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lapack/SRC/clacrm.f
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FortranFixed

*> \brief \b CLACRM multiplies a complex matrix by a square real matrix.
*
* =========== DOCUMENTATION ===========
*
* Online html documentation available at
* http://www.netlib.org/lapack/explore-html/
*
*> \htmlonly
*> Download CLACRM + dependencies
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/clacrm.f">
*> [TGZ]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/clacrm.f">
*> [ZIP]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/clacrm.f">
*> [TXT]</a>
*> \endhtmlonly
*
* Definition:
* ===========
*
* SUBROUTINE CLACRM( M, N, A, LDA, B, LDB, C, LDC, RWORK )
*
* .. Scalar Arguments ..
* INTEGER LDA, LDB, LDC, M, N
* ..
* .. Array Arguments ..
* REAL B( LDB, * ), RWORK( * )
* COMPLEX A( LDA, * ), C( LDC, * )
* ..
*
*
*> \par Purpose:
* =============
*>
*> \verbatim
*>
*> CLACRM 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.
*> \endverbatim
*
* Arguments:
* ==========
*
*> \param[in] M
*> \verbatim
*> M is INTEGER
*> The number of rows of the matrix A and of the matrix C.
*> M >= 0.
*> \endverbatim
*>
*> \param[in] N
*> \verbatim
*> N is INTEGER
*> The number of columns and rows of the matrix B and
*> the number of columns of the matrix C.
*> N >= 0.
*> \endverbatim
*>
*> \param[in] A
*> \verbatim
*> A is COMPLEX array, dimension (LDA, N)
*> On entry, A contains the M by N matrix A.
*> \endverbatim
*>
*> \param[in] LDA
*> \verbatim
*> LDA is INTEGER
*> The leading dimension of the array A. LDA >=max(1,M).
*> \endverbatim
*>
*> \param[in] B
*> \verbatim
*> B is REAL array, dimension (LDB, N)
*> On entry, B contains the N by N matrix B.
*> \endverbatim
*>
*> \param[in] LDB
*> \verbatim
*> LDB is INTEGER
*> The leading dimension of the array B. LDB >=max(1,N).
*> \endverbatim
*>
*> \param[out] C
*> \verbatim
*> C is COMPLEX array, dimension (LDC, N)
*> On exit, C contains the M by N matrix C.
*> \endverbatim
*>
*> \param[in] LDC
*> \verbatim
*> LDC is INTEGER
*> The leading dimension of the array C. LDC >=max(1,N).
*> \endverbatim
*>
*> \param[out] RWORK
*> \verbatim
*> RWORK is REAL array, dimension (2*M*N)
*> \endverbatim
*
* Authors:
* ========
*
*> \author Univ. of Tennessee
*> \author Univ. of California Berkeley
*> \author Univ. of Colorado Denver
*> \author NAG Ltd.
*
*> \ingroup complexOTHERauxiliary
*
* =====================================================================
SUBROUTINE CLACRM( M, N, A, LDA, B, LDB, C, LDC, RWORK )
*
* -- LAPACK auxiliary routine --
* -- LAPACK is a software package provided by Univ. of Tennessee, --
* -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
*
* .. Scalar Arguments ..
INTEGER LDA, LDB, LDC, M, N
* ..
* .. Array Arguments ..
REAL B( LDB, * ), RWORK( * )
COMPLEX A( LDA, * ), C( LDC, * )
* ..
*
* =====================================================================
*
* .. Parameters ..
REAL ONE, ZERO
PARAMETER ( ONE = 1.0E0, ZERO = 0.0E0 )
* ..
* .. Local Scalars ..
INTEGER I, J, L
* ..
* .. Intrinsic Functions ..
INTRINSIC AIMAG, CMPLX, REAL
* ..
* .. External Subroutines ..
EXTERNAL SGEMM
* ..
* .. 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 ) = REAL( A( I, J ) )
10 CONTINUE
20 CONTINUE
*
L = M*N + 1
CALL SGEMM( '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 ) = AIMAG( A( I, J ) )
50 CONTINUE
60 CONTINUE
CALL SGEMM( '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 ) = CMPLX( REAL( C( I, J ) ),
$ RWORK( L+( J-1 )*M+I-1 ) )
70 CONTINUE
80 CONTINUE
*
RETURN
*
* End of CLACRM
*
END