zlacrm.f

          SUBROUTINE ZLACRM( M, N, A, LDA, B, LDB, C, LDC, RWORK )
    *
    *  -- LAPACK auxiliary routine (version 3.1) --
    *     Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd..
    *     November 2006
    *
    *     .. Scalar Arguments ..
          INTEGER            LDA, LDB, LDC, M, N
    *     ..
    *     .. Array Arguments ..
          DOUBLE PRECISION   B( LDB, * ), RWORK( * )
          COMPLEX*16         A( LDA, * ), C( LDC, * )
    *     ..
    *
    *  Purpose
    *  =======
    *
    *  ZLACRM performs a very simple matrix-matrix multiplication:
    *           C := A * B,
    *  where A is M by N and complex; B is N by N and real;
    *  C is M by N and complex.
    *
    *  Arguments
    *  =========
    *
    *  M       (input) INTEGER
    *          The number of rows of the matrix A and of the matrix C.
    *          M >= 0.
    *
    *  N       (input) INTEGER
    *          The number of columns and rows of the matrix B and
    *          the number of columns of the matrix C.
    *          N >= 0.
    *
    *  A       (input) COMPLEX*16 array, dimension (LDA, N)
    *          A contains the M by N matrix A.
    *
    *  LDA     (input) INTEGER
    *          The leading dimension of the array A. LDA >=max(1,M).
    *
    *  B       (input) DOUBLE PRECISION array, dimension (LDB, N)
    *          B contains the N by N matrix B.
    *
    *  LDB     (input) INTEGER
    *          The leading dimension of the array B. LDB >=max(1,N).
    *
    *  C       (input) COMPLEX*16 array, dimension (LDC, N)
    *          C contains the M by N matrix C.
    *
    *  LDC     (input) INTEGER
    *          The leading dimension of the array C. LDC >=max(1,N).
    *
    *  RWORK   (workspace) DOUBLE PRECISION array, dimension (2*M*N)
    *
    *  =====================================================================
    *
    *     .. Parameters ..
          DOUBLE PRECISION   ONE, ZERO
          PARAMETER          ( ONE = 1.0D0, ZERO = 0.0D0 )
    *     ..
    *     .. Local Scalars ..
          INTEGER            I, J, L
    *     ..
    *     .. Intrinsic Functions ..
          INTRINSIC          DBLE, DCMPLX, DIMAG
    *     ..
    *     .. External Subroutines ..
          EXTERNAL           DGEMM
    *     ..
    *     .. Executable Statements ..
    *
    *     Quick return if possible.
    *
          IF( ( M.EQ.0 ) .OR. ( N.EQ.0 ) )
         $   RETURN
    *
          DO 20 J = 1, N
             DO 10 I = 1, M
                RWORK( ( J-1 )*M+I ) = DBLE( A( I, J ) )
       10    CONTINUE
       20 CONTINUE
    *
          L = M*N + 1
          CALL DGEMM( 'N', 'N', M, N, N, ONE, RWORK, M, B, LDB, ZERO,
         $            RWORK( L ), M )
          DO 40 J = 1, N
             DO 30 I = 1, M
                C( I, J ) = RWORK( L+( J-1 )*M+I-1 )
       30    CONTINUE
       40 CONTINUE
    *
          DO 60 J = 1, N
             DO 50 I = 1, M
                RWORK( ( J-1 )*M+I ) = DIMAG( A( I, J ) )
       50    CONTINUE
       60 CONTINUE
          CALL DGEMM( 'N', 'N', M, N, N, ONE, RWORK, M, B, LDB, ZERO,
         $            RWORK( L ), M )
          DO 80 J = 1, N
             DO 70 I = 1, M
                C( I, J ) = DCMPLX( DBLE( C( I, J ) ),
         $                  RWORK( L+( J-1 )*M+I-1 ) )
       70    CONTINUE
       80 CONTINUE
    *
          RETURN
    *
    *     End of ZLACRM
    *
          END