This has already happened to me several times:   a user posts a question; I provide an answer; the user deletes the question.   I know that the person who asked the question can do this at will if my answer is the only answer and if it got no upvotes. And I do not intend to ask to change that. But I think that, in this situation, the user who asked the question should get a warning saying something like “Someone took the trouble of writing and posting an answer to your question. Are you sure that you want to delete it?”
While attempting to delete a question which was answered by myself, and with no other answers, I got the following warning:     Delete this answered question?      We do not recommend deleting questions with answers because doing so   deprives future readers of this knowledge.      Repeated deletion of answered questions can result in your account   being blocked from asking. Are you sure you wish to delete?   I understand that deleting your question when someone else has answered it is effectively nullifying the effort that person put into that answer, which is bad. But is it bad if the only answer that's deleted along with your question is your own?
No group of order 200 is simple Show that any group of order 200 is not a simple group.   I have started with the sylow 5-subgroup, but the sylow 2 subgroups i found that they are 25 subgroup but i couldnt proceed in the proof any more! Please help. Why doesn't this C++0x code call the move constructor? Google Spreadsheets: IF not working I have problems with my IF command in Google Sheets. If gives #ERROR! all the time. See this simple test:    Not even if I put in the number directly and avoid references:    Am I using the IF wrong? Or what could such a problem be? This example is from a new document. What does the "static" modifier after "import" mean? Odd behavor with POSIXct/POSIXlt and subsecond accuracy Table with actions per row Derivatives: enter "evaluated at" vertical bar with multiple values as subscripts Sorry for the long title, but how do I enter evaluated at (for a derivative), with multiple valuation criteria at the bottom of the the big | line?  Thanks! How does the pull down resistor work in this circuit? Javascript Closures and 'this' I have a problem with an object I have created that looks something like this:  var myObject = {      AddChildRowEvents: function(row, p2) {         if(document.attachEvent) {             row.attachEvent('onclick', function(){this.DoSomething();});         } else {             row.addEventListener('click', function(){this.DoSomething();}, false);         }     },      DoSomething: function() {         this.SomethingElse(); //&lt;-- Error here, object 'this' does not support this method.     } }   The problem is that when I am inside the 'DoSomething' function, 'this' does not refer to 'myObject' what am I doing wrong? How to mount an internal HDD on start-up? I'm totally new to Ubuntu/Linux, using Ubuntu Server at the moment. Just trying to  figure out something basic.   How can you tell where you are installing a program. For example I just installed Sphinx search engine by placing the tarball that I downloaded from their site to my:  /home/sphinx   directory. I created the sphinx directory to place that tarball in. Then I ran these commands:  tar xvzf sphinx-0.9.8.1.tar.gz cd sphinx-0.9.8.1/ ./configure --with-mysql-includes=/usr/include/mysql --with-mysql-libs=/usr/lib/mysql   and then these:  make sudo make install   Now I have a lot of files sitting in the directory where I ran these commands. Is this my Spynx installation or did it install somewhere else?  In windows if you run an installer (.exe file) anywhere the program will still install in your C:\Program Files directory. Does something similar apply to linux where all programs are installed in a central place, or can you install programs anywhere on the system.  Questions   I would prefer to keep all my installed programs in one place so what is the right place for this in terms of best practice. In other words what is the Linux equivalent of C:\Program Files? And how does one always install at this location, is it just a matter of placing the tarball and running the install commands from this location? What about if I use sudo apt-get to install a package. How can I point to this location to tell apt-get to always install there? How can a "proper" function have a vertical slope? Plotting the function $f(x)=x^{1/3}$ defined for any real number $x$ gives us:   Since $f$ is a function, for any given $x$ value it maps to a single y value (and not more than one $y$ value, because that would mean it's not a function as it fails the vertical line test). This function also has a vertical tangent at $x=0$.   My question is: how can we have a function that also has a vertical tangent? To get a vertical tangent we need 2 vertical points, which means that we are not working with a "proper" function as it has multiple y values mapping to a single $x$. How is it possible for a "proper" function to have a vertical tangent?  As I understand, in the graph I pasted we cannot take the derivative of x=0 because the slope is vertical, hence we cannot see the instantaneous rate of change of x to y as the y value is not a value (or many values, which ever way you want to look at it). How is it possible to have a perfectly vertical slope on a function? In this case I can imagine a very steep curve at 0.... but vertical?!? I can't wrap my mind around it. How can we get a vertical slope on a non vertical function? I have a project where I have a few layers (State of Texas, cities, roads, etc.). They are all resaved and projected to NAD83 / UTM zone 14N EPSG: 26914. The project CRS is also NAD83 / UTM zone 14N EPSG: 26914 and on the fly projection is enabled. I added a text delimited file and cannot get them to line up. I checked the attribute table of the delimited file and the coordinates are correct. I cross-checked this with a point close to where a few of the points from the delimited file are and they are very close so in theory they should be lining up. I tried to save the delimited file and save it with the same projection and add the shp file back in and that did not work. Anyone have any ideas? I can't think of anything else to try. Posting only once every 40 minutes even for experienced users? I have low rep on Physics &amp; Woodworking, but not so on Stack Overflow.  I just tried to ask &lt; 40 minute interval on those two and got hit with the :    I posted once on Woodworking, then ~5 minutes later tried to post on Physics, and was denied because of the 40 min rule. So apparently the system looks cross-network to assess this rule.  It seems the system is looking at my lowest cross-network rep when applying this rule rather than highest rep? What is the point of this very conservative approach? It would seem there is very little chance that a user with high rep on ANY site is likely to spam or abuse the lower-rep sites. And obviously this discourages participation across the network.  Furthermore, an improvement at least would be to warn the user ASAP so they aren't stuck with a nicely worded question in their browser window only which could be forgotten, lost, etc. As it is you only get the warning when you click [Post Your Question]. Extracting text from HTML file using Python Convergent or divergent $\sum_{n=1}^{\infty} \frac{e^nn!}{n^n}$? As I am seeing this,  the man and boat will have different displacement from ground frame,  so there should be a net work done by friction .  The books says,  total work done by friction is zero when friction is static and internal to system. Please explain.. Why should the substitution be injective when integrating by substitution? I made a silly mistake in evaluating some integral by using a non-injective $u$-substitution.  But why should $u$-substitutions be injective in the first place?  I reasoned in the following way: the formula $$ \int_{\phi(a)}^{\phi(b)}g(x)\ dx = \int_a^b g(\phi(t))\phi^\prime(t)\ dt $$ holds for a general $C^1$ function $\phi$, even if it is not injective.  When you calculate an integral of the form $\int_a^b f(\phi(t))\ dt$, to use the formula above from right to left, you should find a function $f$ such that $$ f(\phi(t)) = g(\phi(t))\phi^\prime(t), $$ which do not exist if $\phi$ is not injective, i.e., $\phi(t) = 0$ for some $t$. This is why substitutions should be injective.  Is my reasoning correct?  If so, I believe that if $\phi^\prime(t) = 0 \Rightarrow f(\phi(t)) = 0$, a function $g$ that satisfies the formula above may exist and $\phi$ should not necessarily be injective.  Is this right?  I am often confused about the fact $\phi$ should be injective.  Is there an intuitive way to interpret this fact, so that I always remember to take a $\phi$ that is injective?  I would be grateful if you could help me understand this matter. how to plot two graphs in a single sheet? I am new to Latex. Cann some one tell me how can I plot two graphs in a single page and How can resize the legend. I have attached the picture how the legend looks. I need it out from the plot and how can i have gridded lines in the plot. Please help me. My code is as follows: \documentclass[12pt, a4paper]{report} \usepackage{filecontents,pgfplots}  \begin{filecontents}{mydata.dat} m0_FEED, AT 773.15K, AT 823.15K, AT 873.15K, AT 923.15K, AT 973.15K 0.005, 1.30E+04, 12959.71536,12959.71536,12959.71536,12959.71536 0.007, 1.81E+04, 18145.78478,18145.78478,18145.78478,18145.784 0.009, 2.33E+04, 23333.9541,23333.9541,23333.9541,23333.9541 0.011, 2.85E+04, 28524.71381,28524.71381,28524.71381,28524.71381 0.013, 3.37E+04, 33718.48576,33718.48576,33718.48576,33718.48576 0.015, 3.89E+04, 38915.61947,38915.61947,38915.61947,38915.61947 0.017, 4.41E+04, 44116.39602,44116.39603,44116.39603,44116.39603 0.019, 4.93E+04, 49321.02848,49321.02848,49321.02878,49321.02849 0.021, 5.45E+04, 54529.67237,54529.67238,54529.67238,54529.67238 \end{filecontents}  \begin{document}   \pgfplotstableread[col sep=comma]{mydata.dat}{\mydata} \begin{tikzpicture}[scale=1.8] \begin{axis}[minor tick num=1, xlabel=Degrees, ylabel = temperature] \addplot [black,very thick] table [x={m0_FEED}, y={AT 773.15K}] {\mydata}; \addplot [red,very thick] table [x={m0_FEED}, y={AT 823.15K}] {\mydata}; \addplot [blue,very thick] table [x={m0_FEED}, y={AT 873.15K}] {\mydata}; \addplot [green,very thick] table [x={m0_FEED}, y={AT 923.15K}] {\mydata}; \addplot [dashed,yellow,very thick] table [x={m0_FEED}, y={AT 973.15K}] {\mydata}; \legend{AT773.15K, AT823.15K, AT873.15K, AT923.15K, AT973.15K} \end{axis} \end{tikzpicture}  \begin{filecontents}{mydatax.dat} m0_FEED AT 773.15K  AT 823.15K  AT 873.15K  AT 923.15K  AT 973.15K 0.005   4.06E+03    4601.511738 5147.966831 5703.120845 6267.035737 0.007   5.69E+03    6439.241858 7204.278989 7981.494608 8625.923 0.009   7.31E+03    8274.205759 9257.824928 10257.10215 11272.14896 0.011   8.92E+03    10105.75535 11307.95656 12529.29539 13769.90815 0.013   1.05E+04    11933.33165 13354.1149  14797.51533 16263.69405 0.015   1.21E+04    13756.46929 15395.83457 17061.29661 18753.04129 0.017   1.37E+04    15574.79159 17432.7389  19320.26254 21237.57317 0.019   1.53E+04    17388.009   19464.53834 21574.12348 23717.00014 0.021   1.69E+04    19195.90581 21491.01717 23822.664   26191.10653 \end{filecontents}  \pgfplotstableread{mydatax.dat}{\mydatax} \begin{tikzpicture}[scale=2] \begin{axis}[minor tick num=1, xlabel=Degrees, ylabel = temperature] \addplot [black,very thick] table [x={m0_FEED}, y={AT 773.15K}] {\mydatax}; \addplot [red,very thick] table [x={m0_FEED}, y={AT 823.15K}] {\mydatax}; \addplot [blue,very thick] table [x={m0_FEED}, y={AT 873.15K}] {\mydatax}; \addplot [green,very thick] table [x={m0_FEED}, y={AT 923.15K}] {\mydatax}; \addplot [dashed,yellow,very thick] table [x={m0_FEED}, y={AT 973.15K}] {\mydatax}; \legend{AT773.15K, AT823.15K, AT873.15K, AT923.15K, AT973.15K} \end{axis} \end{tikzpicture}   \end{document} How do you setup a TeX document to self publish a book online? I am a casual TeX user. Mostly I have used it to type up some reports/homeworks for class in my graduate engineering work. In the past I have used document type "article". And then kept all the defaults.  I need to self publish something online. At the highest level I would like to know: How do you setup a TeX document to self publish a book online?  Some more low level questions:   Is there a document type for "book" and what is its name? I am looking at Amazon Createspace. : filetype=pdf, trim size, margins (gutter and outside margins). All of these various trim size, margins gutter/outside can be adjusted in the Tex document?   Has anyone seen any good TeX templates for Amazon Createspace? If you could demonstrate how to tweak a specific "book" document type that would be very helpful also.    Other than the above questions, please feel free to offer any other sort of help since I am completely new to this process (advice, links to good tutorials, links to wikibooks).