190 lines
4.3 KiB
C++
190 lines
4.3 KiB
C++
/* fortran/ddot.f -- translated by f2c (version 20200916).
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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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#ifdef __cplusplus
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extern "C" {
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#endif
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#include "lmp_f2c.h"
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/* > \brief \b DDOT */
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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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/* DOUBLE PRECISION FUNCTION DDOT(N,DX,INCX,DY,INCY) */
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/* .. Scalar Arguments .. */
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/* INTEGER INCX,INCY,N */
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/* .. */
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/* .. Array Arguments .. */
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/* DOUBLE PRECISION DX(*),DY(*) */
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/* .. */
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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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/* > DDOT forms the dot product of two vectors. */
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/* > uses unrolled loops for increments equal to one. */
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/* > \endverbatim */
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/* Arguments: */
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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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/* > number of elements in input vector(s) */
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/* > \endverbatim */
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/* > */
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/* > \param[in] DX */
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/* > \verbatim */
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/* > DX is DOUBLE PRECISION array, dimension ( 1 + ( N - 1 )*abs( INCX ) ) */
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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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/* > storage spacing between elements of DX */
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/* > \endverbatim */
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/* > */
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/* > \param[in] DY */
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/* > \verbatim */
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/* > DY is DOUBLE PRECISION array, dimension ( 1 + ( N - 1 )*abs( INCY ) ) */
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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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/* > storage spacing between elements of DY */
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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 double_blas_level1 */
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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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/* > jack dongarra, linpack, 3/11/78. */
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/* > modified 12/3/93, array(1) declarations changed to array(*) */
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/* > \endverbatim */
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/* > */
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/* ===================================================================== */
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doublereal ddot_(integer *n, doublereal *dx, integer *incx, doublereal *dy,
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integer *incy)
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{
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/* System generated locals */
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integer i__1;
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doublereal ret_val;
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/* Local variables */
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integer i__, m, ix, iy, mp1;
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doublereal dtemp;
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/* -- Reference BLAS level1 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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/* .. Scalar Arguments .. */
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/* .. */
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/* .. Array Arguments .. */
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/* .. */
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/* ===================================================================== */
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/* .. Local Scalars .. */
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/* .. */
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/* .. Intrinsic Functions .. */
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/* .. */
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/* Parameter adjustments */
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--dy;
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--dx;
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/* Function Body */
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ret_val = 0.;
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dtemp = 0.;
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if (*n <= 0) {
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return ret_val;
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}
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if (*incx == 1 && *incy == 1) {
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/* code for both increments equal to 1 */
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/* clean-up loop */
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m = *n % 5;
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if (m != 0) {
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i__1 = m;
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for (i__ = 1; i__ <= i__1; ++i__) {
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dtemp += dx[i__] * dy[i__];
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}
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if (*n < 5) {
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ret_val = dtemp;
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return ret_val;
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}
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}
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mp1 = m + 1;
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i__1 = *n;
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for (i__ = mp1; i__ <= i__1; i__ += 5) {
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dtemp = dtemp + dx[i__] * dy[i__] + dx[i__ + 1] * dy[i__ + 1] +
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dx[i__ + 2] * dy[i__ + 2] + dx[i__ + 3] * dy[i__ + 3] +
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dx[i__ + 4] * dy[i__ + 4];
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}
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} else {
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/* code for unequal increments or equal increments */
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/* not equal to 1 */
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ix = 1;
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iy = 1;
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if (*incx < 0) {
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ix = (-(*n) + 1) * *incx + 1;
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}
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if (*incy < 0) {
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iy = (-(*n) + 1) * *incy + 1;
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}
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i__1 = *n;
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for (i__ = 1; i__ <= i__1; ++i__) {
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dtemp += dx[ix] * dy[iy];
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ix += *incx;
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iy += *incy;
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}
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}
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ret_val = dtemp;
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return ret_val;
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/* End of DDOT */
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} /* ddot_ */
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#ifdef __cplusplus
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}
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#endif
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