would be nice if holding the mouse over these showed a tooltip or something with the full message text, or if some other way of expanding the message was provided.  The messages can currently be viewed by clicking the timestamp then viewing the whole thing in the transcript. Not difficult, really, but a little cumbersome.  (Unless this feature exists already, and I missed it, in which case: Oops.)


Rules for the usage of "me" VS. "myself"?

What are general guidelines for the use of "me" and "myself"?     Did I describe me or did I describe Maria?   OR     Did I describe myself or did I describe Maria?


Quantum spin in a rotating reference frame

Rather predictably, I'm having a hard time understanding quantum spin. I know that it has units of angular momentum and relates to rotation, but that it can't be thought of as the actual spin of a particle with real size. Also, I understand that it's quantized.  What I'm wondering is, what happens to quantum spin in a rotating frame of reference?  Specifically, are there (rotating) frames of reference in which (for instance) an electron has spin that isn't half-integer? Is there a frame of reference rotating about a single electron such that that one electron acts like a spin-0 particle?


I think the title is self-explanatory but let me add more info:  Ubuntu 12.10 64bit   When I delete a file and then use graphical file manager (nautilus, nemo, etc...) the file does not appear to exist, which is what I expect when deleting a file. However, when I use terminal and look at files (using "ls" or "la" command) I can see the deleted files with "~" added after their names. For instance, a file named "Test.txt" will have a copy named "Test.txt~" after deletion.  Is this a bug? Why don't those files get deleted even after some time?


Is there any way to get back the old style Gmail reply and compose boxes?

Is there any way besides using a 3rd party email application to revert Gmail to the old-style compose and reply email boxes - the style that allows you to use your full screen?   It drives me absolutely insane when a company makes an 'enhancement' and reduces usable window space.  If I am writing a long email I want to be able to use the maximum amount of window space and not be crammed into something that is 25% of my monitor size.


How to prove that the limit of an $n$-gon is a circle?

How does one prove that a regular $n$-gon with perimeter $1$, approaches (becomes) a circle as $n$ goes to (or if $n$ is) infinity?  It is not enough to prove that all points become equal distance to origin, since this also holds for the limiting object of the graph of largest area drawn on the square graph and enclosed by a circle as we make the squares smaller and smaller.  Is the circle the only possible object with all points distance $r$ from another, and total perimeter $2\pi r$?


NullPointerException with zxing library for QR scanning (android app)

I need an independent QR scanner in my app, so I've added the zxing library to my Android app - I've followed this  - I added the dependencies in build.gradle, and this is how I call the method:     btnScanQR.setOnClickListener(new View.OnClickListener() {         @Override         public void onClick(View v) {             new IntentIntegrator(MainScreenActivity.this).initiateScan(); // `this` is the current Activity         }     });  // Get the results: @Override protected void onActivityResult(int requestCode, int resultCode, Intent data) {     IntentResult result = IntentIntegrator.parseActivityResult(requestCode, resultCode, data);     if(result != null) {         if(result.getContents() == null) {             Toast.makeText(this, "Cancelled", Toast.LENGTH_LONG).show();         } else {             Toast.makeText(this, "Scanned: " + result.getContents(), Toast.LENGTH_LONG).show();         }     } else {         super.onActivityResult(requestCode, resultCode, data);     } }   So it's basically exactly like on their github page, so there shouldn't be any problems, right?   However, I get this error when I try to open the scanner through my app, and I can't seem to find any solutions online to this exact problem:       CameraInstance: Configuring camera     W/CameraManager: Failed to set rotation.     W/CameraManager: Camera rejected even safe-mode parameters! No configuration     E/CameraInstance: Failed to configure camera  java.lang.NullPointerException: Attempt to invoke virtual method 'android.hardware.Camera$Parameters android.hardware.Camera.getParameters()' on a null object reference                                                                       at com.journeyapps.barcodescanner.camera.CameraManager.setParameters(CameraManager.java:353)                                                                       at com.journeyapps.barcodescanner.camera.CameraManager.configure(CameraManager.java:139)                                                                       at com.journeyapps.barcodescanner.camera.CameraInstance$4.run(CameraInstance.java:171)                                                                        at android.os.Handler.handleCallback(Handler.java:739)                                                                        at android.os.Handler.dispatchMessage(Handler.java:95)                                                                        at android.os.Looper.loop(Looper.java:148)                                                                        at android.os.HandlerThread.run(HandlerThread.java:61)     D/CameraPreview: pause()     D/CameraInstance: Closing camera     D/CameraPreview: pause()   What is the cause of this (is it because it fails to rotate?) and how could I fix this? I've tried changing the orientation like it says on zxings github page with this:  <activity     android:name="com.journeyapps.barcodescanner.CaptureActivity"     android:screenOrientation="fullSensor"     tools:replace="screenOrientation" />   IntentIntegrator integrator = new IntentIntegrator(this); integrator.setOrientationLocked(false); integrator.initiateScan();   But I keep getting the same error! Please help :(


Learning Python programming with generic GIS goals in mind?

In your opinion, what is the best book/site to learn Python with GIS goals in mind?  By "best", I mean:   not very long (book) easy to understand (book/site) good practical examples (book/site)   For answers specific to learning how to use the ArcPy site-package for Python to customize ArcGIS for Desktop there is a separate Q&A:


How to find the view/page/module that's generating a SQL statement

I have newrelic performance monitoring with my Pantheon hosting account. It shows "slow SQL" reports but I can't tell which page, view or module is generating a SQL statement.  For example:     SELECT node.nid AS nid, node.title AS node_title, users_node.name AS   users_node_name, users_node.uid AS users_node_uid, node.created AS   node_created, '?' AS field_data_field_photo_node_entity_type FROM node   node INNER JOIN users users_node ON node.uid = users_node.uid LEFT   JOIN field_data_field_photo_topic field_data_field_photo_topic ON   node.nid = field_data_field_photo_topic.entity_id AND   field_data_field_photo_topic.field_photo_topic_tid =   :views_join_condition_? WHERE (( (node.status =   :db_condition_placeholder_?) AND (users_node.uid = :users_uid? )   )AND(( (node.type IN (:db_condition_placeholder_?)) AND   (field_data_field_photo_topic.field_photo_topic_tid IS NULL ) )))   ORDER BY node_created DESC LIMIT ? OFFSET ?   How could I get that info?


T4 and first countable topology that is non metrizable

Does anyone know any example of such topology?


I replaced tha hard drive on my Mid-2010 iMac because it failed and was unrecoverable.  Now I need to install Mac Os High Sierra (the latest for Mid 2010), using a USB drive I have to create on Windows, because I have no other Macs.  Now, I know I can use TransMac, but the problem is that I can't find any install DMG online. I also tried to search for Sierra instead of High Sierra, but I couldn't find nothing.  I can't download Sierra from Mac App Store, because I'd need a Mac I don't have right now.   So the main question is: where can I find the DMG file I can use to create the USB recovery drive with TransMac?  Thank you and sorry for bad english!


Idiom request for describing someone who just makes frustrating or disappointing remarks

I'm looking for an idiom or expression that means someone just makes frustrating or disappointing remarks. Maybe some of you have watched the TV cartoon  in which there was as a character named "Glum". He was all the time pessimistic about everything and used statements like:  "We'll never make it"; "We'll never get out of here alive"; and "We're doomed."  I want to use that idiom or expression in examples like this:  Husband: After getting my promotion, I will take you to a fantastic trip. Wife: Oh, stop talking nonsense! I know It won't never happen, it's impossible you get a promotion. Husband: You remind me of 'Glum'! All the time _____ (i.e. acting like Glum, just having a gloomy outlook on everything). Please stop using such remarks and be a little optimistic!  I have found  for describing such people. PS: We Iranians use an expression that literally says "to read a frustrating or disappointing verse". So in above example, the husband might reply like this:  Hey Glum, the only thing you know is reading a frustrating/ disappointing verse!  (Sometimes we call these people 'Glum'.)


Need to check if Indian Passport holder have USED/EXPIRED UK Visa and travelling on below routing, does he require airport side transit visa at FRA  DEL -x FRA -x PTY - POS  Note : Connecting flight from FRA to PTY will be within 12hrs


For each $\alpha\in I$, let $A_\alpha$ be a subset of some nonempty set $S$. So if $I=\emptyset$, then $$ \bigcup_{\alpha\in I} A_\alpha=\emptyset $$ and $$ \bigcap_{\alpha\in I} A_\alpha=S. $$  Why is this true?


Time Machine is Determined to Delete Old Backups to Make Space it Doesn't Need

Okay, so my machine suffered a power loss this morning, and when Time Machine went to back-up it seems to have decided it can't trust the usual event log that it uses:  02/10/2014 14:56:43.351 com.apple.backupd[63107]: Event store UUIDs don't match for volume: Macintosh HD   It then proceeds to do a deep-scan, which is understandable I suppose.  02/10/2014 14:56:43.428 com.apple.backupd[63107]: Deep event scan at path:/ reason:must scan subdirs|new event db| 02/10/2014 15:04:58.809 com.apple.backupd[63107]: Finished scan 02/10/2014 15:10:53.693 com.apple.backupd[63107]: Found 402101 files (1.8 TB) needing backup 02/10/2014 15:10:53.747 com.apple.backupd[63107]: 2.16 TB required (including padding), 1.04 TB available   However, the required space estimate is far too high; my back-up volume's total size is only 3tb, and the total data on Macintosh HD is around 2tb, this means that if I let Time Machine continue to run it's going to delete all of my backup history and then fail with a warning that it can't backup because there isn't enough space.  This is clearly wrong however, as the back-ups on the disk are valid, and should be matching most of the files found on Macintosh HD.  Is there a way I can get Time Machine to recognise this and adjust its estimate accordingly? If not then I'm going to have to start fresh with a new back-up, but that will take days to get up to date again!  [edit] I've just tried using tmutil associatedisk -a and tmutil inheritbackup to no avail, after an even longer deep scan it just starts trying to discard old backups again.


Prove that $$3^n > n^2$$  I am using induction and I understand that when $n=1$ it is true. The induction hypothesis is when $n=k$ so $3^k>k^2$. So for the induction step we have $n=k+1$ so  $3^{k+1} > (k+1)^2$ which is equal to $3\cdot3^k > k^2+2k+1$. I know you multiple both sides of the induction hypothesis by $3$ but I'm not sure what to do next.


Minimal polynomials and cyclic subspaces

I'm trying to make my way through two problems in Curtis's Linear Algebra, chapter 25.  One of the two problems is this one, #5:     Prove that $V$ is cyclic relative to a linear transformation $T \in \mathcal{L}(V)$ if and only if the minimal polynomial of $T$ is equal to the characteristic polynomial.   Part of the issue is that I'm not really sure what it's asking. The statement that $V$ is cyclic seems to suggest that the entire vector space (say it has dimension $n$) is generated by some vector $v \in V$, along with $Tv, T^2v, \ldots T^{n-1}v$; Curtis's definition of a cyclic subspace (as opposed to a space, though I can't see why there should be a difference) seems to reinforce this:     A $T$-invariant subspace $V_1$ of $V$ is called cyclic relative to $T$ if $V_1 \neq 0$ and there exists a vector $v_1 \in V_1$ such that $V_1$ is generated by $\{ v_1, Tv_1, T^2v_1, \ldots T^kv_1 \}$ for some $k$.   However, I've seen several examples that seem to directly contradict this interpretation. For example, we recently had a take-home midterm that required we find elementary divisors, rational canonical form, etc., of a $6\times 6$ matrix; a classmate who received a perfect score on her test found that her matrix's characteristic polynomial was equal to its minimal polynomial — it was $(x+8)^2 (x+14)^2 (x^2+61x+80)$ — and yet the vector space could be written as $\left< v_6 \right> \oplus \left< v_4 \right> \oplus \left< -v_2+v_3+v_6 \right>$ — i.e., as the direct sum of three cyclic subspaces, not as one cyclic subspace.  So that suggests that "$V$ is cyclic" might mean the direct sum of cyclic subspaces. However, while working on the exercise that follows (#6), I came across this:  $$S= \left(\begin{array}{ccc} -1 & 0 & 0 & 0\\ 0 & 1 & 0 & 0\\ 0 & 0 & 1 & 0\\ 0 & 0 & 0 & 2 \end{array}\right)$$  Here, the characteristic polynomial is not equal to the minimal polynomial, which is $m(x) = (x-1)(x+1)(x+2)$. The eigenspace associated with $\lambda = 1$ has dimension $2$. And so it seems as though, if $V$ has basis $\{ v_1, v_2, v_3, v_4 \}$, we can write $V = \left< v_1 \right> \oplus \left< v_2 \right> \oplus \left< v_3 \right> \oplus \left< v_4 \right> $. This would seem to contradict my second interpretation of the original question.  Obviously I'm missing something. Could someone fill me in on what it might be? (I've tried to be thorough, but I'm also trying not to make this ridiculously long; if I've left out necessary information, I'll be happy to append it.)


When to scale or standardize data in regression

Many statistical software ask whether to standardize data or no:   What is a general rule to when data should be standardized? Do we standardize categorical variables? Is there a difference in how standardization effects or is interpreted in   different regressions (linear, logistic, cox)


Disable Drag and Drop Functionality In Document Library in SharePoint 2013

In SharePoint we have default functionality that we can drag and drop documents in document library.  I want to disable drag and drop functionality. How can I do that?  I do not want to change in drag and drop's js that is reside in layout folder. Because it will effect on entire farm.   I want to change for specific site collection and only for document library.


How to restore the original size of this flash drive?

Using GParted:    This flash drive is a 1GB Kingston flash drive, in GParted it shows 8MB of space remaining, and when I try to create a partition table for it, it loads but nothing changes at all, so I can't create a partition for this disk.  I just want to use this flash drive normally for saving files, or maybe using Porteus, I just want to make this flash drive a normal one.


I have a .sql file with insert statements in C:\sqldata\MyData.sql. I need to insert data into sqlite database in my Android App using this .sql file.   How could I do this?


Does by 2010 for example means before 2010? I read a post here that by Tuesday means before Tuesday. I would like to know are they the same?  Best,


How is "it's" different from "its"? They look pretty much the same. How do they work? For example, in sentences such as:  It's collar was shaking.   Its collar was shaking.


Reword "Would you like to automatically move this discussion to chat?” so it is clear what it does

My suggestion is to change     Please avoid extended discussions in comments. Would you like to automatically move this discussion to chat?   to     Please avoid extended discussions in comments. Would you like to continue this discussion in chat?   When I have used this option for the first time, I was sure that comments will be removed from the post after moving them to the chat. And it appears that  the .


Wouldn't it be a good idea to be able to vote for questions to be moved to any Stack Exchange site? For example, I just voted  as off topic, but that was all I could do. I wish I could've voted it be moved to .  It's OK to have the predefined list of sites that is now when voting to move, but it would be nice to have a more link, where we could pick any Stack Exchange site.  Here's a quick mockup of how I see this implemented:    When the more link is clicked, a list of all the Stack Exchange sites should appear.


Ubuntu 13.04 Install says there is "Not Enough Space"

"Not Enough Space"? I have plenty of space! What space is it talking about? How can I fix it?  Not too much additional info to give:  For starters, my /boot area is 243 Mib according to GParted.   I clicked the Upgrade button on the Update window It proceeded to download some workfiles It started the Upgrade process Showed a dialog with a list of things it was going to do     (Upgrading Ubuntu to version 13.04) Step 1 was finished OK (Preparing to upgrade) Step 2 almost finished (Setting new software channels) Then it crashed at sub-step "Calculating the changes"   Error text:  Not enough free disk space     The upgrade has aborted. The upgrade needs a total of 26.0 M free   space on disk '/boot'. Please free at least an additional 5,029 k of   disk space on '/boot'. Empty your trash and remove temporary packages   of former installations using 'sudo apt-get clean'.


Is there a positive function $f$ on real line such that $f(x)f(y)\le|x-y|, \forall x\in \mathbb Q , \forall y \in \mathbb R \setminus \mathbb Q$?

Does there exist a  function $f:\mathbb R \to (0,\infty)$ such that $f(x)f(y)\le|x-y|, \forall x\in \mathbb Q , \forall y \in \mathbb R \setminus \mathbb Q$ ?


I am looking for a regular expression that will extract the first word containing the character "@" on a given string. Additionally, it must not return the character "+" that prefixes words (except the first).  1) If I have the following string:  test@example.com +555 +blabla +@gmail.com   It must return: test@example.com  2) And if I have this one:  555 +@gmail.com +test@example.com   I want to get: @gmail.com  What I tried was \b.*@.*\b


For which $n\in\mathbb{N}$ is $(n+2)\mid(n^3+14)$ true?

Tried substitution $n+2=p$, but it only gets more complicated.   For   $ n=1 $ this is true, but how can I find other  $ n$'s?


I've been battling the castle guards for ages and I have been getting no where! just losing a bunch of candies from all the health potion making. What is the quickest way to beat all the guards?


nth derivative of $\frac{e^x−1}{x}$ (both taylor series and finite sum)

Consider the functiong $g(x) =\frac{e^x−1}{x}$.  Find a general formula for $g^{(n)}(x)$and prove that this formula is correct.  If you want it as a  finite sum,  Based on guess and check, I think this one would work:  $$\frac{d^n}{dx^n}\frac{e^x−1}{x}=\frac{e^xn!(-1)^n+n!(-1)^{n+1}}{x^{n+1}}+ \frac{e^x}{x^{n+1}}\sum_{j=1}^{n}\frac{x^jn!(-1)^{n-j}}{j!}$$


Why didn't anyone else hear the Basilisk hiss?

I understand that as Harry can speak and understand Parseltongue, he could hear the Basilisk's voice from through the walls.   (So, people who can't understand Parseltongue would hear it speak, as a hiss.)  But, when a basilisk is speaking, it means that people who aren't Parseltongue should hear a hissing sound?   Then, why didn't Ron and Hermione hear the hissing sound, even though when they are straining their ears to hear one?    Some points to keep in mind:   The basilisk spoke only to Harry, as it's on a mission. So, it might not have even hissed apart from the two occasions when it spoke(or inform?) to Harry through the walls/pipes. []


Ball & Chute Interaction - Ball "sits on top" of chute

I'm very new to Blender, and I want to roll a ball down a chute. I stretched out a cube, deleted three of its faces, then smoothed it out to make a trough shape & solidified it. Then I made a cylinder, deleted the face on either edge, and solidified it into a tube. Both are set as passive rigid bodies.  My ball does not recognize the empty space these deletions have created, however. If I try to drop my ball into the chute,  If I try to put the ball "into" the trough instead of dropping it in,   I think you can tell from the gifs what I'm trying to accomplish. Any idea what I'm doing wrong?


I would like to append an arrow at the end of my plot, in the direction of the path.  Here my snippet:  \begin{tikzpicture}      \draw[line width=2pt, color=red, smooth,domain=0.2*pi:0.8*pi,->]  plot (\x,{0.75*sin(\x r)}); \end{tikzpicture}   But unfortunately, the arrow looks straight up, instead of looking along the path.


Using the time-independent Shrödinger equation to model photons

The time-independent Shrödinger equation (TISE) is   $$\dfrac{-\hbar^2}{2m} \nabla^2 \psi + V \psi = E \psi,$$  where $m$ is the mass of the particle.  I just had a thought: If $m$ is the particle's mass, then the TISE is invalid for photons, since they're massless! But I know that the Shrödinger equation is used to model photons. So how can this be?


In The javascript code variable newFunc is declared as const on the next line it turns to a function can you explain?

I want to know how newFunc(); works. Is it a function or not? const first = () =>  {     const greet = 'Hi';     const second = () => {         alert(greet);     }     return second; }   const newFunc = first(); newFunc();


Why can't I piggy back / Daisy chain surge protectors or a surge protector and an ups?

Assuming I don't exceed the wattage rating of the whole system then why can't a piggy back let say ups to a surge suppressor in order to let say increase the protection of my system.  Let's assume: I have 1500va APS UPS that has built in surge suppressor and now I want to plug in a Tripp-Lite 6 outlet metal housed surge suppressor to single output of the battery side of the ups.  Everything else is connected to the Tripp lite and nothing else besides the Tripp lite is connected to the ups.  The total draw is let say 1500watts.   So what is negative about piggy backing surge suppressors?  Can I use the above setup without any detrimental effects.


How to select what tag should be "primary" for the question?

When a user visits a question, the HTML page header contains the whole title of a question, prepended by a tag, one of those the question bears. How to determine which tag is displayed there, and how to choose a tag that an asker desires to be displayed in the page header?   This is also frustrating when you open multiple tabs of SO, searching for a problem regarding one language, then accidentally close the one you really needed because it displays some tag that's relevant to the question but is completely irrelevant to the problem you face. Is there a criteria which tag should be displayed if there are multiple tags assigned to the question? So far I am unable to guess which criteria is applied to select a tag that's displayed. For example,  on ruSO displays cmd tag, which is not most popular among selected tags (89 question against 540 for xml), is not the first and not the last tag listed under the question.


What is the reasoning behind limiting "recidivists" to post one question per week?

currently restricts recreated accounts to "posting only one question per week..."  I would like to understand why this rate was picked, and not, say, once a day or once a month?  The reason why I ask is that some users limited or banned at Stack Overflow . I expect that learning more about the limitation would help me better understand its impact on Programmers.


I have some data in input that I'll have to use to set all properties of a POJO. The POJO might be partially set. My problem is to set the property only if related input data is not null. I know I can do this in two ways:  if (input != null) {     obj.setData(input); }   or   obj.setData(input != null ? input : obj.getData());   I'm looking for a solution less ugly and better for objects with a big number of properties to set.


For some reason, I discovered I have an old iCloud email that is associated with my account. However, the section of the email before the domain (XXXX@icloud.com) is based on a retired AOL email that I haven't used in about 10 years. How do I either delete this email from my account (unsure what this is associated with as a side note, my Apple ID?) or change this email if I am forced to keep it?


How can I get coordinates of where I was at a specific point in time?

I built an amazing underground house but accidentally fell out of the world. How do I get my coordinates at a specific moment in time so I can get back to my house without scouring the entire world?  I need to know exactly where I was at a certain tick in Minecraft. How do I determine this?


When do you use "relate to" versus "relate with"?

I have a feeling that maybe you use one preposition with people, and the other with situations. For example, you might relate with a student who's nervous about an exam, whereas you relate to test anxiety. Am I correct in assuming this? If not, what grammatical rules determine whether you use "to" or "with" following the verb "relate"?


Is it Possible to Rollback Table Deletion in Mysql

We Have Mistakenly Dropped a Table in my DB and am using MySql . Is it Possible to ROLL Back or any other options . Please Provide your Valuable Suggestions


What is the spatial representation of a momentum eigenstate and why?

The short version of my question: What is $\langle x | p \rangle$ and why does it look like it looks?  Now the long version: Let $|x\rangle$ be the orthonormalized eigenstates and of the spatial operator $\hat x$ with eigenvalues x and $|p\rangle$ be the orthonormalized eigenstates and of the momentum operator $\hat p$ with eigenvalues p. I'm "guessing" that $$ \tag{a}\label{eq:x_on_p} \langle x | p \rangle = \frac 1 {\sqrt{(2 \pi)^d \hbar}} e^{ipx/\hbar},  $$ where $d$ is the number of spatial dimensions, but I haven't found a convincing proof for this. So I tried to find one on my own, which has a problem that I want to share, hoping to find a solution with your help.  As a postulate I'm assuming that $$  \tag{b}\label{eq:x_on_p_operator} \langle x | \hat p = -i \hbar \nabla \langle x |. $$  Using this, I now want to find out how $\langle x | p \rangle$ looks. Starting with the equation $$ \hat p | p \rangle = p | p \rangle,$$ multiplying it with $\langle x|$ from the left and using \eqref{eq:x_on_p_operator} leads to $$   -i \hbar \nabla_x \langle x|p \rangle = p \langle x|p \rangle. $$ This ODE has the solution $$   \tag{c}\label{eq:unnormalized_solution}   \langle x|p \rangle = C \exp\left( i p x / \hbar \right) $$ with $C$ being a constant. Now let's assume that $| q \rangle$ are the same eigenstates of $\hat p$ as our $|p\rangle$, but of course with eigenvalues $q$. Then $$ \tag{d}\label{eq:one_equals} 1  =  \int \text{d} q \ | q \rangle \langle q | \int \text{d} x \ | x \rangle \langle x | \int \text{d} p \ | p \rangle \langle p | \overset{\eqref{eq:unnormalized_solution}} =  |C|^2 \int \text{d} q  \int \text{d} p \ | q \rangle \langle p |  \int \text{d} x \ e^{i(p-q)x/\hbar} . $$ Now I'm using the fact, that the delta distribution has a representation $$ \delta(p-q) = \frac 1 {(2\pi)^d \hbar} \int \text d x \ e^{i(p-q)x/\hbar}, $$ where $d$ is the number of dimensions of the argument $(p-q)$. Plugging that into \eqref{eq:one_equals} yields $$ |C| = \frac 1 {\sqrt{(2 \pi)^d \hbar}}. $$  This looks very close to what I wanted to proof, but i'm stuck at this point. How can I show that $C$ has no imaginary party? Usually when textbooks on QM come to this point, it's said that the complex phases of the eigenstates don't matter and can therefore chosen that $C$ appearing in \eqref{eq:unnormalized_solution} is real valued. But I think this is not the true story in this case. My thoughts go like this: Take an arbitrary $|x_0\rangle$. Then we can modify all of our $|p\rangle$s so that $C$ in $\langle x_0 | p \rangle$ is real valued. By doing so, the phases of all our $|p\rangle$ are now fixed. Now lets take a different spatial eigenstate $|x_1\rangle$. Of course we can adjust it's phase, that for some specific $|p_0\rangle$ the $C$ in $\langle x_1 | p_0\rangle$ is real, but what we need is $\langle x_1 | p \rangle$ to be real for ALL $|p\rangle$. Summing it up, it seems as the problem of making $C$ real valued can not be solved by modifying the phases of the spatial and momentum eigenstates.  Is there another way to show that $C$ is real?


Click to ROOT even without PC? How is this possible?

There are many apps which says you can root in single click, like framaroot, one click root, kingo root. I'm not sure whether everythings works, but, YouTube videos claim that. How these apps root a phone with just a single click? If a app can root a phone with a click, it can also do that without the knowledge of a user. So, How do these apps work?


Let $G$ be a group. For $c \in G$ a fixed element let us define a new operation in $G$ defined by $a*b=a\cdot c \cdot b$ Prove that the funtion $f: (G, \cdot)\longrightarrow  (G, *) $ given by $f(x)=c^{-1} \cdot x$ is an isomorphism my attempt: $f(x)=c^{-1}x $ $f(y)=c^{-1}y $ $f(x)= f(y): c^{-1}x = c^{-1}y  \Longrightarrow{x=y} $ How do I test for surjectivity and morphism? Thanks


How to check whether a variable is a class or not?

I was wondering how to check whether a variable is a class (not an instance!) or not.  I've tried to use the function isinstance(object, class_or_type_or_tuple) to do this, but I don't know what type would a class will have.  For example, in the following code  class Foo: pass   isinstance(Foo, **???**) # i want to make this return True.   I tried to substitute  "class" with ???, but I realized that class is a keyword in python.


Converting string to float using sscanf() gives slightly different results in C

I am taking numerical string as an input from user and than converting it to float with the help of sscanf() function : #include<stdio.h>  float getfloat(void);  int main() {     float a;     a=getfloat();     printf("You entered %f\n",a);     return 0; }  float getfloat(void) {     float n;     char nstr[50];     printf("Enter a numeric string\n");     gets(nstr);     sscanf(nstr,"%f",&n);     return n; }  Now let's suppose I enter a string 100.1234. After converting to float with help of sscanf when i print the float value i am getting 100.123398 as stored value. Now these are very close values but why am i not getting the same result as i entered. What is going on inside sscanf ?


Is there a name for this ambiguity problem or for the construction that solves it?

I read a sentence,     John has published research in academic journals of philosophy and law.    The author meant John has published research in academic journals of philosophy and in academic journals of law. But one could take the sentence to mean John has published research in academic journals that cover both philosophy and law.  I remember reading an article about these sorts of 'and' constructions;  I don't have any sufficiently specific keywords in mind to search for the answer.   Do you know what keywords relate to these sorts of constructions?


is there a way to find out if a drive can be ejected and removed (since it is a drive connected via USB) programatically?  If yes: how can this be done?


Can TOR Browser hide my online activity at work? Or only from the ISP?

I am not sure how TOR browser works, and wanted to know if I get it at work - will the IT guys be able to see what I am surfing? What kinda of info can they see anyhow?


Shell command output to file with command being executed

How can I output the command itself in addition to its output to a file?  I know that I can do  to capture the output. My use case is specific to pytest.  pytest /awesome_tests -k test_quick_tests -n auto &> test_output_$(date -u +"%FT%H%MZ").txt   It would be really helpful to have the command executed in the output so I knew specifically what the results were for.


For example, RSA relies on a mathematically hard problem, factoring, while ECDSA or similar rely on discrete logarithm problem.  What makes SHA-256 and similar hash functions, of the same family, secure against pre-image and collision attacks? What's the math behind it?


Is it possible to run xmonad inside unity?

I would like to have xmonad control my window behavior, but still have the ubuntu panel at the top of the screen.  Is this feasible?


A better proof for $\det(P) = \pm1$ if $P$ is an orthogonal matrix

Looking for elementary proof for $\rm~det(\textbf{P})$ = $\pm 1$ if $P$ is an orthogonal matrix.  I prefer a proof without using determinant of transpose matrix. My First Proof, with $\det(\textbf{P}^{t}) = \det(\textbf{P})$ If $P$ is orthogonal matrix,  $\textbf{P}^{t}=\textbf{P}^{-1}$. So, $$\det(\textbf{P}^{t}\textbf{P})=\det(\textbf{I}) \implies \det(\textbf{P}^{t}\textbf{P}) = 1 \implies \det(\textbf{P}^{t}) \det(\textbf{P}) = 1$$ because $ \det(\textbf{P}^{t}) = \det(\textbf{P})$. Therefore, $\det(\textbf{P}^{t})=\det(\textbf{P}) = \pm 1$. My Second Proof,  without $\det(\textbf{P}^{t}) = \det(\textbf{P})$ Let $\lambda$ be an eigenvalue for orthogonal matrix $\textbf{P}$. $$\textbf{P}\vec{v}=\lambda\vec{v},\quad\vec{v} \neq \vec{0}$$ $$\implies \rVert \textbf{P}\vec{v}\lVert = \lVert \lambda\vec{v} \lVert \implies \rVert \textbf{P}\vec{v} \lVert = \rvert \lambda \ \lvert \lVert \vec{v} \rVert = 1$$ because $\lVert \vec{v} \rVert = 1$ Therefore $\lvert \lambda \rvert = 1$ because $\textbf{P}$   is orthonormal matrix. $$\textbf{P} = \textbf{P}^{t}$$ Therefore $\textbf{P} = \textbf{U}^{t}\Lambda\textbf{U} $ $$\det(\textbf{U}^{t}\Lambda\textbf{U}) = \det(\textbf{U}^{t})\det(\Lambda)\det(\textbf{U})$$ $$\det(\textbf{U}^{t}\Lambda\textbf{U}) = \det(\textbf{U}^{t})\det(\textbf{U})\det(\Lambda)$$ $$\det(\textbf{U}^{t})\det(\textbf{U}) = 1 $$ (because $\textbf{U}$ is orthogonal matrix}) $$\det(\textbf{P}) = \det(\textbf{U}^{t}\Lambda\textbf{U}) = \det(\Lambda) = \prod_{i=1}^{n}\lambda_i = \pm 1 $$ $$\implies \det(\textbf{P}) = \pm 1$$


I have 2 BI object in different files, now I want to extend the first object with other ones.  1st Object  var BI = BI || {}; BI = {     firstInit: function () {         console.log('I am first init');     } }   Other file  2nd Object  BI = {    init: function () {      console.log('I am init');    } }   Now I want 2nd Object should contain the firstInit as well. Let me know I can explain further. I am using jQuery.


Confusion regarding fundamental particles

As per standard model, particles like electron and quarks are considered as the elementary particles (no further division into simpler particles possible).  Are those particles really elementary or people don't have enough resources (theories, instruments, energy) to break them into simpler particles at present?


How to compute $\int_0^{\infty} \ln (1 + e^{-x})\, dx$ and $\int_0^{\infty} \ln (1 - e^{-x})\, dx$?

Bierenes de Haan's book (page 377) shows that $\int_0^{\infty} \ln (1 + e^{-x})\, dx = \frac{\pi^2}{12}$, and  $\int_0^{\infty} \ln (1 - e^{-x})\, dx = -\frac{\pi^2}{6}$. Anybody know how to compute them? Thanks.


Why do using a getter for an object returns NullPointerException

I'm trying to use a getter for an object, in order to store the information of that object in another object. Yet, just by using the getter, it immediately returns a NullPointerException.   This is the code of the class that has the object as a field (and the getter):  public class NodoAnos implements Serializable { private int ano; private NodoAnos proximo; private ListaEquipos equipos;  public NodoAnos(int año)  {     this.ano = año;     this.proximo = null;     this.equipos = new ListaEquipos(); }  public int getAno()  {     return ano; }  public void setAno(int año)  {     this.ano = año; }  public ListaEquipos getEquipos() {     return equipos; }   Here are all the methods before the NullPointerException (exception in code sample 6):  Code Sample 1:  private void informacion() throws IOException, FileNotFoundException, ClassNotFoundException {     int ano = elegirAnoPopup(); //SEE CODE SAMPLE NUMBER 2     NodoAnos nodAno = new NodoAnos(ano);      nodAno = anos.buscarAños(nodAno); //SEE CODE SAMPLE NUMBER 5      datosComboBoxUniversidad(nodAno); //SEE CODE SAMPLE NUMBER 6 }   Code Sample 2:  private int elegirAnoPopup() throws IOException, FileNotFoundException, ClassNotFoundException {     NodoAnos aux = new NodoAnos(1);     List<String> choices = new ArrayList<>();      anos = anos.leerArchivo(anos); //SEE CODE SAMPLE NUMBER 3      while(aux != null)     {         aux = anos.llenarDialogo(aux); //SEE CODE SAMPLE NUMBER 4          if(aux != null)             choices.add(Integer.toString(aux.getAno()));     }      ChoiceDialog<String> dialog = new ChoiceDialog<>("Elegir año",choices);     dialog.setTitle("Consultar Informacion");     dialog.setHeaderText("Por favor, introduzca la informacion requerida");     dialog.setContentText("Introduzca el año a consultar:");      Optional<String> result = dialog.showAndWait();     return Integer.parseInt(result.get()); }   Code Sample 3:  public ListaAnos leerArchivo(ListaAnos anos) throws FileNotFoundException, IOException, ClassNotFoundException {     ListaAnos lista = anos;      try     {         FileInputStream fis = new FileInputStream("lista.DAT");         ObjectInputStream ois = new ObjectInputStream(fis);          if(ois != null)         {             ListaAnos objeto = (ListaAnos) ois.readObject();             lista = objeto;              ois.close();         }     }     catch(FileNotFoundException e)     {         System.out.println("No existe un archivo");     }      return lista; }   Code Sample 4:  public NodoAnos llenarDialogo(NodoAnos aux) {     if(aux.getAno() == 1)         aux = cabeza;     else         aux = aux.getProximo();      return aux; }   Code Sample 5:  public NodoAnos buscarAños(NodoAnos nodAño) {     NodoAnos aux = cabeza;      while(aux != null)     {         if( nodAño.getAno() == aux.getAno() )         {             return aux;         }         else         {             aux = aux.getProximo();         }     }      return null; }   Code Sample Number 6:  private void datosComboBoxUniversidad(NodoAnos nodAno) {     ListaEquipos listaEquipo = new ListaEquipos();     NodoEquipos nodEquipo = new NodoEquipos(null, 0, 0);      listaEquipo = nodAno.getEquipos(); //NULLPOINTEREXCEPTION      while(nodEquipo != null)     {         nodEquipo = listaEquipo.buscarEquipos(nodEquipo);          if(nodEquipo != null)         {             comboUniversidad.getItems().add(nodEquipo.getUniversidad());         }     }  }   IMPORTANT NOTE: nodAno is not Null. Already made sure of it. it prints as follows: torneodetenis.NodoAnos@12539123


Let ABC be a triangle in which $AB = AC$ and $\measuredangle CAB = 90^{\circ}$. Suppose $M$ and $N$ are points on the hypotenuse $BC$ such that $BM^2 + CN^2 = MN^2$. How do I  prove that $\measuredangle MAN = 45^{\circ}$.


How do I enter code between two list items?

Look below. The code block does not get recognized between a list.   The first item. The second item. bla bla bla:  from bs4 import BeautifulSoup soup = BeautifulSoup(response.text, 'lxml') csrf_token = soup.select_one('meta.x_csrf')['value'] Third item. No luck!   But it works fine after a normal paragraph:  from bs4 import BeautifulSoup soup = BeautifulSoup(response.text, 'lxml') csrf_token = soup.select_one('meta.x_csrf')['value']   Well, is it not a bug in the Markdown formatting?


Differential geometry: vector bundle cover of base that consist of charts that are also trvialising neighbourhoods

I am taking a first course in differential geometry, and we have looked at vector bundles and principle G bundles (I suppose that the following will hold for fibre bundles in general where the base is a manifold). My query concerns a point in several of the proof we have looked at, namely that we can find an open cover of the base manifold $B$, say $\{U_\alpha \}$, where the $U_\alpha \subset B$ are both coordinate charts and trivialising neighborhoods.  By trivialising neighborhood, I mean that there is a diffeomorphism $\Phi_\alpha$ such that $\Phi_\alpha : \pi^{-1}(U_\alpha) \rightarrow U_\alpha x V$ with $\pi : E \rightarrow B$ the map in the vector bundle and $V$ the typical fibre.  Naturally, it is nice if we have this is problems because then we can use local coordinates along with a chosen basis on the typical fibre, to have local coordinates on open sets of the total space $E$. We have used this assumption often when treating connections. Another case is in proving the existence of a smooth positive definite inner product on the total space E. We use this along with partition of unity, which requires the open neighborhoods that are both charts and trivialising neighborhoods to cover B.  EDIT:  I think in fact this is trivial. By virtual of being a fibre bundle, for every $p\in B$ we have an open neighborhood $p \in U \subset B$ and a corresponding local trivialisation $\phi _U$. Likewise, since $B$ is a manifold then we have an open cover of coordinate charts $V_\alpha$. Since topology is closed under finite intersection, we need simply take the intersection $U_p \cap V_\alpha$ where $p \in V_\alpha$ and take the union of these for all $p \in B$. Now we have our open cover of $B$ consisting of coordinate charts that are trivialising neihborhoods.


In which direction plants' root grow in weightlessness?

As far as I know, roots of plants grow to the direction of Earth's gravity - this is called gravitropism.  But what happens if plants are in space? Are they able to perceive gravity in state of weightlessness? Either way, where do they grow their roots in those circumstances?  Note: this question may fit better either to Space.SE or to Astronomy.SE, but I was not sure about it.


Keeping Ubuntu 17.10 Installation whilst reinstalling Windows 10

I have a single hard disk which has both Ubuntu 17.10 and Windows 10. Unfortunately, I have to go through the pain of reinstalling Windows due to some corrupt file system issue or something else that causing its performance to grind to a halt.   However, what I don't want to do is lose Ubuntu and everything that is on it. So, what I would like to do is to use my Windows bootable iso DVD disk and simply do a clean install at that location. Therefore, I on reboot I can hopefully carry on as normal.  Can someone please give me some step by step instructions?


Why does a stock price suddenly drop for no reason? There is no bad news coming out, the S and P 500 is going up. My stock dropped by 4% today. Should I be concerned there is some bad news that I don't know coming out soon?  Edit: The company is Chemours Company ticker code:CC.  Thanks for your help!


Finding the function for a given power series in $\mathbb{C}$

The question is as follows:  The power series $$\sum _{ k=0 }^{ \infty  }{ k{ z }^{ k } } $$ represents an analytic function $f$ in its disk of convergence, the disk of radius $R=1$, centered at the origin. Find $f$.  The answer is:  $$f\left( z \right) =\frac { z }{ { (1-z) }^{ 2 } } $$    I proceeded by a hand-crafted method, ie. I wrote down the beginning of $\sum _{ k=0 }^{ \infty  }{ k{ z }^{ k } } $, and just below the $\sum _{ k=0 }^{ \infty  }{ { z }^{ k } } $ and take the sum of them term by term. It yielded into an expression already known:  $$f(z) (= \sum _{ k=0 }^{ \infty  }{ k{ z }^{ k } }) = \sum _{ k=0 }^{ \infty  }{ (k+1){ z }^{ k } } - \sum _{ k=0 }^{ \infty  }{ { z }^{ k } } $$  As,  $$ \sum _{ k=0 }^{ \infty  }{ { z }^{ k } } =\frac { 1 }{ 1-z } \quad (1)$$ and $$ \sum _{ k=0 }^{ \infty  }{ (k+1){ z }^{ k } } =\frac { 1 }{ { (1-z) }^{ 2 } } \quad (2)$$  I reached the solution.  But I feel like cheating, because the conclusion about $(2)$ was evaluated in the course; also my instructor used another method for this question: She differentiated the power series and manipulated analyticity. I also tried to integrate first, then differentiate by regrouping terms, but neither could I achieve nor could I understand the professor's method.  I'd much liked you help me to find alternative solution -as my professor did- to this?


"He is no different than you and I" or "He is no different than you and me"

I have no difficulty in normal cases knowing whether to say "you and I"or "You and me." But this situation confuses me. On one hand, I can justify I by saying there is an implied "are" at the end:     He is no different than you and I are   On the other hand, this is a comparative, and if I were to change the sentence up just a bit, it feels like it would be correct to say "me":     He is the same as me


Are UK visas granted to travel to the UK usable elsewhere?

I am a Mongolian citizen currently in England on a one year visa.  Can I travel to British Virgin Islands, or other Caribbean islands that require a British visa using the visa I have for the UK, or do I need a separate visa for each country or island I visit?


I was confused by a company slogan I saw, and that made me wonder: Is it correct to write "a dream come true"?  If I was the one writing it I would use "a dream comes true" but is the initial form wrong?


Sample size and margin of error in polls and surveys

I've become interested in the way various polls and surveys are conducted. I already know something about terms like sample size, margin of error and confidence level. I don't understand why such large sample sizes are required to get low margin of error with small population size.  Let's pretend that I'm conducting a poll about political preferences in the town with population of 1000. I want the poll to reflect preferences only in this town, not the whole country, etc. I made some calculations and it seems that in order to get a result with 2% margin of error and 95% confidence I'd need 707 people in my survey, which seems extremly high (70% of population).  To get 2% margin of error with 95% confidence in the country of 40 million people, I'd need just 2401 people (0,006% of population).  I'd like to ask for a mathematical expaination about why do I need such large sample sizes in small population and why do sample sizes seem to be so similar wheter I have a population of 20000 or 100000000 for example?


Is it mathematically valid to separate variables in a differential equation?

I read the following statement in a book on Calculus, as part of my mathematics course:  Technically this separation of $\frac{dy}{dx}$ is not mathematically valid. However, the resulting integration leads to correct answer.  The book also contains the following:  To solve a differential equation by separation of variables:  get all the $x$ values on one side and all the $y$ values on the other side by multiplication and division. separate $\frac{dy}{dx}$ as if it were a fraction. integrate both sides.   Note: This box doesn't refer to a particular problem. It refers to a class of problems of differential equations which can be solved using the Method of Separation of Variables. My high school mathematics teacher told me that this is the most fundamental way to solve differential equations but the textbook says it is not mathematically valid. I am not able to understand why are certain methods being followed without having a mathematical proof. Or am I wrong?


exception when trying to use a method in java

Hi guys im trying to get back to coding after a long break and im running into some problems. Im building a program which has a library of user uploaded books(not really uploading anything) and im running into an   Exception in thread "main" java.lang.NullPointerException     at Library.beans.User.uploadBook(User.java:107)     at Library.LibraryApplication.main(LibraryApplication.java:22)   when im trying to add a new book via a user.Im using spring btw.  coding snippets  User bean @Entity @Table(name = "Users") public class User {     @Id     @GeneratedValue(strategy = GenerationType.IDENTITY)     private int id;     @Column(nullable = false, unique = true)     private String email;     @Column(nullable = false)     private String password;     @Column(nullable = false, unique = true)     private String userName; //  ** Books added to a user private library **     @ManyToMany(fetch = FetchType.EAGER, cascade = CascadeType.ALL)     private List<Book> userLibrary; //  ** Books uploaded by user **     @OneToMany(cascade = CascadeType.ALL)     private List<Book> userBooks;      public User(String email, String password, String name) {         super();         this.email = email;         this.password = password;         this.userName = name;     } public void uploadBook(Book book) {         this.userBooks.add(book);     }   Book bean  @Entity @Table(name = "Books") public class Book {     @Id     @GeneratedValue(strategy = GenerationType.IDENTITY)     private int id;     @Column(nullable = false)     private String name;     @Column(nullable = false)     private String synopsis;     @Column     private String image;     @Column     private double rating;     @Column     private GenreType genre;     @ManyToOne(fetch = FetchType.EAGER, cascade = CascadeType.ALL)     private User author;     @OneToMany(fetch = FetchType.EAGER, cascade = CascadeType.ALL)     private List<Review> reviews;   The code in main which causes the exception  User user = new User("admin", "admin", "user1");  user.uploadBook(new Book("book1", "a", "b", GenreType.Action));   Extra notes If i creat a book outside a user by (book new book) and add an author to the ctr it works one way,the book will state its author is the "user" i inputed on creation but the same "user" wont have it listed under his uploaded books list. what am i missing here?


I need help to prove the following result   Let $p$ be a prime. If a group has more than $p − 1$ elements         of order $p$, why can’t the group be cyclic?   Thanks for the help.


What is the meaning of the matrix determinant?

When studying linear algebra, you are constantly dealing with determinants. I read their definition on Wikipedia, saw all kinds of formulas, but found that if someone will ask me WHAT EXACTLY is a matrix determinant, I could not answer. All people who know math answered this question to me like this: "Well, this is such a thing, here is the formula to calculate it, it is very important in linear algebra." I understand that a determinant is the volume (or area) of a figure formed by vectors. I can’t understand why someone came up with the idea to use them. I realize that the question sounds like a request to explain the multiplication, and yet I ask it, since I am very curious about what a determinant really is.  If possible, answer as detailed and exhaustive as possible.


Checking Normality of Numerical, and Categorical Data

I have come across 3 questions on the title subject.   Why is it necessary to do a normality test? To check if data is imbalanced or not? Are these 4 methods of checking if the data follows normal distribution criteria both applicable to numerical and categorical variable? I am trying to check if the data follows normal distribution by following 4 methods.   Checking Distribution Drawing Box Plot Drawing QQ Plot Use skewness, kurtosis criteria  Skewness for Normal Dist is 0, Kurtosis for Normal Dist is 3. Is there a certain bound that I can use to guarantee that the data is normally distributed? (such as, 0 +/- 1 OR 3 +/- 1)


Stars and bars but with distinct objects

The total number of ways which 5 balls of different colors can be distributed among 3 persons so that each person gets at least one ball is..?  My attempt: So, first we can choose any three balls to allocate to any person, so $\binom{5}{3}$ and, then distribute them then in 3! ways. And, so we have, $\binom{5}{3} \cdot 3! $. Now I have two remaining balls and this I can give randomly to any of the three people. For the first ball I have three choices and so do I for the second ball. Hence,  The net number of cases is $ \binom{5}{3} \cdot 3! \cdot 3^2$ Now, I know that like the thing can happen in reverse. For example distributing three then distributing two, I could have some overlapping cases where the items which are distributed in the distributing two case is actually distributed in the distributing three step. How do I account for the overlapping case? Ans: 150 Stars and bars attempt: We have five objects and introduce two objects as dividers, subtract cases where one guy gets nothing (3 x 6!) and add cases where two people get nothing and third guy everything (3) What I am looking for : A fix to this method such that it gives me the correct answer, in the other stack post linked to this one, it has ample amount of methods based on other ways to solve it but my question here is how to fix this method.


How to return subtype in overridden method of subclass in C#?

I have a subclass with an over-ridden method that I know always returns a particular subtype of the return type declared in the base class.  If I write the code this way, it won't compile.  Since that probably doesn't make sense, let me give a code example:  class BaseReturnType { } class DerivedReturnType : BaseReturnType { }  abstract class BaseClass {     public abstract BaseReturnType PolymorphicMethod(); }  class DerivedClass : BaseClass {     // Compile Error: return type must be 'BaseReturnType' to match      // overridden member 'BaseClass.PolymorphicMethod()'     public override DerivedReturnType PolymorphicMethod() {          return new DerivedReturnType();      } }   Is there any way to accomplish this in C#?  If not, what's the best way to achieve something similar?  And why isn't it allowed?  It doesn't seem to allow any logical inconsistency, since any object returned from the over-ridden method still is BaseReturnType.  Maybe there is something I hadn't considered though.  Or maybe the reason is technological or historical.


BitLocker Drive Encryption Disappeared after Windows 8.1 Pro Upgrade

In view of the fact that I have new information about this problem, I have requested that the moderators remove this post, and have made a fresh new one. The new question can be found .  Prior to upgrading to Windows 8.1 Pro from Windows 8 Pro, BitLocker was enabled on my computer and appeared in the Control Panel, but after my upgrade, it is no longer in the Control Panel, and going to "This PC" and selecting the drive and choosing the "Manage" tab shows the BitLocker icon disabled.    What happened to BitLocker, and how do I get it back? I just checked on my mom's computer, and it is still available after the upgrade and working properly.


def my_function(fname):     print(fname + " Refsnes")  my_function("Emil") my_function("Tobias") my_function("Linus")  def my_greeting(*fname):     print(fname + " Smith")  my_greeting("Don")   The first part runs fine the second part crashes. Here are the results.  Emil Refsnes Tobias Refsnes Linus Refsnes  Traceback (most recent call last):   File "C:/Data/Python/turtleFun/kikiFunction.py", line 19, in <module>     my_greeting("Don")   File "C:/Data/Python/turtleFun/kikiFunction.py", line 17, in my_greeting     print(fname + " Smith")  TypeError: can only concatenate tuple (not "str") to tuple   I haven't created a tuple, I'm not trying to concatenate. The structures are the same but one runs and the other crashes. Why does Python 3.8.3 think I have a tuple? How do I fix? Tuples would be   myTuple = ("Don", "Fred", "George", "Paul", "John", "Ringo")


Algorithm to find the irreducible polynomial

What algorithm can be used find an irreducible polynomial of degree $n$ over the field $GF(p)$ for prime $p$. The reason I ask is I want to make a program for finite field arithmetic, but creating a field $GF(p^k)$ requires finding a irreducible polynomial. (I'm mostly interested in $GF(2^k)$.)


Units in quotient ring of $\mathbb Z[X]$

An exercise from Dummit & Foote:      Determine the units of the ring $A = \mathbb{Z}[X]/(X^{3})$ and the structure of the unit group $A^{\times}$.   Help would be great.  Thanks!


What dash should be used for attribution of authorship?

Say I want to mention an author and their work, i.e. The Beatles—Abbey Road or Herman Melville—Moby Dick, which dash should go betwixt the two?  This question has been marked as a possible duplicate of  However, my question is very different as I want to attribute a work, not a quote. The dashes are used quite differently in the opposing scenarios.   What can be inferred from the other question is that em dashes are used for quote attribution.


Section-wise Table of Contents for Articles

Is it possible to have a section-wise Table of Contents in the article class?


Create windows installation media from Ubuntu 19.04

I recently broke my windows installation but I dual boot with Ubuntu  So now I need installation media  I tried just dd'ing the iso to my USB drive on /dev/sdb1 but it refused to boot inisisting I was trying to boot uefi in bios mode (even though my pc is set up to boot either)  I really need windows for college so how do I make install media without another windows install?


Coincidence, purposeful definition, or something else in formulas for energy

In the small amount of physics that I have learned thus far, there seems to be a (possibly superficial pattern) that I have been wondering about.  The formula for the kinetic energy of a moving particle is $\frac{1}{2}mv^2$.  The formula for kinetic rotational energy is $\frac{1}{2}I\omega^2$.  The formula for energy stored in a capacitor is $\frac{1}{2}C \Delta V^2$.  The formula for energy delivered to an inductor is $\frac{1}{2}LI^2$.  Finally, everyone is aware of Einstein's famous formula $e=mc^2$.  I realize there are other energy formulas (gravitational potential energy, for example) that do not take this form, but is there some underlying reason why the formulas above take a similar form? Is it a coincidence? Or is there a motivation for physicists and textbook authors to present these formulas the way they do?


choosing $5$ non consecutive books from a shelve of $12$

In how many ways can you pick five books from a shelve with twelve books, such that no two books you pick are consecutive?   This is a problem that I have encountered in several different forms ("In how many ways can you paint five steps of a twelve step staircase, without any two consecutive steps being painted?", etc.) but the idea is the same. Here is how I solved it:  Consider a shelve with $13$ books, and then calculate the number of ways you arrange $5$ pairs and $3$ single books on that shelve. The answer to that question is ${8 \choose 5} = 56$. This question is equivalent to the original, because the pairs prevent you from choosing two consecutive books, and a shelve of $13$ books rather than $12$ is considered because otherwise, it would not be possible to choose the last book on the shelve.  This approach has its downside: writing a formal proof of this is not easy, as you can see. I tried to explain this proof to a friend of mine in order to give him the intuition ${8 \choose 5}$ is the right answer (which is usually easier than a formal proof) but I already had a hard time doing that.  My question is: Is there a more rigorous proof this is the right answer? Not only would that help me explain my answer, but it would probably allow me to use that technique to a broader range of problems.


As a student in a highschool physics class, my teacher has repeatedly told me that photons are massless. Yet, I have also heard from other sources that photons have momentum. If photons were to have momementum, that would mean that they have mass as according to p = mv.  Do photons really have mass?  Also, how would this mass be calculated?


Integrating trigonometric function problem $\int \frac{3\sin x+2\cos x}{2\sin x+3\cos x}dx$

\begin{eqnarray*} \int \frac{3\sin x+2\cos x}{2\sin x+3\cos x}dx &=&  \int \frac{(3\sin x+2\cos x)/\cos x}{(2\sin x+3\cos x)/\cos x}dx\\ \\ &=& \int \frac{3\tan x +2}{2\tan x +3} dx\\ && u = \tan x \text{ and } du = \sec^2 x \ dx  \end{eqnarray*} Am I going in the right direction with this one? It seems like not.


Is there a way of hiding my network profile from my profile on individual sites?

I participate in several of the SEs. I use different aliases for each one, but I notice that regardless, people can look at my profile on all of them once they access my profile on one of them.  On some of the technical ones, I would like to use my real name on some of the technical SEs, but at the same time, I would like to keep my real identity hidden on the philosophy SE, where I occasionally discuss my views on religion and I'm not comfortable with those being made public, given my family background.   Is there a way of hiding that particular SE from my network profile?     This seemed to be a duplicate of these tow posts:      However, there seems to be a problem:   The communities are hidden from the network profile, but posts from those hidden communities still show up in the top network questions and top network answers section in the network profile.   How can I fix this?


I'm trying to password protect a page but it doesn't seem to be working. I've set the password for the page but when you navigate to it it just loads up like normal and doesn't ask for any passwords.  This is the loop I have on my page:  <?php /**  * @package WordPress  * @subpackage Default_Theme  * Template Name: Page  */  get_header(); ?>  <?php global $post; if ( post_password_required( $post ) ) { ?>  <?php $fields = get_acf(); ?>

  <?php } else { ?>     Not passworded        <?php if (have_posts()) : ?>         <?php while (have_posts()) : the_post(); ?>          <?php endwhile; ?>     <?php endif; ?>         <?      } // Page isn't password-protected     ?> <?php get_footer(); ?>   I want to password protect everything within the page.  UPDATE:  I have custom content on the page so if possible I need to be able to wrap some code around it all.  Update:


quotient ring (R/I) has multiplicative identity but R does not

Does there exist a quotient ring R/I (I-ideal) with a multiplicative identity such that R has no multiplicative identity ?If so please give example


Canada/Chinese dual passport. Currently in the UK as Canadian student. How should I return to China?

I was born in China, immigrated to Canada and obtained Canadian citizenship. I did not renounce my Chinese citizenship. After obtaining my Canadian passport, I went back to China for a while. I later returned to Canada via the US. I have a 10-year US visa on my Chinese passport and I used to it to travel to the US. Then I flew to Canada using my Canadian passport. Therefore, the last record on my Chinese passport is me entering the US. While in Canada, I decided to go study in the UK, so I applied for a student visa using my Canadian passport.  Currently I am in the UK as a Canadian international student and have just completed most of my studies. My dissertation is on the Chinese consumer market, so I am planning to return to China to conduct my research. However, I am very confused as to how I could return to China without the Chinese authorities finding out that I have two passports. Which passport should I use to travel?


How does the CBC Padding Oracle Attack work in General?

Right now we don't have a single generalized question asking how the CBC padding oracle attack works. We have e.g.  and  but the former is distracted by the concrete values being thrown around and the specific problem the poster has and the latter is distracted by the complications introduced by ASP.NET.  So (representatively) my question is: How does the standard CBC padding oracle attack work?  Optional extensions which may be interesting here: What if the padding oracle checks the (untamperable) ciphertext length before checking padding?


Till now, I have learned a lot from this network. I believe that there is unlimited knowledge here. It is a good place to share and gain knowledge of almost all types. This network inspired all the skills in me. I wanna pay thanks to this community. Here are some gifts from me:  You can achieve all your goals with the help of this network:  (Designed with Studio Bricklink)(Rendered with Eyesight Bricklink) Also share your contributions and love for this network... Edit: Here is another version of the first model:  Edit 2: Here is the Blender edition of that model rendered with cycles:


Android 10 forensics - Root a cellphone without SD Card and without installing any external apps

I would like to root my Samsung J6 mobile phone that is running Android 10 in order to apply forensically sounding techniques on it (basically recovering deleted data etc). So far, as I researched on web, all of the rooting methods require installing of softwares such as magisk to a component such as either SD card or internal memory of mobile phone. The thing is, I don't have an SD Card inserted on the phone, and I don't want to install any external software into my cellphone memory. Is there any way to root this cell phone without installing any app into its memory(rooting via using only connected computer)? Any help will be appreciated.


Proof of orthogonality of binomial coefficients

My Combinatorics notes mention the theorem Orthogonality of Binomial Coefficients which states: $$\sum_0^n{{n \choose k}{(-1)}^kp(k)} = 0$$ where $n \in \mathbb{N}$ and $p(k) \in \mathbb{R}_{n-1}[k]$ The proof given is to differentiate $$(1-t)^n = \sum_0^n{{n \choose k}{(-1)}^kt^k}$$ $r$ times, where $r<n$ and then evaluate at $t=1$, which is where I get stuck, since all terms in the sum where $k\geq r$, the inside of the sum is $\frac{k!}{(k-r)!}$ inside the sum, while for $k<r$, the $t^k$ term becomes $0$, so I'm left with $$0 = \sum_r^n{{n \choose k}{(-1)}^k\frac{k!}{(k-r)!}}$$ which would be enough to finish the proof if the sum indices ran from $0$ as I could just use linear combinations of this sum with different values of $r$ to get any polynomial of degree at most n-1 What I want to know is how am I meant to take this derivative to keep the sum index from $0$ to $n$, or is there another step after having taken the derivative to show the equality is true for all $n-1$ degree polynomials?


Disable autostart for a service without uninstalling?

How can I disable autostart for a service without uninstalling?  For example, I'd like to leave tomcat installed, but I don't want it turning on every time I restart.


When I create VirtualHost in .conf file and /etc/init.d/apache2 reload error

My Task :  The domain www.mynewsite.lk is configured and hosted in a hosting server with the IP address 192.168.1.100. Another domain called www.mysite.lk should also be configured with the same content without any duplication. Here I want to configure the Apache server with name-based virtual hosting.  First of all I Created directory which contains the file of my site and add 'home.html' file.  sudo mkdir /var/www/website sudo vim /var/www/website/home.html   After I created new virtual host file as default.conf in /etc/apache2/sites-available folder and it is look like  <VirtualHost 192.168.1.100>      ServerAdmin webmast@new.lk      DocumentRoot /var/www/website      DirectoryIndex home.html      ServerName www.mynewsite.lk      Serveralias www.mysite.lk      ErrorLog /var/log/error/website/error.log      CustomLog combined </VirtualHost>   Next I created directories to hold 'Error.log'      sudo mkdir /var/log/error     sudo mkdir /var/log/error/website   Then I set the DNS using sudo vim /etc/hosts and I added following line that file      192.168.1.100 www.mysite.lk www.mynewsite.lk   After I enabled the default.conf file that I created using sudo a2ensite default.conf command  Then I run the this command  sudo ifconfig vmnet0: 192.168.1.100 netmask 255.255.255.0 up   And last I reloaded the apache server using sudo /etc/init.d/apache2 reload command  I had an error as Job for apache2.service failed. See 'systemctl status apache2.service' and 'journalctl -xn' for details.  what do I do to make this error...? Please help me to complete my task. Is there an any error I created .conf <VirtualHost> ...?


Looking for 1970's SF novel title where people travel to other planets by transmitting their consciousness to a replica body at the destination

This was a 'young-adult' SF novel I read in the late 1970's, about the same time I was reading Voorloper by Andre Norton, Madeleine L'engle's Wrinkle In Time books and the Dragonfall 5 young adult novels. so I am not sure if it is actually one of the Dragonfall 5 stories, but I can't confirm it is or isn't by reading available synposes online.   As I recall, the story went something like this...    * SOME SPOILERS BELOW *  A young person and sibling - I think female protag and younger brother, but not sure - is scheduled to visit their aunt and uncle on another planet but to make the voyage in a timely fashion, must utilize this new consciousness transference technology to transmit their consciousness across the cosmos to a host replica body at the destination. After arriving at the destination the protagonist is impressed by their new body and is aware of the only way to tell they are in a replicant body is a small seam, scar or patch on their back, I think near the top of their spine, just below the collar of whatever clothing they wore.  The mystery begins when the protagonist realizes their hosts also sport the same scar when they should legitimately be in their real bodies.  The plot thickens when the protag or sibling finds a room of people in stasis when their replicant counterparts are roaming the same planet, and is subsequently caught in the act.  Sadly, I do not remember anything else, including the reasoning behind the deception.  I was quite young when I read this novel, so I probably got some of the details mixed up, but would love to know the name and author of the novel if anyone remembers.


Does the effect of field travels faster than light?

As I was going through some work of my college level courses of fundamental physics, the formula caught my attention $F={G}\frac{Mm}{r^s}$. "r" seems can be any value; there would still be an output for F. Does that mean when r (the distance between two objects) changed from $6*10^9$ m to $6.1*10^9$ (assuming the object moved), the corresponding forces between the two object will also change instantly (as the instance when the object moved)? Or will there be a lag/delay, after the object was further taken apart? The same question applies to $F_E={k}\frac{Qq}{r^s}$ I know there must be some answer if I dig deep enough into Einstein's relativity theories, but I simply do not have the mathematics knowledge backing me up to understand his points nor someone trying to explain it.


Return hierarchical data from a self-referencing table (parents, children)

I have the following SQL Server 2008 table and data:  CREATE TABLE dbo.MyTable (Sno int, refid int);  INSERT INTO dbo.MyTable VALUES   (17, 8),   (16, 8),   (15, 7),   (14, 7),   (13, 6),   (12, 6),   (11, 5),   (10, 5),   (9, 4),   (8, 4),   (7, 3),   (6, 3),   (5, 2),   (4, 2),   (3, 1),   (2, 1),     (1, 0);   Note that Sno 2 and 3 are referencing Sno 1 in the same table (self-reference). So 2 and 3 are children of 1 and 1 is the parent of 2 and 3.  Requirement  I will pass in a single Sno value (e.g. 4) and I need:   All the parents of that Sno in a result set. All the children of that Sno in another result set.   I need to display the top 10 levels for each result set.  This illustrates the relationships and shows what I have tried so far:  SELECT refid FROM dbo.MyTable  WHERE Sno = (SELECT refid FROM dbo.MyTable WHERE Sno = 4); GO SELECT refid FROM dbo.MyTable WHERE Sno = 4; GO Select Sno FROM dbo.MyTable  WHERE refid = (SELECT refid FROM dbo.MyTable WHERE Sno = 4); GO


Curved arrow describing a step in a equation derivation

Is it possible to achieve something like this in LaTeX?    I want a curved arrrow pointing from 1st line to the other line and is coupled with an equation number which indicates the equation used. I want to be able to specify equation used manually like for example


Single particle passing through the double slit at a time

In modern experiments,  With the classical setup of photons or electrons passing through double slit, the intensity is kept extremely low, such that one can detect a single particle passing through the double slit at a time.   Why this fact is so important?  Here I am asking for why there is need to keep Intensity to extremely low to detect a single particle ?


explaining LARS algorithm in a simple way

I am thinking to write a LARS algorithm that uses different optimizations in each step. Can somebody briefly explain Least angel regression, LARS () to me? then I will try to write my own LARS in R. Or if you have a simple R code (that shows just core of the function and not lots of details) I will appreciate to have a look at that.


How to publish a post with empty title and empty content?

Why I'm doing this you might ask? I'm developing a website for a business with a portfolio where the gallery items are posts. These posts are populated through custom fields and category selections, nothing else.  For each item, there could be a title/content or not, it depends on the item in question and that's entirely up to the client. They are the ones populating their portfolio and not me. I'm just building the system for them to easily publish whatever they want.  I realize that WordPress might have some issues with posts without a title, that's why I implemented (in functions.php) a function to auto set a title for the post if none was attributed. This post auto title will never be shown on the website cause I look for it and omit it if it's there, otherwise, show the attributed title to the post.  The function for that is:  add_action('publish_post', 'insert_automatic_post_title', 10, 2);  function insert_automatic_post_title($postID, $post) {     if($post->post_title === '') {         $post->post_title = '['.get_the_date('d/m/Y @ H:i:s').']';          if($post->post_name == $postID) {             $post->post_name = sanitize_title($post->post_title);         }          $result = wp_update_post($post);     } }   The only problem is that if title is empty and the content is also empty (with some custom fields already defined) that function above will never be called and the post won't be published, it will remain in draft status.  The only solution I could think of was to create some shortcode like [empty_post] and ask the client to set that on the post content when he does not wish to attribute a title/content to the post. That shortcode could print something like <!-- EMPTY POST --> or even nothing at all. The fact that there's something in the post content, the function above is called, an automatic title is set and the post is published.  But I'm looking for a way where the client doesn't need to have more trouble (i.e: inserting a shortcode into the post content) than what's needed, I want it to be as simple as possible. Without messing with WordPress source code of course.  Can anyone think of another way with actions/filters?


i have this lines of code:  $veo = mktime (0,02,0,0,0,0); $veo1 = mktime (0,03,0,0,0,0); $dif = ($veo1 - $veo); echo date("H:i",strtotime($dif));   The output is: 18:00 when it should be 00:01  Can you please help me?  I need to calculate the difference between those two times (of course in this example is easy)  Thanks


"I bought (or) have bought all their records after the concert"

I have bought all their records after the concert. I bought all their records after the concert.  Which one is correct? I understand when we use the present perfect and when the past simple, I just wanted to know if the expression 'after the concert' could also mean the period of time since the concert and up to the present day? Would that allow the use of the present perfect?


Find a normal subgroup in $A_4$ and identify the quotient of $A_4$ by this normal subgroup  How do you find a normal subgroup in $A_4$? What I did is that I listed all the combinations of two cycles. For example, $(12)(34), (13)(24)..(34)(12)$. So there are 12 elements in $A_4$ From here, how do I find a normal subgroup other than trivial ones? I can't check every element that satisfies $gH = Hg$ where $H$ is a normal subgroup and $g \in A_4$.