proposition: Lemma fnegZ f c : 0 <= c -> fneg (c \*o f) =1 c \*o fneg f.
proof: Proof. move=> ge0_c x; rewrite /= -!fposN; have /=<- := (fposZ (- f) ge0_c x). by apply/eq_fpos=> y /=; rewrite mulrN. Qed.
imports: mathcomp(all_ssreflect all_algebra) mathcomp.classical(boolp) xfinmap ereal reals discrete realseq mathcomp.classical(classical_sets functions mathcomp_extra) topology