fact: Definition fdist_prod_take : R.-fdist ('rV_i * A * B) := fdistmap (fun x : 'rV[A]_n.+1 * B => (row_take (widen_ord (leqnSn _) i) x.1, x.1 ord0 i, x.2)) P.
imports: mathcomp(all_ssreflect ssralg fingroup perm matrix) mathcomp(all_algebra vector reals normedtype) mathcomp(mathcomp_extra boolp) mathcomp(Rstruct) ssrR logb realType_ext ssr_ext ssralg_ext bigop_ext