363 lines
9.1 KiB
C
363 lines
9.1 KiB
C
/* -- translated by f2c (version 20240504).
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You must link the resulting object file with libf2c:
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on Microsoft Windows system, link with libf2c.lib;
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on Linux or Unix systems, link with .../path/to/libf2c.a -lm
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or, if you install libf2c.a in a standard place, with -lf2c -lm
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-- in that order, at the end of the command line, as in
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cc *.o -lf2c -lm
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Source for libf2c is in /netlib/f2c/libf2c.zip, e.g.,
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http://www.netlib.org/f2c/libf2c.zip
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*/
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#include "f2c.h"
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/* > \brief \b DGEMV
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=========== DOCUMENTATION ===========
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Online html documentation available at
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http://www.netlib.org/lapack/explore-html/
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Definition:
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===========
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SUBROUTINE DGEMV(TRANS,M,N,ALPHA,A,LDA,X,INCX,BETA,Y,INCY)
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DOUBLE PRECISION ALPHA,BETA
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INTEGER INCX,INCY,LDA,M,N
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CHARACTER TRANS
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DOUBLE PRECISION A(LDA,*),X(*),Y(*)
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> \par Purpose:
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=============
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>
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> \verbatim
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>
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> DGEMV performs one of the matrix-vector operations
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>
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> y := alpha*A*x + beta*y, or y := alpha*A**T*x + beta*y,
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>
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> where alpha and beta are scalars, x and y are vectors and A is an
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> m by n matrix.
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> \endverbatim
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Arguments:
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==========
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> \param[in] TRANS
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> \verbatim
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> TRANS is CHARACTER*1
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> On entry, TRANS specifies the operation to be performed as
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> follows:
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>
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> TRANS = 'N' or 'n' y := alpha*A*x + beta*y.
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>
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> TRANS = 'T' or 't' y := alpha*A**T*x + beta*y.
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>
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> TRANS = 'C' or 'c' y := alpha*A**T*x + beta*y.
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> \endverbatim
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>
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> \param[in] M
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> \verbatim
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> M is INTEGER
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> On entry, M specifies the number of rows of the matrix A.
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> M must be at least zero.
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> \endverbatim
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>
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> \param[in] N
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> \verbatim
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> N is INTEGER
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> On entry, N specifies the number of columns of the matrix A.
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> N must be at least zero.
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> \endverbatim
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>
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> \param[in] ALPHA
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> \verbatim
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> ALPHA is DOUBLE PRECISION.
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> On entry, ALPHA specifies the scalar alpha.
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> \endverbatim
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>
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> \param[in] A
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> \verbatim
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> A is DOUBLE PRECISION array, dimension ( LDA, N )
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> Before entry, the leading m by n part of the array A must
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> contain the matrix of coefficients.
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> \endverbatim
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>
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> \param[in] LDA
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> \verbatim
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> LDA is INTEGER
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> On entry, LDA specifies the first dimension of A as declared
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> in the calling (sub) program. LDA must be at least
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> max( 1, m ).
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> \endverbatim
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>
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> \param[in] X
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> \verbatim
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> X is DOUBLE PRECISION array, dimension at least
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> ( 1 + ( n - 1 )*abs( INCX ) ) when TRANS = 'N' or 'n'
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> and at least
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> ( 1 + ( m - 1 )*abs( INCX ) ) otherwise.
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> Before entry, the incremented array X must contain the
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> vector x.
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> \endverbatim
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>
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> \param[in] INCX
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> \verbatim
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> INCX is INTEGER
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> On entry, INCX specifies the increment for the elements of
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> X. INCX must not be zero.
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> \endverbatim
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>
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> \param[in] BETA
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> \verbatim
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> BETA is DOUBLE PRECISION.
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> On entry, BETA specifies the scalar beta. When BETA is
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> supplied as zero then Y need not be set on input.
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> \endverbatim
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>
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> \param[in,out] Y
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> \verbatim
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> Y is DOUBLE PRECISION array, dimension at least
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> ( 1 + ( m - 1 )*abs( INCY ) ) when TRANS = 'N' or 'n'
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> and at least
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> ( 1 + ( n - 1 )*abs( INCY ) ) otherwise.
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> Before entry with BETA non-zero, the incremented array Y
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> must contain the vector y. On exit, Y is overwritten by the
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> updated vector y.
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> If either m or n is zero, then Y not referenced and the function
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> performs a quick return.
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> \endverbatim
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>
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> \param[in] INCY
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> \verbatim
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> INCY is INTEGER
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> On entry, INCY specifies the increment for the elements of
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> Y. INCY must not be zero.
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> \endverbatim
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Authors:
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========
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> \author Univ. of Tennessee
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> \author Univ. of California Berkeley
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> \author Univ. of Colorado Denver
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> \author NAG Ltd.
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> \ingroup gemv
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> \par Further Details:
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=====================
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>
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> \verbatim
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>
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> Level 2 Blas routine.
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> The vector and matrix arguments are not referenced when N = 0, or M = 0
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>
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> -- Written on 22-October-1986.
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> Jack Dongarra, Argonne National Lab.
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> Jeremy Du Croz, Nag Central Office.
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> Sven Hammarling, Nag Central Office.
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> Richard Hanson, Sandia National Labs.
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> \endverbatim
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>
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=====================================================================
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Subroutine */ int igraphdgemv_(char *trans, integer *m, integer *n, doublereal *
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alpha, doublereal *a, integer *lda, doublereal *x, integer *incx,
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doublereal *beta, doublereal *y, integer *incy)
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{
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/* System generated locals */
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integer a_dim1, a_offset, i__1, i__2;
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/* Local variables */
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integer i__, j, ix, iy, jx, jy, kx, ky, info;
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doublereal temp;
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integer lenx, leny;
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extern logical igraphlsame_(char *, char *);
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extern /* Subroutine */ int igraphxerbla_(char *, integer *, ftnlen);
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/* -- Reference BLAS level2 routine --
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-- Reference BLAS is a software package provided by Univ. of Tennessee, --
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-- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
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=====================================================================
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Test the input parameters.
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Parameter adjustments */
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a_dim1 = *lda;
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a_offset = 1 + a_dim1;
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a -= a_offset;
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--x;
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--y;
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/* Function Body */
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info = 0;
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if (! igraphlsame_(trans, "N") && ! igraphlsame_(trans, "T") && ! igraphlsame_(trans, "C")
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) {
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info = 1;
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} else if (*m < 0) {
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info = 2;
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} else if (*n < 0) {
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info = 3;
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} else if (*lda < max(1,*m)) {
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info = 6;
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} else if (*incx == 0) {
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info = 8;
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} else if (*incy == 0) {
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info = 11;
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}
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if (info != 0) {
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igraphxerbla_("DGEMV ", &info, (ftnlen)6);
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return 0;
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}
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/* Quick return if possible. */
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if (*m == 0 || *n == 0 || *alpha == 0. && *beta == 1.) {
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return 0;
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}
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/* Set LENX and LENY, the lengths of the vectors x and y, and set
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up the start points in X and Y. */
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if (igraphlsame_(trans, "N")) {
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lenx = *n;
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leny = *m;
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} else {
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lenx = *m;
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leny = *n;
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}
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if (*incx > 0) {
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kx = 1;
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} else {
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kx = 1 - (lenx - 1) * *incx;
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}
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if (*incy > 0) {
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ky = 1;
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} else {
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ky = 1 - (leny - 1) * *incy;
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}
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/* Start the operations. In this version the elements of A are
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accessed sequentially with one pass through A.
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First form y := beta*y. */
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if (*beta != 1.) {
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if (*incy == 1) {
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if (*beta == 0.) {
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i__1 = leny;
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for (i__ = 1; i__ <= i__1; ++i__) {
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y[i__] = 0.;
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/* L10: */
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}
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} else {
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i__1 = leny;
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for (i__ = 1; i__ <= i__1; ++i__) {
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y[i__] = *beta * y[i__];
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/* L20: */
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}
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}
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} else {
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iy = ky;
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if (*beta == 0.) {
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i__1 = leny;
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for (i__ = 1; i__ <= i__1; ++i__) {
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y[iy] = 0.;
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iy += *incy;
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/* L30: */
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}
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} else {
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i__1 = leny;
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for (i__ = 1; i__ <= i__1; ++i__) {
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y[iy] = *beta * y[iy];
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iy += *incy;
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/* L40: */
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}
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}
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}
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}
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if (*alpha == 0.) {
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return 0;
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}
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if (igraphlsame_(trans, "N")) {
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/* Form y := alpha*A*x + y. */
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jx = kx;
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if (*incy == 1) {
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i__1 = *n;
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for (j = 1; j <= i__1; ++j) {
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temp = *alpha * x[jx];
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i__2 = *m;
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for (i__ = 1; i__ <= i__2; ++i__) {
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y[i__] += temp * a[i__ + j * a_dim1];
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/* L50: */
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}
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jx += *incx;
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/* L60: */
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}
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} else {
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i__1 = *n;
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for (j = 1; j <= i__1; ++j) {
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temp = *alpha * x[jx];
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iy = ky;
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i__2 = *m;
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for (i__ = 1; i__ <= i__2; ++i__) {
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y[iy] += temp * a[i__ + j * a_dim1];
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iy += *incy;
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/* L70: */
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}
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jx += *incx;
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/* L80: */
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}
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}
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} else {
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/* Form y := alpha*A**T*x + y. */
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jy = ky;
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if (*incx == 1) {
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i__1 = *n;
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for (j = 1; j <= i__1; ++j) {
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temp = 0.;
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i__2 = *m;
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for (i__ = 1; i__ <= i__2; ++i__) {
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temp += a[i__ + j * a_dim1] * x[i__];
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/* L90: */
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}
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y[jy] += *alpha * temp;
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jy += *incy;
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/* L100: */
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}
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} else {
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i__1 = *n;
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for (j = 1; j <= i__1; ++j) {
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temp = 0.;
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ix = kx;
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i__2 = *m;
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for (i__ = 1; i__ <= i__2; ++i__) {
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temp += a[i__ + j * a_dim1] * x[ix];
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ix += *incx;
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/* L110: */
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}
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y[jy] += *alpha * temp;
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jy += *incy;
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/* L120: */
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}
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}
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}
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return 0;
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/* End of DGEMV */
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} /* igraphdgemv_ */
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