fact: Definition exprn_nonzero_subdef (xnz nnz : nullity) (xr nr : reality) : nullity := nz_of_bool (xnz || match nr with Real (Sign =0) => true | _ => false end).
imports: HB(structures) Coq(ssreflect ssrfun ssrbool) mathcomp(ssrnat eqtype choice order ssralg ssrnum ssrint) mathcomp(mathcomp_extra)