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lammps/lib/linalg/drot.cpp
2022-12-28 13:18:38 -05:00

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/* fortran/drot.f -- translated by f2c (version 20200916).
You must link the resulting object file with libf2c:
on Microsoft Windows system, link with libf2c.lib;
on Linux or Unix systems, link with .../path/to/libf2c.a -lm
or, if you install libf2c.a in a standard place, with -lf2c -lm
-- in that order, at the end of the command line, as in
cc *.o -lf2c -lm
Source for libf2c is in /netlib/f2c/libf2c.zip, e.g.,
http://www.netlib.org/f2c/libf2c.zip
*/
#ifdef __cplusplus
extern "C" {
#endif
#include "lmp_f2c.h"
/* > \brief \b DROT */
/* =========== DOCUMENTATION =========== */
/* Online html documentation available at */
/* http://www.netlib.org/lapack/explore-html/ */
/* Definition: */
/* =========== */
/* SUBROUTINE DROT(N,DX,INCX,DY,INCY,C,S) */
/* .. Scalar Arguments .. */
/* DOUBLE PRECISION C,S */
/* INTEGER INCX,INCY,N */
/* .. */
/* .. Array Arguments .. */
/* DOUBLE PRECISION DX(*),DY(*) */
/* .. */
/* > \par Purpose: */
/* ============= */
/* > */
/* > \verbatim */
/* > */
/* > DROT applies a plane rotation. */
/* > \endverbatim */
/* Arguments: */
/* ========== */
/* > \param[in] N */
/* > \verbatim */
/* > N is INTEGER */
/* > number of elements in input vector(s) */
/* > \endverbatim */
/* > */
/* > \param[in,out] DX */
/* > \verbatim */
/* > DX is DOUBLE PRECISION array, dimension ( 1 + ( N - 1 )*abs( INCX ) ) */
/* > \endverbatim */
/* > */
/* > \param[in] INCX */
/* > \verbatim */
/* > INCX is INTEGER */
/* > storage spacing between elements of DX */
/* > \endverbatim */
/* > */
/* > \param[in,out] DY */
/* > \verbatim */
/* > DY is DOUBLE PRECISION array, dimension ( 1 + ( N - 1 )*abs( INCY ) ) */
/* > \endverbatim */
/* > */
/* > \param[in] INCY */
/* > \verbatim */
/* > INCY is INTEGER */
/* > storage spacing between elements of DY */
/* > \endverbatim */
/* > */
/* > \param[in] C */
/* > \verbatim */
/* > C is DOUBLE PRECISION */
/* > \endverbatim */
/* > */
/* > \param[in] S */
/* > \verbatim */
/* > S is DOUBLE PRECISION */
/* > \endverbatim */
/* Authors: */
/* ======== */
/* > \author Univ. of Tennessee */
/* > \author Univ. of California Berkeley */
/* > \author Univ. of Colorado Denver */
/* > \author NAG Ltd. */
/* > \ingroup double_blas_level1 */
/* > \par Further Details: */
/* ===================== */
/* > */
/* > \verbatim */
/* > */
/* > jack dongarra, linpack, 3/11/78. */
/* > modified 12/3/93, array(1) declarations changed to array(*) */
/* > \endverbatim */
/* > */
/* ===================================================================== */
/* Subroutine */ int drot_(integer *n, doublereal *dx, integer *incx,
doublereal *dy, integer *incy, doublereal *c__, doublereal *s)
{
/* System generated locals */
integer i__1;
/* Local variables */
integer i__, ix, iy;
doublereal dtemp;
/* -- Reference BLAS level1 routine -- */
/* -- Reference BLAS is a software package provided by Univ. of Tennessee, -- */
/* -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..-- */
/* .. Scalar Arguments .. */
/* .. */
/* .. Array Arguments .. */
/* .. */
/* ===================================================================== */
/* .. Local Scalars .. */
/* .. */
/* Parameter adjustments */
--dy;
--dx;
/* Function Body */
if (*n <= 0) {
return 0;
}
if (*incx == 1 && *incy == 1) {
/* code for both increments equal to 1 */
i__1 = *n;
for (i__ = 1; i__ <= i__1; ++i__) {
dtemp = *c__ * dx[i__] + *s * dy[i__];
dy[i__] = *c__ * dy[i__] - *s * dx[i__];
dx[i__] = dtemp;
}
} else {
/* code for unequal increments or equal increments not equal */
/* to 1 */
ix = 1;
iy = 1;
if (*incx < 0) {
ix = (-(*n) + 1) * *incx + 1;
}
if (*incy < 0) {
iy = (-(*n) + 1) * *incy + 1;
}
i__1 = *n;
for (i__ = 1; i__ <= i__1; ++i__) {
dtemp = *c__ * dx[ix] + *s * dy[iy];
dy[iy] = *c__ * dy[iy] - *s * dx[ix];
dx[ix] = dtemp;
ix += *incx;
iy += *incy;
}
}
return 0;
/* End of DROT */
} /* drot_ */
#ifdef __cplusplus
}
#endif