"Roll-Back" or Undo Any Manipulators Applied To A Stream Without Knowing What The Manipulators Were
Restore the state of std::cout after manipulating it
Eigenvalues of a matrix whose square equals its transpose Let $A$ be a $n\times n$ matrix with $A^2=A^t$. Show that every real eigen value of $A$ is either $ 0$ or $1$ I have data in an Excel file that I want to join with a shapefile in my project. The Excel file contains values like volumes. The Excel file and the shapefile I want to join it with both contain the same property names.  The problem is, when I join the two, I get too many decimals in the attribute table. I get six, but I only want it to be one.  I tested to change the format of the cells to one decimal, and then I saved the file as *csv. But, somehow I seem to loose data in the process? It should be 42 rows that contains data in the column i am working with, but I end up with only like 10?  Another thing is that my property names contains the letters Å. Ä and Ö, perhaps this complicates things?  I read the question , but it doesn't mention the problem with the data loss.  My question was tagged with , but I didn't write what version I'm using. I use QGIS 2.2.0. Would it help to upgrade to the latest version? There was a great SF story I read some time ago (probably 25+ years ago) where there was a well known treasure trove, guarded by a killer robot that would ask all comers a series of difficult questions from all areas (math, physics, literature, history, etc.)  But everyone eventually failed and died... until the last person managed to make it past the robot:     By just answering gibberish to the robot.  Unfortunately, after collecting a ton of treasure, the robot casually asked him why he wanted it, he answered in a sensible way (something like "because it's valuable"), and the robot killed him, because he failed the final test.   Any ideas who wrote this?  What it was titled? I know that who is used when asking about a subject (Who is at the door?) and whom is used when asking about an object (By whom was the door opened?). How do you determine which one to use when the object becomes the subject of another clause?   For example, take the sentence:      I gave the prize to ____ deserved it most.   Would it be whomever because it's the object of "gave," or would it be whoever because it's the subject of "deserved"? Is their a hard-and-fast rule to rely on in situations like this? How does a lurker gain reputation to receive privilege for commenting? I have been reading Stack Exchange for years - mostly not logged in, and have never posted (this is my first). I'm simply not very talkative, and very good at googling.  Recently a few occasions have come up when I've wanted to comment on a question.  I wanted either to ask for, or provide, clarification which did not warrant a new answer.  How do I gain enough reputation to comment without:   asking questions which have already been answered or that I can figure out on my own, or posting my comment like as an answer (i.e. being  rude)? Local html file AJAX Call and jQuery Woes Is Dishonored an open-world game? I was considering whether or not to buy Dishonored, and watching gameplay of it on Youtube, when a thought popped into my head: is Dishonored free-roam? Can you go anywhere you want, similarly to Fallout or The Elder Scrolls? If I have a sentence that starts with additionally, finally, consequently, etc. do I always have to put a comma after it? Or is there a different rule? Are static class variables possible in Python? Is it possible to have static class variables or methods in Python? What syntax is required to do this? I just created a plane and added a wave modifier to it, to simply make it look like something fluid. Now, I have an Object that I want to place on the surface of this fluid plane. But how do I do that?  I thought of adding a driver to my Objects location, but I have no clue how to get the location of a certain vertex in runtime. Setting a custom RGB background color in beamer I believe I've correctly followed the manual in defining a custom background color in the example below.     But as the example shows, the background color is black rather than an extremely pale beige.    Could anybody advise what I'm doing wrong please?  \documentclass{beamer} \definecolor{MyBackground}{RGB}{1.0000    0.9451    0.6549} \setbeamercolor{background canvas}{bg=MyBackground} \begin{document} \begin{frame} Hullo world \end{frame} \end{document} Using "recently" with past simple Is it fine to use recently with the past simple tense in the following sentence?     Did you read any books recently?   Is it grammatically correct?  Or do I have to use:     Have you read any books recently? CSS Selector that applies to elements with two classes Why does pizza cheese seem hotter than the crust? When I eat hot pizza or a melted cheese sandwich, the cheese feels a lot hotter than the crust or bread: in particular, the cheese might scald the roof of my mouth. but the crust will not. Is this   my imagination, or because the crust cools a little faster than the cheese, so has already cooled a bit by the time I eat it, or because the cheese cools a little faster than the crust, so transfers heat to the roof of my mouth a bit more, or what? Maximum weight an average bicycle can carry? A few years ago, I've bought  (see edit) bike. At that time I was around 90 kgs and I didn't have any problems.  Today I'm around 120 kgs and I was considering (among other things) starting cycling again. Is this bike "good" enough to carry me? What should I expect? Any tips?  EDIT! Apparently, Drag have renamed some of their bikes in the last few years, so the above information is a bit wrong.  seems to be my bike. At first I didn't recognize much difference, but this one has suspension on the front which mine also has. Does this change anything What is the function of this circuit? Just wondering if someone can give me an explanation for this capacitor layout - what is it's function? The chip to the right is an ADC.  Circled in blue.    I'm guessing it is well known but i don't know how to search for it. Minecraft pocket edition restoring skin problem I updated Minecraft PE so I can have custom skins. I clicked on 'restore skins' without selecting any particular skin, It is now stuck with a  message saying 'we're restoring your skins!' but it has been like that for 20 minutes. Is there a reason why it is like this? A post here on DBA.StackExchange () has spawned an interesting question (at least, interesting to me) regarding performance in MySQL.  The context is that we want to insert a record in a table for each row that is updated.  Before the row is updated, we want to store off a previous value and then increment one of the columns (a "version" column).  If we do this inside a trigger, it works out nicely.  For MySQL, the triggers are , so it would be an easy solution.  Select the data currently in the table, insert it into the logging table, and the update the "version" column in the new data.  However, it's possible to move this logic to a stored procedure. If you do that, you're performing the insert, then incrementing the "version" column in the table.  The entire thing would be set based.   So, when it comes to performing this insert, would this be more performant to use the set-based stored procedure approach or a trigger based approach?  This question is for MySQL (since it has row-by-row triggers), although it could apply to other row-by-row trigger DBMSs. Count total number of files in particular directory with specific extension I want to count the total number of files in particular directory that ends with ".mp4" extension.  I am getting following command:  ls -F |grep -v / | wc -l   It count all the files in particular directory, but I want the count of files that end with .mp4 extension.  Is there any Ubuntu command for that? 3D bodies in TikZ Is there like a library that has default geometric figures like the ones shown below. Am not acquainted yet with 3D diagrams in TikZ.