In my application, I need to generate excel files on the fly. I have an option of using Excel  library. But it is mandatory to have excel installed on the machine.  Is there any other .NET API to generate excel files at runtime which doesn't require excel.
How can I create an Excel spreadsheet with C# without requiring Excel to be installed on the machine that's running the code?
I've purchased a Canon EF 50mm f/1.8 II. But I'm really disappointed in the results, especially when using it for night photography. :(  In my night shots a lot of lens flare appears in my photos. I've tried to change the angle and position of the camera to no avail. Also I cannot do any night photo without directing my camera to direct light like in street photography!  This photo was taken with my Canon 650D and 50mm 1.8 Lens in a long exposure night shot, and as you notice there is a bunch of lens flare in it. Some people suggested I remove the UV filter. This decreased the lens flare a little but there is still some flare in the photo .    I want to know if there is a problem with the lens? Or is this normal for a $100 lens? Does anyone else have a similar experience with this lens? Recursive grep vs find / -type f -exec grep {} \; Which is more efficient/faster? Differentiation operator and eigenvalues Let $V = \{p(x) \in F[x] \ | \ \deg(p(x)) \le n\}$. Let $T : V \to V$ be given by differentiation, in essence $$T(p(x)) = p'(x)$$ It seems to me that the only eigenvalue that can exist is $\lambda =0$, since the given operator lowers the degree of any given polynomial and hence makes it impossible for a constant multiple of a polynomial to be equal to the polynomial's derivative. Is my claim correct? What really is an indeterminate form? We can apply l’Hôpital’s Rule to the indeterminate quotients $ \dfrac{0}{0} $ and $ \dfrac{\infty}{\infty} $, but why can’t we directly apply it to the indeterminate difference $ \infty - \infty $ or to the indeterminate product $ 0 \cdot \infty $?  Furthermore, why can’t we call $ \infty + \infty $ and $ \infty \cdot \infty $ indeterminate forms?  I’m new to calculus, so please clear up my concepts if you can. Thanks! How to animate multiple lines I wonder what would be the best way of animating multiple 2 dimensional lines in blender.  Lets say I have lots of line, that are parallel and have some sort of rule, kind of like a PCB board with hundreds of circuits.  The starting frame would be when nothing is visible and during the animation the lines would slowly build up from nothing all the way to the end forming the finished lines.  I have a couple of ideas that might work, but all include heavy hand animation, like:   grease pencil animation, drawing them one by one, converting to curve, then build up modifier some dynamic paint hack   There maybe other more efficient methods that I don't know of and if so, please let me know. Novel about a teleportation device and a con artist alien I tried Libreoffice, but its Import option while pasting in the cell is very  annoying.I also tried Gnumeric but I am not able to paste using middle button.Parcellite to make copy paste faster and middle button pasting is not working with Gnumeric. Is there any simple table maker app available that can accept only simple unformatted text? All these software are very complicated for this simple work. Sorting Directory.GetFiles() System.IO.Directory.GetFiles() returns a string[].  What is the default sort order for the returned values?  I'm assuming by name, but if so how much does the current culture effect it?  Can you change it to something like creation date?   Update: MSDN points out that the sort order is not guaranteed for .Net 3.5, but the 2.0 version of the page doesn't say anything at all and neither page will help you sort by things like creation or modification time.  That information is lost once you have the array (it contains only strings).  I could build a comparer that would check for each file it gets, but that means accessing the file system repeatedly when presumably the .GetFiles() method already does this.  Seems very inefficient. Several airline and trip planning sites will allow you to check "I am flexible with my dates" or a similar option.  Is there any way to also search more broadly for location?  For example, if you wanted to leave from YYZ or YKF and arrive at any airport in California, can a search for such flights be done somehow?  I ask because when I plan plane trips, I want the lowest price.  I'm OK with leaving a day or two later if I save $200 (same with the return trip).  There are 3 airports within 80 km of me, I'll leave from the one with the cheapest flight. And I'm also OK with changing the trip to spend time exploring San Francisco instead of lying on the beach near San Diego, and that sort of thing.  Normally this would take dozens of searches, but I'd like to see it all at once. I understand that the eigenvectors of a linear transformation are the vectors that, when transformed, are simply scaled by a factor of the corresponding eigenvalue. Therefore $$ A\vec{x}=\lambda\vec{x}. $$ We can replace the scaling of the vector $\vec{x}$ by $\lambda$ with its equivalent linear transformation, $\lambda I$. Then we can rearrange this equation as follows: $$ A\vec{x}-(\lambda I)\vec{x}=\begin{bmatrix}0\\0\end{bmatrix}\\  (A-\lambda I)\vec{x}=\begin{bmatrix}0\\0\end{bmatrix}\\  $$ For this to be true either $\vec{x}$ must be a zero vector or the transformation $A-\lambda I$ must have $\vec{x}$ in its null-space. The course I'm following says that we can solve for $\lambda$ by finding when the determinant of $A-\lambda I$ is zero, but why does that guarantee that $\vec{x}$ will become the zero vector when transformed by $A-\lambda I$? I understand that for $\vec{x}$ to be an eigenvector this transformation must have a determinant of zero, but I don't see how the inverse can be true; having a determinant of zero doesn't gaurantee that $\vec{x}$ will be transformed into the zero vector. For example, let $$ (A-\lambda I) = \begin{bmatrix}1&amp;2\\0&amp;0\end{bmatrix}, \vec{x}=\begin{bmatrix}1\\1\end{bmatrix} $$ Then, although $\det\begin{bmatrix}1&amp;2\\0&amp;0\end{bmatrix} = 0$, it does not gaurantee $(A-\lambda I)\vec{x}$ to be the zero vector. $$ \begin{bmatrix}1&amp;2\\0&amp;0\end{bmatrix}\begin{bmatrix}1\\1\end{bmatrix}=\begin{bmatrix}3\\0\end{bmatrix}  $$ We can see that the transformation gives us $\begin{bmatrix}3\\0\end{bmatrix}$ and not the zero vector. Why does finding when the determinant of this transformation is equal to zero help us find the eigenvectors? Am I missing something? I'm searching for a template which makes a document look like it's written with a real typewriter. Ideally, this means it's not only in mono-spaced font, but the hyphenation is adjusted accordingly. Also, some randomness would be nice (e.g. some characters more bold than others), so that it looks more natural. What do bookcases do for enchanting? Why can't you use the keyword 'this' in a static method in .Net? How do I call one constructor from another in Java? Is it possible to call a constructor from another (within the same class, not from a subclass)? If yes how? And what could be the best way to call another constructor (if there are several ways to do it)? Uninstalling Ubuntu from Windows Dual Boot if I don't have Windows recovery CD I installed Ubuntu (I had already had Windows 8.1) from USB (I still have live Ubuntu on it). Is there a way I can uninstall Ubuntu in a way that my Windows will remain bootable? All the tutorials I have seen say that uninstalling ubuntu will delete GRUB also so I will need a Windows recovery CD to boot into it, but I don't have one. Is there a solution? Prove or the disprove the existence of a limit of integrals Let $A \subset \mathbb{R}^2$ be the annulus defined, in polar coordinates, as  $$ A = \{ (r, \theta) \in [0, \infty) \times [0, 2\pi) : 2 \leq r \leq 3 \} \, .$$ Let $F: A \to A$, $F:(r, \theta) \mapsto (r, r \theta \text{ (mod } 2\pi))$. Let $g : A \to \mathbb{R}$ be a continuous function. Discuss the existence of the limit $$ \lim_{n \to \infty} \int_A g \circ F^{(n)}(x) \, \text{d}x \, ,$$ where $F^{(n)} = F \circ F \circ \dots \circ F$ denotes the composition of $F$ with itself $n$ times.  I cannot find a way to attack this problem. Here's what I tried: if $g \circ F^{(n)}$ converged, I think we could take the limit under the integral sign. So I tried to show the convergence of $F^{(n)}$. If it converged, then the limit function must send every point to a fixed point of $F$. So I determined the fixed points of $F$. But I don't think $F^{(n)}$ converges. How can I use the subdivision surface modifier to create more high poly meshes without ruining sharp edges? For example this mesh  The sphere should be subdivided but the rim of the cylinder should stay the same because it is a sharp edge. This is the result of the subdevision  How can I get sharp edges to not be affected by the sub surf mod? Linux Debian codenames I've got a few, quite silly, non-technical questions about giving  to  releases.  Each Debian release has its unique codename, which is (so far) a characters' name from  movies by .  Here is list of all assigned codenames so far:   release 1.1 is  (Buzz Lightyear) - the spaceman, release 1.2 is  - the tyrannosaurus, release 1.3.x is  (Bo Peep) - the girl who took care of the sheep, release 2.0 is  - the piggy bank, release 2.1 is  (Slinky Dog) - the toy dog, release 2.2 is  - Mr. Potato, release 3.0 is  -  the cowboy, release 3.1 is  - the sergeant of the Green Plastic Army Men, release 4.0 is  - the toy blackboard (Etch-a-Sketch), release 5.0 is  - the toy binoculars, release 6.0 is  - the name for the three-eyed aliens, release 7.0 is  - the name of the rubber toy penguin with a red bow tie, release 8.0 is  - the name of the yodelling cowgirl, release 9.0 is  - a purple rubbery octopus toy at , release 10.0 is  - 's pet dachshund (currently ).   List of upcoming major Debian releases' codenames after :   release 11.0 is  - 's horse (currently ), release 12.0 is  - intelligent worm toy with a built-in flashlight.   There are also:   special codename  () which is symbolic link to codename which is currently unstable,  which is symbolic link to codename which is currently stable,  which is symbolic link to codename which is currently testing.   The list of Toy Story  is quite  but at some time, there will be no more characters' names to assign.  My questions are:   What codenames will be assigned if we run out of characters' names? Who decides what is codename of next release (please don't answer ambiguously like: 'community')? How many releases' names are planned ahead?   BTW: Interesting quote from :     The  of using Toy Story names was  by  who   was, at the time, the Debian Project Leader and was working also at   , the company that produced the movies.     by  (: ). What is a suitable word to describe a place where two rivers meet? I've googled for a while and on some sites I've found the word "watershed" as the proposed word. Is it the word that best suits it? If I use the starting wealth rolls of my class, do I keep any remaining money left over? If I use the starting wealth rolls of my class, do I keep any remaining money left over after I buy equipment?  In D&amp;D 5e you can roll the 4d4 &times; 10 to determine starting gold, forgoing any equipment your class and background  gets.  This is not up for question.  What is up for question is whether or not the PC keeps any remaining gold that they don't spend on equipment.   As far as I have been able to tell, this is not explicitly stated in the PHB nor in the Basic Rules documents.