RFC: extracting coefficients of a multivariate polynomial

andre maute wrote:
>> You're doing several substitutions, re-assignments, and three loops. Did
>> you try Fateman's code in his reply? I would bet that it will run
>> faster. It does one nested loop and functions written in lisp. Also, you
>> could try the 'compile' option.
>>     
>
> I never got the replies from Fateman with KMail under KDE.
> Using the web interface of the mailinglist I saw them the first time.
>
> the substs can easilly be removed, they are a leftover from a maple migration.
>
> the timing for Fateman's
> my_coeff5 : 14m10.050s
>
> the fastest is at the moment
> my_coeff6: 13m49.501s
>
> I'm using maxima 5.13.0 with clisp 2.41
>
> -------------------------------------------------------
> my_coeff6(v,exps,poly) := block(
>
>         [c,k,l,h],
>
>         c : [],
>         for k : 1 thru length(exps) do block(
>                 h : poly,
>                 for l : 1 thru length(v) do block(
>                         h : coeff(h,v[l],exps[k][l])
>                 ),
>                 h : ratsimp(h),
>                 c : append(c,[h])
>         ),
>
>         return(c)
> )$
> -------------------------------------------------------
>
> I expected a more sensational speedup.
>
>   
>> Having written your program, try
>> compile(all);
>>     
>
> I'll try it.
>
>   
>> Where are these polynomials coming from? Can you convert them to rat form
>> *once* instead of each time you call my_coeff?
>>     
>
> Polynomials living on 3d solids.
>
> Products of different Jacobi Polynomials and Lagrange Polynomials,
> with an additional nonlinear transformation.
>
> They are generated *once*, expanded *once*, then the coefficients are computed
> *once* and dumped *once* to a text file. ;-)
>
> I only wanted to minimize the maintainment hassle
> for the Maxima part of my application.
>
> Nevertheless, thank you all
>
> Andre
>
>   
>> and then execute it.
>>
>> HTH,
>> -sen
>>     
>
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> .
>
>   
clisp is known to be slow. Try gcl, cmucl, and sbcl to see which is 
better for your purposes.

-sen