unit_matrix Subroutine

	SUBROUTINE unit_matrix(mat)
	REAL(SP), DIMENSION(:,:), INTENT(OUT) :: mat
	INTEGER(I4B) :: i,n
	n=min(size(mat,1),size(mat,2))
	mat(:,:)=0.0_sp
	do i=1,n
		mat(i,i)=1.0_sp
	end do
	END SUBROUTINE unit_matrix