RFC: extracting coefficients of a multivariate polynomial

> 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