fact: Definition bcap_wr m n (I : 'cV_m) (J : 'cV_n) : 'rV[R]_n := let a := principal_gen I in let b := principal_gen J in (odflt 0 (a %/? (gcdr a b)))%:M *m principal_w1 J.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat div seq path) mathcomp(ssralg fintype perm choice matrix bigop zmodp mxalgebra poly) ssrcomplements dvdring stronglydiscrete