wolfram-mathematica

For better or worse, Mathematica provides a wealth of constructs that allow you to do non-local transfers of control, including Return , Catch / Throw , Abort and Goto . However, these kinds of non-local transfers of control often conflict with writing robust programs that need to ensure that clean-up code (like closing streams) gets run. Many languages provide ways of ensuring that clean-up code gets run in a wide variety of circumstances; Java has its finally blocks, C++ has destructors, Common Lisp has UNWIND-PROTECT , and so on. In Mathematica, I don't know how to accomplish the same thing

Is there a way to do symbolic matrix algebra in Mathematica for matrices where the dimensions are unknown? For example, if I have an MxL matrix A and an LxN matrix B, I would like to be able to enter A.B And have it give me a matrix whose element ab[i,j] is given by Sum[a[i,l]*b[l,j],{l,1,L}] The problem I'm working on is like this one, but involves the product of 12 matrices, including the same matrix (and its transpose) repeated several times. It will probably be possible to simplify the values of the resulting matrix, but it's not obvious whether this is possible until after I do the

Is there any way to profile the mathkernel memory usage (down to individual variables) other than paying $$$ for their Eclipse plugin (mathematica workbench, iirc)? Right now I finish execution of a program that takes multiple GB's of ram, but the only things that are stored should be ~50MB of data at most, yet mathkernel.exe tends to hold onto ~1.5GB (basically, as much as Windows will give it). Is there any better way to get around this, other than saving the data I need and quitting the kernel every time? EDIT: I've just learned of the ByteCount function (which shows some disturbing results

Is there a way to avoid having to do ⋮[[⋮ to obtain those great looking brackets for Part ? Is there a way for this to be done automatically after you ran a function or a definition ? abcd I have the following addition in /Applications/Mathematica.app/SystemFiles/FrontEnd/TextResources/Macintosh/KeyEventTranslations.tr which lets me enter double brackets with key combinations. You can do the same by modifying the file (where ever it is on your OS). I first learnt of this from Szabolcs's website here . He has other mathematica related stuff there that might be of help to you. The commands added

I'm looking for a fast implementation for the following, I'll call it Position2D for lack of a better term: Position2D[ matrix, sub_matrix ] which finds the locations of sub_matrix inside matrix and returns the upper left and lower right row/column of a match. For example, this: Position2D[{ {0, 1, 2, 3}, {1, 2, 3, 4}, {2, 3, 4, 5}, {3, 4, 5, 6} }, { {2, 3}, {3, 4} }] should return this: { {{1, 3}, {2, 4}}, {{2, 2}, {3, 3}}, {{3, 1}, {4, 2}} } It should be fast enough to work quickly on 3000x2000 matrices with 100x100 sub-matrices. For simplicity, it is enough to only consider integer matrices

Is there a way to separate open Mathematica notebooks so that they don't share any variables? How about making it so some variables are shared but not all? Yes, there is. I recommend reading documentation related to Mathematica contexts. In a nutshell, all variables belong to some context (namespace), and all variables can be accessed via their fully-qualified names of the form "ContextName`varName". If you just use "varName", Mathematica will search contexts in $ContextPath (try evaluating the variable $ContextPath to see what it is), and will use the first context where it finds that