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MathGroup Archive 2005

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Re: solve question/simplify question

  • To: mathgroup at smc.vnet.net
  • Subject: [mg55572] Re: solve question/simplify question
  • From: "Jens-Peer Kuska" <kuska at informatik.uni-leipzig.de>
  • Date: Wed, 30 Mar 2005 03:21:05 -0500 (EST)
  • Organization: Uni Leipzig
  • References: <d2341s$lgg$1@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

Hi,

solving a linear system of equations of dimension 
n is
a n^2 process and for nonlinear systems it depends 
on the
system. So a larger system will need more time.

To impove the memory usage you may substitute 
common terms
in your expression. But this depend on the 
detailed form of
the expression .

Regards
  Jens

"Paul Schneider" <paulibaer at uboot.com> schrieb im 
Newsbeitrag news:d2341s$lgg$1 at smc.vnet.net...
> Hi,
>
> I have a list called equns of linear equations 
> which are independent of
> each other. The according variables are in a 
> list called params. I solve
> the equations into a list called sol using
>
> sol = Solve[equns, params];
>
> Can I expect the solution procedure to be faster 
> or in favor of memory
> usage if I iterate through the elements of the 
> lists and solve for each
> equation separately? Same question goes for 
> Simplify.
>
> I don't want to try and find out myself because 
> I have noticed big
> differences in running times with Mathematica 
> and I am not sure how to
> test for improved speed. The equations are 
> enormous and I don't know in
> advance how they look like, so I can't use the 
> linear algebra routines.
>
> My second question goes to memory management. 
> Even though I have lots of
> memory it gets maxed out pretty quickly when I 
> use Simplify, or
> FullSimplify on the solutions of those huge 
> equations. So I tried to get
> rid of expressinos that are not needed anymore 
> by
>
> Clear[var]
> or
> var = .
>
> as is proposed in the help files. I also tried 
> Share[ ]. But it doesn't
> seem to do anything. How can I improve this 
> situation.
>
> Thank you,
>
> Paul
> 



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