矩阵直积（Kronecker积）

对n×m阶矩阵A和p×q阶矩阵B，A和B的Kronecher乘法运算可定义为：

大图

Module KroneckerProduct_Mod
  Implicit None
  Integer , parameter , private :: DP = Selected_Real_Kind( 9 )
contains

  Subroutine KroneckerProduct( A , B , H )
    Real( Kind = DP ) , Intent( IN )  :: A(:,:) , B(:,:)
    Real( Kind = DP ) , Intent( OUT ) :: H(:,:)
    Integer :: i , j , m , n , p , q
    m = size( A , dim = 1 )
    n = size( A , dim = 2 )
    p = size( B , dim = 1 )
    q = size( B , dim = 2 )
    Do i = 1 , m
      Do j = 1 , n
        H( p*(i-1)+1 : p*i , q*(j-1)+1 : q*j ) = B * A(i,j)
      End Do
    End Do
  End Subroutine KroneckerProduct

End Module KroneckerProduct_Mod

Program www_fcode_cn
  use KroneckerProduct_Mod
  Implicit None
  Integer , parameter :: DP = Selected_Real_Kind( 9 )
  Integer , parameter :: m=2 , n=3 , p=4, q=5 , index1 = m*p , index2 = n*q
  Real(kind=DP) :: A(m,n) , B(p,q) , H(index1,index2)
  integer :: i
  A = reshape( (/1,2,3,4,5,6/) , (/2,3/) )
  B = reshape( (/1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20/) , (/4,5/) )
  call KroneckerProduct( A , B , H )
  Do i = 1 , index2
    Write(*,'(8(f5.1,1x))') H( :, i)
  End do
End Program www_fcode_cn