Hi, since I can't post to the thread http://groups.google.com/group/sympy/browse_thread/thread/135ed5dc84d87dd5/18b2d34a997b3139?#18b2d34a997b3139 anymore, here is a summary/continuation of the discussion:
Thank you very much for your help. I have a differential equation such as ddq = B^-1(q) * ( T - rest(q,dq)) which I want to numerically evaluate where ddq is a 7x1 sympy matrix, B 7x7 (can not invert it symbolically anymore) and q, dq are the supplied input variables. So far I used lambdify successfully with ddq (2x1), B (2x2) (can invert sym.). To summarize (correct me if I'm wrong / sth. missing) and current states: - symbolic simplification has been primarily discussed. (I will open a new thread for this) - expand + rewrite(exp) + expand + rewrite(cos) works but takes too much memory for larger expressions (especially the 2nd expand) - with disabled cache it uses much less memory but becomes too slow - my calculations are done in sympy, but I export to Mathematica, simplify, and reimport to sympy at the moment - I also tried the improved trigsimp which has been posted to the mailing list recently (was not more successful) - cse is an option - there were problems with solve (in which repo is your version, smichr?) and chop (I use the function you supplied) To get back to the original topic (Numerical Evaluation): - I want to use results I obtained with sympy for simulations using scipy's ode integrators. A fast numerical evaluation is therefore desireable. It would be nice to save the conversion results accross program executions. - is it a good idea to use lambdify for large matrices? - it is quite slow and since I get a function I can't pickle it, it has to be done each run - what about generating a py file with function evaluating the expression with numpy? - afaik, lambdify replaces functions / operators for e.g. numpy. could one get the actual expression (to save it, make a module)? - what about evalf(var1=1234.....)? - what about using autowrap / binary_function? - see e.g. http://ojensen.wordpress.com/2010/08/10/fast-ufunc-ish-hydrogen-solutions/ .I got the example working, but I am not sure if this would help me (element-wise application) - What about http://code.google.com/p/numexpr/ ? What would be a way to convert my sympy expressions so they can be evaluated with numexpr I appreciate if you could comment and share your experiences regarding similar problems. Vinzenz PS: Google Groups is funny, hides the list answer buttons without any hint. @Chris Smith: Sorry for writing directly to you. Also, google search does not show messages from this mailing list, but 3rd party sites (which also show the complete mail addresses). -- You received this message because you are subscribed to the Google Groups "sympy" group. To post to this group, send email to sympy@googlegroups.com. To unsubscribe from this group, send email to sympy+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/sympy?hl=en.