fact: Definition mderiv (i : 'I_n) p := \sum_(m <- msupp p) ((m i)%:R * p@_m) *: 'X_[m - U_(i)].
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq path) mathcomp(choice fintype tuple finfun bigop finset binomial) mathcomp(order fingroup perm ssralg zmodp poly ssrint) mathcomp(matrix vector) mathcomp(bigenough) ssrcomplements freeg