Fortran：实现矩阵直积

!.. 下面的fortran代码实现了Kronecker product
function kron( a, b, m, n, p, q ) !.. 矩阵A:m*n; 矩阵b:p*q
  implicit none 
  integer :: m, n, p, q 
  real(kind=8) :: a(m,n), b(p,q), kron(m*p,n*q)
  integer :: i, j
  
  Do i = 1, m 
    do j = 1, n
      kron( (i-1)*p+1:i*p, (j-1)*q+1:j*q ) = a(i,j)*b(:,:)
    end do
  End do
end function kron