Re: Options for a very large computation

*To*: mathgroup at smc.vnet.net*Subject*: [mg77853] Re: Options for a very large computation*From*: Bill Rowe <readnewsciv at sbcglobal.net>*Date*: Mon, 18 Jun 2007 07:01:28 -0400 (EDT)

On 6/17/07 at 6:04 AM, rdobrow at carleton.edu (Bob D) wrote: >I'm solving a 24-by-24 linear system symbolically. After getting >what I want using NullSpace, I get a very complicated expression in >4 variables. When I try to Simplify the expression (before viewing) >my system dies. Either I run out of memory, or, when I add >TimeConstraints -> Infinity to the Simplify function, it takes >"forever" (nothing after 8 hours). >Two questions: (1) Any suggestions for how I can get more processing >power, memory to do the calculations. I suppose this can be accomplished in the same manner as anyone else would, i.e., buy a faster machine, more memory etc. Possibly, your code can be improved. But since you didn't post any code, it isn't possible for me to offer meaningful suggestions along these lines. >(2) I have access to more power, but the programs need to be written >in C++. Is there a way to convert the Mathematica code and the >Simplify command, in particular, to C++ and run it offline? Take a look at the built in function CForm which converts a Mathematica expression to C syntax. But while I've no doubt CForm performs as designed I haven't used it and I strongly suspect it will not be all that helpful to you. I don't believe CForm will output C compatible code for specialized built in functions such as Simplify. I also strongly suspect even if Mathematica did output C code for built in functions, it would not solve your problem to move this to C or C++. The amount of computation needed to symbolically solve a 24 x 24 system and find a simplified solution is quite simply enormous. -- To reply via email subtract one hundred and four