The Dutch GVB transportation features and all daypass for the .    I am strongly considering using it for transportation between the Rennaisance Hotel (near Centraal station) and the Rijksmuseum.  Is there an all-day transportation pass the includes both the trips from:   Schiphol to Centraal station and ?   Does said GVB day-pass include transportation between Airport and Central or is there a possible GVB daypass 'upgrade'?  Update: I need transportation from:    Schiphol to Central Station, check into hotel and then  Centraal to Rijksmusem (day visit) Rijks to Centraal  (return to hotel)

I have read  and  and  but I am still a bit confused as to which kind of card I need.  I'll be coming to Amsterdam for 4 days (only Amsterdam) and need to move about the city to go from my hotel to the conference location.  As per  from the airport to Amsterdam central, I can get a 4 EUR ticket for the train:     An addition about the train tickets: you can indeed still buy paper   tickets. The price for a ticket from Schiphol to Amsterdam CS is €4.   However within the city if I am to use the tram or bus, do I need to buy the ov-chipkaart or the GVB day pass?


I have the following code: (just a test file for encryption/hashing)  <!doctype html>       <?php      error_reporting('off');      if (isset($_POST['submit'])) {         $salt = "2bZ@<^$";         $hash = hash("sha512", $_POST['hash']);         $hash = $salt . $hash;         $hash  = md5($hash);         echo $hash;         $hashLen = strlen($hash);         echo "
The length of the hashed word is " . $hashLen . " characters long!";     }      ?>      <form action="hashed.php" method="post">       <input type="text" name="hash">       <input type="submit" value="Hash" name="submit">     </form>      How safe is this? I know this most probably can be hacked, but how long would it take? I am currently making a php/mysqli registration form and want to make the user's passwords as secure as I can, so that it would take a hacker a very long time to crack one of the user's passwords. To encrypt it even more I can use this for example:   Hashing it with sha512, md5(md5), adding a different salt, two more sha512, another md5 and another different salt!  How secure does that sound? How long would it take a hacker to crack that password? Please could you advise me with using a very, very secure encryption method. Also, I want to keep a user logged in with a cookie: need a secure way to store their information in a cookie!  Thanks in advance :)

It is currently said that MD5 is partially unsafe. Taking this into consideration, I'd like to know which mechanism to use for password protection.  This question,   suggests that hashing multiple times may be a good idea, whereas  suggests using salt.  I'm using PHP. I want a safe and fast password encryption system. Hashing a password a million times may be safer, but also slower. How to achieve a good balance between speed and safety? Also, I'd prefer the result to have a constant number of characters.   The hashing mechanism must be available in PHP It must be safe It can use salt (in this case, are all salts equally good? Is there any way to generate good salts?)   Also, should I store two fields in the database (one using MD5 and another one using SHA, for example)? Would it make it safer or unsafer?  In case I wasn't clear enough, I want to know which hashing function(s) to use and how to pick a good salt in order to have a safe and fast password protection mechanism.  Related questions that don't quite cover my question:


I installed Ubuntu 16.04 alongside Windows, giving it 50 Gb of space. Now, I need more space. I'm using gParted and I managed to unallocate a piece of partition. How can I extend Ubuntu with the space I reserved? Many thanks

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


Can a creature that is charmed, incapacitated, and dazed using Hypnotic Gaze, be suffocated? Suffocation specifically states that the creature doesn't take any damage until it runs out of breathe, and then its hit points drop to 0. If the method of suffocation doesn't do any damage other than restrict the creature from breathing, would is still be considered that the creature doesn't take any damage? Hypnotic Gaze states (PHB 117):  Starting at 2nd level when you choose this school, your soft words and enchanting gaze can magically enthrall another creature. As an action, choose one creature that you can see within 5 feet of you. If the target can see or hear you, it must succeed on a Wisdom saving throw against your wizard spell save DC or be charmed by you until the end of your next turn. The charmed creature's speed drops to 0, and the creature is incapacitated and visibly dazed. On subsequent turns, you can use your action to maintain this effect, extending its duration until the end of your next turn. However, the effect ends if you move more than 5 feet away from the creature, if the creature can neither see nor hear you, or if the creature takes damage. Once the effect ends, or if the creature succeeds on its initial saving throw against this effect, you can't use this feature on that creature again until you finish a long rest.  With the rules for suffocation stating (PHB 183):  A creature can hold its breath for a number of minutes equal to 1 + its Constitution modifier (minimum of 30 seconds). When a creature runs out of breath or is choking, it can survive for a number of rounds equal to its Constitution modifier (minimum of 1 round). At the start of its next turn, it drops to 0 hit points and is dying, and it can't regain hit points or be stabilized until it can breathe again. For example, a creature with a Constitution of 14 can hold its breath for 3 minutes. If it starts suffocating, it has 2 rounds to reach air before it drops to 0 hit points.  Charmed states (PHB 290):  A charmed creature can't attack the charmer of target the charmer with harmful abilities or magical effects. The charmer has advantage on any ability check to interact socially with the creature.  Incapacitated states (PHB 290):  An incapacitated create can't take actions or reactions

Is the act of suffocating itself considered to be taking damage?  Example:  A  is poisoned with the  poison and falls unconscious. She is then carefully placed into a  and then the hole is closed.   After 10 minutes, the Hag should be out of air due to the properties of the Portable Hole.  At that point she would be suffocating, but not taking any “damage” until after her third turn (she has a Con mod of +3). At the start of her 4th turn in the Portable Hole, she would immediately drop to 0 hit points and be dying.  Would the poison's effect immediately wear off as soon as she starts suffocating? Or would she stay unconscious until she started dying?


I'm using PDO. I want to be able to fetch 3 values from 3 different rows using a single query. I've got a table as below.   itemID    |  Item_Name ____________________ 125       |  apple 297       |  Lychee 851       |  Mango 005       |  Orange 1009      |  Strawberry   I want to be able to send an Item_Name and sort the table by Item_Name and to be able to call the next Item_Name and the previous Item_Name. How can I do this?  e.g.:    if the $passedItem is Orange I want to output Mango and Orange and Strawberry. if the $passedItem is Mango I want to output Lychee and Mango and Orange   Using the on() operator did not work because only one Item_Name could be passed on to the query.  $sql = "SELECT Item_Name FROM itemsTable WHERE Item_Name = :passedItem" ORDER BY ASC; $stmt = $con_db->prepare($sql); $stmt->execute(array(':passedItem'=>"Orange")); $rslt = $stmt->fetchAll(PDO::FETCH_ASSOC);

You see how at the bottom there're links to the next and previous articles ("Unprepared For Divide_By_Zero" and "A Completely Different Game")? How do I do that, but selecting the next and previous non-private articles? This works for selecting the next article:  SELECT * FROM articles WHERE id > ? AND private IS NULL   But I cannot find a way to select the previous article.  What is the proper/efficient way to do this, preferably in one query?


I often confuse symbols :, |, / and * in the R formulas, particularly when fitting mixed models with lme4. Can somebody explain clearly the differences between them?   Later edit by @amoeba (Jan 2018): this question had a long and extremely confusing R code. I cut it all out for the benefit of future readers. Please see edit history if interested.

There's a lot of discussion going on on this forum about the proper way to specify various hierarchical models using lmer.  I thought it would be great to have all the information in one place. A couple of questions to start:   How to specify multiple levels, where one group is nested within the other: is it (1|group1:group2) or (1+group1|group2)? What's the difference between (~1 + ....) and (1 | ...) and (0 | ...) etc.? How to specify group-level interactions?


The story was basically the Seven Samurai, plucky local boy goes in search of help to defend his homeworld from bad invaders.  I remember the plucky-local-boy's spaceship looked like a flying moose's head when viewed head on.  I saw it on TV in the early eighties, and that flying moose head cracked me and my big brothers up, even though overall we thought the movie was dead cool :)

When I was a child, I'm sure I remember part of a film or maybe TV movie where a boy or maybe a teenager is in a spaceship. The ship has an intelligent computer. Somehow the computer becomes damaged or faulty.  It can no longer properly function. But it still tries to do as requested.  So when a self destruct is commenced the computer counts down. But due to the damage, the numbers are not in a decreasing sequence. Instead they are jumbled up.  Finally the computer announces zero and the ship explodes.   I think the computer had a female voice.   Can anyone remember what this film or TV movie was called?


For some reason when I add a class to an element using Jquery I cannot perform a function using the class name just added:   $('.openslidecontent .arrow.off').click(function() {           $('.openslidecontent,.rightwrapper .arrow').removeClass('off')         $('.openslidecontent,.rightwrapper .arrow').addClass('on');       return false;      });      $('.openslidecontent .arrow.on').click(function() {   // THIS FUNCTION DOES NOT EXECUTE         $('.openslidecontent,.rightwrapper .arrow').removeClass('on');         $('.openslidecontent,.rightwrapper .arrow').addClass('off');       return false;      });

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.


For a standard logistic regression problem I'm interested in examining the impact of individual weighting of the parameters and in general the impact of regularization for completely separable data.  Does anyone know of a package in python which allows individual regularization weights for each parameter?   Thanks  (logistic regression, not SSE).

I want to do the following:  1) OLS regression (no penalization term) to get beta coefficients $b_{j}^{*}$; $j$ stands for the variables used to regress. I do this by   lm.model = lm(y~ 0 + x) betas    = coefficients(lm.model)   2) Lasso regression with a penalization term, the selection criteria shall be the Bayesian Information Criteria (BIC), given by  $$\lambda _{j} = \frac{\log (T)}{T|b_{j}^{*}|}$$  where $j$ stands for the variable/regressor number, $T$ for the number of observations, and $b_{j}^{*}$ for the initial betas obtained in step 1). I want to have regression results for this specific $\lambda_j$ value, which is different for each regressor used. Hence if there are three variables, there will be three different values $\lambda_j$.   The OLS-Lasso optimization problem is then given by  $$\underset{b\epsilon \mathbb{R}^{n} }{min} = \left \{ \sum_{t=1}^{T}(y_{t}-b^{\top} X_{t}  )^{2} + T\sum_{j=1}^{m} ( \lambda_{t}|b_{j}| )\right \}$$  How can I do this in R with either the lars or glmnet package? I cannot find a way to specify lambda and I am not 100% sure if I get the correct results if I run   lars.model <- lars(x,y,type = "lasso", intercept = FALSE) predict.lars(lars.model, type="coefficients", mode="lambda")   I appreciate any help here.    Update:  I have used the following code now:  fits.cv = cv.glmnet(x,y,type="mse",penalty.factor = pnlty) lmin    = as.numeric(fits.cv[9]) #lambda.min fits    = glmnet(x,y, alpha=1, intercept=FALSE, penalty.factor = pnlty) coef    = coef(fits, s = lmin)   In line 1 I use cross validation with my specified penalty factor ($\lambda _{j} = \frac{\log (T)}{T|b_{j}^{*}|}$), which is different for each regressor.  Line 2 selects the "lambda.min" of fits.cv, which is the lambda that gives minimum mean cross-validation error. Line 3 performs a lasso fit (alpha=1) on the data. Again I used the penalty factor $\lambda$. Line 4 extracts the coefficients from fits which belong to the "optimal" $\lambda$ chosen in line 2.  Now I have the beta coefficients for the regressors which depict the optimal solution of the minimization problem   $$\underset{b\epsilon \mathbb{R}^{n} }{min} = \left \{ \sum_{t=1}^{T}(y_{t}-b^{\top} X_{t}  )^{2} + T\sum_{j=1}^{m} ( \lambda_{t}|b_{j}| )\right \}$$  with a penalty factor $\lambda _{j} = \frac{\log (T)}{T|b_{j}^{*}|}$. The optimal set of coefficients is most likely a subset of the regressors which I initially used, this is a consequence of the Lasso method which shrinks down the number of used regressors.  Is my understanding and the code correct?


Obviously $ \{A_t\}_{t\in I} $ is basically a family of desired set. I believe the proof must have something to do with the definition of unions and also the power sets. I had previously proved a similar problem with almost the same structure where instead of unions, intersections were used. However, nothing came to my mind for this one. $$\bigcup_{t \in I}P(A_t) \subseteq P(\bigcup_{t \in I}A_t) $$

Prove or Disprove: For any family of sets $\{A_n\}_{n\in\mathbb N}$  $$\bigcup_{n=1}^\infty\mathcal P \left({A_n}\right)\subseteq \mathcal P \left({\bigcup_{n=1}^\infty A_n}\right)$$  How do I approach proving this? I know how to unpack the definition of powersets ($\mathcal P \left({A}\right) = \{x | x \subseteq A\}$) but I'm not sure what else I can do. I've done powerset proofs before but none involving indexed family of sets.


I want the regular expression to validate the URL with below condition,   It should start with http or https It should end with the valid domain. Ex: .com or .in but after the . can have any string. Specially, check whether the . is there and there is a string following the ..   Valid URL: http://www.cnn.com  Invalid URLS:  htt://www.yahoo.com http://www.yahoo. http://www.yahoo   I have compose the regular expression as below.  /^(http|https):\/\/[-a-zA-Z0-9+&@#/%?=~_|!:,;]+([\-\.]{1}[-a-zA-Z0-9+&@#/%?=~_|]+)*\.[a-zA-Z]{2,5}(:[0-9]{1,5})?(\/.*)?$/   It worked fine for most of the scenarios.  But if I enter http://www.yahoo didn't validate correctly, but If I enter http://www.google it throws the validation error.  Can anybody please help me to resolve this issue?

How can I check if a given string is a valid URL address?  My knowledge of regular expressions is basic and doesn't allow me to choose from the hundreds of regular expressions I've already seen on the web.


Where should I exchange euros to rubles once I arrive in Russia (Example: Moscow (at any of the three airports))? Is there a special place directly at/near the airport that takes care of this?  Or  Should I exchange euros to rubles while in home country (France).  It was mentioned on  site that:      It's better to change USD or Euro in banks, it's more safer. At the   airport there`s not best rates.   Is that even true?  Or   Can my visa card withdraw rubbles at an ATM in Russia?

I have Euros.   I will be in Russia along the Trans-siberian railway for about 12 days. I might go to Moscow by plane or by train.   So, what is the best way to change money? I do not know how much I will spend.


I was watching Obi-Wan fight Grievous in this clip and happened to pause right after he cuts off Grievous's second hand as the saber falls away (the 2:36 mark):                                  Here's a couple screen grabs of what I noticed:     What the heck!? That looks identical to Kenobi's saber!    Given that Grievous never made his own and had a love for collecting the sabers of Jedi he'd killed, my question is who did the sabers used in this battle originally belong to (especially the Obi-Wan look alike I spotted)?

In Revenge of the Sith, General Grievous has four lightsabers. Later on in the film, we see him use those lightsabers when he fights Obi-Wan and there's not a single red lightsaber - just 2 blues and 2 greens. Are they trophies?


The production site is on , while the development site is on . Bringing the production database to the development site breaks all links.  How can I fix this so I can work comfortably and move things between the development and production sites (both running Drupal 8)?

In Drupal 7, we can quickly change the base URL of the website. How can I do this, in Drupal 8?


First I assumed that it converges uniformly. But the following step is to get a series that is diverge.   Any ideas?

Say we use the usual definition of $$E_n(x)=1+x+...+\frac{x^n}{n!}$$  I know that on any bounded interval it converges uniformly, I am trying to show that it does not converge uniformly on $[0,\infty)$  I know that uniform convergence maintains boundedness so I am thinking it will definitely have to do with that, but I am just not sure the best way to show it without using things like convergence of series.  Any help?


I'm in doubt about this problem! How do I show that $3(1^2 + 2^2 + ... + n^2)$ is divisible by $(1+2+...+n)$? I thought about using that $ (1 + 2 + .. + n) =\frac{n (n+1)}{2}$ and that $(1^2 + 2^2 + ... + n^2)=\frac{n (n+1)(2n+1)}{6}$, but it didn't work out very well! Can someone help me? Thanks.

I'm supposed to prove that, for every integer $n > 0,$ it is true that $(1 + 2 + ... + n)$ divides $3(1^2 + 2^2 + ... + n^2)$.  Should I use induction?    This was given as an exercise in a chapter about divisibility in my algebra textbook.


I have an ArrayList of type Boolean that requires to be manipulated as a boolean[] as I am trying to use:  AlertDialog builder; builder.setMultiChoiceItems(items, checkedItems, new DialogInterface.OnMultiChoiceClickListener() { ... });   However, while I can create a Boolean object array, I cannot find an efficient way to covert this object array to a primitive array that the builder function calls for (the only method I can come up with is to iterate over the Object array and build a new primitive array).  I am retrieving my Object array from the ArrayList as follows:  final Boolean[] checkedItems = getBoolList().toArray(new Boolean[getBoolList().size()]);   Is there something I can do with my ArrayList? Or is there an obvious casting/conversion method that I am missing??  Any help appreciated!

If you have an array of Java objects which have a primitive type (for example Byte, Integer, Char, etc).  Is there a neat way I can convert it into an array of the primitive type?  In particular can this be done without having to create a new array and loop through the contents.  So for example, given  Integer[] array   what is the neatest way to convert this into  int[] intArray   Unfortunately, this is something we have to do quite frequently when interfacing between Hibernate and some third party libraries over which we have no control.  It seems this would be a quite common operation so I would be surprised if there's no shortcut.  Thanks for your help!


I am getting confused while using an article an. Because an is used while referring to vowels (a,e,i,o,u).  But today I read an article where for user they used a user.  My question is, why was an not used?  Could someone explain this with an example?

Which indefinite article should precede hour — a or an?        an hour     a hour      Does the usage of an vs a depend on the pronunciation — a history, a hobby, but an hour, an honor?


I have a figure which occupies around 75% of the page and Latex keeps putting this figure alone on a page (in the middle of the page). What I want is to have some of the lines of the following paragraph right after the figure, even if there is space for only 4 or 5 lines. I tried with \nopagebreak and minipage, but nothing seems to work. Thanks!  EDIT: I fixed it by setting the [ht] parameters for the figure.

I have a couple of floats in my document, which contain large Images (it consumes the half of the page). In this case, the figure get's its own page and no text goes on this page.  How can I configure this? I'd like to have text before and after the floats until the float doesn't use more then 75% of the page height.


So this is fairly complicated. I am making a sign, that when clicked, will give you a book, that when you click the text will execute a give command:  /blockdata ~ ~ ~-1 { Text1: "{ text:\"[Click For Book]\", color:dark_blue,clickEvent: { action:run_command, value:{"command":"/give @p written_book 1 0 {pages:%s,title:Book,author:Shop}","jobject":[{"text":"Click For 1 Gold","color":"gold","clickEvent":{"action":"run_command","value":"/scoreboard players add @p Gold 1"}},{"text":"     --------------                                                          "},{"text":"Click For 5 Gold","color":"gold","clickEvent":{"action":"run_command","value":"/scoreboard players add @p Gold 5"}},{"text":"     --------------                                                          "},{"text":"Click For 10 Gold","clickEvent":{"action":"run_command","value":"/scoreboard players add @p Gold 10"}}],"jtemplate":"book"} }}"}    However when I execute this command it gives me:  [17:10:33] Data tag parsing failed: Unexpected token 'c' at: command":"/give @p written_book 1 0 {pages:%s,title:Book,author:Shop}","jobject":[{"text":"Click For 1 Gold","color":"gold","clickEvent":{"action":"run_command","value":"/scoreboard players add @p Gold 1"}},{"text":"     --------------                                                          "},{"text":"Click For 5 Gold","color":"gold","clickEvent":{"action":"run_command","value":"/scoreboard players add @p Gold 5"}},{"text":"     --------------                                                          "},{"text":"Click For 10 Gold","clickEvent":{"action":"run_command","value":"/scoreboard players add @p Gold 10"}}],"jtemplate":"book"} }}"   I do not understand why I am getting this error, can someone who is good at command proof-scan the command to make sure there are no errors? Thanks!

I need help with a specific command that I am using in a new game that I am creating inside of Minecraft. The command is:  /give @p sign 1 0 {BlockEntityTag:{Text1:"{"text":" [MF2]","color":"gold","clickEvent": {"action":"run_command","value":"tellraw @a [""{"text":"[MF2]  ","color":"gold"},{"selector":"@p","color":"dark_aqua"},{"text":" is now an admin of the server!","color":"white"}]"}}",Text3:"{"text":"Click to join Admin","color":"dark_aqua","clickEvent": {"action":"run_command","value":"scoreboard teams join admin @p"}}"},display: {Name:"Custom Sign"}}   If I take out the /tellraw command then the command works fine, but I need the command in there to announce to the game that a new admin has joined.  With the tellraw command, the error message is the following:  Data tag parsing failed: Unexpected token 't' at: text":" [MF2]","color":"gold","clickEvent":{"action":"run_command","value":"tellraw @a [""{"text":"[MF2] ","color":"gold"}, {"selector":"@p","color":"dark_aqua"},{"text":" is now an admin  of the server!","color":"white"}]"}}",Text3:"{"text":"Click to join Admin","color":"dark_aqua","clickEvent": {"action":"run_command","value":"scoreboard teams join admin @p"}}"   If anyone knows how to fix this, please let me know.


My Illustrator artboard in a new project is like this:    and i want it be like this(Without the white side out of artboard):

I recently opened an Illustrator file made by my employer's previous graphic designer and found that it had these rulers along the side that have the appearance of guides, but didn't go away when I hid guides, smart guides, or rulers. They're not a problem and I don't need to recreate them, I'm just wondering if anyone has any idea what they are because I've never been them before.


Construct in $\Bbb R^k$ a random variable $X$ that is uniformly distributed over the surface of the unit sphere in the sense that $|X|=1$ and $UX$ has the same distribution as $X$ for orthogonal transformations $U$. Hint Let $Z$ be uniformly distributed in the unit ball in $\Bbb R^k$, define $\phi(x) = \frac{x}{\|x\|}$ and take $X=\phi(Z)$.   I understand the intuition behind the solution i.e. orthogonal transform does not change the angles between points therefore the area of the $\phi$ preimage of the orthogonal transformed set on the surface remains unchanged. But, how do I formalize it ?

I have a sphere of radius $R_{s}$, and I would like to pick random points in its volume with uniform probability.  How can I do so while preventing any sort of clustering around poles or the center of the sphere?    Since I'm unable to answer my own question, here's another solution:  Using the strategy suggested by  for picking points on the surface of a sphere: Let $\theta$ be randomly distributed real numbers over the interval $[0,2\pi]$, let $\phi=\arccos(2v−1)$ where $v$ is a random real number over the interval $[0,1]$, and let $r=R_s (\mathrm{rand}(0,1))^\frac13$. Converting from spherical coordinates, a random point in $(x,y,z)$ inside the sphere would therefore be: $((r\cos(\theta)\sin(\phi)),(r\sin(\theta)\sin(\phi)),(r\cos(\phi)))$.  A quick test with a few thousand points in the unit sphere appears to show no clustering.  However, I'd appreciate any feedback if someone sees a problem with this approach.


I've created a Vim text file that I would like to save elsewhere (say on the desktop, or perhaps email it to myself). How could I do that? I would be glad to add any detail necessary, but I'm not quite sure what I need to add. It is purely a text file, no code in it. I'm doing this on a chromebook in developer mode, with Ubuntu installed via crouton. It is Ubuntu Version 12.04, I believe. I am rather new to Ubuntu/Linux/Bash/vim so the more detailed on how to do it, the better.   Any help would be appreciated. Thanks!  EDIT: Thanks to all answerers for their help!

I'm new in the world of ubuntu and vim editor. My question is: how can I save a file on my localhost using vim? When I use the command :w I save the file, but where? And how can I change the file location to /var/www/?


I'm trying to re-create an old script that I already have working in Ruby, and I'm doing it with C# because I'm migrating a project of mine to Unity. This Script searches for files inside folders inside 3 different levels. This is what I mean, is a filepath, Folder1/Folder2/Folder3/files_are_here. Explanation: My working script (on Ruby) performs that by searching every "Folder1", and assigning the name of each one as a Key to a Hashtable. (So now I have a Hashtable in which every key is the name of a Folder that will represent the "Folder1" part of the filepath that I mentioned above). I've also defined as a Value for each of this keys, a new Hashtable. Thereafter, for each "Folder1" in my Hashtable, it performs a second search for every "Folder2" that is inside each "Folder1", and here I add each Folder name of each "Folder2", as a Key for the Hashtable of the "Folder1" that contains that "Folder2". For each "Folder2" for each "Folder1", I search each "Folder3" inside that "Folder2" that is inside that "Folder1", etc. I'm having a problem. I have my main Hashtable with every key representing a "Folder1", and I can perform the search for every "Folder2" inside every "Folder1". My problem is when I try to do: main_hash[first_folder.Key].Add(folder_2_name, new Hashtable())  It says that ('object' does not contain a definition for 'Add'), but if I: Debug.Log(main_hash[first_folder.Key])  It prints System.Collections.Hashtable, so it is a Hashtable, and it should have to have an .Add() Method. What is going on? Anyone knows?. (Even if you tell me to do it other ways so I can improve it, I would love to know why I'm having that error).

In most programming languages, dictionaries are preferred over hashtables. What are the reasons behind that?


I have below mentioned string  String str = "\nArticle\n\nArticle\nArticle";   I want total number of count. How can i get this? As the string contain \n so always it gives 1 instead of 3

I have the string   a.b.c.d   I want to count the occurrences of '.' in an idiomatic way, preferably a one-liner.  (Previously I had expressed this constraint as "without a loop", in case you're wondering why everyone's trying to answer without using a loop).


I have tried cooking beef (mostly London broil type) so many times... And it never comes out tender! I've tried different methods... Temperatures... Everything! It always comes out tough and chewy. I thought maybe it was the type of meat I was using, but I had my mother cook the same exact type of beef at her house... & it came out perfectly. I asked her how & she said she just does it! And she sautéed it on the stove... I did the same thing a week later, & it turned out bad. What am I possibly doing wrong?

When cooking steak on my grill it seems that even at a steady temp of 350 Degrees F and for 20 minutes the steak seems to change in the way of texture. I get my meat from the same Hanaford and I always get the 1 Inch cut. So what makes a moist steak. Does it have to do with the weather outside when I'm grilling?


Suppose I have a list as the following:  a = ['111', 213, 74, '99', 't', '88', '-74', -74]   The list contains number-like string, number and string of the data types.  I consider number-like string can convert number, so it's can see as a number.  This is my method:  a = ['111', 213, 74, '99', 't', '88', '-74', -74]  def detect(list_):     for element in list_:         try:             int(element)         except ValueError:             return False     return True  print detect(a)   But it looks so lengthy and unreadable, so anyone has better method to detect it?  Additionally, my list contains negative number and negative-number-like string, how do I do?

What is the best possible way to check if a string can be represented as a number in Python?   The function I currently have right now is:  def is_number(s):     try:         float(s)         return True     except ValueError:         return False   Which, not only is ugly and slow, seems clunky. However I haven't found a better method because calling float in the main function is even worse.


How do I remove Windows 8 & load only Ubuntu as my OS on an Intel i7 7348

I would like to see a full how-to guide on how to install Ubuntu.


The is keyword in python is described like that: is is used in Python for testing object identity. While the == operator is used to test if two variables are equal or not, is is used to test if the two variables refer to the same object. It returns True if the objects are identical and False if not. >>> True is True True >>> False is False True >>> None is None True  We know that there is only one instance of True, False and None in Python, so they are identical. >>> [] == [] True >>> [] is [] False >>> {} == {} True >>> {} is {} False  An empty list or dictionary is equal to another empty one. But they are not identical objects as they are located separately in memory. This is because list and dictionary are mutable (value can be changed). >>> '' == '' True >>> '' is '' True >>> () == () True >>> () is () True  Unlike list and dictionary, string and tuple are immutable (value cannot be altered once defined). Hence, two equal string or tuple are identical as well. They refer to the same memory location. Till now there is no problem. My issue is that I have two instances of two variables as string type a = 'yasser' b = 'yasser' a is b  This code returns True while a = 'yasser!' b = 'yasser!' a is b  This returns False althought these are of string types. Any explanation..?

My  has failed me.  In Python, are the following two tests for equality equivalent?  n = 5 # Test one. if n == 5:     print 'Yay!'  # Test two. if n is 5:     print 'Yay!'   Does this hold true for objects where you would be comparing instances (a list say)?  Okay, so this kind of answers my question:  L = [] L.append(1) if L == [1]:     print 'Yay!' # Holds true, but...  if L is [1]:     print 'Yay!' # Doesn't.   So == tests value where is tests to see if they are the same object?


I read a book when I was young, it was about space alien cats. I believe the title was Quzzles, but I really don't know. The book was stolen from me before I was finished. I don't know much else about it.

I'm trying to identify a novel about an alien race coming to Earth. They are rabbit-like.    I thought it was Niven or Pournell but I cannot remember the title.  It was Quotzal or something like that.


I wrote the following code using ObjectOutputStream: class ClassToTestOutputStream implements Serializable{      int a;     String b;      public ClassToTestOutputStream(){         a=10;         b="Deepak";     }      public String toString() {          String s = ""+a+" "+b;         return s;     } } public class UsingOutputStreams {      ClassToTestOutputStream ref;     private ObjectOutputStream oos;      public UsingOutputStreams(){     try {          oos = new ObjectOutputStream(System.out);     } catch (IOException e) {         e.printStackTrace();     }     ref = new ClassToTestOutputStream(); }  public void writeOnScreen(){      try {         System.out.println("Writing on Screen");         oos.writeObject(ref);     } catch (IOException e) {         e.printStackTrace();     } }      public static void main(String[] args) {          UsingOutputStreams obj = new UsingOutputStreams();         obj.writeOnScreen();     }  }  And I got answer :  �� Writing on Screen sr ClassToTestOutputStream����S��M I aL bt Ljava/lang/String;xp t Deepak  Please help me figure out why such output gets printed.

What is meant by "object serialization"? Can you please explain it with some examples?


I am trying to create a method that allows for a variable number of inputs. I was trying to implement  answer (see the code below) however, I got an error when I tried to run my code.  Code  header:  template<typename T, typename... Args> void vSend ( T tIn, Args... AArgs ); template <typename T> void vSend ( T tIn );   CPP  template<typename T, typename... Args> void Connector::vSend ( T tIn, Args... AArgs ) {     pPacketToSend << tIn;      vSend(AArgs...); }  template <typename T> void Connector::vSend ( T tIn ) {     pPacketToSend << tIn;      tSocket.send(pPacketToSend); }   Error  Undefined symbols for architecture x86_64:   "void Connector::vSend<int, int>(int, int)", referenced from:       Updater::Update(sf::Image*) in updatedirector.o ld: symbol(s) not found for architecture x86_64 clang: error: linker command failed with exit code 1 (use -v to see invocation)   Edit (Answer)  Turns out templates may only be implemented in the header file.

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 know that work is the energy transferred by a force, and energy is the ability to do work, but I cannot contain my imagination to just that.  Does energy do anything else other than doing work? It seems to me that for energy to do just work doesn't seem to chime with me. I feel that there are other alternative uses of energy.

The simplistic undergrad explanation aside, I've never really understood what energy really is. I've been told that it's something when converted from one kind of something to another kind, or does some "work", as defined by us, but what is that something?  Moreover, if the total amount of energy in the universe is finite and we cannot create energy. Then, where did it come from? I've learned from thermodynamics where it goes, but where does it come from?  I know this sounds like something trivially simple, but there is so much going on in the physical universe and I just can't grasp what it is. Maybe it is because I lack the mathematical understanding that I can't grasp the subtle things the universe is doing. Still, I want to understand what it is doing.  How do I get to the point of understanding what it's doing?  (Note: What prompted me to ask this was . I'm afraid that it just puzzled me further and I sat there staring at the screen for a good 10 minutes.)


The air at 10.000m altitude is mostly a lot colder than at the ground. Even if you are in the desert in temperatures of 40 degrees Celsius, the air above you will be significantly colder (below 0 degrees Celsius).  Considering that warm air is lighter than cold air, wouldn't one expect that the air on the surface of the earth is colder than in the atmosphere? Why doesn't the warm air just ascend while the cold air descends such that in the end the ground is cold while the high atmosphere is warm?  I suppose it has something to do with the pressure difference, but I can't figure out how exactly at the moment.

Why there is always cold at high altitudes. e.g. at peak of mountains. Also as we go high from sea level, temperature starts decreasing. Why is it?


I would like to be able to replace every single user-defined macro in papers written in TeX by its definition. That is, if TeXing is considered to be a function f and my standardizing script is function g I want fg(x)=f(x)for any TeX code x that can be TeXXed without errors.  From similar questions others have asked before it is clear that this will require some really hard work because TeX is extremely customizable. Well, I still want to do it.  I do want to know what I'm about to get into though.    Do I essentially need to almost create half of a TeX engine (i.e. the input processor and the expansion processor)? Assuming that the work is actually finished. Will I have to keep updating my code for the rest of my life in order for it to remain compatible with latest packages even though Knuth's TeX engine itself permanently remains stable? If the goal in 1 and 2 are indeed infeasible for one person to reach during leisure time, is it feasible for me to achieve something less ambitious, namely making sure that at least 50% of the actually existing papers on arXiv gets successfully standardized? The papers are almost always written in LaTeX often using one of the AMS packages. However they tend to include low-level code such as \def and sometimes even \let which causes de-macro to be ineffective in standardizing them.   I'm reading Knuth's The TeXbook right now.

Is it possible to have LaTeX (or another program) to expand a the macros in a .tex file, and output the expanded LaTeX source?   If no such program exists: are LaTeX macros processed simply as string substitutions, before the document is interpreted? If so, it might be easy enough to write my own such converter.  Edit: The reason I ask is journals which don't accept LaTeX submissions with macros. It would be useful to be able to develop with my usual macros, and convert automatically to the 'macro-expanded' format for submission.


I have recently started to use Emacs editor to type latex documents. For a while everything was going smooth and fine but one good day I got this annoying error message while compiling my document. It says there is some error and tells to use key combo C-c'   to view the error. But when I do so, the message "Error occurred after last TeX file closed" keeps appearing. It doesn't show the actual error. What should I do to get the proper error message?

I often have this error when using AUCTeX:  TeX-error: Error occured after last TeX file closed  However, when running for instance pdflatex on the command line, I have a proper error message. But the line number information is not always useful, especially if multiple files are included. I'd like to be able to see the error in Emacs.


Has  ever been observed?  If not, is it likely that it ever will, assuming current technology?    Note: This is not a question of space bending light, but of light bending space.

For instance evidence that a highly energetic laser beam attracts objects nearby?  In the framework of Einstein's general relativity all energy curves spacetime and hence exerts an attraction, but my question is whether it is an experimentally verified fact that energy that doesn't come from mass (such as photons) indeed attracts massive objects?


I have exercise 4.4 from Haim Brezis's book: Let $f_{1},\dots,f_{k}$ be $k$ functions such that $f_{i}\in L^{p_{i}}(\Omega)$ whit $1\leq p_{i}\leq\infty$ for all $i\in\{1,\dots,k\}$, and $\sum_{i=1}^{k}\frac{1}p_{i}\leq1$. Set \begin{equation*}     f(x)=\prod_{i=1}^{k}f_{i}(x) \end{equation*} Prove that $f\in L^{p}(\Omega)$ with $\frac{1}{p}=\sum_{i=1}^{k}=\frac{1}{p_{i}}$. I tried to reason by induction from $ k = 2 $ as the author's indication says, but in inductive step I have $g(x)=f(x)f_{k+1}(x)$ with $f(x)=\prod_{i=1}^{k}f_{i}(x)$, I would like to see what \begin{equation*}     \|g\|_{p} \leq \|f\|_{a} \|f_{k+1}\|_{p_{k+1}}, \text{whit } 1\leq a \leq\infty \end{equation*} for $p$ such that $\frac{1}{p}=\sum_{1}^{k}\frac{1}{p_{i}}\leq 1$ and $1 =\sum_{i=1}^{k+1}\frac{1}{p_{i}}$ for conclude that $g\in L^{p}$. Could you give me any ideas on how to tackle this problem?

Let $(X,\mathcal{M},\mu)$ be a measurable space, $1<p_{k}<\infty$ for $k=1,2,\ldots,N$ with $\sum_{k=1}^{N}\frac{1}{p_{k}}=1$ and $f_{k}\in L^{p_{k}}(\mu)$ for $k=1,\ldots,N$.  Show that $$\left\|f_{1}f_{2}\cdots f_{N}\right\|_{1}\leq \|f_{1}\|_{p_{1}}\|f_{2}\|_{p_{2}}\cdots\|f_{N}\|_{p_{N}}.$$  Remark: I tried to use the Holder inequality with $p=p_{1} $ and $q=\frac{1}{\sum_{k=2}^{\infty}\frac{1}{p_{k}}}$, but when I try to continue the process, it becomes complicated until I think that this is not the way.


I keep getting a segmentation error when I try to add a character to the string test.  I have tried multiple iterations and can't figure out why I get the error.  I tried having the test set to \0.  I can't figure out how I am accessing outside test.  #include <stdio.h> #include <cs50.h> #include <ctype.h> #include <string.h>  #define _XOPEN_SOURCE #include <unistd.h> #include <crypt.h>  //this intializes the argument count and argument vector int main(int argc, string argv[]) {     //this makes sure it is a string     if (argv[1] != NULL) {         //this makes sure that the user typed 2 arguments,          //  the second being the keyword         if (argc != 2) {             printf("no hash inputed\n");             return 1;         }          //main program once the keyword has been verified         int h_len = strlen(argv[1]);          string hash = argv[1];         string test = "A";         int p_len = 0;         printf("H len is %i and P len is %i\n", h_len, p_len);         printf("%s and test: %s\n", hash, test);          //this will iterate through the 1st space and test the charachters         for (int j = 0; j < 4; j++) {              //iterates through the characters that can be used in the  password             //for (int i = A; i < z; i++)             //for (char ch = 'A' ; ch <= 'z' ; ch == 'Z' ? ch = 'a' : ++ch )             for (char i = 'A'; i <= 'z'; i++) {                 //this skips the ASCII inbetween Z and a                 if (i > 'Z' && i < 'a') {                     i = 'a';                 }                 printf("%c", i);                  //test[j] = test[j] + (char)i;                 test = strncat(test, &i, 1);                 printf("  test is %s\n", test);                 ...

The following code receives seg fault on line 2:  char *str = "string"; str[0] = 'z';  // could be also written as *str = 'z' printf("%s\n", str);   While this works perfectly well:  char str[] = "string"; str[0] = 'z'; printf("%s\n", str);   Tested with MSVC and GCC.


I am running UBUNTU 17.10 and have more than one Linux kernel that I might want to run.  According to the , GRUB_DEFAULT is "the default menu entry. This may be a number, in which case it identifies the Nth entry in the generated menu counted from zero, or the title of a menu entry, or the special string ‘saved’. Using the id may be useful if you want to set a menu entry as the default even though there may be a variable number of entries before it."  The grub menu no longer gives the various OS options. It provides a menu element named Advanced. Selecting this menu item brings up a submenu of bootable kernels. GRUB_DEFAULT does not index this submenu.  Should I add my own custom boot options to /etc/grub.d/40_custom and reference these menu items in the grub.menu? This solution seems cumbersome. Defining a default kernel was much simpler in the past.

Each time I've tried to dual boot Ubuntu with Windows I always have difficulty with the same thing... editing the default option on the grub boot loader. I'm now running 11.10 and have run into the same problem.   Startup-manager didn't work on 11.04, neither does it work on 11.10. Editing GRUB_DEFAULT= in the /etc/default/grub file doesn't seem to work either.   This shouldn't be difficult, and I'm sure there's a simple explanation. Could someone please tell me what it is?


I having binary data set (yes/no), so can I apply PCA on that. Is it mathematically correct to do that. In my opinion Binary variable can only be subjected to logical operations, so how it can be legal to apply PCA on the binary varaibles . Previously Question similar questions have been asked  but I could not clear my doubt.

I have a dataset with a large number of Yes/No responses. Can I use principal components (PCA) or any other data reduction analyses (such as factor analysis) for this type of data? Please advise how I go about doing this using SPSS.


By assigning the date to awk, I can get current date as following in yyyy-mm-dd:  awk -F, -v date="20$(date +%y-%m-%d)" '{print date}'   Output:  2019-02-17   Is there a way to add number of days to current date, let's say 7, so the output would be:   2019-02-24   Noting that using a method like below isn't providing the required output:  awk -F, -v date="20$(date +%y-%m-%d +7 days)" '{print date}'   Solution  is not providing same date format

I  have Linux ( RH 5.3) machine  I need to add/calculate 10 days plus date so then I will get new date (expiration date))  for example   # date   Sun Sep 11 07:59:16 IST 2012   So I need to get        NEW_expration_DATE = Sun Sep 21 07:59:16 IST 2012   Please advice how to calculate the new expiration date ( with bash , ksh , or manipulate date command ?)


Prove that if $f(z)$ is a complex holomorphic function in the domain $D$ and $f'(z)=0$ so $f(z)$ is constant     My thoughts was to say that since $f'(z)=0$ so it is obvious $f(z)$ is constant I don't understand what the "holomorphic" is giving me here, any hints? or spoilers?

Let $G\subseteq\mathbb{C}$ be a domain and $f\colon G\to\mathbb{C}$ holomorphic. Show:     $$ f'=0\mbox{ in }G\Rightarrow f\mbox{ is constant} $$      Cauchy-Riemann: $$ f'(z)=f_x(z)=u_x(x,y)+i v_x(x,y), z=x+iy=0\\ \Leftrightarrow u_x(x,y)=0~\wedge v_x(x,y)=0 $$  and $$ f'(z)=-if_y(z)=-iu_y(x,y)+v_y(x,y)=0\\\Leftrightarrow u_y(x,y)=0~\wedge~v_y(x,y)=0 $$  That means: If one derivates u and v to x, one gets 0, and therfore the x-part of these functions must be constant. The ssame for the y-part of u and v. So u and v are constant and so is then f.  Is that okay?


When the server port is not open then receive the [SYN] header TCP, is the response of [RST, ACK] normal?

I'm scanning a server which should have a pretty simple firewall using iptables: by default everything is DROPped besides RELATED and ESTABLISHED packets. The only type of NEW packets allowed are TCP packets on port 22 and 80 and that's it (no HTTPS on that server).  The result of nmap on the first 2048 ports gives 22 and 80 as open, as I expect.  However a few ports appear as "filtered".  My question is: why do port 21, 25 and 1863 appear as "filtered" and the 2043 other ports do not appear as filtered?  I expected to see only 22 and 80 as "open".  If it's normal to see 21,25 and 1863 as "filtered", then why aren't all the other ports appearing as "filtered" too!?  Here's the nmap output:  # nmap -PN 94.xx.yy.zz -p1-2048  Starting Nmap 6.00 ( http://nmap.org ) at 2014-06-12 ... Nmap scan report for ksXXXXXX.kimsufi.com (94.xx.yy.zz) Host is up (0.0023s latency). Not shown: 2043 closed ports PORT     STATE    SERVICE 21/tcp   filtered ftp 22/tcp   open     ssh 25/tcp   filtered smtp 80/tcp   open     http 1863/tcp filtered msnp   I really don't get why I have 2043 closed ports:  Not shown: 2043 closed ports   and not 2046 closed ports.  Here's an lsof launched on the server:  # lsof -i -n COMMAND   PID USER   FD   TYPE   DEVICE SIZE NODE NAME named    3789 bind   20u  IPv4     7802       TCP 127.0.0.1:domain (LISTEN) named    3789 bind   21u  IPv4     7803       TCP 127.0.0.1:953 (LISTEN) named    3789 bind  512u  IPv4     7801       UDP 127.0.0.1:domain  sshd     3804 root    3u  IPv4     7830       TCP *:ssh (LISTEN) sshd     5408 root    3r  IPv4 96926113       TCP 94.xx.yy.zz:ssh->aa.bb.cc.dd:37516 (ESTABLISHED) sshd     5411    b    3u  IPv4 96926113       TCP 94.xx.yy.zz:ssh->aa.bb.cc.dd:37516 (ESTABLISHED) java    16589    t   42u  IPv4 88842753       TCP *:http-alt (LISTEN) java    16589    t   50u  IPv4 88842759       TCP *:8009 (LISTEN) java    16589    t   51u  IPv4 88842762       TCP 127.0.0.1:8005 (LISTEN)   (note that Java / Tomcat is listening on port 8009 but that port is DROPped by the firewall)


I have a sum with a subscript placed in an equation environment. The subscript is placed down the sum in this way:    However I want the subscript to be placed next to the sum, like this other sum:    The code for the first sum is as simple as this: \sum_l, so even without specifying the \limits parameter I encounter this problem.  How can I control this behaviour?

I'm very familiar with how symbols display differently in inline mode (with $ ... $) vs. how display math shows them (with \[ ... \] or $$ ... $$).  Two examples would be with limits  $\lim_{n\rightarrow \infty}f(x)$   vs.  \[ \lim_{n\rightarrow \infty}f(x) \]   and with sums  $\sum_{n=1}^{x} n^2$   vs.  \[ \sum_{n=1}^{x} n^2 \]   My Question is:     How do you display these things in inline mode (with all the nice inline formatting) as if they were in display mode ?   The inverse -- how to display things in display mode as if they were in inline mode -- is also of interest.


I use Linux not Windows for several years at home and consider using command line quicker way to do things.  However sometimes I could not easily recall name of needed command, for example instead of adduser I try to use mkuser in analogy to mkdir,  chperm in analogy to chown.  I remember in MS Office in help pages in see also/related there were usually several other topics close to it and I was able to find what I needed if I could recall related topic. In Linux man pages see also is very short,  e.g. for chown it's chown (2) only.  Before Internet was widespread,  how do you find name of the needed program?

As a Unix beginner, I often find myself wanting to know the name of the command that achieves a particular function I'm after. How can I go about finding out the name of the command, given a description of what it does?


I was observing mirrors recently and I was thinking about how an mirror would look atomically. I was always used to looking at atoms as being colored that said, I was always concerned at how they looked. I looked at previous questions and found silver atoms could play a part in it but now a days the mirrors are not made of pure silver now a days so I am confused.  Not to mention how do mirrors function atomically? Its hard because if say I shoot light towards a very black object then the radiation is absorbed but however when I shoot it at mirror it reflects it back. That said, how do they work?    How do atoms reflect the photons back? If so how and why does the black body atoms not do the same?

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?


I know that IQueryable has the advantage of running filters on server rather loading all records in memory like IEnumerable, but how does exactly this look like in code, for example, if I have this code:  var data = context.Books.Where(x => x.Id > 930);   if I have 1000 records then it will only load 70 records, and to iterate over them, I convert data to List:  var list = data.ToList(); //has only 70 records   but what are the cases that IEnumerable load all records if it has to pass through IQueryable first i.e. to get the IEnumerable version of the example above:  var eData = context.Books.Where(x => x.Id > 930).ToList();   Aren't they the same? the last code is no more than combining the above two lines of code?

What is the difference between IQueryable<T> and IEnumerable<T>?    See also  that overlaps with this question.


My question: Is it possible to copy the contents of RAM to the file-system? (Windows)  Additionally, is it possible to copy the RAM contents for a specific process?  Reason:  This largely revolves around CryptoLocker (as well as similar malware) and making it possible to recover data quickly without having to pay for the private key that it uses.  While CryptoLocker doesn't store the private key anywhere on the file-system, it does need to keep it in memory to continuously encrypt files. So given that you can capture an active CryptoLocker process, know the length of the private key, and you know what encryption was used, you theoretically could loop through each bit attempting to decrypt a specific (small) file.

Are there any tools to dump the running application from memory in Windows 7?


How do you make the camera in blender cycles render everything so it looks like pixels? I want everything in my scene to look pixelly like this image I found:

I thought it would be interesting to create a .blend that filters any regular video or image with vintage television look.   Edit: Although this question initially arose from my desire to create a vintage look, it has since been pointed out in a comment that all displays use arrays of RGB emitters, so it's not really an issue of vintage or not. How vintage it will end up looking is probably more a matter of the shape, size, and density of the emitters.  Reference images:       Upon examining the structure of screens, the most common seems to be rows of vertical RGB bars:    Here is another type which I believe is common in computer displays - circular dots in a hexagonal grid:    I have been thinking about how to make a screen in Blender that takes its input from an image or image sequence and for each frame converts the RGB value for a pixel (or region) and uses that to illuminate the red green and blue phosphors in the correct ratios so that when viewed from a distance an image is distinguishable.  Do you think this will require python scripting? I made some initial attempts modeling an array of phosphors then using a Light Path node and a Separate RGB node in Cycles but I haven't gotten very far. I would love to hear what you all can suggest.  Thanks!


I would like to understand the definition of a simple transcendental extension and the theorem that states all such extensions are isomorphic. So for example, if $K \subseteq \mathbb{C} $ is any subfield and $L:K$ a field extension with $\alpha \in L $ then $K(\alpha) \cong K(X)$, where $K(X)$ is the field of rational functions in the indeterminate $X$. First, what makes a field extension transcendental? And second, what is the explicit isomorphism between $K(\alpha)$ and $K(X)$? I've heard this isomorphism called the "evaluation homomorphism" so could you please explain what this map is doing specifically?  My understanding of this theorem is that in this context $\alpha$ (like $X$) is purely a mathematical symbol, and is no longer considered as the root of some polynomial over $K$. Thus, it is as if we are writing rational expressions in $X$ as those in $\alpha$. However, this interpretation seems banal to me (why even write it in $\alpha$ if we have it in $X$?) and what exactly makes $K(X)$ transcendental in the first place?

Let $E$ be an extension field of $F$ and $\alpha \in E$. Then $\alpha$ is transcendental over $F$ if and only if $F(\alpha)$ is isomorphic to $F(x)$, the field of fractions of $F[x]$.   This was a theorem in an abstract algebra textbook with a very brief proof. Can someone please explain why this theorem holds? I'm having difficulty grasping the concepts at hand.  Thanks!


I have a Windows XP machine where I have installed WAMP and made a PHP based web application. I can access the web application from within this machine by using the browser and pointing to: http://localhost/myApp/ --- and the page loads fine.  Now I want this site (http://localhost/myApp) to be accessible to all machines within the network (and may be later, to the general public as well). I am quite new to this, how do I make my site accessible to all machines within the network and to the general public in the internet?  I tried modifying the httpd.conf file in Apache (WAMP) by changing  Listen 80 to Listen 10.10.10.10:80 (where I replaced 10.10.10.10 with the actual IP of this windows xp machine). I also tried "Put Online" feature in WAMP. None seem to work though.  How do I make it accessible?

This is a  about  the use of a *AMPP's stack.    I recently had a talk with some experienced people and they suggested to me not to use a WAMP stack, and instead install apache, mysql and php separately.  I don't understand why they have suggested this, though, so can anyone tell me?  Is there a particular disadvantage of WAMP, or a particular advantage to installing all of them separately?  Since a WAMP stack itself is composed of apache, mysql and php, then what's the difference between using the WAMP stack and installing them all separately?


When orbiting a massive object, perhaps a neutron star, you maintain your altitude while at the same time you are close to a very strong gravitational field. Being in orbit, and being in free fall is indistinguishable for the object in question. The object is not affected by gravity, locally.  Another free falling object can't be "less affected" than this first object, since the first object is in fact not noticing any gravity. Logically, both object should age equally fast if we ignore the relativeness of aging.  There is no doubt that the gravitational field is strongest around the first object, but neither object experiences any gravitational field. Object one looks at object two is in free fall, and vice versa.  Of object one records a video of object two, and then later plays that video - but adjust the playback rate to account for all doppler shift effects - what would object one see?  Is doppler the only effect causing the difference in relative aging in this case?

Imagine a space ship orbiting the sun at near relativistic speeds, when compared to Earth (say from the reference frame of the sun) there would be x amount of time dilation.  This would mean people on the ship could live for 100's of Earth years.  My question is what would happen if a second ship flew directly away from the Sun and back (ignoring acceleration) at the same speed the orbiting ship is travelling, would the time dilation for the ship that travels in a straight line be the same as that moving in a circle?  The reason I ask is that I was imagining a scenario where intergalactic travel is possible as time dilation means even a journey of light years only ages the crew a fraction of that time, with space stations orbiting certain star systems at similar speeds so that people that don't work on ships can live a similar length of time. I understand that time dilation is all linked to a certain reference frame but working with a reference frame of the sun what would the time dilation be for the different objects taking different paths but at the same speed relative to the sun? If the ship docked back with the space station would they both say the same amount of time had passed?


This sentence is from Modern Family  I want to know meaning of this.

Annie wanted to have Helen all to herself so that she could do anything with her.   Note: In this context, Annie (full name, Annie Sullivan) is the teacher of Helen (full name, Helen Keller).  What is the meaning of "to have Helen all to herself", and is the clause "she could do anything with her" correctly used in the sentence? The sentence above is the answer to the question " Why did Annie want to have Helen all to herself?" The question was created from the passage " The next day, I told Helen's father, " I can't do anything with Helen unless I have her all to myself. I want her to depend on me for her food, her clothes,everything. ....."


I've been trying to create this wine glass object for my game and 3D modelling is completely new to me and I followed all the steps of a tutorial to the best of my knowledge.  But when I convert it to fbx and export the object doesn't have the " Glass BDF " material to it; So, I added one of the materials from the material folder that was created when the fbx file was exported but the end result isn't transparent.   I recalculated the normals but I'm still not getting it.I also checked the UV swap option.

I have been experiencing an issue that once I have a material created and looking the way I want it, I cannot seem to export it correctly with the textures mixed.  I don't know the correct words to use, but in blender I have the material created using the nodes editor, and I have placed two textures inside of there (one for the rock texture and one for moss, my object is a rock). When I export this model and import to Unity (the game engine I am using), I find a materials folder but the material inside of it does not have the textures assigned, it's just a plain white material?  How can I export my material from blender in a way that it will allow me to import it WITH TEXTURES into Unity?


This was the question in one of the online test I was giving for preparation of an exam. I was not convinced by the final answer so I wanted to discuss it.  Consider a set S = {1000, 1001, 1002, ........ 9999}. The numbers in set ‘S’   that have atleast one digit as 2 and atleast one digit as 5 are ________.  I solved it using complimentary counting.  Final answer will be  All total numbers from 1000 to 9999 both inclusive - All such numbers that do not have either a 2 or a 5.  Now Let A:All 4 digit numbers do not having 2 B : All 4 digit numbers do not having 5  $|A|=8*9*9*9=|B|$  $|A \cap B |=7*8*8*8$  $|A \cup B|=|A|+|B|-|A \cap B|=2(8*9*9*9)-(7*8*8*8)=8080$  So my answer will be $9000-8080=920$  But in solution they have given answer to be 2752. Which one is correct?

Let T = {1000,1001...,9999}. How many numbers have at least one digit that is 0, at least one that is 1 and at least one that is 2. For example, 1072 and 2101 are two such numbers.  I have no idea to solve such probability question, I should use Permutation or Combination? why the answer is 150.  Thanks you guys.


Sorry for the title it may be a very bad one. The whole question is as following:  How many terms of the Maclaurin expansion of $(1+x)^{82}$ are needed to guarantee finding a value of $1.1^{82}$ accurate to within $10^{-6}$?

I found this question in a book.   How many terms of the Maclaurin expansion of $(1+x)^{82}$ are needed to guarantee finding a value of $1.1^{82}$ to an accuracy of $10^{-6}$?  This is how I tried to do it:  We want the Lagrange error to be less than $10^{-6}$:  $$R_{n}(0.1)<10^{-6}$$  Now to find $R_{n}(0.1)$:  $$R_{n}(0.1)=\frac{f^{(n+1)}(0.1)\cdot0.1^{n+1}}{(n+1)!}$$  After writing the values of ${f^{(n+1)}}(x)$, I find a pattern and say that  $${f^{(n+1)}}(x)=\frac{82!}{(82-n)!}(1+x)^{82-n}$$  $${f^{(n+1)}}(0.1)=\frac{82!}{(82-n)!}(1.1)^{82-n}=\frac{82!(1.1)^{82-n}}{(82-n)!}$$  Now just substitute all of this back to $R_{n}(0.1)<10^{-6}$:  $$\frac{\frac{82!(1.1)^{82-n}}{(82-n)!}\cdot0.1^{n+1}}{(n+1)!}<10^{-6}$$  Great! Now I have an inequality that I can solve. I can't graph this so I just use trial and error (which seems like quite an intensive way to do it, so if anyone has a better way I'd love to know).  $$\frac{\frac{82!(1.1)^{82-n}}{(82-n)!}\cdot0.1^{n+1}}{(n+1)!}-10^{-6}<0$$  This seems to work first for $n=28$. That means the highest power of $x$ that I need is 28, so the number of terms in the expansion needs to be $n+1=29$. But the book's answer is       30   What am I doing wrong here? I'm still quite new to the power series expansions so if there's anything unclear in my working, please let me know (also, as a side note, the book itself may be wrong, though that isn't very likely I'd assume).


I read a short story in an anthology around 1998 (the book could have been older than that) which went like this - A human space exploration scientific crew is exploring an alient planet (peaceful planet, as I recall) when they run into an alien spaceship (from a different planet which also happened to be there) - the aliens were telepaths.   The alien commander and first officer discuss the earthlings after a meeting and realize that the human crew are the descendants of a species (Banthu/Klanthu/Zantha, something like that) which had tried to violently take over the galaxy some 20/30/50,000 years ago and which had been beaten back by the combined might of the rest of the galaxy. They had supposedly been eliminated but they somehow managed to survive and are back in space only a few thousand years after they were completely beaten (which is something the aliens are amazed by).   The alien commander kills the human explorers via telepathy but realizes that there is no information available to locate their home planet and speculate that they will be meeting again soon given the past history of the humans.  I vaguely think there was also a fantasy short by L Sprague de Camp in the same anthology, but can't be 100% sure. Any thoughts/ideas? Thanks!

So the story goes, humans in a spaceship search for an inhabitable planet, being surprised they found none in the vicinity of Earth. They find one, and it seems uninhabited. At the same time are observed by the aliens, who go down on the planet to meet them. The aliens sit them down and tell them a story about war and conflict that ruled the galaxy, and how all the sentient races in the galaxy got together and got rid of the race that tried to conquer all by blowing up their planets.  In the end you realise man is this terrible conqueror the aliens are talking about.


I have an object   let obj = {   a : [     {       name : 'op'     }] };   I want to clone it. I used JSON.parse(JSON.stringify(obj)). But this does not scale well for huge data when used again and again. Is there any other way to shallow copy the object?

What is the most efficient way to clone a JavaScript object? I've seen obj = eval(uneval(o)); being used, but . I've done things like obj = JSON.parse(JSON.stringify(o)); but question the efficiency.  I've also seen recursive copying functions with various flaws.  I'm surprised no canonical solution exists.


Error:     System.IndexOutOfRangeException    at   System.Data.ProviderBase.FieldNameLookup.GetOrdinal(String fieldName)   at  System.Data.SqlClient.SqlDataReader.GetOrdinal(String name) at    System.Data.SqlClient.SqlDataReader.get_Item(String name) at   I alter my stored procedure to add two new columns to my result, the stored procedure by itself seems to be working but when i add the new columns to my SQlDataReader im getting that error  Model  public class StudentRecordFull : StudentRecord {     public double CreditProgress { get; set; }     public string EnrollmentStatus { get; set; }     public int IsEnrolled { get; set; }     public string YRQLastAttended { get; set; }     public int Mandatory { get; set; }     public double GPA { get; set; }     public string TotalPrint { get; set; }     public int Balance { get; set; }  }   my Method  public StudentRecordFull GetStudent(int sid)     {         StudentRecordFull s = new StudentRecordFull();         using (SqlConnection myConnection = new SqlConnection(ProductionDataConnString))         {             SqlCommand myCommand = new SqlCommand("usp_GetStudent", myConnection);             myCommand.CommandType = CommandType.StoredProcedure;             SqlParameter SIDParameter = myCommand.Parameters.Add("SID", SqlDbType.Char, 9);             SIDParameter.Value = sid;              myConnection.Open();             using (SqlDataReader oReader = myCommand.ExecuteReader())             {                 while (oReader.Read())                 {                     s.SID = SafeGetString(oReader, "SID");                     s.FirstName = SafeGetString(oReader, "FirstName");                     s.LastName = SafeGetString(oReader, "LastName");                     s.AdvisorName = SafeGetString(oReader, "Advisor");                     s.AdvisorSID = SafeGetString(oReader, "AdvisorSID");                     s.PathwayName = SafeGetString(oReader, "PathwayName");                     s.PathwayID = SafeGetInt(oReader, "PathwayId");                     s.SubPathwayID = SafeGetInt(oReader, "SubPathwayId");                     s.SubPathwayName = SafeGetString(oReader,                                                        "SubPathwayName");                     //s.TotalPrint = SafeGetString(oReader, "ploplo");                     s.Credits = SafeGetInt(oReader, "CreditsEarned");                     s.Phone = SafeGetString(oReader, "DaytimePhone");                     s.DOB = SafeGetString(oReader, "DOB");                     s.Address = SafeGetString(oReader, "Address");                     s.City = SafeGetString(oReader, "City");                     s.State = SafeGetString(oReader, "State");                     s.Zip = SafeGetString(oReader, "Zip");                     s.Email = SafeGetString(oReader, "Email");                     s.CreditProgress = SafeGetDouble(oReader,                                             "CreditProgress");                     s.EnrollmentStatus = SafeGetString(oReader,                                             "EnrollmentStatus");                     s.IsEnrolled = SafeGetInt(oReader, "IsEnrolled");                     s.YRQLastAttended = SafeGetString(oReader,                                              "YRQLastAttended");                     s.Mandatory = SafeGetInt(oReader, "Mandatory");                     s.GPA = SafeGetDouble(oReader, "GPA");                     s.Balance = SafeGetInt(oReader, "Balance");                     //s.TotalPrint = SafeGetString(oReader, "TotalPrint");                  }                 myConnection.Close();             }         }         return s;     }   Helper  private int SafeGetInt(SqlDataReader reader, string colName)     {         int i = 0;         if (!DBNull.Value.Equals(reader[colName]))         {             int.TryParse(reader[colName].ToString(), out i);         }         return i;     }   If i remove the new columns everything works great is like it cant not read those columns .  Any idea?

How do I check to see if a column exists in a SqlDataReader object?  In my data access layer, I have create a method that builds the same object for multiple stored procedures calls.  One of the stored procedures has an additional column that is not used by the other stored procedures.  I want to modified the method to accommodate for every scenario.  My application is written in C#.


I'm stuck on navigate to privileges link, in old header I can access through the privilege link on profile picture mouse over. but now I can not find the link even in my profile page. How can I go to my privileges ?

It used to be off the top bar, now its gone  Where has it moved?  EDIT:  It moved onto the profile page !  Right side same row as your name in profile:    Thank you


Yesterday, I was playing with the . So, I thought why not develop some more interesting SQL queries and implement into your site. So, my questions are:  Am I allowed to execute queries to Data Explorer from my site?  The first time I used it, it asked for a CAPTCHA. Do, I have to take permission somewhere to prevent asking of captcha's?

Now that we have an awesome tool , won't its usefulness be multiplied manifolds if we could have a way of embedding queries onto a site that can fetch the results without the user having to actually go to the StackExchange website?    Something like this:    goes to    select top 10 u.Id as [User Link],   (select sum(len(Body)) from posts where owneruserid = u.id) posts,  (select sum(len(Text)) from comments where userid = u.id) comments,  (select sum(len(Body)) from posts where owneruserid = u.id) +  (select sum(len(Text)) from comments where userid = u.id) total from users u order by total desc   and produces the result  User Link        posts   comments total    ---------------- ------- -------- -------  Jon Skeet        6895871 1616661  8512532  Marc Gravell     4454304 800243   5254547  Alex Martelli    4018617 737938   4756555  VonC             3688197 355679   4043876  BalusC           3235636 740699   3976335  Pascal Thivent   3298339 427297   3725636  S.Lott           2473343 1177130  3650473  paxdiablo        2870220 745320   3615540  Jonathan Leffler 2663832 885100   3548932  tvanfosson       2972126 564040   3536166   (10 row(s) affected)     I am not an expert on web designing and might have not used the perfect language while describing this. So, if you find any technical faults with the question, please edit.   Can this be done already? If not, what do you think about its usefulness?


I have been revisiting English grammar lessons for a test & I'm reading Pronouns. During a self test I came across this sentence "My dog can run much faster than ___".  I selected "me" & computer said its wrong.  Is "My dog can run much faster than I" correct?

Consider the sentence "I can run faster than 15 miles per hour." Its meaning is clear and to my eyes obviously grammatically correct. Now let me present some variations that have given me trouble for a long time.  I am faster than 15 miles per hour. – To me this is clearly incorrect. Directly comparing me to a speed doesn't seem right. We need to compare my speed to a speed, or me to another person.  I can run faster than him. – Compared to the base sentence, there is a distinct shift in meaning of the comparison. While before I named a speed faster than which I can run, now I am naming a person. It doesn't seem quite right. I realize the parts of speech can change, but my initial objection is that "him" is not a speed.  I can run faster than he. – This seems most correct to me, but still somehow feels objectionable. Is this in fact the correct way to say it? And if so, is it proper as is or need I say "... faster than he can" or even "... faster than he can run?"  I am faster than him. – With "am" instead of "can run" it now seems slightly more correct. But is it?  I am faster than he. – I'm in doubt here. It doesn't seem wrong to me to say, "I am faster than he is" or even "I am faster than he is fast." (Though I suppose that is a given since I could hardly properly compare to some other category as in "I am faster than he is smart.")  My speed is faster than his. – Hmm. This seems more proper as "my speed is greater than his."   So which of these constructions is correct and which is incorrect? Is there a general rule that I can follow? UPDATE The scholarly article  may be of great interest to some readers!  Once we accept that the elided constituent and its antecedent can differ in form, it becomes reasonable to ask how large this difference can be. The answer in Rooth (1992), Fiengo and May (1994), Chung et al. (1995) and subsequent work is that the wiggle room is actually quite small: the elided constituent and its antecedent are allowed to differ only in the realization of inﬂectional morphology. Other than that, both constituents have to be syntactically and lexically isomorphic.


Edit: It's not something as simple as a nullpointerexception being thrown. The thread is working severable times before throwing the nullpointerexception meaning that it suddenly decides to stop working and I can't figure out why  Hello I have the following thread  private class IsCreditAdded implements Runnable{     ActionEvent evt;      public IsCreditAdded(ActionEvent evt){         this.evt = evt;     }      @Override     public void run(){         while (AddMinutes.creditChosen != true){         }         creditAdded(evt, AddMinutes.getEvt());      } }   It waits for a boolean to change from a GUI class with options to select a value, and then when the boolean changes it executes a method called creditAdded with values evt(passed in from constructor), and a static getMethod which contains the ActionEvent which was selected  public void creditAdded(ActionEvent evt, ActionEvent duration){     System.out.println(evt.getActionCommand() + " " + duration.getActionCommand());     switch (evt.getActionCommand()){         case ("voipCredit"):             switch (duration.getActionCommand()){                 case ("cancel"):                     System.out.println("CANCEL");                     disableButtons(evt, duration);                     break;             }     addMinutes.dispose();     AddMinutes.reset();     sessionStorage.printTransActions(); }   Here is where the thread is created:  private void creditButtonActionPerformed(java.awt.event.ActionEvent evt) {                                                   switch (evt.getActionCommand()){         case ("voipCredit"):             addMinutes = new AddMinutes();             addMinutes.setService("VOIP");             addMinutes.setVisible(true);             addMinutes.setDefaultCloseOperation(DO_NOTHING_ON_CLOSE);             addMinutes.setPrices(nf.format(SessionPrices.getVOIP_10_MINS()), nf.format(SessionPrices.getVOIP_30_MINS()),                      nf.format(SessionPrices.getVOIP_1_HOUR()), nf.format(SessionPrices.getVOIP_ALL_DAY()));             threadVar = new Thread(new IsCreditAdded(evt));             threadVar.start();               disableAllButtons();             break;     } }   Now the problem Im having is whenever I select the button which gives the getActionCommand 'cancel' it works two times, sometimes three, but then if I try it again I get a nullpointerexception. The actual error message I get is:     Exception in thread "Thread-6" java.lang.NullPointerException        at com.aidanmoore.InternetCafeGUI.creditAdded(InternetCafeGUI.java:416)        at     com.aidanmoore.InternetCafeGUI$IsCreditAdded.run(InternetCafeGUI.java:411)        at java.lang.Thread.run(Thread.java:745)        BUILD STOPPED (total time: 9 seconds)"   I can't figure out why it is throwing this exception after hours of searching for similar problems others have had and since the thread works x amount of times before throwing the exception I Cant work out why it suddenly breaks

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?


Is it okay/good practice to return different number of return values from a function in Python? If yes, how should the caller handle the return values? e.g.  def func():     if(condition_1):         return 1,2     if(condition_2):         return 1     if(condition_3):         return 1,2,3,4   Note: condition_1,condition_2 and condition_3 are local to the function func so the caller has no idea how many values will be returned.

In python, you can have a function return multiple values.  Here's a contrived example:  def divide(x, y):     quotient = x/y     remainder = x % y     return quotient, remainder    (q, r) = divide(22, 7)   This seems very useful, but it looks like it can also be abused ("Well..function X already computes what we need as an intermediate value.  Let's have X return that value also").  When should you draw the line and define a different method?


My son was needing help with some food because he was laid off from work. So i told him i would leave him care package on the porch that consisted of an armour canned ham. It was late at night in October so it was cool out and i thought it would be ok, but had text me saying he wouldn't be able to come get it until the next day sometime, but i didn't see the message until around 11:15am. So by the time i got it and put it back in the fridge it was already starting to get a little warm. I went ahead and stuck it in the fridge immediately. I just need to know if it would be safe for him and his family to eat it. All opinions appreciated. Thanks!

If I left food out of the refrigerator for some period of time, is it still safe? If I left it out too long, can I salvage it by cooking it more?


How to display an alert message when the values already present in an array using javascript    var names = [];  var nameInput = document.getElementById("txt1"); var messageBox = document.getElementById("display");  function insert() {   names.push(nameInput.value);   clearAndPush(); }  function clearAndPush() {   nameInput.value = "";   messageBox.innerHTML = "";   messageBox.innerHTML += "Names:" + names.join(", ");    function removeDups(names) {     let unique = {};     names.forEach(function(i) {       if (!unique[i]) {         unique[i] = true;       }     });     return Object.keys(unique);   }   document.getElementById("display").innerHTML = removeDups(names); } Name:<input type="text" id="txt1" placeholder="Enter Name"> <input type="button" value="Click" onclick="insert()">

What is the most concise and efficient way to find out if a JavaScript array contains a value? This is the only way I know to do it: function contains(a, obj) {     for (var i = 0; i < a.length; i++) {         if (a[i] === obj) {             return true;         }     }     return false; }  Is there a better and more concise way to accomplish this?


I use my Mac a lot to show movies or play video games on a larger display without a keyboard or mouse attached.  How can I set up my Mac so that it continues to display to an external screen when closed without a keyboard or mouse attached?

So I saw a lots of old discussion on this topic, but I'm trying to find out an actual solution that still works on Mojave / Catalina, without the use of external monitor/keyboard/mouse/with power adapter.  When looking up Amphetamine, they claimed that you can only do it when the 4 criteria are met, and cannot overridden it.     But on the other hands, Anti Sleep provide the feature in their pro version...     So, which one gets the real deal ? Is Anti Sleep lying about it or Amphetamine (and all other caffeine app on the appStore) is out of date ?  I also heard about InsomniaX and built-in caffeine  but it's really not user friendly, and appear not to be supported anymore...


Every time I type sudo apt update this information appears: The box was unticked when I check the software and updates  elizabeth@elizabeth:~$ sudo apt-get update Get:1 http://security.ubuntu.com/ubuntu bionic-security InRelease [88.7 kB] Hit:2 http://gb.archive.ubuntu.com/ubuntu bionic InRelease                      Get:3 http://gb.archive.ubuntu.com/ubuntu bionic-updates InRelease [88.7 kB]    Get:4 http://gb.archive.ubuntu.com/ubuntu bionic-backports InRelease [74.6 kB]  Fetched 252 kB in 1s (175 kB/s)                               Reading package lists... Done   Is there a fix?

I'm running a Ubuntu server (9.0.4 'Jaunty') as a VMware image.  It's a real pain on the odd occasion I need to install a new package to have to fish out the install CD-ROM, and make it available to the VMware image so I can continue the package install.  Is there any way to take the original installation media out of the list of source packages - I'm assuming all packages will be available on the internet.  Thanks.


I tried to browse posts in Close Votes section from Review Beta by tag. I think it is not possible or at least I couldn't figure it out.  I think it will be interesting to enable this option as it is easier and faster to judge close votes about a topic you are kind of expert at. When I review close votes I select "not sure" button for most of them.   I believe that browsing close votes by tag will encourage users to review more close votes.

I've had the ability to review suggested edits for a while now, however I don't often do so because the list is usually full of questions about languages and technologies I'm not familiar with or not interested in, and can sometimes be hundreds of questions long.  I would like to help out more, but most of my rep has been gained by questions within a specific technology, so I only feel comfortable reviewing edits within that tag.   Can you allow us to filter suggested edits by tag?  Edit:   Actually, can you let us filter the entire Review section by tag, and not just Suggested Edits?  I would find it much more interesting to review questions in tags I'm familiar with and can  understand the question content of, and it would give me a bit of pride to help maintain "my" section of SO.


I am using Ubuntu 14.10 default GUI, how can I see all the applications installed ? if I don't give a search keyword I can't see anything.

In Gnome, we have applications grouped up based on their type (like - games, accessories, et al). But in Unity, we need to manually type in the Unity to get the App.  Is there any keyword/utility to display the applications in GUI?  Ubuntu Version : 14.04 Hardware : Dell Inspiron 3437


I know the meaning of mass in classical physics, the ratio of force and acceleration. But what do we mean when we talk about the mass of an electron in quantum mechanics?

Consider a free theory with one real scalar field: $$ \mathcal{L}:=-\frac{1}{2}\partial _\mu \phi \partial ^\mu \phi -\frac{1}{2}m^2\phi ^2. $$ We write this positive coefficient in front of $\phi ^2$ as $\frac{1}{2}m^2$, and then start calling $m$ the mass (of who knows what at this point) and even interpret it as such.  But pretend for a moment that you've never seen any sort of field theory before:  if someone were to just write this Lagrangian down, it's not immediately apparent why this should be the mass of anything.  So then, first of all, what is it precisely that we mean when we say the word "mass", and how is our constant related to this physical notion in a way that justifies the interpretation of $m$ as mass?  If it helps to clarify, this is how I think about it. There are two notions of mass involved: the mathematical one that is part of our model, and the physical one which we are trying to model. The physical mass needs to be defined by an idealized thought experiment, and then, if our model is to be any good, we should be able to come up with a 'proof' that our mathematical definition agrees with the physical one.  (Of course, none of this at all has anything to do with this particular field theory; it was just the simplest Lagrangian to write down.)


Given the following SQL  SELECT      T1."PN" as "Part Number",     T2."QTY" as "Quantity",     T2."BRANCH" AS "Location", T3."STOCK" as "Bin" FROM      "XYZ"."PARTS" T1,     "XYZ"."BALANCES" T2,     "XYZ"."DETAILS" T3 WHERE (T2."PART_ID" = T1."PART_ID") AND (T3."PART_ID" = T1."PART_ID") ORDER BY "Part Number" ASC, "Location" ASC   We get results such as  YZ-7-CA-080                 88  01  STOCK7 YZ-7-CA-080                 88  01  03482  YZ-7-CA-080                 88  01  A8K2D   For location 01, there are 88 pieces of that part number YZ-7-CA-080 and they can be found in any of the 3 bins STOCK7, 03482, or A8K2D. The location value refers to a common branch like a warehouse and the quantity is for the entire warehouse, not the bins.  I need to change the output so we can write out instead one entry with bins as a list  YZ-7-CA-080                 88  01  STOCK7,03482,A8K2D   So I am looking for a good way to do this refactoring of the results in SQL. I feel there should be a way to use a function or subquery or something like that and hoping there is a single multi-db solution but assume there could be a need for different solutions on different dbs. (Oracle is the primary solution we are trying to solve but secondary priority db we need this for is SQL Server).  Note: There are multiple locations per part number so its not enough to set distinct on the first column to reduce the multiple part number entries. There would be multiple of the same part number at location 02 also with the same issue.   Ideas?

I have a simple query:  select * from countries   with the following results:  country_name ------------ Albania Andorra Antigua .....   I would like to return the results in one row, so like this:  Albania, Andorra, Antigua, ...   Of course, I can write a PL/SQL function to do the job (I already did in Oracle 10g), but is there a nicer, preferably non-Oracle-specific solution (or may be a built-in function) for this task?  I would generally use it to avoid multiple rows in a sub-query, so if a person has more then one citizenship, I do not want her/him to be a duplicate in the list.  My question is based on the similar question on .  UPDATE: My function looks like this:  CREATE OR REPLACE FUNCTION APPEND_FIELD (sqlstr in varchar2, sep in varchar2 ) return varchar2 is ret varchar2(4000) := ''; TYPE cur_typ IS REF CURSOR; rec cur_typ; field varchar2(4000); begin      OPEN rec FOR sqlstr;      LOOP          FETCH rec INTO field;          EXIT WHEN rec%NOTFOUND;          ret := ret || field || sep;      END LOOP;      if length(ret) = 0 then           RETURN '';      else           RETURN substr(ret,1,length(ret)-length(sep));      end if; end;


I've setup a caching DNS server with bind9 using a root-hints method (like ). It works as desired--but, our IPv6 traffic goes through a gateway outside of my country that makes Netflix think we're visiting from that other country, and this prevents my kids from watching their favorite shows. So I'm thinking that if I can prevent bind9 from returning any AAAA records for netflix.com, the clients will only attempt IPv4 connections to Netflix.  That is: how do I configure bind9 so that AAAA record look-ups for netflix.com are suppressed while valid A record results are returned for netflix.com?  I realize I can create a zone file with just the Netflix domain and have it contain all of the A records for netflix.com that I can find and no AAAA records. But I'm wondering if maybe the above is possible so I don't have to keep the A records in the zone file updated.

With OpenDNS now needing one to be on the pro package to have filtering turned on, being on a tight budget, we are in need of free DNS filtering.  After reading , I collected SquidGuard blacklists and concatenated domains in the categories i needed into one big list. I then fed it to  generating a file containing about 2 million zones.  named-checkconf parses it just fine, but reloading named takes almost 10 minutes, then it wont resolve anything, and the server slows down to a crawl. Removing the include results in named working properly again.  Whats the proper way to set up BIND9 to work as a DNS firewall efficiently? If it's possible to also block any domain that resolves to specific IP addresses that would solve the whole problem.   I'm running bind as non-authoritative, just a caching server.


Hello all Stacoverflow members!  I guess this question have been asked a lot in the past but when I searched at "C++ Books" I only got threads from 2008 and up to 2012... I also tried to filter my question to the newest thread but I didn't find a thread regarding books in 2020 so I'm now making this thread. And please, have in mind that this is my first day as a member on this site so I'm probably making a mistake asking this question. But try to be kind anyways, thanks! =)  Anyway, I have decided to learn C++. I'm an absolute beginner at programming, I have no experince at all with it. I have been looking aorund on the internet to see if C++ is a good language to start with and some people say yes and some people say that you can start with it but it can take some time. But thats okey, I have time atm.  Since I really want to learn programming and C++ I think reading a book or 2 will get me started more then looking at youtube tutorials, even tho they are good aswell I fell that books explain more in-depth.  A lot of people have been recommending C++ Primer 5th Edition. But I have one question... Is this book outdated (If that's possible) Since it's written for C++11 and there is C++20 now? Or is this book still very good for beginners that wanna learn C++ in 2020?  I really appreciate all the help I get, I really do!! Take care and stay safe!

This question attempts to collect the few pearls among the dozens of bad C++ books that are published every year. Unlike many other programming languages, which are often picked up on the go from tutorials found on the Internet, few are able to quickly pick up C++ without studying a well-written C++ book. It is way too big and complex for doing this. In fact, it is so big and complex, that there are very many very bad C++ books out there. And we are not talking about bad style, but things like sporting glaringly obvious factual errors and promoting abysmally bad programming styles. Please edit the accepted answer to provide quality books and an approximate skill level — preferably after discussing your addition in . (The regulars might mercilessly undo your work if they disagree with a recommendation.) Add a short blurb/description about each book that you have personally read/benefited from. Feel free to debate quality, headings, etc. Books that meet the criteria will be added to the list.  Books that have reviews by the Association of C and C++ Users (ACCU) have links to the review. *Note: FAQs and other resources can be found in the  and under .


I know that $$\sum_{k=0}^n \binom nk k^2=2^{n-2}(n^2+n),$$ but I cannot find a way how to prove it. I tried induction but it did not work. On wiki they say that I should use differentiation but I do not know how to apply it to binomial coefficient.  Thanks for any response.  (Presumptive) Source: Theoretical Exercise 1.12(b), P18, A First Course in Pr, 8th Ed, by S Ross

I found crazy (for me at least) induction example, in fact it just would be nice to prove. (Even have problems with starting) Any hints are highly valued: $$0^2\binom{n}{0}+1^2\binom{n}{1}+2^2\binom{n}{2}+\cdots+n^2\binom{n}{n}=n(1+n)2^{n-2} $$


How many bits can a qubit hold? I know there are probabilities involved in a qubit, but there must be some limit to how many bits a qubit can take. If different qubits can have different amounts of information then we can think of these as different sizes of processor-registers: $8$-bit, $16$-bit, $32$-bit or $64$-bit, can't we?  But my question is really, is there a limit to how much information content (discreete-wise) a qubit can store?

How many bits of information can be stored in a qubit? On making a measurement on a qubit, one can catch it in either $|0\rangle$ or $| 1\rangle$. Seems that measurement on a qubit can not reveal more than a single bit. But does it mean the a qubit can't store more than 1 bit of information?


I'm confused with the nature of the force produced by tires that pushes the car forward. This is what I understand:  Let us have a driving torque applied on the wheel axle clockwise. This will produce a force on the bottom of the wheel trying to push the ground backwards. According to Newton's 3rd Law, the ground will exert a force of equal magnitude towards the right. According to some textbooks, this is the driving force accelerating the car forwards.  However, other text books say that this 'driving force' is the static friction. I guess both of them are right, but I don't see the equivalence. For me, if the force exerted on the tire by the ground is in the direction of motion, static friction will point backwards, opposing the eventual relative motion (slipping).  It is probably a very basic misunderstanding, but I would be grateful if anyone could clarify this.

I am a bit confused regarding how car moves. Following is the explanation which I've come up with after reading but I would like if someone verifies and corrects it.     If a car is moving, the rotation of it's tyre will exert a backward force on the road. Due to newton's third law, the road also exerts a force on the tyre. The force will be in the forward direction. This force causes the tire and hence the car to move forward.