This is taken from , p. 214, Release 2020-06-25. Extensionality is formulated as: $$ \forall x \forall y ( \forall z (z \in x \leftrightarrow z \in y) \to x=y). $$ Now, by the definition of implication ($\to$), $\forall z (z \in x \leftrightarrow z \in y)$ can be false while $x = y$ is true and the implication is true. But this is absurd, as that means that the statement: "Two sets which do not have all their elements in common are the same set," is valid, though it is clearly not. I must be missing something big here. Where is my reasoning faulty?

To familiarize myself with axiomatic set theory, I am reading Kenneth Kunen's  that presents ZF set theory. I haven't gotten really far since I am stuck at the axiom of Extensionality, stated as follows:  $$\forall x,y \; [\forall z(z \in x \leftrightarrow z \in y) \rightarrow x = y]$$  As far as I understood it, the purpose of this axiom is to state that every two sets that have exactly the same members are the same set. In terms of the above formula, when antecedent is true, the consequent needs to be true. What confuses me here is the case when the antecedent is false. Then, the consequent can be false or true, i.e., we can't say much about the consequent. But, don't we really want to say that in that case those two sets are not equal? More precisely, shouldn't we use equivalence instead of implication? If not, what is the reason?


i am using PDO package to manage my application database. i use PDO::prepare , PDOStatement::execute and somtimes PDO::quote , PDO::query / PDO::exec to excute my queries  are PDO::prepare and PDO::quote completely secure? or shoud i make more work to properly validate my inputs.not only for databaase but for php code either Thank you

If user input is inserted without modification into an SQL query, then the application becomes vulnerable to , like in the following example:  $unsafe_variable = $_POST['user_input'];   mysql_query("INSERT INTO `table` (`column`) VALUES ('$unsafe_variable')");   That's because the user can input something like value'); DROP TABLE table;--, and the query becomes:  INSERT INTO `table` (`column`) VALUES('value'); DROP TABLE table;--')   What can be done to prevent this from happening?


How to resixe the inline visualforce page in the pagelayout. Is there any ap exchange products or any code that I can do this ?

Since it seems to me, that a lot of people still need sidebar workarounds, I would be interested to learn about the use-cases, experienced challenges and (most important) possible strategies to avoid them by using different approaches. This is related to the methods discussed here:   In my experience there are a few extremely important and constantly repeating patterns, which to my knowledge are still very hard to be solved using more official techniques. I will also contribute my own top-N use-cases, which are mostly related to UX and UI concerns. You are very welcome to add your own scenarios as answers and add comments on how you would avoid a workaround. My dream would be to team-elaborate strong and repeatable solution-patterns for the most common use-cases.  Finally I would be interested in the experiences of all of you who participate in the Aura pilot, which hopefully could make this kind of workarounds obsolete.


We have two scripts, first.sh and second.sh. We run first.sh from second.sh using the . (source) command.  I am stuck at this script,   first.sh   value="myvalue"  export value   oldvalue="othervalue"  export value   After initializing the value and exporting, we have initialized the oldvalue and again exported value instead of oldvalue , but still the othervalue is available in the script second.sh, even though we didn't export oldvalue in first.sh.

What's the difference between executing a script like this:  ./test.sh  and executing a script like this:  . test.sh?  I tried a simple, two-line script to see if I could find if there was a difference:  #!/bin/bash ls   But both . test.sh and ./test.sh returned the same information.


I'm trying to generate a GUID in a platform agnostic manner, most search results suggest using BOOST or platform specific libraries. I remember once coming across the following snippet and I was wondering if this is a reliable way of generating GUID's:   unsigned int generateGuid() {     char c;     return (unsigned int)&c; }   More specifically, does this guarantee a unique value always? And if not, what are some good lightweight and cross-platform approaches of doing this?

What is the best way to programmatically generate a GUID or UUID in C++ without relying on a platform-specific tool? I am trying to make unique identifiers for objects in a simulation, but can't rely on Microsoft's implementation as the project is cross-platform.  Notes:    Since this is for a simulator, I don't really need cryptographic randomness.  It would be best if this is a 32 bit number.


From American Sphinx: The Character of Thomas Jefferson by Joseph J. Ellis:  Even if we take Jefferson at his word, that he did not copy sections of the Declaration from any particular books, he almost surely had with him copies of his own previous writings, to include Summary View, Causes and Necessities and his three drafts of the Virginia constitution.  I don't comprehend the use of infinitive "to include" here. Shouldn't it be better to substitute it by "including," which sort of like a reduced relative clause—which includes?

In the hot story of today (the ), I noticed the following:     He was subjected to numerous and repeated torture techniques, to include being waterboarded 83 times.   The same construction is there in the report itself. To include? What happened to including?


My question is why do we need to do feature selection even when have build in mechanics to prevent overfitting? More specifically, for svm, it regulate the training use L2 norm, so that the model is "small" in a sense. Why do we need another way to keep the model simple by using feature selection?

I have one question with respect to need to use feature selection methods (Random forests feature importance value or Univariate feature selection methods etc) before running a statistical learning algorithm.   We know to avoid overfitting we can introduce regularization penalty on the weight vectors.   So if I want to do linear regression, then I could introduce the L2 or L1 or even Elastic net regularization parameters. To get sparse solutions, L1 penalty helps in feature selection.   Then is it still required to do feature selection before Running L1 regularizationn regression such as Lasso?. Technically Lasso is helping me reduce the features by L1 penalty then why is the feature selection needed before running the algo?   I read a research article saying that doing Anova then SVM gives better performance than using SVM alone. Now question is: SVM inherently does regularization using L2 norm. In order to maximise the margin, it is minimising the weight vector norm. So it is doing regularization in it's objective function. Then technically algorithms such as SVM should not be bothered about feature selection methods?. But the report still says doing Univariate Feature selection before normal SVM is more powerful.   Anyone with thoughts?


Is using the two together going to damage my phone in any way?

The older iPads have 10W power adapter (charger), and the iPhones supposed use only 5W chargers.  But the iPad 4th gen, probably due to the larger power consumption, uses a 12W power adapter / charger.  Is this charger safe to use with the older iPads and iPhones.  Will it overcharge or overheat or damage the battery?  A more serious worry is that if it overheats, then can the battery explode?


Question Solve the congruence 2x ≡ 7 (mod 17). I have tried working out this problem but I am stuck midway. Could someone help me out by showing me or explaining how to proceed further? Here is the work that I have so far: Inverse of a modulo m is an integer b for which ab ≡ 1 (mod m), a = 2 m = 17 17 = 8 ⋅ 2 + 1 2 = 2 ⋅ 1 + 0 The greatest common divisor is the last non-zero remainder values, that is, gcd (a, m) = 1. Expressing the greatest commmon divisor as a multiple of a and m, gcd (a, m) = 1 = 17 - 8 ⋅ 2 = 1 ⋅ 17 - 8 ⋅ 2 The inverse would then be the coefficient of a = 2, which in this case, would be -8. And, since, -8 mod 17 = 9 , 9 is also the inverse of a modulo m. Solving the congruence 2x ≡ 7 (mod 17) by multiplying each side by the inverse 9, 9⋅2x  ≡ 9⋅7 (mod 17) 18x ≡ 63 (mod 17) And, this is the part where I am stuck. Could anyone help out? Thank you.

Isn't finding the inverse of $a$, that is, $a'$ in $aa'\equiv1\pmod{m}$ equivalent to solving the diophantine equation $aa'-mb=1$, where the unknowns are $a'$ and $b$? I have seem some answers on this site (where the extended Euclidean Algorithm is mentioned mainly) as well as looked up some books but there is no mention of this. Am I going wrong somewhere or is this a correct method of finding modular inverses? Also can't we find the Bézout's coefficients by solving the corresponding diophantine equation instead of using the extended Euclidean Algorithm?


So, if I don't claim my 17 year old as a dependent, then she is eligible for the first 2 stimulus pymts totaling $1800 (versus only a $500 savings on my taxes if I claim her as a dependent)  Except that she would have to indicate that nobody can claim her as a dependent. I do not wish to be untruthful, but certainly want to limit our tax liability if possible. Is she required to disclose that another person can claim her as a dependent, even if they do not do so??  If anyone has more info to confirm, one way or the other, it would be appreciated.

Let's say that an adult is living with his parents.  He meets all of the  of his parents.  Now let's say that he wants to file a tax return and claim the , as he did not receive any of the stimulus payments in 2020.  His parents decide not to claim him as a dependent on their taxes.  Can he leave the "Someone can claim me as a dependent" box on his  unchecked and claim the Recovery Rebate Credit?  This does not apply to me, but it could apply to many people this year, with the new Recovery Rebate Credit putting people in the situation where it could be advantageous to not be claimed as a dependent. Surprisingly, the  do not provide any guidance on checking this box in any way, that I can find.  I have seen it asserted many times in answers and comments here on Money.SE that because the form says, "Someone CAN claim...," the box must be checked whether or not anyone actually will claim them.  But I have not yet found this explicitly stated in any official IRS website or publication.  The ideal answer here will cite an official source.


If you live or fly to London (center) which of the following airports you choose in respect of time and cost to the center?   STN (Stansted Airport) LTN (Luton Airport) LGW (Gatwick Airport)  SEN (Southend Airport)     I just left Heathrow Airport (LHR) because it is direct connected with metro.

I am trying to find a neat, tabular, or clear depiction of how much time and money you'll need to travel to London from one of its six airports (that is Gatwick, Luton, City, Heathrow, Southend, Stansted).  I need this for comparing total prices among flights to London.   There are similar questions on this site, but they only partially answer this question.


I am a new user to the Ubuntu OS and want to do everything to understand it's complete functionality. Recently I have read so much about it. I have the 12.04 LTS 32bits running on my HP 430 laptop. Installing programs that I like from bloggers and articles on youtube. But I have a big problem installing the adobe flash player. Like for instance, the GLOBAL FLASH SETTINGS page doesn't show with java embeds, rather all I see is just texts and a message saying This page needs Adobe Flash Install. I will appreciate if someone help me get over this problem. Thanks.

Even though I have the latest Adobe Flash player 11.2 for Linux in Firefox -   - a particular online flash game still requests that I update to the latest flash player.  I've tried this online game on my laptop (Windows 8 with Flash Player 11.8) and it has no problems.  Is there a way to trick Ubuntu or this game into thinking Flash Player 11.8 is "installed"?


I have a question I can't seem to find the answer to regarding SQL injection. Let's say I have code where there is a submit button labeled "delete" and if the user clicks it, the databased deletes that record. There is no user input here besides clicking that button. Is that safe from sql injection, or does this still need to be coded in PDO vs good old php? Also, are select statements safe if they are just returning results rather than inputing user data? As I understand it, I only need to worry if it is an insert or update query I am dealing with, but I can't verify this...

If user input is inserted without modification into an SQL query, then the application becomes vulnerable to , like in the following example:  $unsafe_variable = $_POST['user_input'];   mysql_query("INSERT INTO `table` (`column`) VALUES ('$unsafe_variable')");   That's because the user can input something like value'); DROP TABLE table;--, and the query becomes:  INSERT INTO `table` (`column`) VALUES('value'); DROP TABLE table;--')   What can be done to prevent this from happening?


I tried with 2 scenarios , In one I could access data variable and other couldn't. need clarification for clearing my scopes concept Scenario 1 : data not accessible    function test() {   var data = "from Test";   secondFunction(); }  function secondFunction() {   return function() {     console.log(data);   }(); }  test();     Scenario 2: data is accessible    function test1() {   var data = "from Test1";   var secondFunction1 = function() {     return function() {       console.log(data);     }()   }   secondFunction1(); }  test1();

What is the scope of variables in javascript? Do they have the same scope inside as opposed to outside a function? Or does it even matter? Also, where are the variables stored if they are defined globally?


Given that $\frac{a}{c} + \frac{b}{d} > 1$, I am attempting to show that  $$\lim_{(x,y)\rightarrow(0,0)} \frac{|x|^{a}|y|^{b}}{|x|^{c} + |y|^{d}} = 0$$  My attempt at a solution:  Let's assume the limit is in fact zero, and prove it with the Squeeze Theorem.  We have that  \begin{align*} \Bigg|\frac{|x|^{a}|y|^{b}}{|x|^{c} + |y|^{d}}\Bigg| &= \frac{|x|^{a}|y|^{b}}{|x|^{c} + |y|^{d}} \\ &\leq \frac{1}{2}|x|^{a-\frac{c}{2}}|y|^{b-\frac{d}{2}} && \text{using the fact that } a^{2} + b^{2} > 2ab \end{align*}  But I'm not quite sure how to proceed from here to apply the inequality given and find a limiting function, if I am even on the right track with the inequality I applied. This isn't homework ( a practice question I found ), any help would be greatly appreciated.

I have some trouble with this: Show that if $a, b \ge 0$, $c, d > 0$ and $\frac{a}{c} + \frac{b}{d} > 1$ then   $$\lim_{(x,y)\rightarrow (0,0)}\frac{\left|x\right|^a\left|y\right|^b}{\left|x\right|^c + \left|y\right|^d} = 0$$  we were not really shown how to evaluate multivariable limits other than trying different paths, which wouldn't work when the limit exists, or by applying the squeeze theorem which is my initial plan. Unfortunately I cannot find a proper bound for the denominator and so I am quite lost right now. Any help would be appreciated.


Prove that $\sum_{r=1}^n r\binom n r^2 = n\binom{2n-1}{n-1}$   I tried: $\sum_{r=1}^n r\binom n r^2 = n\sum_{r=1}^n \binom {n-1}{r-1}\binom n r$ using the identity $\binom n r = \frac n r \binom {n-1}{r-1}$ for $r \ge 1$.    Not sure how to proceed from there. I tried expanding the RHS but can't seem to find a way to cancel out the factorials.

I can calculate $\sum_{i=0}^k \binom{n}{i}\binom{m}{k-i}$ using $(1+x)^{n+m} = (1+x)^n(1+x)^m$.  I would like to calculate the two sums $\sum_{k=0}^n (-1)^k \binom{n}{k}^2$  and $\sum_{k=0}^n k \binom{n}{k}^2$  with the same method.  I don't see what polynomial I have to consider.  For the first one, if i consider $(1-x)^n(1+x)^n=\sum_{k=0}^n \sum_{i=0}^{k}(-1)^i \binom{n}{i} \binom{n}{k-i} x^k$ and the sum we want doesn't appear.  EDIT : indeed, I only have to look at the coefficient of $x^n$, which is $\binom{n}{i}\binom{n}{n-i} = \binom{n}{i}^2$.


Ubuntu 16.04 could not be upgraded to 18.04 due to ppa conflict. I have submitted the . The comment about this bug is not sufficient to solve this issue, simply, because I could not able to determine which ppa(s) responsible to this issue.  I also unchecked all ppa(s) like the following screen shot    Is there any suggested solution that allows me to upgrade 16.04 to 18.04?

What are the different ways I can use to upgrade Ubuntu from one release to another?


Is there a way to set a program as default, for all file types it can open? I know there is a setting for this in windows, but how can I do this on Mac? Or at least a menu where I can toggle all files that can be opened, like you can in windows?  1. Set as default 2. List of files

I want to make an application, say , the default player for all the file types it supports, without going through all of them individually.  I might not even know what all the supported formats are (as VLC can read 100s of formats) and still want to set it as the default player for all of them.  I was able to do this using the terminal, with the procedure posted below.  Is there an easier way to do it that doesn't require the user to be a developer?


I'm given numbers in cents:  eg.     102042   982123   121212   I want to convert them to dollars. I figured the easiest way to do this is to convert the digits into a string and add a decimal.   eg.     1020.42   9821.23   1212.12   I'm currently doing this but it only rounds to 1 decimal. What would I need to do it make it round to 2 decimals?   var number = 102042 number.toString().match(/^-?\d+(?:\.\d{0,2})?/)[0]   UPDATE: I found out what my issue was. It wasn't the rounding but the fact that I combined a lodash filter to a division incorrectly. Thanks again!

I would like to format a price in JavaScript. I'd like a function which takes a float as an argument and returns a string formatted like this: "$ 2,500.00"  What's the best way to do this?


I need help with this question. I tried, but couldn't do it. How do I approach it?    I tried this approach. The problem is, even though it's obvious (by intuition) that the series (A1+A2+A3+......) adds up to less than 1, I can't show it that it does indeed add up to less than 1. Because the series is irregular, without a pattern. How do I prove it? I don't even know if this is the right approach, so please help me with it. Thanks

Define sequence ${a_n}$ as follows: $a_1 = \frac {1}{2}, 2ka_k = (2k-3)a_{k-1}.$  Show that for any natural number $n, \sum_{k=1}^{n} a_k <1$ (No calculus is allowed).  I'm really just stuck on the right way to approach this. It is sufficient to show that $\sum_{k=1}^{\infty} a_k <1,$ but this isn't a series I am familiar with. I tried defining a partial sum series $b_n$ such that $b_n = \sum_{k=n}^{\infty} a_k,$ but that didn't help to find a non-trivial relationship.


Is there a way to use the Apple iPad as an external monitor for Ubuntu? I see that there are applications for that purpose for Macintosh computers.

I've noticed people using a product for Windows and Mac called  which lets you use your Android or iPad as a secondary display. This seems like a great idea, and something that could be done on Ubuntu. Unfortunately, I've got no idea how to get started.  How could you re-create this setup on Ubuntu?


I'm trying to dual boot Ubuntu 16.04 with Win10 on my MSI and do understand that they're fairly notorious for making linux installs a hassle. I've made pretty minimal progress with the install and get stuck and the load screen whenever I try to install from an ISO on a usb. Ive turned off secure boot, fast boot, and Intel speed technology in the BIOS. I can only boot to the USB when its in Legacy mode, but I feel like it needs to be in UEFI mode for it to boot properly to Ubuntu. I used RUFUS for the USB installer which is compatible with UEFI. Am I no longer looking at BIOS issues and should be looking elsewhere? Any help is appreciated.  EDIT 1: Ive now got a working Ubuntu partition on the HDD however now when I boot the computer back up I can't access grub no matter the priority I set in the BIOS. It just goes straight to windows...  EDIT 2: Ive successfully got my computer to boot to grub every time giving me the option of windows or ubuntu, now there are issues with ubuntu allowing me to log on and use the os. Ive done editing with nomodeset after hitting E with Ubuntu highlighted, but that change doesn't save and if I dont do it every time I cant boot to ubuntu...  EDIT 3: Now I run into a new boot issue. I had it working for a while, got some drivers and Gnome set up, then when I went to restart to check it was solid and sturdy on boot, it hung at the boot screen. Typical purple/black hang error usually solved by nomodeset or nvidia/nouveau.modeset=0, however these solutions didn't work for me. I either experienced the same hang or was left with a text-based boot screen that yet again got stuck  EDIT 4: Last update before I let this question sit. I reinstalled Ubuntu, had to do nomodeset in the try ubuntu option and then install it back into the reformatted partition. Got into the os, it was scaled pretty large so I downloaded the nvidia driver. Restarted to apply changed and wasnt able to boot so went back and did nomodeset again. Got access into OS but the nvidia driver was gone. Redownloaded it with some other drivers and Gnome. Went to log out to change to gnome and every time Id log in the Id get a notification saying Ubunutu has encountered an error followed by a short pause and then I would get kicked from my account and put back to the log in screen. I'm now right back to where I was. Ive narrowed it down to graphic drivers and possibly gnome? I will wait to see if there are other options.  GRAPHICS CARD: Nvidia Geforce 970M CPU: Intel i7 6700 HQ

I have a computer with a video card that has no Linux support.  I discovered this issue while trying to use a persistent usb to boot from.   I found that I can boot like that if I change options and edit so as to add nomodeset there (see ).  Also, editing the syslinux.cfg file from my live persistent USB and adding nomodeset in a line there made this setting automatic for booting from the persistent USB.  Can I make a similar edit for proper install from the same live USB?  Is it possible to edit something on the live USB in order to install the SO from it,  -- that is: having automatically the nomodeset setting already there when the installation starts?  My problem is that in order to install I think I already have to have added nomodeset or I'll see nothing on my display. I need a way to be sure that nomodeset it's permanent from the start.


I just saw a number of comments complaining about the first n in the phrase ‘an Herculean task’, claiming it implied a mute h. But is that true? My impression has been that earlier all words on h + vowel got an an, regardless of whether or not the h was mute. Was ‘an hundred’ pronounced ‘an undred’?  PS. Let me be clearer that I am not asking about standard contemporary usage. I never doubted that ‘an Herculean task’ had an archaïc ring to it. But the fact that something is archaïc does not make it wrong.

Some h-words need 'an' for the indefinite article (I will be there in an hour).  Other h-words need 'a' for the indefinite article (It is a history of sadness).  Is there a general rule?


I need a word for when an event or situation that is very unlikely to happen, happens. For example, let's say the nerdy kid in school, who is an outcast with no friends, dates the popular girl in school. From a stereotypical view point, the likely hood of a "nerd" to date the popular girl in school is very unlikey, but what if it did happen? Is there a word for this type of scenario?

I've read , but none of them are what I am looking for. I once read a book that used a word to describe an event that has happened in the past, but the odds were so astronomical that it will likely never happen a second time. The context I read these words in were the creation of the first life on earth (without any theological ideas). Basically, the text said that the scenario for the creation of the first living organism happened on a planet where conditions were just right by complete chance, and that the odds of this were so astronomical that it would likely never happen again anywhere in the universe over any length of time.  Sample sentence: "The creation of the first organisms was incredibly unlikely, the event can be called a _________ event, or an event that will likely never happen again."   I can't pretend to understand the validity of the claims by the text, but the words they used to describe these events were quite clever (and scientific sounding) that it would make a fun hyperbole.  I thought it was something along the lines of singularity event, but that doesn't sound quite right.


i want get current time, when i convert new Date() into sting but when it converts reduces 5.30 hours based on my time zone.  How can i get same time which returns in new Date() method?

I want the server to always serve dates in UTC in the HTML, and have JavaScript on the client site convert it to the user's local timezone.  Bonus if I can output in the user's locale date format.


I am trying to install a module  on Drupal 9 site. CookiePro has no Drupal 9 release. But this  can make it work on  D9. Now confusion is that how do i install this module and patch both together. I tried lando composer require drupal/cookiepro and added the patch to extras --> patch section in composer.json. With both ways i am getting compatibility issue drupal/cookiepro 1.0.0 requires drupal/core ~8.0

Given I have Drupal 9 composer installation with composer-patches plugin and given a contrib module with a stable v8 release, but no v9 release (not even dev branch) and given that contrib module has a working v9 patch in the issue queue  is there any method to install that module + patch in composer? Even if I manually add both, the package and patch, to my composer.json, I still can't require or update this module with composer due conflicting versions. I really want to avoid duplicating /contrib code into my project's /custom codebase. My current workaround is:  forking that module to my own, private git repo applying patch there creating a new composer.json in my private git, and changing the package vendor to my custom_private_vendor adding my private git as VCS repo in the D9 project's composer.json and then composer require custom_private_vendor/contrib_module  This fulfills my goal of not duplicating the contrib module in my project's custom codebase, but every time I do this I feel the urge to wash my dirty hands. Is there something more elegant like composer require drupal/contrib_module --apply-patch-first or can I somehow target drupal.org's git with a specific patch included?


had a 12.04 disk and installed on a vista laptop for a friend, did not realize till install that 14.04LTS was available. should I burn a disk and reinstall 14.04, upgrade or stick with 12.04?

I just installed Ubuntu 12.04 LTS about 2 weeks ago. A week later a newer LTS came out. Now I know that I will get to upgrade in June but I don't know if I should upgrade or not. Please give me suggestions.


I wanted to upgrade my Ubuntu 14.04.2 to Ubuntu 15.10. I learned I first had to upgrade to 14.10 then to 15.04 and then finally to 15.10. In terminal I entered:  sudo apt-get dist-upgrade   About 315 MB data was downloaded and text went on scrolling in the terminal window. At last the process wound up. I restarted system and ran in terminal:  lsb_release -a   and It gave the output:  LSB Version:    core-2.0-ia32:core-2.0-noarch:core-3.0-ia32:core-3.0-noarch:core-3.1-ia32:core-3.1-noarch:core-3.2-ia32:core-3.2-noarch:core-4.0-ia32:core-4.0-noarch:core-4.1-ia32:core-4.1-noarch:security-4.0-ia32:security-4.0-noarch:security-4.1-ia32:security-4.1-noarch Distributor ID: Ubuntu              Description:    Ubuntu 14.04.2   etc... I was shocked that it is not upgraded what should I do now to upgrade and what went wrong with me? Thanks!

What are the different ways I can use to upgrade Ubuntu from one release to another?


I want an explanation for this:     "The centre of mass & centre of gravity of an extended body on the surface of earth is different for objects with sizes greater than 100m"   As a matter of fact I was under the impression that the centre of mass(CM) always coincides with the centre of gravity(CG).

What is the difference between  and ?  These terms seem to be used interchangeably.  Is there a difference between them for non-moving object on Earth, or moving objects for that matter?


I am a UK citizen and I also have a Canadian passport. I am in the process of applying for a work visa in the US with my UK passport. I have an upcoming trip in Europe (I am currently in the UK). My question is: Will I be able to leave the UK with my Canadian passport (as I didn't enter the UK with my Canadian passport)? I'm slightly concerned there might not be time between getting back my passport from the US Embassy and my travel.  Thank you.

I have a fairly convoluted situation:  I'm a British national currently resident in Bermuda. I have a Brazilian passport and also up until recently a British passport.  Earlier this month I lost my British passport while on holiday in Canada. This weekend I also have a trip back home (planned long ago) to the UK for 3-4 days.  The British consulate in Canada gave me emergency travel documents entitling me to travel to the UK via Bermuda, so that I could make the UK trip (since full UK passports take 6 weeks to reissue and there is no consulate in Bermuda). I'm now in Bermuda, half-way through my documents' journey. On them I can reenter the UK this week, but my issue is how I'm going to get back having now discovered the 1-day premium service for renewing passports is in fact not available for replacing lost passports and one cannot obtain more emergency travel documents in the UK, contrary to the advice of the consulate in Canada.  After fairly extensively analyzing my options I've deduced they're fairly limited. Extending the length of my trip in the UK is not desirable due to possible tax implications. However, one potential solution I've not been able to verify is whether I could travel into the UK on these emergency documents, then leave back for Bermuda on the Brazilian passport instead.  I know you can't enter the UK on a non-UK passport if you're eligible for one - but what about leave? Would Bermuda accept my Brazilian passport? Might it being a British overseas territory complicate things?


Say I work remotely whilst traveling around the world for a year or two. During this time I will not have a home address.  Would I have to pay income taxes during my travels? If so to which government? My "home" country where I lived before starting my travels? The country whose passport I have? The country in which I was when I got paid?  If it helps I live in the U.K and am thinking about traveling whilst working part time for a couple years. Mostly within the E.U.

We're in the EU (EU passports) and planning on spending the next couple years traveling. Income is coming through a company I have set in a country I was never a resident of.  The only taxes I'm normally liable for is my personal income, at my place of residence.  During the travel period, we will not stay longer than 2-3 month in a specific country, therefore we don't establish tax residence in any of them.  In that situation, can I avoid paying income tax during that time?


How can I make an appended element clickable? In this case, clicking "Hello" should change the background of #div1.  <!DOCTYPE html>

     <button type="button">Click Me!</button>      Thank you!

I have a bit of code where I am looping through all the select boxes on a page and binding a .hover event to them to do a bit of twiddling with their width on mouse on/off.  This happens on page ready and works just fine.  The problem I have is that any select boxes I add via Ajax or DOM after the initial loop won't have the event bound.  I have found this plugin (), but before I add another 5k to my pages with a plugin, I want to see if anyone knows a way to do this, either with jQuery directly or by another option.


Given the following sentence:     You should always use prefixes with your table names   Is the word table properly labeled as a noun or an adjective, as it is functioning as an adjective but the base word is a noun?  Context:  I am prefixing the words in some phrases with abbreviations. Some of the words are giving me trouble in classification. (The message is supposed to be an implicit proof of why adding prefixes to table names in a database is terrible. But I'd like to get it right.)  Here's the full set of sentences for your amusement. However, please restrict your comments to the stated question, for the most part.        com-Don't ver-Listen prep-To adj-Those adj-Other nou-People.    pro-You aux-Should adv-Always ver-Use nou-Prefixes prep-With pro-Your adj-Table nou-Names.    pro-I aux-Have adv-Even ver-Started ver-Using pro-Them prep-In adj-Normal nou-Writing.   com-See adv-How adj-Effective pr-It ver-Is?    nou-People aux-Can ver-Understand pro-Your nou-Writing adv-Better!      This question is part of 3 related questions:    This question    It originally came from

I read this recently in :     At the end of the summit, the French and European officials had   claimed a points victory over the Germans by getting them to agree   more firmly to a target date of January 1st next year to entrust the   European Central Bank (ECB) with the ultimate authority to supervise   the euro zone’s 6,000-odd banks.   "Points" is a plural, and I suppose it doesn't function as a noun in this sentence since it's following the article "a", so is it an adjective adorning "victory"?


If $F$ is a field with $q$ elements, $V$ a $F$-vector space of dimension $n$, then how many ordered basis does $V$ have ?   First, $V$ has $q^n$ elements, am I correct ? Let $\{v_1,\dots,v_n\}$ be a basis then for example $\{v_1+v_2,v_2,\dots,v_n\}$ is also a basis, So can I say $n\times n$ identity matrix represents the first basis, then for the second basis we have also the identity matrix but with the first row replaced by $(1,1,0,\dots,0)$ (instead of $(1,0,0,\dots,0)$), hence any invertible matrix would give another basis, but it should be ordered, does it mean that the matrix should not be symmettric (axis ?) and don't we need some information about $q$, for example $q=p^n$ then number of elements depend on $p$ ?

If I have an n-dimensional vector space over a field with q elements, how can I find the number of bases of this vector space?


I was reading articles and forum posts about using version numbers in CSS/JS files.        It turns out that embedding version numbers in file names are more reliable than using a query string. The articles and discussions I found were back in 2008 or so. I was just wondering if this is still the case today or have things changed with browsers and servers handling things differently? Is the query string now equally reliable?

As per Yahoo's much-ballyhooed , we serve up static content from a CDN using far-future cache expiration headers. Of course, we need to occasionally update these "static" files, so we currently add an infix version as part of the filename (based on the SHA1 sum of the file contents). Thus:  styles.min.css   Becomes:  styles.min.abcd1234.css   However, managing the versioned files can become tedious, and I was wondering if a GET argument notation might be cleaner and better:  styles.min.css?v=abcd1234   Which do you use, and why? Are there browser- or proxy/cache-related considerations that I should consider?


I would like to write a program to get every sum from a list. For example:  L = [['7'], ['3', '8'], ['8', '1', '0']]  I would like to get:  8 + 3 + 7  8 + 8 + 7  1 + 3 + 7  1 + 8 + 7  0 + 3 + 7  0 + 8 + 7  So, I wrote my program in this way:   for x1 in L[-1]:      for x2 in L[-2]:          for x3 in L[-3]:              print (int(x1) + int(x2) + int(x3))   However, there may be a huge number lists. In this way, I have to write a huge number of for loop. Is there any other way that I can use to write my program?  itertools.product works well for this question, but is there any way to do not import anything to solve this question?

How can I get the Cartesian product (every possible combination of values) from a group of lists?  Input:   somelists = [    [1, 2, 3],    ['a', 'b'],    [4, 5] ]   Desired output:  [(1, 'a', 4), (1, 'a', 5), (1, 'b', 4), (1, 'b', 5), (2, 'a', 4), (2, 'a', 5) ...]


I know this looks like a dumb question, but how do I simplify this? Does it uses some square root property or factorization? The wolfram alpha has no step-by-step solution for this, so it may use some crazy technique, I guess.  $$\frac{\sqrt{4+h}-2}{h} = \frac{1}{\sqrt{4+h}-2}$$

The following expression:  $$\frac{\sqrt{4+h}-2}{h}$$  should be simplified to:  $$\frac{1}{\sqrt{4+h}+2}$$  (even if I don't agree that this second is more simple than the first).  The problem is that I have no idea of the first step to simplify that.. any help?


I'm trying to create new taxonomies. What is the best practice? Many thanks.

Is there an easy to understand scheme to decide what kind of code belongs to a plugin or the theme’s functions.php?  There    and many  about that topic, mostly because there are some misconceptions about the inner workings of WordPress. I am asking for an answer based on facts, not on opinions.  It should explain how to handle these points (and probably more):   custom post types and taxonomies contact forms shortcodes custom widgets  SEO functions like custom meta elements theme switch   There are often pros and cons for both sides. Our most popular question  got a lot of code snippets as answers that are at least debatable. We need criteria a beginner can understand, maybe a check list – with reasons.  See also the related question by Chip Bennett on our meta site:   Related:


I am trying to access BAWSAQ and it keeps showing me an error. Is it currently under maintenance? Or am I doing something wrong? I am signed in to my PSN account.

I can purchase stocks at LCN website but the BAWSAQ is still under maintenance, I've completed 45% of the game and can't buy stocks from that website. Am I missing something? Do I need a special mission to unlock it?


How to say if a person earns lot of money especially in a bad ways or through illegal business. I want to know the verb of earning money through illegally and how can we call such a person.

Money/Assets/Property that is earned through unethical sources is   called ?   Money that is earned through bad sources like corrupted politics, corrupted business, ransom money, stolen or theft money. What is such money called?  Is it bad money, black money. What is one particular name for it?


I currently own a Sony z1 and had not hqve any troubles with an otg storage device. But I coulndt make the same storage device this to work with my galaxy ace. ROOTED Version 2.3.6  I have so far scoured google for answers but have found no satisfactory info.  So id like to know if there is any kind of step/procedure the I can do to make it work?  Im a fan of keepong old stuff from trash unless they really stop working specially electronics. Pls help

Some Android devices can act as a USB host, so that you can use other USB devices attached to them. For instance, browse or import the photos stored on a camera from your phone, or copy files onto a USB memory stick attached to your tablet, plug a full-size USB keyboard or mouse into a tablet, or use an external GPS or wifi device.  How can I tell if my device can do this?


I am new to Latex and I am trying to incoorperate references/bibliography in my document. First I want to get the code working that I got from here   \documentclass[11pt]{article} \usepackage{cite}  \begin{document}  \title{My Article} \author{Nobody Jr.} \date{Today} \maketitle  Blablabla said Nobody ~\cite{Nobody06}.  \bibliography{mybib}{} \bibliographystyle{plain} \end{document}   The .bib file is as follows  @misc{ Nobody06,    author = "Nobody Jr",    title = "My Article",    year = "2006" }   This doesn't work. It doesn't show my list of references and when it should cite  ~\cite{Nobody06}   then it just displays     [?]   If have read that this has something to do with bibtex not running the right files. I should see this in my blg file. But I have not been able to find my blg file yet.  It's probably a super simple solution but I haven't found it. I am using TexWorks and MikTex.   Thank you for your help

I've browsed the forums and found a number of posts that have addressed this issue, but none of the solutions seem to work for me. I have the following script that I just copied from the bibtex home page to get familiar with it. Instead of the citation number I get a question mark. I compile using Latex+Bibtex+Latex+Latex+PDFLatex+ViewPDF just as has been previously suggested and the problem persists.   \documentclass[11pt]{article} \usepackage{cite}  \begin{document}  \title{My Article} \author{Nobody Jr.} \date{Today} \maketitle  Blablabla said Nobody ~\cite{Nobody06}.  \bibliography{mybib} \bibliographystyle{plain} \end{document}   My bibliography (Bib.bbl)  @misc{ Nobody06, author = "Nobody Jr", title = "My Article", year = "2006" }    Looking at previous posts one thing that is concerning is that my .bbl looks empty as shown below. Further, I don't have a .blg  \begin{thebibliography}{}  \end{thebibliography}


I had this problem a few weeks ago where my C: drive would fill up over night. When I came to work in the morning my drive would be full, after reboot I'd about 200GB free. I tried cleaning up with disk clean but that didn't free enough up, then I looked at winDirStat and it only show 300GB of space being used.  After getting super confused I found out how to display the "unknown" file type and found that was filling all of the free space. After a lot of duck(and google)-fu I found about the storage sense and cleared up the storage issue. Today I get a notice from backblaze that my disk space is low, and sure enough these unknown files are back, but this time StorageSense isn't removing them. so I'm sitting on 101GB of spacing being used by non-file objects. Sorry for the novel, TLDR:  Drive was full Windirstat(as admin) shows 200 gigs not used by files, taken up by unknown Cleaned unknown space hogs with StorageSense, stopped being and issue Wait couple weeks free space is fill again with unknown data StorageSense isn't cleaning

I recently noticed that one of my external hard drive seems to be missing a lot of space. It was recommended that I try WinDirStat, as it could help identify how much space each file was taking up. This is the result:     As you can see, there is about 244.7GB "unknown" usage.  Doing a bit of research online, the most common suggestion was (a) Recycle Bin and (b) System Volume Information.  (a) As you can see, empty. To double check, I ran Disk Cleanup. It confirmed that it was empty. (Note that a new file appeared by the time I took this screenshot, but it's only 129 Bytes.)  (b) Harder to tell. However, according to various forums, the most common reason for System Volume Information to grow large is due to System Restore Files. I had a look, and it is definitely turned off for this drive, as seen here:     What else could be causing this issue? It is an enormous amount of storage to have gone missing!


I have an $n\times n$ matrix where the diagonals are equal to one and the off diagonals all have magnitude smaller than one. Is this matrix invertible? What is the quickest way to prove it?

I ran into this problem recently.  If $A$ is a $n\times n$ matrix with $1$s in the diagonal and all off diagonal entries have absolute value less than $1$, is $A$ invertible?  It it definitely true for a $2\times 2$ matrix and seems to be true for larger matrices, just by trying to compute the determinant, however, my expression seems to get messy, and I was wondering if there was a easier method to solve this. If not, direction on how to argue from definition of determinant would be appreciated. Although I can see that an argument might come from there, I am having problems with that too.  Thank you for any help, and any help is much appreciated.


In Jurassic Park, we're told that the dinosaurs are built with a failsafe.     ARNOLD: The lysine contingency is intended to prevent the spread   of the animals is case they ever got off the  island.  Dr. Wu inserted   a gene that makes a single faulty enzyme in protein metabolism. The   animals can't manufacture the amino acid lysine.  Unless they're   continually supplied with lysine by us, they slip into a coma and die.   Which is all fine and good-- unless you then make three sequels filled with dinosaurs, none of which are being provided lysine. The first two sequels take place on an island that's been completely abandoned by In-Gen. Jurassic World features the original T-Rex, even though it should have died after the first Jurassic Park was abandoned.  Did they ever address this address this in the sequels?

I was watching the movie recently and noticed that one of the characters (very) briefly mentions a safety they built into the system should any of the dinosaurs escape. They called it the Lysine Contingency saying that all the dinos have been genetically modified to depend heavily on lysine in their diet, so if any of them escape they wouldn't be able to survive without the food supplements that the park gives them.   Why doesn't the story end right there? Does the Michael Crichton book actually explain this in depth?


This is definitely the most irritating aspect of an otherwise excellent service:  As of 6/4/14:  No Italics:  app/controllers/users_controller.rb  Italics:  app/models/user.rb  Why? Because there's an underscore in the first path? This is a bug, right?

of mine has some italicized words containing underscores in the first line. These look good in the preview, but in the answer they appear non-italicized with surrounding asterisks.  Is this a known bug, and is there a workaround?


Definition of "Consistent nearest neighbour", runs our usual KNN classifier but instead of viewing k as a hyper-parameter it always sets k = ceil[log(n)].  So far, I looked-up many references and websites and researched on how to determine if a method is between parametric or non-parametric. I came up with below definitions,     A parametric algorithm has a fixed number of parameters. In contrast, a non-parametric algorithm uses a flexible number of parameters, and the number of parameters often grows as it learns from more data.   From .  Moreover, I found,     A parametric model, we have a finite number of parameters, and in nonparametric models, the number of parameters is (potentially) infinite.    From .  My question is, why do we count it as a Non-parametric model, while    the number of parameters can increase to infinity in the mentioned    method and it will gets more complicated by increasing test data?

I looked-up many references and websites and researched on how to determine if a method is between parametric or non-parametric. I came up with below definitions,     A parametric algorithm has a fixed number of parameters. In contrast, a non-parametric algorithm uses a flexible number of parameters, and the number of parameters often grows as it learns from more data.   From .  Moreover, I found,     A parametric model, we have a finite number of parameters, and in nonparametric models, the number of parameters is (potentially) infinite.    From .  And many other methods of determination, though the problem is none of them can helo ones to determine if a certain hypothetical method is parametric or not. (For instance, why k-means' number of parameters are constant but KNN is variable or basically what do we call a parameter and what we do not?)


I am working on a development website which involves users posting their favourite content of their book on to the webpage and all the data gets stored in the database and gets displayed on the website. However whenever i try to post big paragraphs using the form I created and php scripts which processes the form, it doesn't give any error but it doesn't store the values to the database as well. It works okay if the content to process is short. Please help me the code is below. Any suggestions would be appreciated.  <?php $hostname = "localhost"; $username = "root"; $password = ""; $database = "library"; $conn = mysql_connect($hostname,$username,$password)or die('Cannot connect'); mysql_select_db("library", $conn); ?>  <?php $title = $_POST['title']; $author = $_POST['author']; $content = strval($_POST['content']); $description = $_POST['description']; $category = $_POST['category'];  if (isset($title) && !empty($title)){     $sql = "INSERT INTO books(title,author,description,content,category) VALUES('$title','$author','$description','$content','$category')";     mysql_query($sql);     echo 'Successfully Added the book'."
Check it out here"; } else{     echo 'Title is missing'; } ?>   Thanks.

If user input is inserted without modification into an SQL query, then the application becomes vulnerable to , like in the following example:  $unsafe_variable = $_POST['user_input'];   mysql_query("INSERT INTO `table` (`column`) VALUES ('$unsafe_variable')");   That's because the user can input something like value'); DROP TABLE table;--, and the query becomes:  INSERT INTO `table` (`column`) VALUES('value'); DROP TABLE table;--')   What can be done to prevent this from happening?


Consider a scenario where a mail will be sent to contacts in Data Extension. The mail contains a button that will redirect to CloudPage.   This cloud page has a smart capture that will prepopulate some fields like EmpId, FirstName, LastName in text fields from contacts in DE and there are Other input fields where the user will enter Data to input fields and click the submit button.   After hitting the submit button the cloud page, Contact in DE gets updated by adding newly entered data by the user.  My problem in this scenario is how to update the contact in DE. smart capture is unable to update because it is trying to add the record in DE but EmpId(Primary Key) already exists in DE.

This might be a stupid question but is there a way to update records (yes many records and duplicate ones) in a DE without a primary key? I am not the owner of the DE which is already structured for several years so I cannot change its fields.  Thanks.


If a massless observer is going at the speed of light, what speed will it measure of a light beam going parallel to it?

Quite a few of the questions given on this site mention a photon in vacuum having a rest frame such as it having a zero mass in its rest frame. I find this contradictory since photons must travel at the speed of light in all frames according to special relativity.  Does a photon in vacuum have a rest frame?


Can there be such a quantity which has units but not dimension?    In case of gravitational constant for instance, it's also just a number, then it has units, but suppose to be dimension less because it's a constant number.    Also what does this physically mean?    [please try to clarify what things are suppose to have units and dimensions]

If I say Height of a block = 2m, then would "Height" be called as a dimension


Good morning I have imported a obj with textures in blender and i would like to cut it and eliminate margins. in the image you can see several trees in margins, and i would like to cut and only remain the area of the green square. How can i do this? Thanks

Coming from SketchUp one of the tools I miss most is the circle draw tool which lets you draw a circle on any face and then you could extrude it in/out. The only tool that I know of that comes close to this is the knife tool but this would be very impractical to cut out with the knife  Example:    Is there any tool in blender that can match this function? also how could you do this with squares?


I'm new to tikz and I am trying to make a perpendicular angle mark on a triangle by  \path[clip](C)--($(B)!(A)!(C)$)--(A);   and  \node[draw=black, rectangle,inner sep=0pt, outer sep=0pt, minimum size=4mm] at ($(B)!(A)!(C)$){};   But I am only getting a bottom of the square on the angle.   I am trying to save the hassle of finding the right angle to rotate for the square. So is there any easier way to draw the right angle mark with rotation?  Below is the code for my shape.  \begin{tikzpicture}     \coordinate[label=-90:$A$] (A) at (0,0);     \coordinate[label=-90:$C$] (C) at (4,0);     \coordinate[label=45:$B$] (B) at (1.25,3);     \draw (A)--(B)--(C)--(A);     \draw ($(A)!(B)!(C)$)--(B);     \draw ($(B)!(A)!(C)$)--(A);     \draw ($(A)!(C)!(B)$)--(C);         \begin{scope}         \path[clip](B)--($(A)!(B)!(C)$)--(C);         \node [draw=black, rectangle,minimum size=4mm,inner sep=0pt,outer sep=0pt] at ($(A)!(B)!(C)$) {};         \end{scope}         \path[clip](C)--($(B)!(A)!(C)$)--(A);         \node[draw=black, rectangle,inner sep=0pt, outer sep=0pt, minimum size=4mm] at ($(B)!(A)!(C)$){};         \begin{scope}         \end{scope}         \begin{scope}         \end{scope} \end{tikzpicture}   thank you for your help.

This provides good details on . What I would like to do is to extend this somehow to add the usual geometry symbol to indicate that the two lines are indeed perpendicular. I could code a manual solution for each situation, but would like a macro, one that would draw it of an appropriate size, and allow me to choose the orientation (i.e., select one of the four quadrants) for this symbol.


Looking for turnkey solution for 12.04 lts.  That is the equivalent of doing an apt-get install ia32-libs from earlier Ubuntu distros  Reason: games that need 32 bit support or anything really. Just want to install all 32 bit equivs of installed 64 bit libs with out having to do it one at a time trial and error style.

The ia32-libs package is no longer present in Ubuntu 12.04 repositories for a 64bit system. Are there any available replacement packages available for download?


I am sourcing our GIS data (ESRI ArcGIS) into a data warehouse for reporting. I am trying to join our sites in Table_A (with a point geometry column) to our markets in Table_B (with a polygon geometry column) by using the STContains() function. However, I found that these two columns are using different SRIDs (4326 and 4269 respectively) so the function will not work. I've done a lot of reading, and found that SQL Server has no transform function. So I used the .STAsText() function to store the text and STGeomFromText function to recreate the geometry, but this time matching the SRIDs. Now the STContains() function returns 1 that they do overlap as expected. My concern is I don't fully understand the impact of changing this SRID. By doing so, did I shift the point/polygon from where it should be on the map? Is what I'm doing a valid solution?

I have US census data against state boundaries stored as  SRID 4269, in an MSSQL DB.  The input data used for calculations against that dataset is stored as SRID 4326.  As far as I can infer from the , SRID 4269 is just a subset of SRID 4326 and no coordinate re-projection is necessary.  Do I actually need to re-project from SRID 4326 to SRID 4269, provided that the input data is always within the bounds of the SRID 4269?


I can not figure out how to control the output from jsonlite::toJSON() so that high precision numbers are represented as is.   For example:  l <- list(x = 1.001000000000987466525, y = 0.0000022624065747878902023) jsonlite::toJSON(l, pretty = TRUE, digits = NA, auto_unbox = TRUE)  {   "x": 1.00100000000099,   "y": 2.26240657478789e-06 }    I would like the output of toJSON to preserve the exact value in l as follows:   {   "x": 1.001000000000987466525,   "y": 0.0000022624065747878902023 }    Can this be done?

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


I argued with my I.T. teacher who is also our research adviser because as far as my knowledge is concerned I insisted that using they, them and their is acceptable based on APA style. She prohibited us from using she and he, which is understandable, but they, their and them? I don't understand that.   So the words left for us to use is  us and students who are the subject of the research and these words eventually become so redundant in our research paper. I think this is very stupid.  Is she correct?

Is there a pronoun I can use as a gender-neutral pronoun when referring back to a singular noun phrase?  Each student should save his questions until the end. Each student should save her questions until the end.


Two dice are rolled. What is the chance of rolling at least ONE six? (The answer is $\frac{11}{36}$.)  My solutions manual has a very elaborate table drawing method and I don't want to do that. I need something more quick. (I could have drawn the table in the time it took me to answer this question and so forth, but I'm keen on learning new methods!)

$11$ out of $36$? I got this by writing down the number of possible outcomes ($36$) and then counting how many of the pairs had a $6$ in them: $(1,6)$, $(2,6)$, $(3,6)$, $(4,6)$, $(5,6)$, $(6,6)$, $(6,5)$, $(6,4)$, $(6,3)$, $(6,2)$, $(6,1)$. Is this correct?


How does delete operator work in C++?  int *ptr = new int[2]; delete[] ptr;   How does delete operator know the amount of memory allocated, since ptr is just a int pointer and increment-ing(++) it would simply make it point to the next location in the continuously allocated structure.

Foo* set = new Foo[100]; // ... delete [] set;   You don't pass the array's boundaries to delete[]. But where is that information stored? Is it standardised?


The electron absorbs the energy of photon(with specific frequency)and re-emits the photon.The photon can be emitted in any direction. So why do they get re-emitted in a specific direction after reflection? On hitting normal to surface the photons follow path in reverse normal direction and hitting at an angle it follows V path.

The "equal angles" law of refection on a flat mirror is a macroscopic phenomenon. To put it in anthropomorphic terms, how do individual photons know the orientation of the mirror so as to bounce off in the correct direction?


In the interstellar movie, the black hole shown has a ring of light orbiting around it. From what I know, (correct me if I'm wrong) that light is unable to escape the gravity of the blackhole and therefore is orbiting the blackhole. If it is unable to escape, why can we see that light?

I was expecting a whirlpool in 3D and the matter glowing from friction as it nears the center, as I expected a event horizon to be negligible visually.  How does this depiction work? How big is the central sphere? I am puzzled by the perpendicular circles. Are they the event horizons if they are both visible? What would be a path of a particle as it gets swallowed into the singularity?


This is same bug as  which is . This got reproduced. It is on Area51 this time.    help, chat and logout should be in the first line but they moved down. The padding in the communities list is also affected.    This is how it should be.   I believe that the reason is same as the previous bug report i.e., experiments on layout for .

The content in the site switcher, inbox and achievements of the Area 51 are misaligned. I can verify the issue in recent Google Chrome and Mozilla Firefox browsers with 100% zoom.


Sometimes I use the indirect questions as stated below,     Could you please tell me, where is this address??   Sometimes, I feel it's not correct, although it's understandable to any person. So tell me, is it grammatically correct?   I usually use phrase before the direct questions. Is that the correct way for polite questions?

Why did you not tell the truth? Can you tell me?  Now join them in one sentence. What is the result?  Can you tell me why did you not tell the truth?  or  Can you tell me why you did not tell the truth?   I'm guessing the second one should be correct. You did something i.e. hide the truth and I'm asking you the reason behind it. Can you tell me why(the reason for which) you did not tell the truth?  Right or wrong?


I have this variable in file.sh: IMAGE_MANIFEST=sha256:c41d9adf556bb500d2834292d84e8dacfcea5c2d1bbd24f80c3ff9061b9925b1  When I run the command below: export $IMAGE_MANIFEST  I get an error: ': not a valid identifier line 35: export: `sha256:c41d9adf556bb500d2834292d84e8dacfcea5c2d1bbd24f80c3ff9061b9925b1  How can I fix it?

I'm trying to setup cocos2dx in Ubuntu 14.04 LTS but after setting the environmental variables (in .bashrc) I start getting this error:  bash: export: dev/cocos2d-x-3.2/tools/cocos2d-console/bin': not a valid identifier  bash: export:/home/john/android': not a valid identifier  bash: export: dev/android-ndk-r10b': not a valid identifier  bash: export:dev/adt-bundle-linux-x86_64-20140702/sdk': not a valid identifier   And I don't know what to do to fix it.


$R=R_1=R_2=R_3=R_4=R_5=R_6= 10 \Omega$ $R_2 \quad and \quad R_3 \quad with \quad R_4 \quad and \quad R_5 \quad are\quad in \quad series$  Therefore, $\frac{1}{R_{tot}} = \frac{1}{R_1}+ \frac{1}{R_2+R_3}+\frac{1}{R_4+R_5}= \frac{1}{R}+\frac{1}{2R}+\frac{1}{2R}= \frac{2}{R}$  $R_{tot} = \frac{R}{2}$    What I don't get is, why we can ignore $R_6$?

What's the equivalent resistance in this circuit (between points A and B)?


I am asked to show that      $$\displaystyle \int_{0}^{\infty} \frac{\ln(x)}{(x^2-1)} = \frac{\pi^2}{4}.$$   So I think I'm supposed to use residues to solve this integral and integrate around a contour on the real line. The thing is that I don't know how to choose this contour since the poles will lie on the path and I would also have to bent around zero since $\ln(x)$ has a non essential singularity there. I tried to do this with the methods that I've learned but I got as an answer $-\pi^2$ which is wrong. Any help on how to proceed is appreciated.

I have to calculate $$\int_0^\infty\frac{\log x dx}{x^2-1},$$  and the hint is to integrate $\frac{\log z}{z^2-1}$ over the boundary of the domain $$\{z\,:\,r<|z|<R,\,\Re (z)>0,\,\Im (z)>0\}.$$  I don't understand. The boundary of this domain has a pole of the integrand in it, doesn't it? Doesn't it make this method useless?


In Avengers: Infinity War      Thanos gathers the Infinity Stones one at a time.   I realize the MCU and comics are different but in the comics is it important which Stone goes in which slot and the order they are placed there?

In Avengers: Infinity War,      Thanos obtains the Power Stone, Space Stone, Reality Stone, Soul Stone, Time Stone and Mind Stone in that order.   Each object seems to go into the next notch with no rhyme or reason.   Is there an order to the acquisition or is it a matter of which one(s) become available?      It bears mentioning that the Mind Stone appears larger in the Infinity Gauntlet but appears the same size as the other stones before it's placed.


I am looking for information pertaining to German soldiers during World War II. My significant other's great grandparents were from Germany during the second world war. His great-grandfather was in the Nazi youth program, and fought as a soldier in Italy. He was captured by the Americans in 1941 or 1942 in Italy. I was wondering what kind of records can I find surrounding german POW's or german records.

Where can I find information on German soldiers from World War I and World War II?   I am curious to find out about my ancestors' role in the wars, i.e. what rank they had, where they where fighting, with whom and anything else.


im trying to grab the value of a text field in a Data extension. It has a specifix syntax: example_IWantToGrabThis_example I want to grab the value between the underscores. I think i need to use CHARINDEX  with Left and right but cannot seem to find examples that work in Marketing Cloud. Kind regards Rob

I am storing the URL given below in a field in DE:    From this , i want to trim the utm_campaign value in the field .  Finally it should look like this  4in1tbd_20170421  Is this possible through SQL? Can anyone give me a suitable solution please?


Just loaded Ubuntu on an older PC and it seems to be running very slow and “choppy”.   I am running ubuntu 14.04 LTS on my 2003 Compaq Presario S4000NX.    RAM = 993MB Processor = Intel Celeron 2.40GHz Graphics = on board Intel 845Gx86/MMX/SSE2 OS = 32bit Hard Disk = 156GB   Am I under powered for this version? Would I be better off trying to install a graphics card or using a different version of Linix? I appreciate any suggestions.

For a given hardware configuration, how do I find out if Ubuntu will run on it? What considerations should I take into account when choosing an Ubuntu version and  such as:    with a lighter desktop than the usual Gnome and Unity  with the even lighter LXDE desktop   Obviously Ubuntu does not run on some processor architectures. So how do I go about choosing the right version and derivate. How can I find out the minmal system requirements?


my network are disabled after update kernel to 3.13.0-77-generic on ubuntu 14.04.1 (Voyager Live 14.04.1 amd64).  After update and reboot Wifi indicator on panel is disappeared and conky on desktop don't show WiFi power signal and led on my edimax EW-7811Un not blinks  i'm try this:  lshw -C network  *-network DISABLED               description: Ethernet interface  *-network DISABLED               description: Wireless interface  then this:  sudo ifconfig wlan0 up  sudo ifconfig eth0 up  DISABLED are disappeared in terminal and conky show WiFi 0 and led now blinks, but indicator on panel not appeared and window of network connection doesn't have any connection (window is empty, look like Ethernet and Wi-Fi connections has been deleted after update kernel). Then i'm try to add new connection but after choose connection type of  Ethernet or Wi-Fi or something else, window are not active (can't change connection name and any network settings or save it). After reboot network are DISABLED again. Downgrade to old kernel 3.13.0-40-generic hasn't helped. I noticed after update (when network disabled) in *-network Wireless interface show line of product: edimax etc., but until update (when network enabled) there is no this line.  my desktop system:  Os:  Voyager Live 14.04.1 amd64 (ubuntu 14.04.1), ASUS P7H55, Core i3-550, RAM ddr3 4Gb, HDD WD 320Gb, Video GF GTS 250, Wifi edimax EW-7811Un  I waste 2 days try to solve this problem to prevent reinstall anew ubuntu 14.04.1 (on old kernel 3.13.0-40-generic), but eventually i'm was reinstall it.  Is there any normal solution of this problem? Normal means without fully reinstall os and without disabled updates.

While upgrading today, something caused my wireless network manager to disappear. Not even connecting via wired connection.  This error is being shown by files:  **(nm-applet:2716): WARNING **: Could not initialize NMClient /org/freedesktop/NetworkManager: The name org.freedesktop.NetworkManager was not provided by any .service files   (nm-applet:2716): nm-applet-WARNING **: Error connecting to ModemManager: Error calling StartServiceByName for org.freedesktop.ModemManager1: GDBus.Error:org.freedesktop.DBus.Error.Spawn.ExecFailed: Cannot launch daemon, file not found or permissions invalid   (nm-applet:2716): nm-applet-WARNING **: Could not find ShellVersion property on org.gnome.Shell after 5 tries   (nm-applet:2716): nm-applet-WARNING **: Failed to register as an agent: (2) The name org.freedesktop.NetworkManager was not provided by any .service files    Is there a patch I can download through windows and send through to my ubuntu, or is it a case of having to reload everything? I tried running two versions back but still no internet access.


#!/usr/bin/python  x = [0, 2, 1, 1, 1, 1, 3, 3, 5, 1, 1, 4, 1, 2, 1, 2, 2, 2, 1, 7, 2, 1, 0, 3, 1, 1, 2, 0, 1, 0, 1, 1]  y = [1 for z in x if z > 0]  #WANT TO DO #y = [1 for z in x if z > 0 else 0]   I want to do both an if statement and an else statement within a list comprehension in Python. How can I do this?   I figured out y = [int(bool(z)) for z in x], but i was wondering if you could do both an if and an else statement in a list comprehension.

If Python does not have a ternary conditional operator, is it possible to simulate one using other language constructs?


Me and wife were planned to travel to France to attend a wedding.  She is from the EU region and i am not, i apply for schengen visa as an EU spouse which recently is required of her to sign a letter saying that she will be travelling with me.  Now, something has come up and she will not be able to travel with me.  Will i be allowed to travel alone ?  regards r

I am India citizen married to a UK national who has been issued a Schengen Visa from the Italian consulate as a spouse of a UK national. My husband was supposed to travel with me but now can’t. We have decided that I should still pursue the trip without him as I will be joining our friends there. Please can someone let me know if I will still be allowed to travel to the Schengen region with a valid Schengen Visa issued as a spouse of a EEA national but without my husband joining me there in person ?


I  don't  have any clue . Can  chinese  remainder  theorem  can  be  used?  I am  studying  number  theory  but I am not  an  expert  as  you  can  see. This  question  was  set  in  the exam  and  I could  not  answer.

Which of the following primes satisfy the congruence   $$a^{24}\equiv6a+2\pmod{13}$$  1) 41  2) 47  3) 67  4) 83  I am interested in Theorem statement, corollary, or Trick or Logic which solves this problem within one minute. Thank you in Advance


In c++, why we can overload operator -> and can't overload operator .? Similarly, why we can overload operator ->* and can't overload operator .*? I will be appreciated if you can help me!

It would be very useful to be able to overload the . operator in C++ and return a reference to an object.  You can overload operator-> and operator* but not operator.  Is there a technical reason for this?


I bought a bmx with 2.35 inch tyres on them , could I buy and put 2.4 inch tyres in the same rim and do I have to get another inner tube for it ?

We often get questions on bicycles.stackexchange about fitting wider or narrower tires to bicycles. We have a large number of these with answers suiting the specific bike or style of bicycle in question, but I have been unable to find one that provides a generic answer covering off all things that need to be considered. For most bicycles, the answer is the same regardless of the specific style and sizes of tires in question.   This is intended as a canonical question that we can point closed questions to.


Michael Wolff's new book Fire and Fury sure has generated quite a lot of controversy. However, one important topic seems to have been overlooked by the Mainstream Media: Wolff (or his editors) consistently use the singular verb form when describing actions taken by 'Jarvanka', Steve Bannon's catchy nickname for the Jared Kushner and Ivanka Trump duo. (For example, "Jarvanka was surprised" instead of "Jarvanka were surprised.")  Is this correct? or does Jarvanka take a 'were' as it most certainly is two people?  (Note: IMHO, this is not comparable to plural nouns such as media, because here Jarvanka is (or are) obviously two different distinct persons, unlike media which is merely a collective noun.)

I'd say Microsoft have a way of bending the rules and I know that McLaren have won the championship. While this sounds strange, I believe it is correct English (sorry, I'm not native).   But when it's a small company, would you still use it this way? Is a company always plural, or are small companies singular? I.e., would you say Bakery Johnson makes fine bread or Bakery Johnson make fine bread? Is it My book seller, Woody's, have moved or is it has moved?


Suppose $a>b>0$, compute   $$\int_0^1 \frac{x^b-x^a}{\ln x} dx$$  I tried to use substiution $t=\ln x$, but it didn't simplify the computation. Thank in advance.

$$\int^1_0\frac{x^b-x^a}{\ln x} d x =\ln{{\frac{1+b}{1+a}}}$$ The  part inside $\ln$ is absolute value. A solution including integration under the integral can be found . Which used the identity $$\int^1_0x^{\alpha} dx =\frac{1}{1+\alpha}$$. Multiplies both side by $d{\alpha}$ and integrates with respect to $\alpha$. Are there other methods to prove this identity?  Thank You.


I think I'm going crazy. Every time I create a folder it automatically is set to readonly, but I can still then rename the folder or add folders to it. If I attempt to uncheck the readonly flag it becomes checked again when I next open the folder properties. What the heck? Could my IT dept really have set up a policy like this somehow? If so, how?  Seems crazy that Windows would even do this -- no errors when I uncheck read-only and hit ok but the change fails.  Also, it is the halfway checked state -- greyed out and checked, but uncheckable.

I am having trouble with a folder that needs to be read-write for iTunes to open. For a while it was read-write, but it seemingly inexplicably changed to read-only now. When I try to change it back from that, it says it does it, but as soon as I try to open iTunes or the properties for the folder it will be listed as read-only again.  If anyone knows how I can change the folder from read-only so that it will be permanently read-write it would be incredibly helpful.  How can one change the properties of a file/folder from read-only to read-write in Windows XP?


I have a shapefile Water_Districts.shp that consists of several water district polygons. I am trying to use the script below to 'extract' a specific polygon with the name Cache La Poudre River listed under the NAME column in the Water_Districts.shp attribute table. I have been using the python script below, but am not sure how to incorporate the SQL expression in the -where exception of the ogr2ogr command. I am getting the error: FAILURE: SetAttributeFilter(NAME = Cache La Poudre River) on layer'Water_Districts' failed.  import gdal import subprocess  directory = r"F:\IrrigatedLands\FC_test\Water_Districts\Water_Districts.shp" output_shp = r"F:\IrrigatedLands\FC_qgis\boundary.shp"  subprocess.call(["ogr2ogr", "-where", "NAME = Cache La Poudre River", output_shp, directory])

I am writing a shapefile after some processing; however, in the final step I need to do some selection by attributes from the the shapefile.  I am using the command in a shell with the aim of using it in a Python script when it works.  ogr2ogr -f "ESRI Shapefile" -select * where ID="1" outfile.shp infile.shp   I am getting the error message:   FAILURE:  Unable to open datasource `Downloads' with the following drivers.   What could I be doing wrong?


I had a normally working Win7 computer a couple hours ago... I had removed a hard drive from a broken laptop and put it into an enclosure. Then I used ICACLS to reset the permissions on it so the files could be accessed. Anyway, I don't know what happened, but I somehow changed something on my computer, not just the external drive. I couldn't open most programs without running them as administrator (including chrome). I ran icacls "%appdata%*.*" /grant "%username%":(F) /T and now I can run Chrome but it won't sync.   I tried doing a system restore from several points from safe mode but they all fail.  I'm thinking about doing a icacls "c:*.*" /grant "%username%":(f) /T /C will that help or just make it worse?

I attached an hdd to my win7 machine and assigned the drive letter I: to the only partition on the hdd. The hdd was originally from another computer, and to avoid all those "you don't currently have permission..." dialogs, I decided to use icacls to clear all ACLs.  I ran icacls I:\ /reset /t /c /l. After a while, Chrome stopped working. Safari crashed. I traced the problem and find that the ACLs of my home folder (in C:\Users) are all messed up. Chrome and Safari couldn't write to their cache folder. I fixed the ACLs of my home folder and everything seems to be OK now.  Why would icacls mess with my home folder when I specifically told it to work on the I: drive? I have even put in the /L switch so that it won't resolve symbolic links. Did I misunderstood the switch?  For your reference, below is the relevant parts of the help screen.   ICACLS name /reset [/T] [/C] [/L] [/Q]     replaces ACLs with default inherited ACLs for all matching files.      /T indicates that this operation is performed on all matching         files/directories below the directories specified in the name.      /C indicates that this operation will continue on all file errors.         Error messages will still be displayed.      /L indicates that this operation is performed on a symbolic link        itself versus its target.


I want to know why I cant access a list index. I have a list full of words(input) but then t try to acces for example: list[2] and I get an error.  words=[] n =input().split() words.append(n) print (words])   Intput: Hi internet what up Output: [['hello', 'internet', 'what', 'up']]  print(words[0])   Output:['hello', 'internet', 'what', 'up']  print(words[1])   Output: IndexError: list index out of range

What's the difference between the list methods append() and extend()?


I have been coding on VC++ 2015 platform and I always get unresolved external symbol error on non-overridden base class functions. Here is the example :   //BaseClass.h template<class T> class BaseClass { public:    T* setRootPath(std::string&& rootPath); .... }  //Implementations are in BaseClass.cpp  //ChildClass.h class ChildClass:public BaseClass<ChildClass> { public:    ChildClass* setWidth(const int width);    //No redefinition of "setRootPath" and hope not necessary .... }  //Implementations are in ChildClass.cpp and i included BaseClass.cpp in this file as well   When I compile this code it throws no error. On the other hand during linkage time it says that it cannot find the required symbol for setRootPath with appropriate templating. Why can't it find "ChildClass* setRootPath(std::string&& rootPath)" function?   What I want to ask is that "Should I declare the function with an appropriate return type in ChildClass while I want to use the very same definition from the BaseClass"?  The error thrown by MSVC is :   error LNK2001: unresolved external symbol "public: class ChildClass * __cdecl BaseClass<class ChildClass>::setRootPath(class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > &&)" (?setRootPath@?$BaseClass@VChildClass@3@$$QEAV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@@Z)   Thanks for your help in advance.

Quote from :     The only portable way of using templates at the moment is to implement them in header files by using inline functions.   Why is this?  (Clarification: header files are not the only portable solution. But they are the most convenient portable solution.)


I think I have an intuitive understanding of why this is true but I can't prove it I just don't know how to relate $F(-a)$ to the information that was given

Can I get help to prove or Disprove that -   $\int_{-a} ^a F_1(x)F_2(x)dx = 0 \ for \ a > 0$  when I know that $F_2$  is even function and $F_1$  is odd.  I would like to get the idea how to delete and extract Minus in integrals.  thanks!


i have question. I would like to ask my friend something, he is on holiday.  First sentence: Do you have any interesting activities there? - or should i use have you got?  Second: Have you ever got letter from this country?  Are theese sentences correct?

I see these two expressions are used almost identically in different contexts. Is there a difference between I have got and I have gotten?


I read that floats/doubles equality should be implemented using an interval (given by some epsilon):  bool aresame(double a, double b) {     return (fabs(a-b) < EPSILON); }   Is their any predefined value of EPSILON that I can use or do I have to define it myself, something like, 0.0000000001?

What would be the most efficient way to compare two double or two float values?  Simply doing this is not correct:  bool CompareDoubles1 (double A, double B) {    return A == B; }   But something like:  bool CompareDoubles2 (double A, double B)  {    diff = A - B;    return (diff < EPSILON) && (-diff < EPSILON); }   Seems to waste processing.  Does anyone know a smarter float comparer?


I was trying to use the compareTo() method to sort the String array while the user keep inputting Strings into array. But I keep getting errors of: Exception in thread "main" java.lang.NullPointerException at java.lang.String.compareTo(Unknown Source)      public static void main(String[] args) {     Scanner input = new Scanner(System.in);     int numsDVD =0; //eSize     String [] DVD = new String [128];     int [] Length = new int[128];     String choice = "";     do     {         if(choice.equalsIgnoreCase("a")&&numsDVD<=DVD.length-1)         {             numsDVD=addDVD(DVD, Length, numsDVD, input);         }     }while(!(choice.equalsIgnoreCase("Q")));     input.close(); }  public static void sortedinsert(String[] titles, int[] lengths, int numDVDs, String DVD, int length) {     System.out.println("Index to compare : " + (numDVDs-1));     if(DVD.compareTo(titles[numDVDs-1])>=0)     {         titles[numDVDs]=DVD;     }     else if(DVD.compareTo(titles[numDVDs-1])<0)     {         for(int i=0; i<numDVDs-1; ++i)         {             int search = numDVDs-i;             String tmpString = "";             int tmplength = 0;             if(DVD.compareTo(titles[search])>0)             {                 for(int j=numDVDs; j>numDVDs-1; --j)                 {                     tmpString=titles[j-1];                     tmplength=lengths[j-1];                     titles[j]=tmpString;                     lengths[j]=tmplength;                 }                 break;             }         }         for (int i =0; i<numDVDs; ++i)         {             System.out.println(titles[i]);         }     } } // add to titles and lengths arrays at index numDVDs  // return numDVDs + 1 public static int addDVD(String[] titles, int[] lengths, int numDVDs, Scanner stdIn) {     if(numDVDs==0)     {         titles[numDVDs]=getvalidatedinfo(stdIn, "Please enter DVD Title : ", "");         lengths[numDVDs]=getvalidatedinfo(stdIn, "Please enter DVD Length : ", 0);     }     else     {         String input = getvalidatedinfo(stdIn, "Please enter DVD Title : ", "");         int length = getvalidatedinfo(stdIn, "Please enter DVD Length: ", 0);         sortedinsert(titles, lengths, numDVDs, input, length);     }     return numDVDs + 1; }   And this is the errors I keep getting  Exception in thread "main" java.lang.NullPointerException at java.lang.String.compareTo(Unknown Source) at Moviecheckeradv.sortedinsert(Moviecheckeradv.java:105) at Moviecheckeradv.addDVD(Moviecheckeradv.java:148) at Moviecheckeradv.main(Moviecheckeradv.java:21)   Please help me, Thank you

What are Null Pointer Exceptions (java.lang.NullPointerException) and what causes them?  What methods/tools can be used to determine the cause so that you stop the exception from causing the program to terminate prematurely?


$$\sum_{i=1}^n 2^i=2+2^2+2^3+.....+ 2^n=2(2^{n}-1)$$ Any help/explanations would be REALLY appreciated.  Also in the same vein:  By induction, show that   $$∀n∈\mathbb N: 11^{n+2} + 12^{2n+1}$$ is divisible by $133$.  Thank you so much.

Problem taken from a  on mathematical induction by Gerardo Con Diaz. Although it doesn't look like anything special, I have spent a considerable amount of time trying to crack this, with no luck. Most likely, due to the late hour, I am missing something very trivial here.     Prove that for any integer $n$, the number $11^{n+1}+12^{2n-1}$ is divisible by $133$.   I have tried multiplying through by $12$ and rearranging, but like I said with meager results. I arrived at $11^{n+2}+12^{2n+1}$ which satisfies the induction hypothesis for LHS, but for the RHS I got stuck at $12 \times 133m-11^{n+1}-11^{n+3}$ or $12^2 \times 133m-12 \times11^{n+1}-11^{n+3}$ and several other combinations none of which would let me factor out $133$.


I created a simple maze (via surface subdivision, extrusion, smooth shadows and edge split). Now I want to add some 'hedge' textures to the walls. When I drag and drop the texture, I seem to get just one color instead of a texture?     It seems only a few cells got the right texture?    Edit: I've set up the texture manually for some planes, but is it possible to automise this process?    Edit2: It works when I select everything at once and then adding the texture. When I add the texture a second time, it's just a green square.

Because I am pretty new to blender I watched the tutorial  from BlenderCookie.com.  I loaded  onto a sphere but then in all views the texture is just some kind of blurry with no details.


Is this some type of moth, it looks dangerous is it? I have only seen something like this once before. Thank you for any information you can give me.

Any ideas? I didn't know any other way to explain it.  I live in Indiana, USA if that helps.   Someone said it might be a "stink bug" but I'm not sure and not willing to find out!


I'm trying to return to java programming on a new computer. I have JDK installed, but when I try to compile with javac it tells me:  'javac' is not recognized as an internal or external command, operable program or batch file.  I understand this may mean I have to set up the path so that windows can find the compiler, but I have no idea how to do that (the oracle guide I found goes up to windows 7, but I have windows 10)

I am trying to compile a java program I found on the internet and it says that I must check if javac is installed. I installed the JDK a long time ago so it should be working but I get command not found error:    how can this be resolved?


I've inherited of a couple of databases which indexes have never been maintained (rebuilt, reorganized).  I'm using Ola Hallengren's , I've used the following script to record the difference between the pre-maintenance and post-maintenance values.  Script :  SELECT  OBJECT_NAME(IPS.object_id) AS [TableName] ,     SI.name AS [IndexName] ,     IPS.Index_type_desc ,     IPS.avg_fragmentation_in_percent ,     IPS.avg_fragment_size_in_pages ,     IPS.avg_page_space_used_in_percent ,     IPS.record_count ,     IPS.ghost_record_count ,     IPS.fragment_count     -- ,IPS.avg_fragment_size_in_pages FROM         sys.dm_db_index_physical_stats(DB_ID(N'test_db'), NULL, NULL, NULL, 'DETAILED') IPS JOIN      sys.tables ST WITH (NOLOCK) ON IPS.object_id = ST.object_id JOIN      sys.indexes SI WITH (NOLOCK) ON IPS.object_id = SI.object_id                                  AND IPS.index_id = SI.index_id WHERE        ST.is_ms_shipped = 0 ORDER BY      3 Desc, 4 Desc   However, I didn't notice any changes on the various indexes having an avg_fragmentation_in_percent above 30%.   Are index maintenance tasks supported on SQL Server 2008R2 Web Editions?

I have a database which I tried to defragment all the tables at once by running this T-SQL:  SELECT          'ALTER INDEX all ON ' + name + ' REORGANIZE;' + CHAR(10) +         'ALTER INDEX all ON ' + name + ' REBUILD;'     FROM sys.tables   And then copying and pasting the output to a new query window and running that. I got no errors, but I still have fragmentation. I tried running both commands separately too and still have fragmentation. Note: I have been made aware that REORGANIZE is unnecessary by Aaron, and I'm aware I could use dynamic sql to automate this.  I ran this to determine I still have fragmentation:  SELECT * FROM  sys.dm_db_index_physical_stats (DB_ID(), NULL, NULL , NULL, NULL)  WHERE avg_fragmentation_in_percent > 0   And I got:  database_id object_id   index_id    partition_number    index_type_desc alloc_unit_type_desc    index_depth index_level avg_fragmentation_in_percent    fragment_count  avg_fragment_size_in_pages  page_count  avg_page_space_used_in_percent  record_count    ghost_record_count  version_ghost_record_count  min_record_size_in_bytes    max_record_size_in_bytes    avg_record_size_in_bytes    forwarded_record_count  compressed_page_count 85  171147655   1   1   CLUSTERED INDEX IN_ROW_DATA 2   0   36.3636363636364    5   2.2 11  NULL    NULL    NULL    NULL    NULL    NULL    NULL    NULL    NULL 85  421576540   1   1   CLUSTERED INDEX IN_ROW_DATA 2   0   75  7   1.14285714285714    8   NULL    NULL    NULL    NULL    NULL    NULL    NULL    NULL    NULL 85  965578478   1   1   CLUSTERED INDEX IN_ROW_DATA 2   0   14.7058823529412    6   5.66666666666667    34  NULL    NULL    NULL    NULL    NULL    NULL    NULL    NULL    NULL 85  1061578820  1   1   CLUSTERED INDEX IN_ROW_DATA 2   0   40  4   1.25    5   NULL    NULL    NULL    NULL    NULL    NULL    NULL    NULL    NULL 85  1109578991  1   1   CLUSTERED INDEX IN_ROW_DATA 2   0   30.7692307692308    5   2.6 13  NULL    NULL    NULL    NULL    NULL    NULL    NULL    NULL    NULL 85  1205579333  2   1   NONCLUSTERED INDEX  IN_ROW_DATA 2   0   50  5   1.6 8   NULL    NULL    NULL    NULL    NULL    NULL    NULL    NULL    NULL 85  1493580359  1   1   CLUSTERED INDEX IN_ROW_DATA 2   0   50  6   1.66666666666667    10  NULL    NULL    NULL    NULL    NULL    NULL    NULL    NULL    NULL   I know I am missing something real basic, but I don't know what.


I'd like to be able to use a USB pen drive as if it's an internal drive - is this possible?  I saw some info about flipping the 'removable flag bit' of the drive using terminal command  dd if=/dev/zero of=/dev/disk2 bs=1 count=1   however, after trying with a number of 64 GB pen drives from different manufacturer I always get the message  Operation not permitted   I tried SUDO before the command (eek) but no difference.  Any other ways to do this, or perspectives to add?

I own a PNY - StorEDGE 128GB and I remember that it was initially recognized as a fixed/permanent disk like a hard disk.  I reformatted it to add encryption but now the disk is shown as a removable device. This keeps tools like SkyDrive from using it as a target.  Can I set the volume type somehow?


I want to try to enter academia by doing 2 postdocs after my PhD. However, I am bothered by the fact that I have been consistently poor/average in my grades during my undergrad, master's and PhD degree. I had 3.2/4 GPA in undergrad. I had to retake 3 courses in my second year as I had flunked them. They were related to my current field of research. My master's and PhD GPA were 3.75/4 each. I had a bit of TA experience during master's and PhD. I took tutorials for a laboratory course for first and third year undergraduates. Will my performance hinder my shortlisting for interviews in academia when I do apply for tenure track positions?

I have recently passed my qualifiers and research proposal. My research is in computational mechanics. I had two courses (continuum mechanics and finite element method) as part of my research related courses. I will be using the concepts learnt in the courses in my research, though my research will be more applied than theoretical, so will involve utilizing a commercially available software and develop few additional routines for it.  Now, I scored B+ in both the courses (the minimum grade required for being eligible for qualifying exams was a B-). I struggled through few concepts but fared fairly well in the qualifiers and answered most of the questions asked by the committee.  However, I am concerned that my average grades might be an indicator that I might not be fit for the field I have chosen to build a career in. Now, I am confident that I will manage to adequately complete my PhD thesis and publish papers as required.   But, I am worried that academia is going to be a closed door for me. Eventually, if I get tenure track position after my PhD, I will have to teach these subjects (There's no teaching assistantship opportunities in my department for me), and how will I be able to teach something in which I fared poorly? Also, I will have to do theoretical research work after my phd, and I will not fare well in that. What should I do?


How do I combine a .tif file with a .tfw file to create a GeoTiff? There are many answers telling me to use gdal, but I have no clue. So can someone provide a step by step example of how to do this please?

I have a .tiff and a .tfw file that I want to change into a GeoTIFF. When I try to open the file in ArcMap and ENVI 5.0, it is successful. However, in Google Earth it is not.  Is there anyway to create the GeoTiff in ArcMap or ENVI?


root.sh script execution failing with following error please advice  ./root.sh Performing root user operation for Oracle 12c  The following environment variables are set as:     ORACLE_OWNER= grid     ORACLE_HOME=  /u01/app/grid/product/12.1.0/grid  Enter the full pathname of the local bin directory: [/usr/local/bin]: The contents of "dbhome" have not changed. No need to overwrite. The contents of "oraenv" have not changed. No need to overwrite. The contents of "coraenv" have not changed. No need to overwrite.   Creating /etc/oratab file... Entries will be added to the /etc/oratab file as needed by Database Configuration Assistant when a database is created Finished running generic part of root script. Now product-specific root actions will be performed. Using configuration parameter file: /u01/app/grid/product/12.1.0/grid/crs/install/crsconfig_params LOCAL ADD MODE Creating OCR keys for user 'grid', privgrp 'oinstall'.. Operation successful. LOCAL ONLY MODE Successfully accumulated necessary OCR keys. Creating OCR keys for user 'root', privgrp 'root'.. Operation successful. CRS-4664: Node lrma086 successfully pinned. 2015/10/22 01:39:44 CLSRSC-330: Adding Clusterware entries to file '/etc/inittab'  2015/10/22 01:41:50 CLSRSC-214: Failed to start 'ohasd'  Failed to start the Clusterware. Last 20 lines of the alert log follow: 2015-10-22 01:39:34.970: [client(21726)]CRS-2101:The OLR was formatted using version 4. 2015-10-22 01:39:39.368: [client(21753)]CRS-1001:The OCR was formatted using version 4.  2015/10/22 01:41:50 CLSRSC-318: Failed to start Oracle ohasd service  Died at /u01/app/grid/product/12.1.0/grid/crs/install/crsinstall.pm line 2985. The command '/u01/app/grid/product/12.1.0/grid/perl/bin/perl -I/u01/app/grid/product/12.1.0/grid/perl/lib -I/u01/app/grid/product/12.1.0/grid/crs/install /u01/app/grid/product/12.1.0/grid/crs/install/roothas.pl ' execution failed

I have problem in stalling Oracle ASM on RHEL 7, Please advice   [root@localhost grid]# ./root.sh Performing root user operation for Oracle 11g  The following environment variables are set as:     ORACLE_OWNER= grid     ORACLE_HOME=  /u01/app/grid/product/11.2.0/grid  Enter the full pathname of the local bin directory: [/usr/local/bin]: The contents of "dbhome" have not changed. No need to overwrite. The contents of "oraenv" have not changed. No need to overwrite. The contents of "coraenv" have not changed. No need to overwrite.  Entries will be added to the /etc/oratab file as needed by Database Configuration Assistant when a database is created Finished running generic part of root script. Now product-specific root actions will be performed. Using configuration parameter file: /u01/app/grid/product/11.2.0/grid/crs/install/crsconfig_params Creating trace directory LOCAL ADD MODE Creating OCR keys for user 'grid', privgrp 'oinstall'.. Operation successful. LOCAL ONLY MODE Successfully accumulated necessary OCR keys. Creating OCR keys for user 'root', privgrp 'root'.. Operation successful. CRS-4664: Node lrma086 successfully pinned. Adding Clusterware entries to inittab ohasd failed to start Failed to start the Clusterware. Last 20 lines of the alert log follow: 2015-10-19 10:19:43.306 [client(28082)]CRS-2101:The OLR was formatted using version 3. 2015-10-19 10:19:46.259 [client(28109)]CRS-1001:The OCR was formatted using version 3. [client(28227)]CRS-10001:CRS-6021: No msg for has:crs-6021 [l][unlimited] [client(28228)]CRS-10001:CRS-6021: No msg for has:crs-6021 [n][65536]  ohasd failed to start at /u01/app/grid/product/11.2.0/grid/crs/install/roothas.pl line 358, <ALERTLOG> line 6. /u01/app/grid/product/11.2.0/grid/perl/bin/perl -I/u01/app/grid/product/11.2.0/grid/perl/lib -I/u01/app/grid/product/11.2.0/grid/crs/install /u01/app/grid/product/11.2.0/grid/crs/install/roothas.pl execution failed


The max value of $f(x) = \sin(\cos x) + \cos(\sin x)$ is equal to $1 + \sin 1$.  What is the minimum value of $f(x)$?  I found the max value using that range $\sin(\cos x)$ is $[- \sin 1, \sin 1]$ and range of $\cos(\sin x)$ is $[ \cos 1, 1]$ and the maximum of both occurs at $x=0$.  Although I can't find the min value using this approach. Please try to find this  without using graphing calculators.

Given the function: $$f(x)=\cos(\sin(x))-\sin(\cos(x))$$ it has absolute maxima at $x=(2k+1)\pi$ with $k=0,1,..N$ and relative maxima at $x=2k\pi$. It is not clear where are the minima. Putting the derivative to zero doesn't help. Any suggestion on how to find the minimum value and where is it? Thanks.


I am self studying the book Linear Algebra Done Right. That's how I start using this great Stack Exchange in Mathematics!   I do not have a background in mathematics and just finished my undergraduate and want to learn Maths.  I try to read every page and finish all exercise (Now on Chapter 3: Linear Maps). And on average, it takes me an hour to finish a page (exercise included). I can finsih 1/3, if not 1/4 of the questions on my own. For the rest, I need to look at the solutions to get some hints. Sometime, I don't even understand the solutions......  Just want to know if I am too slow on average? Are the questions hard for beginners on average (Not IQ above 160 type)? (Just tell me the truth, I will keep going and finish the book even if you tell me the questions are super easy.)  I know that there is a similar question . But I want more info on the average pace, and difficulty of questions.

Amazon book reviews say it takes unorthodox approach and is for a second exposure to linear algebra. I didn't have a first exposure to linear algebra.  Is this book going to be bad for me, then? Or, should I read another linear algebra book after reading it? I want to avoid reading two linear algebra books because reading such a textbook consumes a lot of time.