Uncertainty about a fit to data
Understanding shape and calculation of confidence bands in linear regression
Evaluating the integral $\int \frac{x^2+x}{(e^x+x+1)^2}dx$ I'm wanting to parse a string into a nullable int in C#.  ie. I want to get back either the int value of the string or null if it can't be parsed.  I was kind of hoping that this would work  int? val = stringVal as int?;   But that won't work, so the way I'm doing it now is I've written this extension method  public static int? ParseNullableInt(this string value) {     if (value == null || value.Trim() == string.Empty)     {         return null;     }     else     {         try         {             return int.Parse(value);         }         catch         {             return null;         }     } }      Is there a better way of doing this?  EDIT:  Thanks for the TryParse suggestions, I did know about that, but it worked out about the same.  I'm more interested in knowing if there is a built-in framework method that will parse directly into a nullable int? apt-get install vs pip install I am a bit confused about the cases in which the above commands must be used when downloading python packages. I was trying to download a package named pyudev in accordance with an answer with this . I executed this command :  sudo pip install python-pyudev   but received the following message :  Downloading/unpacking python-pyudev    Could not find any downloads that satisfy the requirement python-pyudev Cleaning up... No distributions at all found for python-pyudev Storing complete log in /home/vineet/.pip/pip.log   However the following worked fine :  sudo apt-get install python-pyudev   When is apt-get supposed to be used to install packages and when is python-pip used? CSS 100% height with padding/margin With HTML/CSS, how can I make an element that has a width and/or height that is 100% of it's parent element and still has proper padding or margins?  By "proper" I mean that if my parent element is 200px tall and I specify height = 100% with padding = 5px I would expect that I should get a 190px high element with border = 5px on all sides, nicely centered in the parent element.  Now, I know that that's not how the standard box model specifies it should work (although I'd like to know why, exactly...), so the obvious answer doesn't work:  #myDiv {     width: 100%     height: 100%;     padding: 5px; }   But it would seem to me that there must be SOME way of reliably producing this effect for a parent of arbitrary size. Does anyone know of a way of accomplishing this (seemingly simple) task?  Oh, and for the record I'm not terribly interested in IE compatibility so that should (hopefully) make things a bit easier.   EDIT: Since an example was asked for, here's the simplest one I can think of:  &lt;html style="height: 100%"&gt;     &lt;body style="height: 100%"&gt;         &lt;div style="background-color: black; height: 100%; padding: 25px"&gt;&lt;/div&gt;     &lt;/body&gt; &lt;/html&gt;   The challenge is then to get the black box to show up with a 25 pixel padding on all edges without the page growing big enough to require scrollbars. How do I complete "Find the Bitizen"? In tiny Death Star, Palpatine has given me the mission "Find the Bitizen" with the text "Working for tips is acceptable. Find 1 Bitizen(s)."  I assumed I had to wait for one of the events where you have to find a "rebel scum" and tap on it to get rid of. One of those events finally popped up but it did not complete the mission.   How do I complete this mission? 'Loading the question failed.' on a question I just posted Is it possible to make macros give different results at the beginning of a new sentence? Suppose that I want the macro "\secname" to write "Section" at the beginning of a new sentence, and "section" anywhere else. How can I do so? How to find a suitable association of color with data value in a visualization? I'm working on a software project that involves creating a visualizer for flood simulations. As part of this project, I've created a water gradient that shows water depth at particular points. To set what values will represent what colors, I go through the data and get the minimum and maximum values that occur and evenly distribute the colors according to that scale.  However, there are often times points in these simulations that have significantly deeper water at them than anywhere else in the simulation. This causes most of the points on the map to have very similar colors and this is not very informative and makes the areas where the water is deeper very hard to see.  My goal is to dedicate a larger range of colors to depths that occur more frequently. For example, if depths go from 0 to 12 but most depths are between 1 and 2, I want more color variation to occur within that range than does between say 11 and 12 or 4 and 5. It seems I need to use standard deviation or something involving normal distribution to do this, but I'm a bit fuzzy on how these things work and how I can use them to accomplish my goal.  Any help that can be provided will be appreciated. Thank you. 'AND' vs '&&' as operator I just replaced a broken light fixture in my closet. (The switch in the light fixture broke when I pulled too hard on the chain.)   When replacing the light fixture I noticed that there is only 30 V AC between the white and black wires. The ground wire is cut back and is not being used. By the way, the wiring in my house is all aluminum.   I know the new light fixture works. I checked it out with my multimeter, and I tried it in a different closet. But the light bulb won't turn on because there is only 30 V. (Even if I disconnect the light fixture completely there is still only 30 V.   It seems to me that it must be a problem with the wiring.  My attic does provide some (difficult) access to the wiring, but I am not sure where to start looking for the problem or what to look for. Can anyone offer some suggestions? Do we need a global test before post hoc tests? I often hear that post hoc tests after an ANOVA can only be used if the ANOVA itself was significant.    However, post hoc tests adjust $p$-values to keep the global type I error rate at 5%, don't they?  So why do we need the global test first?  If we don't need a global test is the terminology "post hoc" correct? Or are there multiple kinds of post hoc tests, some assuming a significant global test result and others without that assumption? Validity of work-energy theorem in presence of non-conservative forces? Reverse (parse the output) of Arrays.toString(int[]) Is there a good reason for the removal of this FrameTicks syntax? Prove that $\Vert f(b)-f(a)-f'(a)(b-a) \Vert\leq \sup_{x\in [a,b]} \Vert f''(x)\Vert\Vert b-a\Vert^2$ Let $\Omega$ be an open set in $\Bbb{R}^n$ and $f:\Omega\to \Bbb{R}^m $ be of class $\Bbb{C}^2.$ Let $a,b$ be in $\Omega$ such that $[a,b]\subset \Omega.$ Prove that  \begin{align}\Vert f(b)-f(a)-f'(a)(b-a) \Vert\leq \sup_{x\in [a,b]} \Vert f''(x)\Vert\Vert b-a\Vert^2.\end{align} where $$f'(a)(b-a)=\big&lt;\nabla f(x),(b-a)\big&gt;=\sum^{n}_{k=1}\frac{\partial f_i}{\partial x_k}(a)(b_k-a_k).$$  I  think the idea of Mean Value Theorem for $C'$ functions in $\Bbb{R}^n$ () will help me in showing it but I don't know how to! Please, can anyone show me a proof or reference? rent a car, rent out a car, hire a car $ which echo echo: shell built-in command. $ which ls /bin/ls $ which cat /bin/cat   Why is echo not an independent utility like ls, ps, cat etc? Why is it shell specific? Any good reasons? I used to have an icon on the Windows Vista taskbar showing the battery amount remaining (laptop). It has mysteriously vanished.  How can I get it back?  I followed the Windows  (see How can I hide the battery icon in the notification area? - hoping to reverse the instructions) but the Power checkbox on the Notification Area tab was greyed out and could not be checked or unchecked (it is currently unchecked). Why do elementary matrix operations not affect the row space of a given matrix? Numlock turned on on boot-up I have a desktop running ubuntu 10.04  I want numlock to be turned on initially.  What do I have to change to accomplish this?  ~~edit~~  I checked in my BIOS.  It was already set up to have the numlock turned on initially.  Yet it isn't being turned on initially.  I have a USB keyboard: would that break this functionality?   Or, should I ask elsewhere (superuser, perhaps) about how to get that BOIS setting working properly?