[Maxima] RFC: extracting coefficients of a multivariate polynomial

[Richard Fateman]

oops, one more use of "lv" there, and some other items..
 your polynomial variables are not being set up properly;
rat(p,[x,y,z]) is not the same as rat(p,x,y,z).
perhaps try this..
.
 
 my_coeff5(v,exps,poly) := block(
 
         [c:[],k,l,h,rpoly,lv:length(v), ratvars:v], /*maybe should be
ratvars:reverse[v] ?*/
 
         rpoly : rat(poly),
         for k : 1 thru length(exps) do block(
                 h : rpoly,
                 for l : 1 thru lv do block(
                         h : ratcoeff(h,v[lv+1-l],exps[k][lv+1-l])),
                 c : cons(h,c)),
 
         return(reverse(c))
 
 )$
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