Dear Dima Pasechnik, Dear Forum,
Dear all, I'd like to write a function that takes a multivariate polynomial p and produces another polynomial in the same polynomial ring R, by doing a variable subsitution. Is there a way to p about its ring, or at least about the family of the indeterminants of the ring? The family of indeterminate only depends on the coefficients family, but there is OccuringVariableIndices which takes a (multivariate) polynomial and returns the index numbers of the variables that is uses. You could use base:=Field(ZeroCoefficientRatFun(pol)); # some field in the same characteristic as coefficients List(OccuringVariableIndices(pol),x->X(base,x)); to get the actual variables that occur in the polynomial.Note that a constant polynomial will result in an empty list. Hope this helps, Alexander Hulpke -- Colorado State University, Department of Mathematics, Weber Building, 1874 Campus Delivery, Fort Collins, CO 80523-1874, USA email: hul...@colostate.edu<mailto:hul...@colostate.edu>, Phone: ++1-970-4914288 http://www.math.colostate.edu/~hulpke _______________________________________________ Forum mailing list Forum@mail.gap-system.org http://mail.gap-system.org/mailman/listinfo/forum
