#include "ESMF_LapackBlas.inc" !> \brief \b DGEMV ! ! =========== DOCUMENTATION =========== ! ! Online html documentation available at ! http://www.netlib.org/lapack/explore-html/ ! ! Definition: ! =========== ! ! SUBROUTINE DGEMV(TRANS,M,N,ALPHA,A,LDA,X,INCX,BETA,Y,INCY) ! ! .. Scalar Arguments .. ! DOUBLE PRECISION ALPHA,BETA ! INTEGER INCX,INCY,LDA,M,N ! CHARACTER TRANS ! .. ! .. Array Arguments .. ! DOUBLE PRECISION A(LDA,*),X(*),Y(*) ! .. ! ! !> \par Purpose: ! ============= !> !> \verbatim !> !> DGEMV performs one of the matrix-vector operations !> !> y := alpha*A*x + beta*y, or y := alpha*A**T*x + beta*y, !> !> where alpha and beta are scalars, x and y are vectors and A is an !> m by n matrix. !> \endverbatim ! ! Arguments: ! ========== ! !> \param[in] TRANS !> \verbatim !> TRANS is CHARACTER*1 !> On entry, TRANS specifies the operation to be performed as !> follows: !> !> TRANS = 'N' or 'n' y := alpha*A*x + beta*y. !> !> TRANS = 'T' or 't' y := alpha*A**T*x + beta*y. !> !> TRANS = 'C' or 'c' y := alpha*A**T*x + beta*y. !> \endverbatim !> !> \param[in] M !> \verbatim !> M is INTEGER !> On entry, M specifies the number of rows of the matrix A. !> M must be at least zero. !> \endverbatim !> !> \param[in] N !> \verbatim !> N is INTEGER !> On entry, N specifies the number of columns of the matrix A. !> N must be at least zero. !> \endverbatim !> !> \param[in] ALPHA !> \verbatim !> ALPHA is DOUBLE PRECISION. !> On entry, ALPHA specifies the scalar alpha. !> \endverbatim !> !> \param[in] A !> \verbatim !> A is DOUBLE PRECISION array of DIMENSION ( LDA, n ). !> Before entry, the leading m by n part of the array A must !> contain the matrix of coefficients. !> \endverbatim !> !> \param[in] LDA !> \verbatim !> LDA is INTEGER !> On entry, LDA specifies the first dimension of A as declared !> in the calling (sub) program. LDA must be at least !> max( 1, m ). !> \endverbatim !> !> \param[in] X !> \verbatim !> X is DOUBLE PRECISION array of DIMENSION at least !> ( 1 + ( n - 1 )*abs( INCX ) ) when TRANS = 'N' or 'n' !> and at least !> ( 1 + ( m - 1 )*abs( INCX ) ) otherwise. !> Before entry, the incremented array X must contain the !> vector x. !> \endverbatim !> !> \param[in] INCX !> \verbatim !> INCX is INTEGER !> On entry, INCX specifies the increment for the elements of !> X. INCX must not be zero. !> \endverbatim !> !> \param[in] BETA !> \verbatim !> BETA is DOUBLE PRECISION. !> On entry, BETA specifies the scalar beta. When BETA is !> supplied as zero then Y need not be set on input. !> \endverbatim !> !> \param[in,out] Y !> \verbatim !> Y is DOUBLE PRECISION array of DIMENSION at least !> ( 1 + ( m - 1 )*abs( INCY ) ) when TRANS = 'N' or 'n' !> and at least !> ( 1 + ( n - 1 )*abs( INCY ) ) otherwise. !> Before entry with BETA non-zero, the incremented array Y !> must contain the vector y. On exit, Y is overwritten by the !> updated vector y. !> \endverbatim !> !> \param[in] INCY !> \verbatim !> INCY is INTEGER !> On entry, INCY specifies the increment for the elements of !> Y. INCY must not be zero. !> \endverbatim ! ! Authors: ! ======== ! !> \author Univ. of Tennessee !> \author Univ. of California Berkeley !> \author Univ. of Colorado Denver !> \author NAG Ltd. ! !> \date November 2011 ! !> \ingroup double_blas_level2 ! !> \par Further Details: ! ===================== !> !> \verbatim !> !> Level 2 Blas routine. !> The vector and matrix arguments are not referenced when N = 0, or M = 0 !> !> -- Written on 22-October-1986. !> Jack Dongarra, Argonne National Lab. !> Jeremy Du Croz, Nag Central Office. !> Sven Hammarling, Nag Central Office. !> Richard Hanson, Sandia National Labs. !> \endverbatim !> ! ===================================================================== SUBROUTINE DGEMV(TRANS,M,N,ALPHA,A,LDA,X,INCX,BETA,Y,INCY) ! ! -- Reference BLAS level2 routine (version 3.4.0) -- ! -- Reference BLAS is a software package provided by Univ. of Tennessee, -- ! -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..-- ! November 2011 ! ! .. Scalar Arguments .. DOUBLE PRECISION ALPHA,BETA INTEGER INCX,INCY,LDA,M,N CHARACTER TRANS ! .. ! .. Array Arguments .. DOUBLE PRECISION A(LDA,*),X(*),Y(*) ! .. ! ! ===================================================================== ! ! .. Parameters .. DOUBLE PRECISION ONE,ZERO PARAMETER (ONE=1.0D+0,ZERO=0.0D+0) ! .. ! .. Local Scalars .. DOUBLE PRECISION TEMP INTEGER I,INFO,IX,IY,J,JX,JY,KX,KY,LENX,LENY ! .. ! .. External Functions .. LOGICAL LSAME EXTERNAL LSAME ! .. ! .. External Subroutines .. EXTERNAL XERBLA ! .. ! .. Intrinsic Functions .. INTRINSIC MAX ! .. ! ! Test the input parameters. ! INFO = 0 IF (.NOT.LSAME(TRANS,'N') .AND. .NOT.LSAME(TRANS,'T') .AND. & & .NOT.LSAME(TRANS,'C')) THEN INFO = 1 ELSE IF (M.LT.0) THEN INFO = 2 ELSE IF (N.LT.0) THEN INFO = 3 ELSE IF (LDA.LT.MAX(1,M)) THEN INFO = 6 ELSE IF (INCX.EQ.0) THEN INFO = 8 ELSE IF (INCY.EQ.0) THEN INFO = 11 END IF IF (INFO.NE.0) THEN CALL XERBLA('DGEMV ',INFO) RETURN END IF ! ! Quick return if possible. ! IF ((M.EQ.0) .OR. (N.EQ.0) .OR. & & ((ALPHA.EQ.ZERO).AND. (BETA.EQ.ONE))) RETURN ! ! Set LENX and LENY, the lengths of the vectors x and y, and set ! up the start points in X and Y. ! IF (LSAME(TRANS,'N')) THEN LENX = N LENY = M ELSE LENX = M LENY = N END IF IF (INCX.GT.0) THEN KX = 1 ELSE KX = 1 - (LENX-1)*INCX END IF IF (INCY.GT.0) THEN KY = 1 ELSE KY = 1 - (LENY-1)*INCY END IF ! ! Start the operations. In this version the elements of A are ! accessed sequentially with one pass through A. ! ! First form y := beta*y. ! IF (BETA.NE.ONE) THEN IF (INCY.EQ.1) THEN IF (BETA.EQ.ZERO) THEN DO 10 I = 1,LENY Y(I) = ZERO 10 CONTINUE ELSE DO 20 I = 1,LENY Y(I) = BETA*Y(I) 20 CONTINUE END IF ELSE IY = KY IF (BETA.EQ.ZERO) THEN DO 30 I = 1,LENY Y(IY) = ZERO IY = IY + INCY 30 CONTINUE ELSE DO 40 I = 1,LENY Y(IY) = BETA*Y(IY) IY = IY + INCY 40 CONTINUE END IF END IF END IF IF (ALPHA.EQ.ZERO) RETURN IF (LSAME(TRANS,'N')) THEN ! ! Form y := alpha*A*x + y. ! JX = KX IF (INCY.EQ.1) THEN DO 60 J = 1,N IF (X(JX).NE.ZERO) THEN TEMP = ALPHA*X(JX) DO 50 I = 1,M Y(I) = Y(I) + TEMP*A(I,J) 50 CONTINUE END IF JX = JX + INCX 60 CONTINUE ELSE DO 80 J = 1,N IF (X(JX).NE.ZERO) THEN TEMP = ALPHA*X(JX) IY = KY DO 70 I = 1,M Y(IY) = Y(IY) + TEMP*A(I,J) IY = IY + INCY 70 CONTINUE END IF JX = JX + INCX 80 CONTINUE END IF ELSE ! ! Form y := alpha*A**T*x + y. ! JY = KY IF (INCX.EQ.1) THEN DO 100 J = 1,N TEMP = ZERO DO 90 I = 1,M TEMP = TEMP + A(I,J)*X(I) 90 CONTINUE Y(JY) = Y(JY) + ALPHA*TEMP JY = JY + INCY 100 CONTINUE ELSE DO 120 J = 1,N TEMP = ZERO IX = KX DO 110 I = 1,M TEMP = TEMP + A(I,J)*X(IX) IX = IX + INCX 110 CONTINUE Y(JY) = Y(JY) + ALPHA*TEMP JY = JY + INCY 120 CONTINUE END IF END IF ! RETURN ! ! End of DGEMV . ! END