I have my HDD with two partitions (C:\ with W7 on it and D:\ with all my data). I really want to leave W7 behind and get my laptop only running Ubuntu :). When I run the installation CD, ¿will it delete my D:\ partition as well? Or can I install Ubuntu just fine without backing up my D:\ partition? I appreciate a lot your help.
I need my pre-installed version of Windows 7 (or any other version of Windows), how could I install Ubuntu without erasing it?
How to generate all permutations of a list? This one is killing me, any help is greatly appreciated! If $a$, $b$, and $c$ are sides of a triangle, then $\frac{a}{b+c}+\frac{b}{c+a}+\frac{c}{a+b}<2$. Let $a,b,c$ be the lengths of the sides of a triangle. Prove that $$\sum_{\text{cyc}}\frac{a}{b+c}=\frac{a}{b+c}+\frac{b}{c+a}+\frac{c}{a+b}&lt;2\,.$$  Attempt.  By clearing the denominators, the required inequality is equivalent to $$a^2(b+c)+b^2(c+a)+c^2(a+b)&gt;a^3+b^3+c^3\,.$$ Since $b+c&gt;a$, $c+a&gt;b$, and $a+b&gt;c$, the inequality above is true.  Is there a better, non-bruteforce way? In C#/VB.NET/.NET, which loop runs faster, for or foreach?  Ever since I read that a for loop works faster than a foreach loop a  I assumed it stood true for all collections, generic collections, all arrays, etc.  I scoured Google and found a few articles, but most of them are inconclusive (read comments on the articles) and open ended.  What would be ideal is to have each scenario listed and the best solution for the same.  For example (just an example of how it should be):   for iterating an array of 1000+ strings - for is better than foreach for iterating over IList (non generic) strings - foreach is better than for   A few references found on the web for the same:               [Edit]  Apart from the readability aspect of it, I am really interested in facts and figures. There are applications where the last mile of performance optimization squeezed do matter. How to remove film from stainless steel pan I have an unsightly film around my stainless pan as shown here:    What is causing this to happen?  And how can I remove the film? I have soaked it in soapy water, scraped it with a plastic scraper, and run it in the dishwasher several times, but I can't seem to get rid of the film.   UPDATE: the pan is an All-Clad stainless, fully-clad frypan: Does the sign of $\Delta x$ matter in this time dilation calculation? I am using lightning:recordEditForm and lightning:inputField for creating a new record. this component is being used inside a lightning community builder. When i click the submit button, i am able to create a new record in my custom object. However i need the created record ID as i need to pass it in the URL for the next page. I want to do:  cat update_via_sed.sh | sed 's/old_name/new_name/' &gt; new_update_via_sed.sh   in my program.  But I want to use variables, e.g.  old_run='old_name_952' new_run='old_name_953'   I have tried using them but the substitution doesn't happen (no error). I have tried:  cat update_via_sed.sh | sed 's/old_run/new_run/' cat update_via_sed.sh | sed 's/$old_run/$new_run/' cat update_via_sed.sh | sed 's/${old_run}/${new_run}/' What exactly did mv /tmp/folder/* /* do to my filesystem? It's hard to search for special characters on google, which is why I'm posting this here.  I recently ran (as root) a mv /tmp/folder/* /* when I meant to run mv /tmp/folder/* ./ Big mistake!  Things broke! A lot of files got mixed up and placed into strange places, none of the normal unix commands worked (ls, dir, cat, etc) and once you logged off, you couldn't ssh back in -- it would give you a prompt, but not accept the old passwords.  Running ls /* shows me that it performs ls on every directory in /. If I tried to draw a parallel, then mv should have simply moved (or copied?) the files to every directory in /. Instead, really weird things happened, and I was just curious what exactly was going on.  More info: The files in /tmp/folder had been transferred from a windows machine, and had been named file (#).txt, where (#) is a number up to two digits, with a space between file and the parenthesis. There were ~40 of these text files. Why are all nonzero eigenvalues of the skew-symmetric real matrices pure imaginary? Assume that $A$ is an $n\times n$  real matrix, i.e. $$A^T=-A.$$  Since $\det(A-\lambda I)=\det(A^T-\lambda I)$, $A$ and $A^T$ have the same eigenvalues. On the other hand, $A^T$ and $-A$ also have the same eigenvalues. Thus if $\lambda$ is an eigenvalue of $A$, so is $-\lambda$. If $n$ is odd, $\lambda = 0 $ is an eigenvalue.  A curious search in Google returns  the nonzero eigenvalues of $A$ are all pure imaginary and thus are of the form $iλ_1, −iλ_1, iλ_2, −iλ_2,$ … where each of the $λ_k$ are real.   Here is my question:     How can I prove the fact that "the nonzero eigenvalues of $A$ are all pure imaginary"? What is an intuitive explanation of the Expectation Maximization technique? Let $G$ be a graph of minimum degree $k&gt;1$. Show that $G$ has a cycle of length at least $k+1$.  How would I show this? I understand that a cycle is a sequence of non-repeated vertices and the degree of a graph is the number of neighbors the vertex has. In which ways did scanning Nero's ship enhance/change Starfleet technology? I've heard the explanation that the Enterprise from 2009's Star Trek looked so much more advanced was because data gathered from the Kelvin initially scanning Nero's ship when it first appeared enabled them to upgrade their tech. I'm wondering if they've ever detailed exactly what technologies were advanced or enhanced or discovered. align vs equation I always use align in my documents, and avoid equation. Is there anything wrong with that? My reasoning behind this: align > equation, so why not use it? What are the possible catch bonuses and how much experience do they reward? I found , earlier, and found out that I can throw a curveball at pokémon to earn an increased experience bonus.  I have since noticed two more bonuses: "Great" and "Nice". I had assumed the bonuses were for throwing a pokéball with the 'catch circle' closer to the center, which according to the FAQ, increases the chances of actually catching the pokémon.  However, I have since noticed that the 'catch circle' is actually bigger in cases where I have earned a "Great" bonus. Despite appearing to be a less powerful throw, I earn more experience than when I earn a "Nice" bonus. "Great" nets me 50 experience, while "Nice" only nets 10 experience.  What are the possible catch bonuses, and how much experience do they reward?  For bonus points, every so often I am awarded an additional 10 experience points that are not accounted for on the experience screen. The screen lists my bonuses, and tells me how much experience I have earned, but I am clearly rewarded additional experience when it is added to my player. Assuming this is another catch bonus, what could this be? Let X be a T1 space, and show that X is normal if and only if each neighbourhood of a closed set F contains the closure of some neighbourhood of F Let $X$ be a $T_1$-space, and show that $X$ is normal if and only if each neighbourhood of a closed set $F$ contains the closure of some neighbourhood of $F$.  I saw this statement in the book Introduction to topology and modern analysis by Simmons. I tried to prove it but I did not get any where. How may it be proved? What is the grammar behind "Thanks be to God"? Let $A$ be a $n \times n$  invertible  matrix.Define a function $F:\mathbb{R}^{n} \times \mathbb{R}^{n} \rightarrow \mathbb{R}$ by $F(x,y)=\langle Ax,y\rangle$. Let $DF(x,y)$ denotes the derivative of $F$ at $(x,y)$ which is a linear transformation from $\mathbb{R}^{n} \times \mathbb{R}^{n} \rightarrow \mathbb{R} $. Then      1) if $x\neq 0$,then  $DF(x,0)\neq 0$      2) if $y\neq 0$,then  $DF(0,y)\neq 0$      3)  if $(x,y)\neq (0,0)$,then $DF(x,y)\neq 0$      4) if $x=0 \; or \;y=0$,then $DF(x,y)= 0$   I don't even know how to start the solution and also how to take derivative in higher dimensions.  Please help!  Thank you. Query is slow in SQL Server 2014, fast in SQL Server 2012 During the migration of one of our databases from SQL Server 2012 (SP1, CU2) to SQL Server 2014 (SP1), we have experienced some strange issues.  One of the queries that completes within seconds on SQL Server 2012 seem to be hanging on SQL Server 2014.  SELECT  DISTINCT      src.[Id] FROM     [stg].[BaseVolumes] src JOIN          [tmp].[Dates] d ON src.[CalWeek_Nmbr] = d.[CalYrWkDense_Nmbr] WHERE        EXISTS (SELECT  *             FROM                     (SELECT     ctry.[ISOCode]                  AS  [Mkt_Code]                             , so.[Code]                     AS  [SlsOrg_Code_AK]                             , so.[DistributionChannelCode]  AS  [DistChnl_Code_AK]                             , prd.[SupplierCode]                AS  [SKU_Code_AK]                             , cl6.[Code]                        AS  [CstHierLvl06_Code_AK]                             , lp.[BaseDateID]                   AS  [Dte_EK]                  FROM   [PM_APP].[edw].[BaseVolumeDayCurrent]   lp                  JOIN   [PM_APP].[dbo].[Country]                ctry    ON  lp.[CountryID] = ctry.[ID]                  JOIN   [PM_APP].[dbo].[SalesOrganisation]      so      ON  lp.[SalesOrganisationID] = so.[ID]                  JOIN   [PM_APP].[dbo].[Product]                prd     ON  lp.[ProductID] = prd.[ID]                     JOIN   [PM_APP].[dbo].[CustomerLevel6]         cl6     ON  lp.[CustomerID] = cl6.[ID]                  WHERE                        lp.[ModifiedByApp] = 1) lkp             WHERE                    src.[Mkt_Code]                  =   lkp.[Mkt_Code]                 AND src.[SlsOrg_Code_AK]        =   lkp.[SlsOrg_Code_AK]                 AND src.[DistChnl_Code_AK]      =   lkp.[DistChnl_Code_AK]                 AND src.[SKU_Code_AK]           =   lkp.[SKU_Code_AK]                 AND src.[CstHierLvl06_Code_AK]  =   lkp.[CstHierLvl06_Code_AK]                 AND d.[Dte_EK]                  =   lkp.[Dte_EK]         )   Row count:   BaseVolumes:            23108  Dates:                  18628  BaseVolumeDayCurrent:   108115503  Country:                249 SalesOrganisation:      29 Product:                18446 CustomerLevel6:         295   Wait stats showing high CXPacket, but there is one hanging task with SOS_SCHEDULER_YIELD, (print from sys.sysprocesses)   spid | blocked | waittime | lastwaittype          | cpu     | physical_io   76   | 0       | 9886044  | CXPACKET              | 13902   | 31192  76   | 0       | 0        | SOS_SCHEDULER_YIELD   | 9829719 | 83077  76   | 0       | 11248    | CXPACKET              | 11110   | 0 . . .   Attached are the execution plans from SQL Server 2012 and SQL Server 2014.       Any help much appreciated. Functions satisfying $f\left( f(x)^2+f(y) \right)=xf(x)+y$