proposition: Lemma fgscaleDl g c1 c2: (c1 + c2) *:g g = c1 *:g g + c2 *:g g.
proof: Proof. by apply/malgP=> x; rewrite !(mcoeffD, fgscaleE) mulrDl. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat) mathcomp(seq path choice finset fintype finfun) mathcomp(tuple bigop ssralg ssrint ssrnum) xfinmap