I was having issues getting SSH to work under my WSL Ubuntu 18.04.3 LTS, I was getting connection refused all the time, so I found , which is to just:   sudo apt-get remove openssh-client openssh-server sudo apt-get install openssh-client openssh-server    remove works, but install gives me:  sudo apt-get install openssh-client openssh-server Reading package lists... Done Building dependency tree Reading state information... Done The following additional packages will be installed: openssh-sftp-server ssh-import-id Suggested packages: keychain libpam-ssh monkeysphere ssh-askpass molly-guard rssh E: Could not read response to hello message from hook [ ! -f /usr/bin/snap ] || /usr/bin/snap advise-snap --from-apt 2>/dev/null || true: Success E: Could not read response to hello message from hook [ ! -f /usr/bin/snap ] || /usr/bin/snap advise-snap --from-apt 2>/dev/null || true: Success   I tried, as suggested :  sudo dpkg --force depends -P lxd sudo dpkg --force depends -P lxd-client   But it didn't work. How can I fix this and what is going on?


Type of Visa for attending a conference in Norway

I intend to travel to Oslo next month from India to present a paper at an academic conference. The University won't pay me for this. Given that Norway doesn't have a provision for Conference Visa, should I apply for a Business Visa under short-term Visitor's visa? Should I specify the purpose of travel as 'Business' or 'Other', given that I am attending an academic and not a business conference?


I am trying to learn probability theory through self study, so I have been working through the MIT open courseware problems. I am pretty stuck on the following one    How do we find the marginal pdf of $f_Y(y)$? I know we need to integrate the joint over $X$ but I don't see how to do it?  Source:


Solving the recurrence: $T(n)=9T(n^{1/6})+\log^2(n)$

I need to solve the following function using recurrence,  $$T(n)=9T(n^{1/6})+\log^2(n)$$  I know for a fact that this is done by making a change of variable but can someone tell me how to go about this? Like questions like this in general.


How to fix "Package hyperref Error: Wrong DVI mode driver option `dvips'"?

I'm having this Error when I try to compile my .tex file with xelatex:  ! Package hyperref Error: Wrong DVI mode driver option `dvips', (hyperref)                because XeTeX is running.  See the hyperref package documentation for explanation.   This is my LaTeX header  \documentclass[10pt, a4paper, dvips,]{moderncv}  \moderncvtheme[grey, roman]{classic}  \usepackage{ifxetex} \ifxetex % only for xelatex \usepackage{xltxtra} % this should load both fontspec & xunicode \usepackage{fontspec} \setromanfont{Helvetica Neue} \else % \usepackage[utf8]{inputenc} \usepackage[T1]{fontenc} \fi % \ifxetex   Any ideas?  EDIT:  I removed the 'dvips', now I get:  ! Package hyperref Error: Wrong driver option `pdftex', (hyperref)                because pdfTeX in PDF mode is not detected.  See the hyperref package documentation for explanation.   Now my first latex line  \documentclass[10pt, a4paper]{moderncv}   Any clues ?


I'm trying to use sed to remove the rest of a line after:  HTTP1.1" 200  I can't figure out how to get sed to understand I want that whole thing as a string to match, including the double quote and the space.  An example for good measure, I want to turn:  "GET /images/loading.gif HTTP/1.1" 200 10819 "https://...   into   "GET /images/loading.gif HTTP/1.1" 200


Prove derivative is continuous - is this $\delta/\epsilon$ proof correct?

I am aware of proofs of this fact, including those given at . This question is not about how to prove it efficiently using MVT or any other clever method, but whether the proof I've sketched here is correct. This is not a duplicate, because I'm trying to get a review of my delta-epsilon reasoning.     Suppose $f$ is differentiable on an open interval $I$, $c\in I$, and $\lim_{x\to c} f'(x) = L \neq\infty$. Prove that $f'$ is continuous at $c$.   In other words, $f'$ cannot have a removable discontinuity. My intuition is this: if $x$ is close to $c$, then the quantity $\frac{f(x)-f(c)}{x-c}$ is close to $f'(x)$ and also to $f'(c)$, therefore they are close to each other. However, I'm having a hard time formalizing this.  I figure that for any $\epsilon >0$, we can find a $\delta$ so that, whenever $x$ is $\delta$-close to $c$, that puts our difference quotient $\frac{\epsilon}{2}$-close to $f'(c)$. That's true because $f'(c)$ exists.  Additionally, I can find another $\delta$ so that $f'(x)$ is $\frac{\epsilon}{2}$-close to $L$ when $x$ is $\delta$-close to $c$. That's true because the limit of $f'$ exists at $c$.  Choosing the smaller of the two $\delta$'s, the triangle inequality gives us that $|f'(c)-L|<\epsilon$, and so they're equal? Does that work?


I just stumbled upon a question from 2009 (that's what I mean by 'old'), .  I think we can all agree that by Today's standards this question would be closed (with a couple of valid reasons to choose from).  However, things were different back then - well from what I can gather, I see quite a few questions like this from back in the day. This kind of question was clearly acceptable at one point.  So, should I vote to close it or leave it be? And just for extra understanding, what would happen to any rep for that question and the answers if it was closed?


How to run a batch file without launching a "command window"?

On Windows XP, can I run a batch (.bat or .cmd) file, via a shortcut, without a "black window"?


How can I see which wifi channel is used by my laptop with Windows 8?

How can I see which wifi channel is used by my laptop with Windows 8 ?


The question was about plain  functions, not  static methods, as clarified in comments.  I understand what a static variable is, but what is a static function?  And why is it that if I declare a function, let's say void print_matrix, in let's say a.c (WITHOUT a.h) and include "a.c" -  I get "print_matrix@@....) already defined in a.obj", BUT if I declare it as static void print_matrix then it compiles?  UPDATE Just to clear things up - I know that including .c is bad, as many of you pointed out. I just do it to temporarily clear space in main.c until I have a better idea of how to group all those functions into proper .h and .c files. Just a temporary, quick solution.


I have Debian installed, and am using XFCE. How do I figure out which login manager I have installed?


How can I break hyperref URLs in a tabular environment. Consider the following example:   \documentclass{article}  \usepackage[colorlinks=true,linkcolor=black,anchorcolor=black,citecolor=black,menucolor=black,runcolor=black,urlcolor=black,bookmarks=true]{hyperref} \usepackage{breakurl}  \begin{document}  \url{http://www.avery/long/url?zz/very/very/long/this/should/break/very/long/long.html}  \begin{tabular}{l l}    A long url & \url{http://www.avery/long/url?zz/very/very/long/this/should/break/very/long/long.html}  \end{tabular}   \end{document}   The first one breaks, the second one doesn't. The output looks like:    I am using pdflatex.


Why is my ethernet interface called enp0s10 instead of eth0?

When I run ifconfig -a, I only get lo and enp0s10 interfaces, not the classical eth0  What does enp0s10 mean? Why is there no eth0?


Warm Wishes I'm a student of Electronics background and I'm very much interested in python and JavaScript I'm planning to shift to Ubuntu (20.04LTS) from Windows 10 My SSD has 101GB Free space. How much space should I allocate to Ubuntu for Machine leaning and other programming stuff? Laptop : Lenovo Legion Y540 RAM    : 8GB SSD    : 256 GB Much Thanks Vraj Parikh :)


How do I tell which wires are Red/Positive and Black/Negative on these fans?

thank you for taking the time to answer this question : Here are the fans in question... I only ask because I burnt both fans trying to find the right wires, so I guess I put the wrong wires on for too long?     **And this fan as well, if you can:   Is there anything I do with my multi-meter to see which wires are the Red/Black or Pos/Neg so I can correctly position my connections, or is there an electronic handyman's way to do it without burning the fans, is it just you try all combinations but quickly so that I don't burn the motor? There are 16 combinations and that is 16 chances to burn the motor.  OR  I will look for a guide on these models?


My reputation on Stack Overflow is not updated in Careers 2.0

Possible Duplicate:          I have created my profile in Careers 2.0. But my reputation is not updated. It shows 392 reputation while it is the reputation when I created the profile. Is there any way to update it? This is my  and here is my


Is it ethical to use a textbook required for a class that was easily found online?

I am taking an online class that requires a textbook to be purchased. I have found the book through my first simple search using the Google search engine. The website where I found the book seems to be foreign and not related to the original authors. Is it ethical for me to use the free version that I have easily found online and not purchase the book? Edit: I think there is a valid distinction between resources found on controversial websites like SciHub and the Google search engine. Furthermore, my intentions were to purchase the book before I stumbled upon it in the first few search results.


Does a nonzero Poynting vector mean that there is propagation of energy?

I don't know how this "paradox" can be solved. I'm given the following system: A permanent magnet with a magnetic field given by ($\hat{a}$ are unit vectors in the x and y directions)  $$\vec{H}=H_0\hat{a}_y$$  and a parallel plane capacitor with an electric field  $$\vec{E}=E_0\hat{a}_x$$  Poynting's vector is given by:  $$\vec{S}=\vec{E}\times\vec{H}=H_0E_0\hat{a}_z \neq 0$$  The funny part comes when the professor told that in a system like that "clearly" there is not propagation (wich I know will imply some short of energy flux) in the $z$ direction, hence the "paradox". Is there or is there not propagation of energy?  Any hint will be appreciated, thank you for your time.


Map a network drive to be used by a service

Suppose some Windows service uses code that wants mapped network drives and no UNC paths. How can I make the drive mapping available to the service's session when the service is started? Logging in as the service user and creating a persistent mapping will not establish the mapping in the context of the actual service.


I accidentally clicked reject on the suggested edit on this question(). I can't find the button to change it to Approve?


Are there any rules when to write a set of two (or more) words or abbreviations forming a name of some entity as separate, when to hyphenate, and when to stick them together?  These are my findings with ngram:        bitwise, bit-wise, but never bit wise   sci-fi, but never sci fi, or scifi   wastelands (increasingly frequent), waste lands (dying out), never waste-lands   fanfiction or fan fiction, but almost never fan-fiction, but   fanfic, never fan fic or fan-fic   read-only or read only, rarely readonly   twofold (frequently), two-fold (rarely), two fold (minimal)   bittersweet (rise), bitter-sweet (decline), bitter sweet (minimal), but...   sour-sweet (frequent), sour sweet (less frequent), soursweet (even less frequent)   all-nighter (dominant), allnighter (infrequent), all nighter (somewhat less frequent)   cross-country (gaining), crosscountry and cross country (about equal, not infrequent)   overnight (rise), over night (same as overnight until 1920, then drops to 0), very rare over-night.      In particular, if I'm coining a new blend, which rules should I follow when deciding which of these three forms to give it?


What exactly the "BatchID" is in tracking Data Views?

Lately, I have been trying to figure out the most generic query for getting tracking data into one table. As suggested in the , I have been using this join:  ... FROM _Sent s LEFT JOIN _Job as j ON s.JobID = j.JobID  LEFT JOIN _Open o ON s.JobID = o.JobID and s.ListID = o.ListID and s.BatchID = o.BatchID and s.SubscriberID = o.SubscriberID and o.IsUnique = 1 LEFT JOIN _Click c ON s.JobID = c.JobID  and s.ListID = c.ListID and s.BatchID = c.BatchID and s.SubscriberID = c.SubscriberID and c.IsUnique = 1 LEFT JOIN _bounce b ON s.JobID = b.JobID and s.ListID = b.ListID and s.BatchID = b.BatchID and s.SubscriberID = b.SubscriberID and b.IsUnique = 1   My results show the same email send, with the same JobID, sent exactly at the same time, to the same subscriber, but with different batch numbers. On top of that, only the first record has an open date:    According to documentation, BatchID   is "The batch ID number for any batches used in the send" - but what does it mean, really? And how should the  BatchID be treated in queries?   Thanks!


Apex Generation Failed (WSDL parsing error)

I'm trying to parse a simple Webservice and I'm receiving this error:      Apex Generation Failed:      Unable to find complexType for {.***}RelationshipReferenceTo   There are two lines in the WSDL file with the RelationshipReferenceTo:  <xsd:complexType name="EntityParticle"> <xsd:element name="ReferenceTo" minOccurs="0" type="tns:RelationshipReferenceTo" nillable="true"/>   And   <xsd:complexType name="FieldDefinition"> <xsd:element name="ReferenceTo" minOccurs="0" type="tns:RelationshipReferenceTo" nillable="true"/>   Can anyone help to solve this problem and allow me to parse this XML file?


Why does excel always say "..may contain features that are not compatible with CSV" when saving a CSV file?

Every CSV I've ever tried to save from Excel (2010, anyway) says filename.csv may contain features that are not compatible with CSV (Comma delimited). Do you want to keep the workbook in this format?. Why is this? Is there any way to save CSV files from excel that do not contain this message?  Even the following file (saved as a .csv) will cause this to happen, if you try to save it:  test1,test2 test3,test4   I've even just created a new spreadsheet in excel and tried to save it, and it still shows this message.   I wouldn't care, but I have someone telling me that I'm not formatting CSV files properly because excel shows that warning message, and I'm looking for ammunition to prove it's Excel and not my format (or if it actually is my format, to fix it).


Proof by induction with variable other than $n$

1) Prove that $(1+x)^{n} \geq 1 + nx$ for every $n \in \mathbb{N}$ and $x \in (-1, \infty)$  Base case: Usually for the base case I just take $n = 1$ but since there's another variable $x$, I wasn't sure which value to use for $x$, so I just set $x = -1$. Not sure if this is correct...  $(1 - 1)^{1} \geq 1 - 1$ which stands, so I proceed with the proof.  $n \rightarrow n + 1$: Assume $(1+x)^{n} \geq 1 + nx$ for every $n \in \mathbb{N}$ and $x \in (-1, \infty)$. I want to show that $(1 + x)^{n + 1} \geq 1 + (n + 1) x$ for every $n \in \mathbb{N}$ and $x \in (-1, \infty)$  $(1 + x)^{n} \cdot (1 + x) \geq (1 + nx) (1 + x)$ by the induction hypothesis  $\Rightarrow (1 + x)^{n + 1} \geq 1 + x + nx + nx^{2} \geq 1 + nx + x$  $ \square$  2) Prove that $\sum_{i = 1}^{n} i(i + 1) = n(n + 1)\frac{(n + 2)}{3}$ for all $n \in \mathbb{N}$  Base case: I get thrown off by $i$ (just like how I got throw off by $x$ in the previous problem), but I just set $i = 1$ and the base case stands:  $1( 1 + 1) = 1 \cdot 2 \cdot 1 \Rightarrow 2 = 2$  So I proceed with the proof.  $n \rightarrow n + 1$: Assume that $\sum_{i = 1}^{n} i(i + 1) = n(n + 1)\frac{(n + 2)}{3}$ for all $n \in \mathbb{N}$, want to show that...  $i(i + 1) = (n + 1)(n + 2) \frac{(n + 3)}{3}$ for all $n \in \mathbb{N}$  Is this correct? If so, wouldn't that imply $(n + 1)(n + 2) \frac{(n + 3)}{3} = n(n + 1)\frac{(n + 2)}{3}$? And that doesn't really make sense to me.


$ (X_n : n = 1, 2, ...) $ is a Markov chain with state space $(-1, 0, 1)$. Then which of the following is the correct answer?   $(sin(X_n) : n = 1, 2, ...$) is a Markov chain. $(cos(X_n) : n = 1, 2, ...$) is a Markov chain. $(|X_n| : n = 1, 2, ...$) is a Markov chain. $(X_n^2 : n = 1, 2, ...$) is a Markov chain. None of the above is correct.   Is it option 5 is the correct answer since option 1&2 are continuous, option 3&4 cannot be negative value, so that the state space cannot be -1?


Let $G$ be a non-abelian group of order $2p$ for a prime $p>2$, $A, B \leq G$ s.t $|A|=p, |B|=2$, then $AB=G$

Let $G$ be a non-abelian group of order $2p$ for a prime $p>2$.  As a small part of an exercise I am trying to show that if we take $A, B \leq G$ s.t $|A|=p, |B|=2$ (existence guranteed by Sylow) then $AB=G$. but I'm having trouble showing that. I thought about looking at $B \curvearrowright G/A$ by left multiplication, if we could show it is transitive that is enough I think.


Upgrading Cassandra from 1.1.0 to latest

I have a single node cassandra database running since 2 years now... never had any issues with it, but I would like to upgrade it to the latest cassandra (2.1.2 at the time I write those lines), of course without having to shutdown the service.  I have multiple servers at my disposal, that can be brought up to add nodes into a cluster if needed, what would be the procedure to update from my 1.1.0 version to the latest version without having any downtime ?  I know that it will be hard work, since I can't upgrading from 1.1.0 to 2.1.2 straight, I'll have to go through steps because of un-interoperable versions...


ubuntu 14.04.01 closing lid freezes laptop

I have a thinkpad yoga s1 with i7 cpu, hd4400 graphic card and Ubuntu 14.04.01 installed. The computer freezes when closing lid but if I suspend it before I close the lid, it won't freeze next time when I open the lid.  I've tried everything I can. I already updated the graphic card driver with the software provided by intel. Nothing changed. Any help please?


How to read and organize academic materials

It's a questions that haunts me for some day. I am a phd in computer science and recently when I need to read materials of different forms and take note, I somehow don't know how to decide. With the research area of mine increases, I have to remember vividly more classic materials, or systemically build a way to review them. Currently, the materials include  Papers : only-mathematical wise, normally of pages 20-40, some are typically lengthy to 60 pages. Classic books : 1) code/system wise, which I prefer to read on pc so I could probably code at the same time; 2) more mathematical wise, which I prefer to read on ipad so I could do derivation and take note.  The trade-off is that, the pc has larger screen and is more natural for me to read the books, while less convenient for me to take notes, especially for hand-written note. And it's even hard to collect the annotations and highlight on pdf reader. So I would like some sharing / suggestions / ideas of how to read materials(papers, books), organize and take notes ? Notice that this is not a question about reference manager as , it's rather to balance the usage between pc and ipad for different materials and find a systematic way to combine the note-after-reading.


I upgraded to the latest version of Kali Linux and all of a sudden I can't open up files. The file manager shows the files exist and I can get in them through the file manager but cannot do so through the CL.


If $Y_1, \ldots, Y_n$ are iid from $Pois(\lambda)$, how to show that the sample mean is a complete sufficient statistic?

If $Y_1, \ldots, Y_n$ are iid from $Pois(\lambda)$, then I know that the sum of iid poisson random variables has the $Pois(n\lambda)$ distribution. However, I am trying to show that $\bar{Y}$ is a complete sufficient statistic. This can be done by showing that $E[h(\bar{Y})]=0$ for all $\lambda$. But, without knowing the distribution of $\bar{Y}$, how is it possible to show this? Thanks!


I'm creating a program to solve problems that are in one-dimension kinematics. I initially started with solving for only one variable--solving for final position--but decided to play around and solve for final velocity. Now, I want to give the user an option. After they input the necessary known variables, prompt them to ask "Would you like to calculate final position or final velocity? " . Based on the user input I want to branch the calculations, however I don't know how to get that done.    This is what I have so far...      Scanner reader = new Scanner(System.in);      System.out.print("Enter time in seconds: ");     double time = reader.nextDouble();     System.out.print("Enter the initial position in meters: ");     double initialPosition = reader.nextDouble();     System.out.print("Enter intial velocity: ");     double initialVelocity = reader.nextDouble();     System.out.print("Enter acceleration: ");     double acceleration = reader.nextDouble();      System.out.println("What would you like to calculate? ");     System.out.print("Final position or final velocity?");     String userInput = reader.nextLine();      if (userInput == "final position") {         double finalPosition = ((0.5) * (acceleration * (time * time)) + (initialVelocity * time) + initialPosition);         System.out.print("The final position is: " + finalPosition);     } else {         double finalVelcoity = (initialVelocity + (acceleration * time));         System.out.print("The final velocity is: ");     }   I understand that the condition I set in the if-statement is not allowed, but what can I replace that with?


I have installed Ubuntu 12.04 and want to increase my swap size from 1Gb to 4Gb. how can I do this?  /dev/sda5                               partition       1046524 568284  -1


div container stretches more than 100% height

I would like to have a scrollbar for a specific div container. So what I currently have is this    $(document).ready(() => {   for (let i = 0; i < 100; i++) {     const newDiv = (`<div>Log Item</div>`);     $("#logsContainer").append(newDiv);   } }); #page {   display: grid;   grid-template-columns: 50% 50%;   height: 100%; }  @media (max-width: 800px) {   #panel {     grid-template-columns: 100%;     grid-template-rows: 50% 50%;   } }  #logsContainer {   overflow-y: scroll;   height: 100px;   /*      calc(100% - 18px);     18px because the "Logs" title has a height of 18   */ }

     Commands

       Logs

     As you can see the logs have their own scrollbar on a hardcoded height of 100px. I would like to stretch this container to the bottom (100%). Of course I have to subtract the title height from it. So if I pass in calc(100% - 18px); I get this result    $(document).ready(() => {   for (let i = 0; i < 100; i++) {     const newDiv = (`<div>Log Item</div>`);     $("#logsContainer").append(newDiv);   } }); #page {   display: grid;   grid-template-columns: 50% 50%;   height: 100%; }  @media (max-width: 800px) {   #panel {     grid-template-columns: 100%;     grid-template-rows: 50% 50%;   } }  #logsContainer {   overflow-y: scroll;   height: calc(100% - 18px); }

     Commands

       Logs

     but as you can see the div container has a height greater than 100% of the page height. How do I stretch that log container correctly?


In quantum mechanics, we know that a change of frame -- a gauge transform -- leaves the probability of an outcome measurement invariant (well, the square modulus of the wave-function, i.e. the probability), because it is just a multiplication by a phase term.   I was wondering about general relativity. Is there something left invariant by a change of frame? (of course, energy, momentum, ... are invariants of Lorentz transform, but these are special relativity examples. I guess there is something else, more intrinsic and related to the mathematical structure of the theory, like a space-time interval or something).   I've tried looking at the Landau book on field theory, but it is too dense for me to have a quick answer to this question. I have bad understanding about GR -- I apologize for that. I'm trying to understand to which respect one calls the GR theory a gauge theory: for me a gauge transform leaves something invariant.  Best regards.  EDIT: Thanks to the first answers, I think I should refine my question and first ask this: To which extent is general relativity a gauge theory? If you have good references to this topic, that would be great(The Wikipedia pages are obscure for me for the moment). Thanks in advance. Best regards.


Python function attributes - uses and abuses

Not many are aware of this feature, but Python's functions (and methods) can have . Behold:  >>> def foo(x): ...     pass ...      >>> foo.score = 10 >>> dir(foo) ['__call__', '__class__', '__delattr__', '__dict__', '__doc__', '__get__', '__getattribute__', '__hash__', '__init__', '__module__', '__name__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__setattr__', '__str__', 'func_closure', 'func_code', 'func_defaults', 'func_dict', 'func_doc', 'func_globals', 'func_name', 'score'] >>> foo.score 10 >>> foo.score += 1 >>> foo.score 11   What are the possible uses and abuses of this feature in Python ? One good use I'm aware of is 's usage of the docstring to associate a syntax rule with a method. But what about custom attributes ? Are there good reasons to use them ?


How can I run a specific command for each find result?

How would one run a specific command for each file that was found by using the find command? For the purpose of the question lets say that I would simply like to delete each file found by find.


How to discard saved password for samba share in unity?

I access samba shares from unity on Ubuntu 11.10 and saved username/pass for it. Now, I want to use a different username. Each time I go to the share and open it, it just opens without asking for credentials.  How can I force it to forget the saved credentials?


"Privileges" / "badges" links in achievements dropdown only appear in chat

I just noticed these very handy links on my achievements dropdown:  Yay! I thought. This looks really useful! It's always a pain to get to the privileges page by going via the help centre. Only problem is, this screenshot was taken in chat, the only part of SE where there aren't "privileges" and "badges" pages. (The links redirect to  and , both of which give me "Page Not Found".) And when I look at my achievements dropdown on any main site, i.e. a place where those links would actually take me somewhere useful, they don't appear. I checked this on one site where I'm a moderator; one where I'm not a mod but have all rep-based privileges; and two sites (one graduated, one beta) where I don't yet have all the privileges. Nix on all of them. Those links should either appear on the dropdown from main sites too (preferable) or not appear at all (since they're certainly useless in chat, the only place where they currently appear).


how to configure a vpn service on ubuntu

I want to make my navigation in secure way and I won't buying  vpn services as expressvpn etc.. openvpn can do this by installing on the PC that I use to navigate?  If yes can you link me any guide to configure it ?  Thanks a lot.


Mathematics behind particle on a ring in QM

In QM particle on a ring, the Schrodinger in cylindrical coordinates is given by $$\frac{d^2\psi}{d\phi^2}=\frac{-2IE}{\hbar^2}\psi$$ where $I$ is the moment of inertia. Setting $ k^2=2IE/\hbar^2$, the solution is supposed to be $\psi_k(\phi)=e^{ik\phi}/\sqrt{2\pi}, \space k\subseteq\Bbb{Z}\tag{1}$ But the general solution is:$$\psi(\phi)=c_1e^{ik\phi}+c_2e^{-ik\phi}\tag{2}$$ I am unable to derive eq(1) from eq(2) using: Normalization: $\int_0^{2\pi}|\psi|^2d\phi=1$ $\space$and Cyclic boundary condition :$\psi(\phi)=\psi(\phi+2\pi)$. Can anyone guide me with the math? Edit: I think that in , OP asks why is $c_-$ is taken as zero. As far as I know we can't take any constant to be zero. I am looking to derive eq(1) systematically, only from the two conditions stated. I think that by solving the integrals, we will eventually get $c_1=\frac{1}{\sqrt{2\pi}}$ and $c_2=0$.


How can I change or hide the ~/snap directory?

I'm not particularly fond of apps cluttering my $HOME directory with their own files or directories. It's rarely a problem, because most apps have the courtesy to hide their data by prefixing it with a dot or conforming to the ~/.config standard. But not snap.  Q1: Have I misunderstood this directory?  Is ~/snap really a directory which I'm supposed to enter and access on a daily basis on a par with ~/downloads, ~/pictures, ~/work, etc?  Q2: In any case: Can I move it e.g. ~/.snap?  I can't find anything like /etc/snap, /etc/default/snap, or ~/.config/snap to tweak things. I tried export SNAP_USER_DATA=$HOME/.snap but it didn't work.


Salutations.  I have a question about evolving certain pokemon. I have a Golbat with a CP of 242 and has two sets of attack with (10,15) power respectively. I also have another Zubat with CP of 105 but with a attack set of (10,25). Which one should I evolve? I am confused between whether to prioritize attack sets or CP for evolution. Thank you!


What's the word for telling on someone, or inform against them?

The informal word for telling on people is "dobbing" (and we call that person a "dibber-dobber", at least here in Australia.   Is there an actual word for it?   Example: Sue went to my mother and told on me when I said that I was having an abortion. Sue is such a [insert word].


Rendering produces a completely transparent image with no objects

I have a scene with animated objects. In 3d view and camera view i can see them perfectly with material and textures  but every time i render (F12) i get this result  just a transperent screen i tried to put the objects into another scene/project but they didn't appear also it once said there aren't any objects in there...


Showing $A-I$ is invertible, when $A$ is a skew-symmetric matrix

Let $A\in M_{n\times n}(\mathbb{R})$ be a skew-symmetric  matrix. show that $A-I$ is invertible and $(A-I)^{-1}(A+I)$ is an orthogonal matrix.   $|A-I|=|(A-I)^T|=|-(A+I)|=(-1)^n|A+I|$  I have no clue to solve this problem, I appreciate any help.


How many spells can a level 1 wizard learn?

I’m kind of new to the game and I want to make a wizard, but I can’t understand the part of the hero’s handbook (pg.29) where it says: “Pick a number of spells from this page equal to 3 + INT”  I have 17 + 3 INT, so what do I do?


Witcher 2 reset skill points / skills guide

Is it possible to reset skill points in Witcher 2 ? If not (still nice to know), what is the best way to spend the skills. Not that you invest in only one tree but in all of them. Can you max all skill trees. What are the most rewarding skills that should be taken first ?  Also how important is the training skill tree ?


Should you email a journal after 3 weeks kindly asking why a manuscript hasn't been sent for review, or is this too soon?

Am I simply being impatient? It's a computer science/biomedical journal. Don't want to seem pushy, yet it seems like it shouldn't take 3 weeks to see if a manuscript is within scope and decide whether to send it for review. It's been sitting at the "with editor" status with no status updates.


Easiest way to carry two laptops to India and back from USA?

I am traveling to India from US soon and I will be carrying with me a work laptop and my personal laptop. I will be bringing both the laptops back to the States with me.   What is the easiest way to explain to customs in India (and US if required) that I'm not importing these items and avoid paying the customs fee?


Highlight text and have it read back to me in Windows 7?

On my Mac, I can highlight text, hit a keyboard command, and it reads the selected text aloud. Is there an analogue for Windows 7? I've tried enabling Narrator... but it's overkill; it seems to read everything on the screen!   So, in short, I want to be able to highlight text and have it read back to me in Windows 7.  If Narrator isn't the right tool for this, can anyone recommend a third party alternative (preferably a free one)?


I have just discovered that if I rotate my left spectacle lens about the vertical axis by 10 degrees in one direction, the vision in that eye becomes much crisper.  Note that the sphere and cylinder prescriptions in the (unrotated) lens were confirmed yesterday by an optometrist as being the best I could get -- but simply by yawing the lens I can see much better.  What is this rotation correcting? Is it physically possible to create a lens with the same correction but without the rotation?


Ubuntu says " not enough space on disk" when trying to install updates

Every time I use my computer it tells me there are updates to install but whenever I try to install them it doesn't work and says there's "not enough space on disk". I've only used 109.2GB of 485.8GB according to the Disk Usage Analyzer. Why does it think that there's not enough space? Can someone please help me with this? Thanks.   Filesystem     1K-blocks      Used Available Use% Mounted on udev             2872800         4   2872796   1% /dev tmpfs             577704      1172    576532   1% /run /dev/dm-1      474434712 106694932 343616800  24% / none                   4         0         4   0% /sys/fs/cgroup none                5120         0      5120   0% /run/lock none             2888504    136268   2752236   5% /run/shm none              102400        60    102340   1% /run/user /dev/sda1         240972    170231     58300  75% /boot


A nomenclature issue in Complex Analysis, what is difference between between writing "f(z)" and "f"?

As stated in the subject, this is just a curiosity about the nomenclature that is used in some Complex Analysis textbooks (particularly in problem statements).  I would think that writing "f(z)" would be the most general method of indicating f is a function in the complex plane.  Does simply writing "f" mean the same thing as "f(z)" or am I missing out on something serious here?  Thanks!


Bash alias defined in script not working within the script

I found a weird thing:  When I do in the console,  alias a='echo aaa' a   I get the output aaa as expected. But when I do a script, let's name it script.sh  #!/bin/bash alias a='echo aaa' a   and run it by doing bash script.sh, I get script.sh: line 2: a: command not found  How is this possible and how can I fix it?


Prove that $\sum_{x\le{n}}\frac{1}{\varphi{(x)}} = \mathcal{O}(ln{}(n))$

So I've never proved anything like this before, as this is my first time working with big O notation. Upon being presented with it, I decided to use induction. From what I understand of this, the equation means that $\exists k \mid \forall x \sum_{x\le{n}}\frac{1}{\varphi{(x)}} \le k\cdot\ln{}n$. So, I was going to show that this is true for $n = 2$, the base case here, and then assume its true for all $n$, then prove for $n+1$. My work was as follows for the inductive step.  $$\sum_{x\le{n+1}}\frac{1}{\varphi{(x)}} \le k\cdot\ln{}(n+1)$$ $$\sum_{x\le{n}}\frac{1}{\varphi{(x)}}+\frac{1}{\varphi{(n+1})} \le k\cdot\ln{}(n+1)$$ $$k*\ln{}(n+1)+\frac{1}{\varphi{(n+1})} \le k\cdot\ln{}(n+1)$$  At this point, we note that $\varphi{(n)}$ has a lower bound of $\frac{n}{\ln{}\ln{}(n)}$. Hence, our left hand side will maximize with this value, so we can write  $$k\cdot\ln{}(n+1)+\frac{\ln{}\ln{}(n+1)}{n+1} \le k\cdot\ln{}(n+1)$$  Raising e to each side of the equation and simplifying yields  $$\sqrt[n+1]{\ln{}(n+1)} \le \left(\frac{n+1}{n}\right)^k$$  At this point, I don't know what to do. Am I going about this right, or am I completely off base?  Edit: While the initial question is the same as the one this was tagged as a duplicate of, the question being asked here is whether induction is a valid approach to solving this problem without using the methods discussed in the other post.


How do single photons travel from here to there

I know there have been similar questions but I'm still unclear what the overall consensus is. (1) I assumed and have read that photons travel in straight lines unless deflected by gravity but there are conflicting theories. (2) I have heard that single photons takes every possible path but that makes no sense. Why would a single photon traveling from here to the moon go to every other place in the universe along the way.  (3) I can understand a single photon traveling as a particle or packet of energy but I have a hard time understanding a single photon traveling as a wave. I have never understood any attempts to answer this.  (4) Does a single photon have a frequency and what causes the frequency? If not then how does it have energy? I have many questions about single photons and their frequency.


Can't compile/link class with templated member from separate .cpp

I have a C++ using a class specified on separate .hpp/.cpp files. This class has the particularity of having a templated member function that takes a const std::vector as argument, and here is the root of the problem.  myclass.hpp:  class myclass {      //...     public:          myclass();         template <typename _t> int myfunction(const std::vector<_t> *values);      //... }   myclass.cpp:  #include "myclass.hpp"  //... template <typename _t> int myclass::myfunction(const std::vector<_t> *values){     // do stuff     return 0; }   and my main.cpp:  #include "myclass.hpp"  int main(int argc, char const *argv[]){      myclass foo;     std::vector<int> bar(5,100);     foo.myfunction(bar);      return 0;  }   However, when I try to compile all this with g++ main.cpp myclass.cpp -o main -I /usr/include I get the error:  undefined reference to `int myclass::myfunction<int>(std::vector<int, std::allocator<int> > const*)'    which is strange since the syntax seems to be correct (and it passes g++ check). The problem is not with how I am building the code or the file setup, since I am able to compile the code if I comment out the templated function.


70s Sci-fi story. Drink-driving motorist sent to be re-educated. Made to drive fast as punishment

What I remember is it's about a teen who has committed crime like drunk driving and is set to some sort of re-education center, meets a girl, has to drive fast a lot.  It was dystopian in nature and turned out that the kids were in a kind of an experiment in mind-control or conditioning due to their juvenile deliquency tendencies. I think the main character would drive at super high speeds on a track but then get shocked or some such.


From kernel all the way up to the Desktop Environment, where does Ubuntu reside?   Linux kernel is the kernel for all distros. The basic utilities (fdisk, ls, bash, whiptail, etc.) are mostly GNU tools and (almost) compatible to almost-all Unix-like variants. The systems of (userspace-resident) device drivers, pamd, udev, upower, etc. are also conformant to kernel APIs and ABIs interfaces. The X system is also not Ubuntu. The desktop environment (Gnome, Kde, etc.) is also not Ubuntu.   So, where is Ubuntu? In particular, where is Ubuntu's source code?


Is there a way to reveal an item in the Finder from Launchpad?

Sometimes I will see something that does not really belong in Launchpad—a readme, for instance—and I'd like to see it to move it. Sure, I can close Launchpad, open the Applications folder, and hunt for it there (perhaps in subfolders), but it seems to me that there ought to be an easier way. Is there? I can't seem to find one. Right-clicking, sadly, seems to do nothing.  I'm not trying to delete items that are in Launchpad from my drive; I just want to see them in the Finder, so that I can move them around or perform other operations on them..


Using running time distributions to determine ordering probabilities in horse racing

For a given horse race, I have the predicted distributions of each horse running the race like below,   Image taken from   I want to calculate what is the probability of each horse winning the race? based on the above normal distributions. And after estimating the same I want the probabilities to add up to 1. The x-axis in the diagram above is the running time of horses. Hence the horse with the lowest time (left-most) could be a potential winner. I know the formula that whenever we have two independent normal distributions, then P(X1 <= X2) i.e. the probability of point taken from distribution X1 will be less than or equal to point taken from distribution X2 can be given as, ss.norm.cdf(-(mu1 - mu2) / np.sqrt(sigma1 + sigma2))  Proof: import numpy as np from scipy import stats as ss  mu1, mu2, sigma1, sigma2 = 0., 100., 1., 1. X2 = np.random.normal(mu2, sigma1, size=(10000,)) assert(np.mean([np.mean(np.where(np.random.normal(mu1, sigma1) <= X2 , 1, 0)) for _ in range(10000)])) == ss.norm.cdf(-(mu1 - mu2) / np.sqrt(sigma1 + sigma2))  So how do I extend the above code to find the winning probabilities of every horse, and that they should add up to 1?


How to get correct textarea scrollHeight after Its width has changed?

I'm trying to change the height of a textarea according to its scrollheight.   This works fine the first time i change the height however i got to a scenario where it doesn't work for me, I've made jsFiddle to show what i'm doing and what's going wrong.  Step by step explanation of jsfiddle scenario:  1: Click button1 and check the current scrollheight.  2: Click button3 and then button1 and notice that the scrollheight value has decreased.  3: Click button2 and then button1 and notice that the scrollheight value is back again.  You can switch back and forth between width 50 and 100 before you continue and check its scrollheight, it will change all the time. Now what happens when we continue is what's going wrong for me.   4: Make sure width is 50% by clicking button2 then Click button4 and notice that the textarea height has increased.  5: Click button1 and check its current scrollheight.  6: Now click button3 to change it's width to 100%  7: Click button1 and notice that the scrollheight is still the same even tho we just changed its width from 50% to 100% ??  As you can see here the scrollheight is no longer changing, and not the textarea height either, even though i changed the textarea width, Anyone know why this is happening? Any help or input is highly appreciated, thanks!   $("#b1").click(function(){     var textaraElement =document.getElementById("TextArea");     alert(textaraElement.scrollHeight); });


In Episode III,  explains to Anakin the power of the Dark Side to save people from death. He mentions  - the Sith who discovered this. Sidious then claims he died, which seems odd, given that kind of power.   Then in Episode VII (The Force Awakens) we find a Sith Lord who has appeared from no where. There seems to be two loose ends that fit nicely together.   My question is: Is there evidence to suggest that Supreme Leader Snoke is Darth Plagueis?


I want to convert rotations given as quaternion from sensors to Unity. The sensors () axis are the following ones:    Unity is the following one:    I don't know how to map axis other than Z is up for the axis. Note that I don't really mind if I have a global rotation offset. I just want the sensors (they are multiple ones) relative orientation to be the same in Unity that in real life  Given  I think the following code should to the transformation:  Quaternion ConvertToUnity(Quaternion input) {     return new Quaternion(         -input.y,         -input.z,         -input.x,         input.w     ); }   Is that correct?


I'm a C++ newbie, but I wasn't able to find the answer to this (most likely trivial) question online.  I am having some trouble compiling some code where two classes include each other.  To begin, should my #include statements go inside or outside of my macros?  In practice, this hasn't seemed to matter.  However, in this particular case, I am having trouble.  Putting the #include statements outside of the macros causes the compiler to recurse and gives me "#include nested too deeply" errors.  This seems to makes sense to me since neither class has been fully defined before #include has been invoked.  However, strangely, when I try to put them inside, I am unable to declare a type of one of the classes, for it is not recognized.  Here is, in essence, what I'm trying to compile:  A.h  #ifndef A_H_ #define A_H_  #include "B.h"  class A {     private:         B b;      public:         A() : b(*this) {} };  #endif /*A_H_*/   B.h  #ifndef B_H_ #define B_H_  #include "A.h"  class B {     private:             A& a;      public:         B(A& a) : a(a) {}  };  #endif /*B_H_*/   main.cpp  #include "A.h"  int main() {     A a; }   If it makes a difference, I am using g++ 4.3.2.  And just to be clear, in general, where should #include statements go?  I have always seen them go outside of the macros, but the scenario I described clearly seems to break this principle.  Thanks to any helpers in advance!  Please allow me to clarify my intent if I have made any silly mistakes!


I have a county-level map that is displaying nicely ... except for around 300 counties, all in 5-6 states, which are blank. All of the FIPs, county names, lats/longs are consistent in the data file, so I'm puzzled. Any clues?  Map:   Data file:


Extra space between gloss and translations

In some examples in which I have an example (especially a multi-tier one) made in an example environment with gb4e, there's a huge gap between the the \glt line and the one directly above it. This looks terrible on the page. I'm not sure why this happens.  \begin{exe} \ex  {\glll  x y z\\  \{ x-acc y-decl z-nom \\ eks why zee\\}  \sn{\glll a b c. \\  a b c \}\\ ay bee see \\ \glt `Chickens like catfood, in my pasta factory.' [Garbo-R124-1]} \label{pastafact} \end{exe}


Does Windows use the fastest drive for the page file?

Suppose I have a 6 GB page file on an SSD and another 6 GB page file on a traditional mechanical 5400rpm SATA drive.  Does Windows take into account the difference in the performance characteristics between the two drives when deciding which page file to use?  If it matters, I'm asking about Windows 7 and higher.  I reviewed this  but it doesn't appear to factor in the case of dissimilar storage speeds.


Python class instances deleting themselves

I am working on a text adventure game written in Python just for fun (to see if I could do it).  I am working on the module for the entities, and am working on a method for them being killed.  When an entity is killed, instead of just displaying a kill message and rendering the entity unable to act, I also want its instance to be deleted to conserve memory.  How can I make an instance of the entity class delete itself?  For example (partly pseudocode):  class Entity(object):     #other methods here      def kill(self):        if self.health <= 0:            self.deleteinstance            or            deleteinstance(self)   Thank you in advance for your help.  EDIT: I understand that this is a duplicate, but the answers in all the others reference that objects are deleted when nothing refers to them.  My question here is how to make nothing refer to the instance of this class, because without a kill method, presumably the instance will still be in memory with negative health.


/boot has become 100% full somehow.  df -k Filesystem              1K-blocks     Used Available Use% Mounted on /dev/mapper/ubuntu-root 191078052 31758960 149612804  18% / udev                      3997520        8   3997512   1% /dev tmpfs                     1602244      856   1601388   1% /run none                         5120        0      5120   0% /run/lock none                      4005600     1792   4003808   1% /run/shm none                       102400       28    102372   1% /run/user /dev/sda1                  233191   218740      2010 100% /boot   mount /dev/mapper/ubuntu-root on / type ext4 (rw,errors=remount-ro) proc on /proc type proc (rw,noexec,nosuid,nodev) sysfs on /sys type sysfs (rw,noexec,nosuid,nodev) none on /sys/fs/fuse/connections type fusectl (rw) none on /sys/kernel/debug type debugfs (rw) none on /sys/kernel/security type securityfs (rw) udev on /dev type devtmpfs (rw,mode=0755) devpts on /dev/pts type devpts (rw,noexec,nosuid,gid=5,mode=0620) tmpfs on /run type tmpfs (rw,noexec,nosuid,size=10%,mode=0755) none on /run/lock type tmpfs (rw,noexec,nosuid,nodev,size=5242880) none on /run/shm type tmpfs (rw,nosuid,nodev) none on /run/user type tmpfs (rw,noexec,nosuid,nodev,size=104857600,mode=0755) /dev/sda1 on /boot type ext2 (rw) binfmt_misc on /proc/sys/fs/binfmt_misc type binfmt_misc (rw,noexec,nosuid,nodev) vmware-vmblock on /run/vmblock-fuse type fuse.vmware-vmblock (rw,nosuid,nodev,default_permissions,allow_other) gvfsd-fuse on /run/user/foo/gvfs type fuse.gvfsd-fuse (rw,nosuid,nodev,user=foo)   How can I make the space allocated to /boot bigger?  There is a related question  but that is not what I want to do.  Added.  Disk /dev/sda: 200.0 GB, 200049647616 bytes 255 heads, 63 sectors/track, 24321 cylinders, total 390721968 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x0007f9dc     Device Boot      Start         End      Blocks   Id  System /dev/sda1   *        2048      499711      248832   83  Linux /dev/sda2          501758   390721535   195109889    5  Extended /dev/sda5          501760   390721535   195109888   8e  Linux LVM  Disk /dev/mapper/ubuntu-root: 198.8 GB, 198784843776 bytes 255 heads, 63 sectors/track, 24167 cylinders, total 388251648 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x00000000  Disk /dev/mapper/ubuntu-root doesn't contain a valid partition table  Disk /dev/mapper/ubuntu-swap_1: 1006 MB, 1006632960 bytes 255 heads, 63 sectors/track, 122 cylinders, total 1966080 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x00000000  Disk /dev/mapper/ubuntu-swap_1 doesn't contain a valid partition table


The output of the ip a command in CentOs 7:  259: veth2060b59@if258: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master docker0 state UP     link/ether c6:1b:2a:b3:f6:c3 brd ff:ff:ff:ff:ff:ff link-netnsid 1     inet6 fe80::c41b:2aff:feb3:f6c3/64 scope link        valid_lft forever preferred_lft forever    Why there is "@" in the interface name? What is the significance of it.?   Note:   Output of ifconfig command:   veth2060b59: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500         inet6 fe80::c41b:2aff:feb3:f6c3  prefixlen 64  scopeid 0x20<link>         ether c6:1b:2a:b3:f6:c3  txqueuelen 0  (Ethernet)         RX packets 1878  bytes 161872 (158.0 KiB)         RX errors 0  dropped 0  overruns 0  frame 0         TX packets 3262  bytes 372175 (363.4 KiB)         TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0    there is no "@" in interface.  List of interfaces in /sys/class/net:   [root@nix-lin415-01 net]# ls /sys/class/net/  docker0  eno16777984  lo  veth2060b59    note that interface name is veth2060b59 and NOT veth2060b95@if258.


Children with a different surname to parent - UK citizen - UK passport control

Assume a child (aged 15) has a different surname from their mother. They live with their mother and father, but the mother did not take the father's name on marriage. All three are UK citizens, have UK passports in their own name, are UK residents, and the father and mother are married. The only thing mildly unusual (and hardly remarkable in the 21st century) is the mother did not take the surname of the father on marriage, and the child has the surname of the father (which is different from that of the mother).  A few weeks ago, the mother and child travelled by plane to an EU destination, without the father.   On flying out of the UK, this presented no problem. On returning to the UK (from the EU), a long dialog with the immigration officer ensued where he threatened to not permit re-entry because the child had a different surname to the parent traveling, and "The Children's Act" (sic - there are several) requires that the child also carries a birth certificate. Eventually (30 minutes later, and after interrogation as to what the child's middle names are etc), common sense prevails.   There were no other factors likely to interest the immigration officer. The child's passport had been issued a month previously and the photograph was thus a good likeness. The child concerned had no difficulty travelling with school to another EU country without a birth certificate or any letters from either parent.  This seems completely bizarre to me, given:   I can find no legal requirement that anyone needs to carry a birth certificate. The child could simply have gained entry as a UK citizen if the mother was not there at all. The risk one would have thought needed addressing was one parent absconding with a child after separation. In this case, should the check not be being made on departure? Returning to where all parties are resident seems unproblematic. The fact that the mother and child have different surnames is not indicative of marital break-up (consider e.g. unmarried parents); indeed when a married couple break up it is likely (if they changed name on marriage) that they will still have the same surname (at least on their passport) for a while.   So, to my questions:   Is there a requirement that children traveling with a parent with a different surname carry their birth certificate? If so, where is the legal origin of such a requirement?   Note: I am not asking this in order to assist in the parent concerned raising a complaint against a particular immigration officer. I am asking so I can tell the parent concerned what the requirements are should she wish to travel with her children unimpeded in future.


I am fairly new to WPF and I am having a problem with inheriting from a user control.  I created a User Control and now I need to inherit from that control and add some more functionality.  Has anyone does this sort of thing before?  Any help would be greatly appreciated.  Thank you


Finding the search terms behind 'not provided'

We use Google Analytics to track the vistors to our websites, were currently putting together a big audit of our SEO and one of the things we want to see is what search terms are working for us.  About 90% of our organic search traffic comes under 'not provided' which as i understand means a user is signed into a Google account when coming to our site, thus Google doesn't track their search terms.   This makes it really hard to conduct a meaningful study, (i suppose we could get the data of the 10% that we do have search terms for and multiply them it but i dont think thats a particularly good or meaningful approach).  Is there a workaround to see behind the 'not provided' data and see the search terms actually used ?    UPDATE  I read  last night from Hacker news, which states :     [using https will allow you] more complete referrer information in Google Analytics for people   visiting from sites already using HTTPS   and contained a link to this , it seems to say that because Google's users are using https that an https site cannot pass data to an http site, as the http site is not secure, none of the sites i manage have https / sll setup, could some one confirm if Google will pass you more referrer data if your site has https implemented ?


On which Stack Exchange site should I ask question about a printer?

Recently I've bought an inkjet printer HP Deskjet 1010 for my personal use. I've some problem with it. On which Stack Exchange site should I ask the question about my printer?


How to write '$a$ is divisible by $b$' in a Latex formula? The symbol \vdots does not look satisfactory.


In my os--debian, i want to open port 1060.  ~# iptables -I INPUT -p tcp --dport 1060 -j ACCEPT   Now to check it with iptables -L -n.  ~# iptables -L -n Chain INPUT (policy ACCEPT) target prot opt source destination ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:1060  Chain FORWARD (policy ACCEPT) target prot opt source destination  Chain OUTPUT (policy ACCEPT) target prot opt source destination   To scan port with tool nmap.  ~# nmap 127.0.0.1  Starting Nmap 7.40 ( https://nmap.org ) at 2019-08-26 23:02 EDT Nmap scan report for localhost (127.0.0.1) Host is up (0.0000080s latency). Not shown: 998 closed ports PORT STATE SERVICE 53/tcp open domain 3306/tcp open mysql  Nmap done: 1 IP address (1 host up) scanned in 1.67 seconds   Why can't open the port 1060 on my debian?


New way to edit bug -- Where are the previous edits?

I was just on this question:  and I saw that it had been edited.  I wanted to see what the previous version was, so as I used to do, I clicked on Edit.  There used to be a dropdown in the title area with the previous revisions.  That is no longer there; is this a bug or is this the current implementation of the edit, where one cannot see the previous revisions (which could be useful to the historical context of a question)?    Update  Even on my own question:  I cannot see the previous versions when I click edit.  This needs to be resolved.    Update #2  If you follow what @M.Tibbits says in  and if you click on edit instead of source you get the old implementation with the dropdown to switch between edits.  Why do we have to do some random convoluted steps to get to the old edit implementation?


A DOI is a commonly used digital object identifier to refer to an electronic document. How do I secure a DOI for a research dataset, to help share and identify it?


calculating the hydrostatic pressure in a non-cuboid shaped container

I want to calculate the hydrostatic pressure on the base at the following containers,but as you can see, the water are affecting the sides,especially in container 1, so does the formula $p$ $=$ $\rho$gh still applies in the these cases ?


Remove file extensions using .htaccess and content duplication issue

I want to know if we strip out file extensions using .htaccess for a new website, do we have to add rel-canonical tag for every page to avoid Google considering them as duplicate content?   To more clarify that, I mean:  I'm looking to use example.com/contact URL instead of example.com/contact.php.  The issue is, I'm worried that Google will detect these as duplicates.  example.com/contact and example.com/contact.php  Then I will be adding rel=canonical tags for every page. I want to know is this the best practice? Or what is the best way?


Getting errors while trying to install ubuntu

When I put my DVD-ROM and select the option to install Ubuntu, a black screen appears that says: Couldn't get size: 0x800000000000e MODSIGN: Couldn't get UEFI db list Couldn't get size: 0x800000000000e    All the answers that I found on the internet were talking about disabling Secure Boot, but my motherboard doesn't support UEFI, so I don't have this option. What should I do?


How can I enlarge an object so that the new object's surface is 1 cm apart from the initial surface?

I am very new to Blender. I have an irregular-shaped object which is a tumor (Figure 1). In order to completely remove the tumor from patient's body, some healthy-looking structures around the tumor also needs to be taken together with the tumor. The margin of the actual removal is 1 cm away from tumor's surface in all aspects (Figure 2). The hand-drawn images are used for illustration I have done the segmentation and reconstructed tumor on Blender (Figure 3 - don't worry about the cubical part, it's not important). Now I would like to develop the removal mass from the tumor by increasing the tumor object size so that the new object surface will be 1 cm away from the tumor object surface. Could you please show me how to do that? Thank you very much


Convert date string format to a datetime Python Object

i've one doubt. I'm doing request to an API which return me event date. I was hope that date will be a timestamp, but i get this value: {"date":"2020-08-24T21:15:00+00:00"}  I want to get a python datetime object. How can I do that?


weak convergence in $l^p$ implies bounded and pointwise convergence

Let $1<p<\infty$, $(u_n)_{n\in\mathbb{N}}\subseteq l^p(\mathbb{N})$ such that $u_n$ converges weakly to $u\in l^p(\mathbb{N})$. Prove that   (1) $(u_n)$ is bounded and (2) for all fixed component $j\in n\in\mathbb{N}$ it is $\lim_{n\to\infty} u_{n,j}=u_j$ (in lecture we called it "pointwise convergence of sequences").   My questions are: (1) is "$(u_n)$ bounded", i.e. $\|u_n\|<\infty$ for all $n\in\mathbb{N}$ already satisfied because $(u_n)_{n\in\mathbb{N}}\subseteq l^p(\mathbb{N})$?   For (2) it is to show that $|u_{n,j}-u_j|\to 0,\; n\to\infty$ for fixed $j\in\mathbb{N}$. But I don't know how to do this.


How to create a visual indicator of Stage on Opportunity record

I want to create STAGE based chart in my salesforce org. Please find the screenshot for the sample.


I'm currently stuck on this problem:     Let $m$ and $n$ be positive integers, and $F_k$ be the free group generated by $k$ elements. Prove that there is a homomorphism from $F_n$ onto $F_m$ if and only if $m$ is less than or equal to $n$.    My thought was to try abelianizing the free groups and using a homomorphism from the abelianized free groups to $\mathbb{Z}^n$ and $\mathbb{Z}^m$ respectively, but that has so far proved unfruitful.   Can someone help me find a better way to approach this problem?


Reliable method to find ISI rated Journal

I searched in internet and all I found was that we have to search the name of journal in "https://mjl.clarivate.com/" and if it indexed as: SCIE or SSCI or ESCI then the journal is indexed as ISI journal. but I wanted to submit my paper in "https://academic.oup.com/painmedicine" and I serached it in clarivate and it said that it is indexed as SCIE. But when I email to the editor of painmedicine journal he said that their journal is not rated or indexed as ISI. Now I am very confused that which journal is ISI?


How to decide what to inherit in a module class?

Say I want to create a new module to provide encryption/decryption for MySQL. In my module, I might simply have something like this:  import mysqlib import cryptolib  class SqlEncryption:      def encrypt(foo):         cryptolib.encrypt(foo)      def decrypt(bar)         cryptolib.decrypt(bar)   but of course I could inherit from the crypto and/or sql libs:  class SqliteEncryption(mysqlib, cryptolib):   of course using super and everything. I usually inherit but this is the first time I've had to wonder if I should inherit from the sql lib, the crypto lib, or both. How should one decide or does it not matter since I'm not actually needing to access anything in those two modules that isn't already exposed in their APIs?


How exactly should I set up DNS to delegate authority for subdomains?

I have servers hosted at a hosting provider and they also host the DNS records for my domain names. Now I want to add subdomains that are resolved by my own DNS service. So for example:   the hosting provider's name server knows the IP address for econemon.com one of my servers knows the IP address for ftp.econemon.com   Also,   unknown or undefined subdomains should be routed to the same IP as the parent domain on failure of my DNS service, it would be great if the requests all go to the IP address that is associated with econemon.com, but I'm not sure how that should work.   Now, I've read through the Wikipedia articles on DNS to dust off my knowledge, but the part that leaves me confused is: how does a client know which server to ask for the IP address for ftp.econemon.com? Does it get that information from the hoster? If so, do I have to register the subdomain there (and what would I need my name server for then)?


Question about vector-matirix derivative in back propagation

Let's say I have a matrix like below: $$ W = \begin{bmatrix} w_{1,1} & w_{1,2} \\ w_{2,1} & w_{2,2} \end{bmatrix} $$ $$ \vec{x} = \begin{bmatrix} x_1 \\ x_2 \end{bmatrix} $$ $$ \vec{y} = W\vec{x} = \begin{bmatrix} w_{1,1}x_1 + w_{1,2}x_2 \\ w_{2,1}x_1 + w_{2,2}x_2 \end{bmatrix} $$ In back-propagation, it is needed to calculate the $\partial {\vec{y}} \over \partial {W}$ to update  $W$. But, according to , there is no consensus about the definition of a derivative of a vector by a matrix. Then, how can I get the value of $\partial {\vec{y}} \over \partial {W}$?


output.value to file not adding new line break when using \n or \r\n

I have tried using both \n and \r\n however, the exported file does not contain the line break. Any idea what I am missing? I would like the text to return as: indexname_text indextype_text  Below is my code <!-- Button to download --> <button type="button" class="button" id="dwn-btn" style="vertical-align:middle">Download as .bat file</button>  document.getElementById("dwn-btn").addEventListener("click", function () { var copyIndexNameField = document.getElementById("indexName"); var copyIndexName = document.getElementById("indexName"); var copyIndexTypeField = document.getElementById("IndexTypeCheckBox"); var copyIndexType = document.getElementById("IndexTypeTextBox"); var output = document.getElementById("output"); if (copyIndexNameField.value) {     indexname_text += "--index-name " + copyIndexName.value + " "; } if (copyIndexTypeField.checked) {     indextype_text += "--index-type " + copyIndexType.value; } output.value =      + indexname_text     + "\n"     + indextype_text; var text = document.getElementById("output").value; var filename = "export.bat"; download(filename, text);  function download(filename, text) { var element = document.createElement('a'); element.setAttribute('href', 'data:text/plain;charset=utf-8,' + encodeURIComponent(text)); element.setAttribute('download', filename); element.style.display = 'none'; document.body.appendChild(element); element.click(); document.body.removeChild(element);


Show that $f$ is integrable $\implies $ $f$ finite a.e.

Show that $f:\mathbb R^d\longrightarrow \mathbb R$ is integrable $\implies $ $f$ finite a.e.  My attempts I wanted to use Borel-Cantelli lemma, but my construction doesn't look good for it since I did like this:  Let $A=\{x\mid |f(x)|=\infty \}$ and suppose that $m(A)>0$. Define $A_n=\{x\mid |f(x)|>n\}$. We have that $A_{n+1}\subset A_n$ for all $n$, and thus $$\lim_{n\to\infty }m(A_n)=m\left(\bigcap_{n\in\mathbb N}A_n\right)=m(A)>0.$$  How can I continue ?


how do you prove if a subset of a set of vectors is linearly dependent, then the entire set is linearly dependent.  i know that linear dependence means that it can be written as a linear combination. so i can take 1 vectors from the set and write it as a linear combination of some of the vectors find it to be linearly dependent and do so for the whole and find it to be linearly dependent.  i do not know how i can prove  without actually resorting to an example and you cant prove by example.


Why does Ubuntu 20.04 not want to install my DEB package?

I just installed my server with Ubuntu 20.04 and cannot install a DEB package. I have the error message below, why and how to install my package ? ubuntu@ov-GFF56:~$ sudo apt install ~/protonmail-bridge_1.3.3-1_amd64.deb Reading package lists... Done E: Unsupported file /home/ubuntu/protonmail-bridge_1.3.3-1_amd64.deb given on commandline


Launch programs by typing their names in 'run' dialogue box

There are some applications such as notepad and cmd which can be launched by typing their name in run dialogue box, can I just create entrys like that for all applications?


Gnome 3.14: Is possible to disable the lock screen?

I want to disable the lock screen on Gnome 3.14 after the computer is woken up from suspension. I've tried different proposed solutions, like , but they does now work.


I'm an avid watcher and lover of the X-Men movies. The original trilogy, the X-men wolverine series, as well X-Men: First Class and DoFP.   With X-Men: The Last Stand, Mystique has lost her powers, Professor X has died, and the closing scene shows Magneto having a hint of his power left.  The next time we actually meet Professor X or Magneto is in Days of Future Past. (Unless I'm mistaken) and this is where my confusion lies.  Is there a story behind how Professor X is still alive, or what has happened over the past years?  Is each subsequent film only lightly based upon the previous? Or are they going to continue to try and fill in the gaps non-chronologically?


The "start a bounty" button doesn't look like one

Currently, the button to "start a bounty" seems to be suffering from Windows 8-syndrome—it looks a bit more like text than an actual button.        This issue isn't specific to Meta.SE either—it's a network wide problem with the new-style designs.  The old designs had nice little backgrounds around the buttons to make it more clear they were... well... buttons.        Can we possibly bring that back?


I was given the following exercise:  Find the gcd of $x^4+x^3+2x^2+x+1 $ and $x^3+4x^2+4x+3 $ in $\mathbb{Q}[x]$ using the Euclidean algorithm.  Well, I  used the Euclidean algorithm and got $10x^2+10x+10$. But then I decided to check it on WolframAlpha and got $x^2+x+1$,that is the same answer divided by 10.   Also,by factorization of the polynomials I got the same answer as WolframAlpha.  I think that I  can “ditch” the 10 on the answer I got using the algorithm but I don’t see why (maybe I am overlooking some propriety of the gcd?)


Why does meat in the crockpot always end up dry?

Just cooked some chicken breasts today. All day in the crockpot and when done the meat was horribly dry.  I put chopped onions, carrots, spices, and coconut milk and 1/2 cup water and 4 chicken breasts.  There was plenty of fluid there when it was done, but the cooked chicken meat was really dry.  This seems to happen with beef roast as well.  Is there some trick to getting meat to be tender when cooking in the crockpot?


Proving that $X^n-a$ is irreducible if $a$ is no $p$-th power for any prime $p$ dividing the degree diving the degree

Let $F$ be a field containing a primitive $n$-th root of unity (for $n \geq 2$) and let $E = F(\alpha)$ where $\alpha \in E$ is an element whose $n$-th power (but no smaller power) is in $F$. Let $\alpha^n := a$.  Question: Assuming $p$ is an arbitrary prime dividing $n$ and $a$ is not a $p$-th power, why is the polynomial $X^n - a$ irreducible in $F[X]$?  What I did by myself?  I know that the roots of $X^n - a$ must be $\zeta^i \alpha$ for $i=0,\dots,n-1$ and $\zeta \in F$ being the primitive $n$-th root of unity from the assumption.  I also know that $E/F$ is a cyclic Galois of order $n$. A generator is $\sigma: \alpha \mapsto \zeta \alpha$.   Is there a way to use one of these facts to prove the statement? If not, what can I do differently? Thanks in advance!


I have a function that looks something like  foo(object& obj) {  }   inside this function I need to call another function like this:  foo(object& obj) {     bar(pointer to obj); }   the bar function takes a pointer to the object as an argument. Could some help I can do convert from non pointer to pointer?


ST_Expand return different results depending on meters

I am very confused by getting different results from st_expand (srid 4326). I want to do a search within a bounding box, therefore I pass a point and I'd like to provide distance in meters in order to see if I will get a macht.  So this  query is returning a result:  select "geo_name_cities".* FROM "geo_name_cities" WHERE (name like '%Ischgl%' AND      ST_Expand(ST_GeomFromText('POINT (10.3298112 46.9809071)', 4326),5000) && lonlat)  my assumption here. Make a bounding box of 5000 meters around the point.  Now I increase to 6000m   select "geo_name_cities".* FROM "geo_name_cities" WHERE (name like '%Ischgl%' AND ST_Expand(ST_GeomFromText('POINT (10.3298112 46.9809071)', 4326),6000) && lonlat)   No result. Ok, I might assume that the place is not within this box, fine. BUT when I use 60000m I get a  result again ?????  select "geo_name_cities".* FROM "geo_name_cities" WHERE (name like '%Ischgl%' AND    ST_Expand(ST_GeomFromText('POINT (10.3298112 46.9809071)', 4326),60000) && lonlat)  So I increased the distance steadily but the results are different, how does this come?


I classified laying logs (tree trunks) from CHM (Canopy Height Model = Digital Surface Model (DSM) - Digital Terrain Model (DTM)) created from LiDAR point cloud. I converted classified logs into polygon shapefile. I now have polygons that represent logs and CHM image. CHM were clipped by polygons (logs), now I am thinking of calculating volume of each log using QGIS. Is there any existing method?


Is there an alternative to Startup Disk Creator for creating a bootable usb in Ubuntu 16.04 ?


Windows shell command to get the full path to the current directory?

Is there a Windows command line command that I can use to get the full path to the current working directory?  Also, how can I store this path inside a variable used in a batch file?


Powering AC Guitar effects processor with a batteries

I am not a tech...so I must ask before burning up my equipment...  1) Can I power my AC effects processor with batteries? (Line6 Amplifi TT) The power jack says DC 3A min. The power adapter also rates at 3A  2)if so...Would I need a 3A battery or would one with higher amps be safe? last longer?  I need it to last at least 5 hours so which option would work best? one 12v sealed lead acid or a custom made Nimh battery pack like the one seen here:    I am trying to stay small and light as possible because this will be used for street performances where ac power will be scarce.


Tag synonyms should show the parent tag's description in the tags page

When looking through the tags page, tag synonyms are shown in the list. When you hover over them, they show the description for the parent tag. For example, when hovering over the  tag on , it correctly shows the tag wiki excerpt for the  tag:    However, it does not show the full description underneath it, like the parent tag does:    To make the tags and synonyms easier to navigate, can the full descriptions please be inherited too?


how to duplicate values of each row under each for n times?


Prove that $\forall n\ge 1$, there are $n$ successive, non-prime,natural numbers.  How can I turn to such a question? I have never dealt with such before. I started to course this week. I would really appreciate it if you led me or assisted me.


How do you pass a member function pointer?

I am trying to pass a member function within a class to a function that takes a member function class pointer.  The problem I am having is that I am not sure how to properly do this within the class using the this pointer.  Does anyone have suggestions?  Here is a copy of the class that is passing the member function:  class testMenu : public MenuScreen{ public:  bool draw;  MenuButton<testMenu> x;  testMenu():MenuScreen("testMenu"){     x.SetButton(100,100,TEXT("buttonNormal.png"),TEXT("buttonHover.png"),TEXT("buttonPressed.png"),100,40,&this->test2);      draw = false; }  void test2(){     draw = true; } };   The function x.SetButton(...) is contained in another class, where "object" is a template.  void SetButton(int xPos, int yPos, LPCWSTR normalFilePath, LPCWSTR hoverFilePath, LPCWSTR pressedFilePath, int Width, int Height, void (object::*ButtonFunc)()) {      BUTTON::SetButton(xPos, yPos, normalFilePath, hoverFilePath, pressedFilePath, Width, Height);      this->ButtonFunc = &ButtonFunc; }   If anyone has any advice on how I can properly send this function so that I can use it later.


Why the super class is empty when define child class?

When creating child class, specify the super class as empty.  class Foo1():pass class Foo2:pass   What is the different of Foo1 and Foo2.  And there are some other class definition.  class Foo3(object):


I have recently accepted a postdoctoral position at a reputed institute in the UK. I am an oversees applicant, who will soon be moving to the UK to take on this role. During the interview, I did not enquire about relocation expenses, assuming there would be support for that, but I have now been told that postdocs in this institute don't get a relocation support. On top of this, new regulations on the UK visa mean that I am now having to pay almost 1200 GBP just to get a visa and permission to be in the UK.   The town I am moving to is quite expensive (almost London rates) and I am now having trouble raising money for the airfare and paying initial rent and deposit, let alone having money for food and miscellaneous expenses. I am in a very tight spot and don't know how to take the next steps. This role has come after a lot of difficulty, and this situation is making it very difficult. Any advice on what I could do ?


Is conventional wisdom about the mechanism of red-eye reduction flawed?

As an example for a typical explanation about red-eye reduction pre-flashes, the description in the Metz SCA3202-M7 flash adapter manual states     Red eyes are always the result of a physical   effect. This arises whenever a person looks more   or less straight into the camera, the ambient light   is relatively dark and the flash unit is mounted on   or directly next to the camera. The flash unit illuminates the back of the eyes, revealing the blood   filled retina through the pupil. This is recorded by   the camera as a red spot in the eyes.      The red-eye reduction function brings about a significant improvement in this respect. When this   facility is used the flash unit triggers, prior to shutter operation, a few weakly visible preflashes   which are followed by the main flash. These preflashes induce the pupils to close down, thereby   diminishing the red-eye effect."   So here are three flash photographs of my eye taken with one self-timer, distance probably 8m.       There is no significant difference in iris size: if any, there is a small overall reduction throughout the (chronologically sorted) sequence with photographs taken with a distance of about 1sec.  Nevertheless the last image not even looking in the direction of the camera (with the reflexes from the flash being almost or entirely off the pupil) clearly has the strongest red-eye, followed by the first image.  The middle image, in spite of having the flash reflex basically straight in the pupil, clearly has a minimal amount of red-eye.  And PostScriptum, to counter theories that some sort of reflection law ignoring the presence of the lens is responsible or that the area conversing with the blind spot is, here another photograph where I am focusing quite closer than flash and camera are but in a completely different direction:  What gives?  The typical description of the red-eye effect strangely does not take into account that the eye is an optical system designed to create a sharp image of what you are looking at on the retina.  If there is no overlap of the image of the flash on the retina and the image of the camera's entrance pupil (the aperture as viewed through the front lens), no retina area lit by the flash will be visible from the camera's entrance pupil and consequently the sensor.  So the main objective of a pre-flash to me appears to be making the eye bringing flash and camera in focus so that their respective images on the retina are sharp and disparate.  While reducing the iris size would also help by increasing the eye's depth of focus (and thus decreasing blurring of the retina images), the effect seems minor compared to what the accommodation reflex can achieve in separation even with comparatively wide pupil.  Interestingly, in the fourth image the right eye on the left side of the image is considerably more red.  Looking closely, the eye on the right side of the image has its vertical aperture narrowed by a drooping eye lid.  This reduces the vertical blurring of the images of flash and camera on the retina, making them overlap less.  So contrary to conventional wisdom, staring focusedly at camera/flash (or a birdie waved at same distance or some other object that shares focus with camera/flash) will do most of the work even without preflash.  An urgently blinking self-timer lamp should be almost equally effective for red-eye prevention as a pre-flash.  Now the people writing about cameras and designing red-eye reduction systems know their place inside out optics.  It seems preposterous to assume that they of all people would not consider the implications of the eye being an imaging device after which cameras have been modeled complete with lens, aperture, and sensor surface.  And money is riding on it: basically every camera review tests for red-eye.  What am I overlooking?


I've added new images into a blender file and they turn up pink. I haven't moved the file, which I understand can affect how Blender finds them. I have tried packing and all sorts of things, but the image doesn't show up in the first place, unlike other questions I've seen where they came back a day later. I have tried both .jpg and .png files and nothing seems to work. I've tried File > External Data > Report Missing Files and nothing comes up as missing.


I want the system to accept the characters M or S both upper and lowercase but it keeps looping endlessly. Where did i go wrong?      MS1 = JOptionPane.showInputDialog("Please enter Marital Status M or S. ");     while(MS1.substring(0) != "S" && MS1.substring(0) != "s" && MS1.substring(0) != "M" && MS1.substring(0) != "m"){         JOptionPane.showMessageDialog(frame, "Please enter S or M.only");         MS1 = JOptionPane.showInputDialog("Please enter Marital Status M or S. ");     }


Show that if $G$ is a group with two normal subgroups $H$ and $K$ such that $G=HK$ and $H\cap K=\{e\}$ then the map $(h,k)\rightarrow hk$ is an isomorphism of groups from $H\times K$ to $G$.  I am not sure whether or not I should be using the homomorphism theorem or not. (If $j:G\rightarrow H$ is a homomorphism then $G/\text{Ker}(j)$ is isomorphic to $\text{Im}(j)$)  Thanks


If $f:\mathbb{R}^2 \rightarrow \mathbb{R}, f(x,y) = (y-x^2)(y-2x^2)$, then $(0,0)$ is a min. point of $f$ restricted to any line through origin.

$f:\mathbb{R}^2 \rightarrow \mathbb{R}, f(x,y) = (y-x^2)(y-2x^2)$. Show that the origin is a minimum point for a restriction of $f$ to any line through origin, but isn't a minimum local point to $f$.  Here's my attempt:  $\partial_x f(x,y) = -2x(y-2x²) + (y-x²)(-4x) = -2xy +4x³-4xy+4x³ = 8x³ - 6xy $  $\partial_y f(x,y) = y-2x² + y-x² = 2y-3x² $  then, partialy differentiating again, we get  $ H(f(x,y))= \begin{pmatrix} 6(4x²-y) & -6x\\  -6x & 2  \end{pmatrix} $ So $\det(H(f(0,0)) = 0 $ and then the origin is a critical degenerated point, therefore can't be a local minimum point for $f$.  Is my argument alright? And how can I think about only the restriction of f to a line through the origin? My teacher suggested analysing the signal of f. So I found:  $ f>0 $ when $(y>2x²)$ or $ (y<x²)$  $ f<0 $ when $(y>x²$ and $y<2x²)$  How can I take conclusions for the restriction now?  Thanks.


Non-linear differential equation example

I'm dealing with the following differential equation   $\frac{dy}{dx} = \frac{(y-x)(a-by)}{(1-\frac{b}{a}x)(a-2by+bx)}$ with $x,y \in [0, \frac{a}{b}]$   Can anyone help me with the non trivial solution?  Thanks.


Oracle query GROUP BY with latest record

I am trying to get a list of records, grouped by client name within a given time period but am getting every single record rather than grouped records. The data looks something like this: ReqTS                      ClientName    ItemID    Outcome 2021-04-25 13:19:20:928    10.20.30.40   ABCD1     X0 2021-04-24 13:20:22:345    10.20.30.40   ABCD2     Y0 2021-04-26 13:21:35:456    10.20.30.40   ABCD3     X2 2021-04-25 13:18:45:589    10.20.40.50   ABCD4     Y1 2021-04-24 13:22:34:832    10.20.40.50   ABCD5     X0  I need to get: 2021-04-26 13:21:35:456    10.20.30.40   ABCD3     X2 2021-04-24 13:22:34:832    10.20.40.50   ABCD5     X0  I tried this but it returns all records: select reqts, clientname,itemid, outcome from reqresplog  where logdate <= to_timestamp('04/26/2021', 'mm/dd/yyyy') and logdate >= to_timestamp('04/24/2021', 'mm/dd/yyyy') group by clientname,reqts,itemid, outcome order by reqts desc;


I'm stuck on this page even after linking stackoverflow and github accounts.


"least riskiest" vs "safest" - double superlative or single is better?

Is "least riskiest" stylistically correct? Can it be considered a double superlative? Would "safest" be a better choice?


we know non-zero eigenvalues of AB is equal to BA, are the eigenvector's is also equal?

we know non-zero eigenvalues of AB is equal to BA, what can we say about eigenvector are they the same or not? also, if the eigenvalue of $A^2$ is known then what is the eigenvalues of $A$.


How to add numbering to reference list but still use authoryear in natbib

Is there an easy way to add numbers to the reference list generated by \usepackage[authoryear]{natbib} with whatever style file (using plainnat for ease)? Specifically, I use \cite and \citenum from natbib in order to have some references show up in the text as author-year and others just appear as numbers. Switching authoryear out for numbers in the natbib options generates a reference list with numbered references, but also causes the references in the text to all appear as numbers, which I don't want.  \documentclass[12pt]{article} % use larger type; default would be 10pt \usepackage[authoryear]{natbib} \begin{document}  \cite{A} said this, but other research \citenum{B,C} says otherwise.  \bibliographystyle{plainnat} \bibliography{MalariaBib,MST} \end{document}


What's the incentive to flag duplicates?

I only say duplicates but I think this could be extended to several other flagging reasons. Since accepted answers/upvotes don't get reverted on questions I see people sometimes cut and paste the answer from a duplicate question without flagging as duplicate. In the end they can usually score a few upvotes and even an accepted answer.  Found this related question:   Seems to have a lot of popularity but nothing ever happened  Jeff on Dupes     Those arguing for “remove reputation from dupes” have no idea of the   Frankenstein monster you’d be creating.      That would be an awesome rep-denial tool for griefing others, first of   all.      Second, it creates a MASSIVE disincentive to participation — even if   you had no idea there were duplicates, you could be bushwhacked at any   time even if you contributed a fantastic answer. Oops sorry dupe!   Zero rep, buddy! Bzzzzt! Go away! Take your awesome answer elsewhere!      Incentives are fine, but penalties are an incredibly bad idea and   would actively hurt users and the network.   I guess this answers my question, even if I disagree with jeff.


I have a major lagging problem with my XPS L501x. It lags in everything: browsing, gaming, opening files, Ctrl+F in txt files takes too long to open, even the right click lags, watching youtube videos, games, programs, applying settings on anything, playing music and video files, switching between tabs in any browser, opening folders, typing, etc..  I formatted all the hard drive including all partitions and done a clean Windows 7 Home Premium 64-Bit Installation, updated all the drivers definitions but problem wasn't resolved. I ran dell diagnostics by pressing the F12 key while starting up and it passed all the tests, updated the BIOS to A08. Also cleaned all vents to remove dust and used a cooling pad under the laptop but the problem still exists.  I uninstalled the Intel Rapid Storage Driver as I found that this may help but with no luck too.  I ran a memtest to check the laptop memory and no errors are found. then I ran a hard disk diagnostics tool (HD Tune Pro.) which came up with some errors and I don't know whether this errors are the cause of lags or not.  It came up with 31 damaged sectors and 104402084 interface CRC error count and I actually don't know what does this error means. I also was monitoring the temperature and it varies between 50 to 52 C, I don't know whether it is normal or not. Last thing I noticed the read access time is 18.9 ms which is yellow highlighted by the software so maybe it is abnormal. I want to know if my hard drive working normal or this results shows a hard disk failure and needs replace? and If I replaced it this will solve the slow/lags problem or not?  Note: Processor temperature on load: 70 to 73c maximum. Intel Core i7 740QM 1.73GHZ.   Any suggestions please?  My Laptop Specs:  Intel Core i7 1.73 GHz with TurboBoost  RAM: 6GB  Nvidia GeForce GT 435M 2GB Dedicated.  Toshiba Hard Disk: 640GB


Why the output of "column" is misaligned with a ANSI colored input?

I'm working on a commandline that retrieve some data (curl), extract the relevant fields (awk) and format it (column).   It work nice, although it's very ugly (but all my script begin from a "too long and ugly" one-liner) but when I try to have some colour column goes wrong.  This is the plain (reduced) version that work:  curl "http://webservices.rm.ingv.it/fdsnws/event/1/query?lat=42.35&lon=13.4&maxradius=5.0&starttime=2016-01-01T00:00:00&endtime=2016-12-31T23:59:59&minmag=5&format=text&orderby=time-asc" 2>/dev/null  \  | awk 'BEGIN { FS= "|"; OFS= "|" }  {print  $1, $2, $5, $10, $11, $13}' \  | column -t -s '|'   Now, I want to underline some fields, and then add some ANSI escape code in awk:  curl "http://webservices.rm.ingv.it/fdsnws/event/1/query?lat=42.35&lon=13.4&maxradius=5.0&starttime=2016-01-01T00:00:00&endtime=2016-12-31T23:59:59&minmag=5&format=text&orderby=time-asc" 2>/dev/null  \  | awk 'BEGIN { FS= "|" ; OFS= "|" }  \      $13~/Rieti/||/Perugia/ {$13="\033[1;31m"$13"\033[0m"} \      $11~/[0-9]+/ && $11 > 5.8 {$11="\033[1;33m"$11"\033[0m"}       {print  $1, $2, $5, $10, $11, $13 }' \  | column -t -s '|'   Now, the alignment is wrong (see the picture).    Why? And how can I fix it?    UPDATE  I already saw the question  but does not solve my problem because his answers are applied and work in the case of a fully colored line.    In my case I can't apply or adapt the answers (or I'm not able to) because:   The problem is circumscribed to the case where the column $11 is colored, regardless of the subsequent column. I can't see a good or elegant way to add color code after column. If I send column's output to awk for the test I don't know how to instruct awk to separate the fields correctly (if the fields were separated by more space I could use a regex but in some cases the separation is by a single space, and awk would not know how to recognize spaces between words and spaces as Fields Separators).   The only thing I can see is that if I move the reset color code from the assignment to the print block the first row was better spaced, like the plain output version (see below, the \033[0m underlined in second commandline):    Then, how can we fix it? There is another way, more elegant, to colorize as I did?  (I know, I can do it better with some lines of perl, but I'm curious about this problem)


Why does it say "User was removed" and not anything else?

I just entered Stackoverflow and saw "-10" on the top, I checked it and it said "User was Removed". I was like "What?".  So: I answered X's question. Y upvoted it. Y's account got deleted. Y's vote got deleted. I lost points.  No problem until here.  I got notification saying "User was Removed".  This is a problem.  It scared me.  I ask you to change it to: "The account of upvoter was removed" or sth.


Bash command to see if any files in dir - test if a directory is empty

I have the following bash script:  if ls /Users/david/Desktop/empty > /dev/null then     echo 'yes -- files' else     echo 'no -- files' fi   How would I modify the top line such that it evaluates true if there are one or more files in the /Users/david/Desktop/empty dir?


What torque for caliper brakes onto carbon-alloy forks?

I've recently got a new bike with a . This comes with deep-drop calliper brakes (Shimano R451 Dual Pivot). The first time out I bumped one of the brakes and it twisted around the single attachment bolt and rubbed on the rim.  I managed to easily twist it back by hand and carry on, however I thought the bolt probably needs tightening. The question is: How tight can it be?  As the fork is part carbon I've so far only dared to take it up to 4Nm, but it still seems possible to twist the whole calliper around with a bump of the hand. Maybe that's normal? Perhaps it's easier to bump around because of the longer deep-drop lever. Should I be aiming to get it really secure?    I'm not sure whether the brake mount in the fork is all carbon, or some of it is alloy underneath, but either way I'd like to know what a sensible torque is. As far as I can see from the  there is no such specification. How can I find this out?


The Earth turns with a very high velocity, around its own axis and around the Sun.  So why can't we feel that it's turning, but we can still feel earthquake.


How find the norm $\|f_x\|$ of linear functional $f_x: C[a,b] \to \mathbb{R}$?

Consider the Banach space $C[a,b]$ with sup norm. For any fixed $x\in C[a,b]$ define $f_x(y)$ for any $y \in C[a,b]$ as follows: $$f_x(y)=\int_a^b x(t)y(t) \; dt$$ Show that $f_x$ is a bounded linear functional and compute $\|f_x\|$. I know that $f_x$ is a bounded linear functional and I am trying to show that $\|f_x\| = \|x\|_1$. How to make this? I know that $\|f_x\| \leq \|x\|_1.$ Thanks in advance.


Please I need help, if I run sudo pip install pip or pip install Django on my computer terminal,  this is the message I get, what can I do.  Last login: Thu Jun 28 18:51:51 on console ➜  ~  sudo pip install pip Password: Traceback (most recent call last):   File "/usr/local/bin/pip", line 7, in <module>     from pip._internal import main ImportError: No module named pip._internal ➜  ~  pip install django Traceback (most recent call last):   File "/usr/local/bin/pip", line 7, in <module>     from pip._internal import main ImportError: No module named pip._internal   I have both pycharm and jupyter notebook installed, the jupyter notebook is not responding. Before the pip was working and also the Django, now I don't know what I have done, my pandas is not working on the jupyter notebook. Please, can someone help me. I downloaded python 3.6 last year but if run python version on the terminal I get python 2.7 and try to download Python 3.6 again a day ago. I don't know if there is some file I have deleted by mistake. This the information I saw on the pycharm if I run the manage.py  "Couldn't import Django. Are you sure it's installed and "                 "available on your PYTHONPATH environment variable? Did you "                 "forget to activate a virtual environment?"             ).   The output reads  /Users/MacBookPro/venv/bin/python Users/MacBookPro/myDjango.py /Library/Frameworks/Python.framework/Versions/3.6/Resources/Python.app/Contents/MacOS/Python: can't open file 'Users/MacBookPro/myDjango.py': [Errno 2] No such file or directory Process finished with exit code 2.   Thanks.


Set a variable inside a object only if its null

Is there a clean/best way to set a variable inside a object only if its unassigned or null ? Example: currently I am doing this. if (item.getLocation() != null) {     item.setLocation("/somelocation"); }


Create something like a timer using a while loop

I have a while loop like this in my Console Application:  count = 0; while (count < 60) {    count++;  }   Okay so this loop runs very fast.  What i want is that it only adds count++ maybe once every second.   Is this somehow possible to do?


Test if player is holding something but the specified item

So I'm making a command block mechanism, but I need to test if the player is carrying something other than a specified item like testfor @p {SelectedItem:{id:minecraft:stick}}, whereas this instance it'd activate if the player is carrying anything but a stick. If that is impossible is there a way to test if the player is not carrying anything at all?


I know that it can be done with graphics packages like TikZ, but it seems to be a bit of an overkill. And for those not already familiar with the TikZ system, learning it can be a bit of a barrier. So my question is     Assuming the advanced graphics capabilities are not necessary, and I just need a bare-bones flow chart (which should be implementable just using the picture environment), is there a LaTeX package for simply making a flow chart?


How to include PHP files that require an absolute path?

I have a directory structure like the following;     script.php      inc/include1.php   inc/include2.php      objects/object1.php   objects/object2.php      soap/soap.php   Now, I use those objects in both script.php and /soap/soap.php, I could move them, but I want the directory structure like that for a specific reason. When executing script.php the include path is inc/include.php and when executing /soap/soap.php it's ../inc, absolute paths work, /mnt/webdev/[project name]/inc/include1.php... But it's an ugly solution if I ever want to move the directory to a different location.  So is there a way to use relative paths, or a way to programmatically generate the "/mnt/webdev/[project name]/"?


Please help me to reinstall ubuntu without losing data!

Not showing free-space while reinstalling Ubuntu 14.04 LTS


I am considering to set up a cyber cafe.   I am considering setting up a cyber cafe.      I think it should be version #2 where the verb considering is followed by the gerund setting. But it sounds unnatural to me.  Can we use a gerund after "Verb+ing"?


How can I draw commutative diagrams in LaTeX?

I would like to learn to make commutative rectangles using Tikz. How can I do that? I have tried \[\begin{tikzcd} A \arrow{r}{\varphi} \arrow[swap]{dd}{g\circ f} & B \arrow{d}{g} \\ & C \end{tikzcd} \]  but it draws only a triangle.


I have trouble with finding out resistance of a resistor. It has 5 bands but somehow I cant get the code right.


for some unknown reason, google seems to be prefixing my page title with the brand rather than leaving the brand at the end.   Example, my title is written like so.   Some Phrase 1 | Some Phrase 2 - MyBrand  Now when google displays my results, it's displayed as  MyBrand: Some Phrase 1 | Some Phrase....  Now my title is only 55 characters long, so well below the the maximum, does anybody know why this might be happening?  Some related info I found


I like to justify the texts inside the block using beamer. I cant do that in presentation. Can any one please help me?


I'm not being able to update with apt update command. I'm getting an error which says: Skipping acquire of configured file 'universe/binary-1386/Packages' as repository 'http://in.archive.ubuntu.com/ubuntu focal-backports InRelease' doesn't support architecture '1386'