fact: Definition ortho m (B : 'M_(m,n)) := (kermx (M *m (B ^t theta))).
imports: HB(structures) mathcomp(all_ssreflect ssralg fingroup zmodp poly ssrnum) mathcomp(matrix mxalgebra vector falgebra ssrnum algC algnum) mathcomp(fieldext) mathcomp(vector)