fact: Definition diag := [seq x <- take (minn m n) (smith_seq M) | x != 0 ].
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat div seq path tuple) mathcomp(perm fingroup choice ssralg fintype finfun poly polydiv) mathcomp(bigop matrix zmodp mxalgebra) ssrcomplements dvdring mxstructure similar minor binetcauchy stronglydiscrete coherent