fact: Definition index_not_const l n := filter (fun v => ~~ is_const (nth (Cst 0) l v) n) (seq.iota 0 (size l)).
imports: Coq(Reals Datatypes ssreflect ssrbool) mathcomp(seq) Rcomplements Hierarchy Derive RInt RInt_analysis Derive_2d Continuity ElemFct