I want to develop MS Excel download feature for some of my data, thus I created a VF page with following attributes on the apex:page tag.  contentType="application/vnd.ms-excel#somefile.xls" cache="true" applyHtmlTag="false" standardStylesheets="false" sidebar="false" showHeader="false"   With this I get the file downloaded but when I try to open it, the Excel application (I use 2013 version) shows a warning message before showing the data.  The file format and extension of 'somefile.xls' don't match. The file could be corrupted or unsafe. Unless you trust its source, don't open it. Do you want to open it anyway?  I've used XML Spreadsheet markup for this and have avoided the use of Visualforce tags wherever I could, just to make sure the output is not HTML but native Spreadsheet markup. The file is not corrupted for sure since I can see the expected data as I open it after clicking "Yes" on the warning message.  Could anybody help me make this download without that warning message ?
Is there a way to view the "printable view" (.xls) in Mac Numbers (version 2.3+) rather than Excel? I am using OS X (Maverick), Numbers (V3.0) and both Safari and Firefox.  When I save a Salesforce report using the "printable view" button, it saves it as an .xls file but when I open it in Numbers I get what looks like the XML code behind it, for example the first cell in the first three rows contains:  &lt;!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"&gt; &lt;html&gt; &lt;head&gt;
Mutual set of representatives for left and right cosets: what about infinite groups? Let $G$ be a group and $H$ a subgroup of $G$. If $G$ is finite, then according to Philip Hall's "marriage theorem" there is a left transversal $T$ of $H$ in $G$ (that is, $T$ contains precisely one element from each left coset of $H$) such that $T$ is also a right transversal of $H$.   Does this theorem generalize to infinite groups? The original theorem treats only the case where $|H| &lt; \infty$ and $[G:H] &lt; \infty$.  What can we say when $|H| = \infty$ and $[G:H] = \infty$? What about $|H| &lt; \infty$ and $[G:H] = \infty$? Also $|H| = \infty$ and $[G:H] &lt; \infty$? Is there a term for switching syllables of words? What does this box icon represent? Since I started playing, I have seen this icon in the bottom right of my screen. Clicking it does nothing.  What does this icon represent?  I'll add a PC tag, as I'm playing on PC, and it could be related to that. Check variable equality against a list of values Environment.TickCount vs DateTime.Now What is $\log(1)$ to the base of $1$? My teacher says it is $1$. I beg to differ, I think it can be all real numbers! i.e., $1^x = 1$, where $x\in \mathbb{R}$.  So I was wondering where I have gone wrong. Show that $\text{C}/c \cong (c/(\text{C}^{\text{op}}))^{\text{op}}$ I'm self studying from Category Theory in Context by Emily Riehl and have encountered the following question regarding slice categories:     Let $\text{C}$ be a category and $c$ be an object in $\text{C}$. Show that $\text{C}/c \cong (c/(\text{C}^{\text{op}}))^{\text{op}}$    The exercise appears in an chapter that introduces the notion of opposite categories and duality proofs.     My intuition of why the statement is true comes from the following observation:  Let $x,y$ be objects in $\mathbf{C}$ (or equivalently $\mathbf{C}^{\text{op}}$). Let $g^{\text{op}} : c \to y$ and $f^{\text{op}} : c \to x$ be objects in $c/(\mathbf{C}^{\text{op}})$. By the definition of slice category, there exists a morphism $h^{\text{op}} : y \to x$ in $\mathbf{C}^{\text{op}}$ such that the diagram below commutes:  $\hskip2in$   Now the 'corresponding diagram' in the opposite category $(c/(\mathbf{C}^{\text{op}}))^{\text{op}}$ would be:  $\hskip2in$    which, as I understand it, would also be commutative. Now, to me, this indicates:   that the objects in $(c/(\mathbf{C}^{\text{op}}))^{\text{op}}$ are the same as the objects in $\mathbf{C}/c$, namely, a morphism in $\mathbf{C}$ from an object $z \in \mathbf{C}$ to $c$. the commutativity of the seconds diagram describes morphisms $h$ in both $\mathbf{C}/c$ and $(c/(\mathbf{C}^{\text{op}}))^{\text{op}}$ if you reverse the arrows again you return to the same diagram. This makes me think you could construct a map between morphisms by first making a map from $ \mathbf{C}/c \to (\mathbf{C}/c)^{\text{op}} ( \cong c/(\mathbf{C}^{\text{op}}) )$ by $h \mapsto h^{op}$     Now, what I am really looking for is a way to structure a proof. I feel like I have some intuition but am very unsure of how to write it down in a concise way. I am new to category theory so I'm still very much learning how to construct these types of proofs using duality; I feel like what I have written is maybe overkill but I'm trying to be as explicit as possible to make sure I understand everything.  In particular, I don't know how I would get a concrete correspondence between morphisms in the two categories that respects associativity of composition etc.  Any help or pointers would be appreciated! Say, for example, you and a group of people were all sailing out in the ocean and something happens...then you say,  "I guess we are all in the same boat"  You are literally in the same boat with everyone else, and your current situation is the same as everyone else.  Now such a phrase can be applied literally and figuratively. I was wondering if there was a word that would mean both literally and figuratively. I know this is a tad bit of an oxymoron, but I was curious to see if there was such an "all encompassing" word for this. Data Not Backed Up, Partition Type: FFFFFFFF-FFFF-FFFF-FFFF-FFFFFFFFFFFF I was trying to install Linux on my MacBook for class when I bricked my computer, which now in an unbootable state.   I made my partition too small, so I was going to delete and create a larger one. However, Disk Utility did not allow me to delete the small partition. I followed the instructions from   However, not only was I still unable to delete it, but upon restarting I realized my primary partition (located on the same disk) changed into FFFFFFFF-FFFF-FFFF-FFFF-FFFFFFFFFFFF, and I had no options to boot.  (I am sure I performed the command on the correct disk and partition)  I saw some similar threads, but my main bootable drive is the one that got corrupt.   I don't want to lose any data. I'm not the most terminal savvy, so ANY help is appreciated, and I will kindly provide any additional information!  (Disk 0, partition 2 is my main partition, and that only one I care about)  Below are the results of  $ diskutil list and $ gpt -r show disk0.        UPDATE: :  I have followed @klanomath 's instructions. At the last step I received the following error:  Checking prerequisites Checking the partition list Checking for an EFI system partition Checking the EFI system partition's size Checking the EFI system partition's file system Problems were found with the partition map which might prevent booting Error: -69766: The partition map needs to be repaired because there's a problem with the EFI system partition's file system Underlying error: 8: POSIX reports: Exec format error    FINAL UPDATE: SUCCESS!  I just wanted thank @klanomath for helping me through this entire process. He spent 11 hours TeamViewing with me until not only my files were accessible, but until I could access my computer as could before this whole debacle (and this was after 5 hours of email correspondence).   To any future reader with this problem: PLEASE don't give up, it can be fixed! Consider a database table holding names, with three rows:  Peter Paul Mary   Is there an easy way to turn this into a single string of Peter, Paul, Mary? Executing a certain action for all elements in an Enumerable How do you iterate backwards through an STL list? How does the Performance Index work? In one of Dota2's recent patches, Valve has added a new feature called "Performance Index" visible in your own in-game profile.  It is not clear how it works. Is there any information available, what "performance" it monitors?  Does it rely on K/D, K/D/A, Gold per minutes, Experience per minute, or all of them? I've created a new C++ project in Visual Studio 2008.  No code has been written yet;  Only project settings have been changed.  When I compile the project, I receive the following fatal error:     fatal error LNK1104: cannot open file 'C:\Program.obj' Failed to download repository information due to missing CDROM Another combinatorics problem: $\sum\limits_{k = 0}^n (-1)^k \binom{2n-k}k2^{2n-2k}=2n+1$ I am dealing with problem 10F in the textbook A Course in Combinatorics by J. H. van Lint and R. M. Wilson.   Problem 10F: Prove directly the equality  $\sum\limits_{k = 0}^n {{{\left( { - 1} \right)}^k}\left( {\begin{array}{*{20}{c}} {2n - k}\\k\end{array}} \right){2^{2n - 2k}} = } 2n + 1$.  Sketch of the proof: Evaluate  $\sum\limits_{n = 0}^\infty  {\sum\limits_{k = 0}^n {{{\left( { - 1} \right)}^k}\left( {\begin{array}{*{20}{c}}{2n - k}\\k\end{array}} \right){2^{2n - 2k}}{x^{2n}}} } $. To do this, use Hint 1. Then, use Hint 2.  Hint 1: $\sum\limits_{j = 0}^\infty  {\left( {\begin{array}{*{20}{c}}{a + j}\\j \end{array}} \right){x^j} = {{\left( {1 - x} \right)}^{ - a - 1}}} ,\,\,a \in {\mathbb{Z}^ + }$.  Hint 2:  ${\sum\limits_{i = 0}^\infty  {\left( {2i + 1} \right){x^{2i}} = \left( {\frac{x}{{1 - {x^2}}}} \right)} ^\prime }$.   Attempt: It is enough to show that  $\sum\limits_{n = 0}^\infty  {\sum\limits_{k = 0}^n {{{\left( { - 1} \right)}^k}\left( {\begin{array}{*{20}{c}} {2n - k}\\ k \end{array}} \right){2^{2n - 2k}}{x^{2n}}} }  = {\left( {\frac{x}{{1 - {x^2}}}} \right)^\prime }$. But I can not use Hint 1. How to cluster time series? I have a question about cluster analysis. There are 3000 companies, which have to be clustered according to their power usage over 5 years. Each company has values for every hour during 5 years. I would like to find out if some companies have the same pattern in usage power over the time period. The results should be used for daily prediction of power usage. If you have some ideas how to cluster time series in SPSS, please share with me. I just bought a used  and it comes with regular rim brakes. I'm perfectly happy with them so far, but have been wondering if disc brakes would come handy when it rains.  What is involved in converting a bike from rim brakes to disc brakes (mechanical or hydraulic)?   Is this something that is feasible, or am I better off buying another bike that already has disc brakes? This looks like a question asked , but it isn't.  $$T(n)=\begin{cases} T (\sqrt{n}) + 1 \quad &amp; \text{ if } n&gt;1 \\  1 &amp; \text{ if }n=1\end{cases}$$  My professor gave this to me in class yesterday. This is where I'm stuck:   $$T(n) =  T(n^{1/2})+1 =  T(n^{1/4})+2 = T(n^{1/8})+3 = \dots =   T(n^{1/ 2 ^k})+k$$  Now this will continue till  $$n^{1/ 2 ^k}=1$$  How do I proceed ahead? If I take log on both sides, then RHS becomes zero. How do I solve the relation?  I don't want to use the Master theorem, I want to know where and why am I stuck. An English book tells me that the following sentence is correct:     This publication is made from paper from sustainable forests.   Shouldn't it be of paper instead?