fact: Definition coord_expanded_def n (X : n.-tuple vT) i v := (v2r v *m pinvmx (b2mx X)) 0 i.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(fintype bigop finfun tuple) mathcomp(ssralg matrix mxalgebra zmodp)