proposition: Lemma patch_indic T {R : numFieldType} (f : T -> R) (D : set T) : f \_ D = (f \* \1_D)%R.
proof: Proof. apply/funext => x /=; rewrite /patch /= indicE. by case: ifPn => _; rewrite ?(mulr1, mulr0). Qed.
imports: HB(structures) mathcomp(all_ssreflect ssralg ssrnum ssrint interval finmap) mathcomp(mathcomp_extra boolp classical_sets fsbigop) mathcomp(functions cardinality set_interval) signed reals ereal topology normedtype sequences