162 lines
3.9 KiB
C++
162 lines
3.9 KiB
C++
/* fortran/idamax.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 IDAMAX */
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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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/* INTEGER FUNCTION IDAMAX(N,DX,INCX) */
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/* .. Scalar Arguments .. */
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/* INTEGER INCX,N */
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/* .. */
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/* .. Array Arguments .. */
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/* DOUBLE PRECISION DX(*) */
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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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/* > IDAMAX finds the index of the first element having maximum absolute value. */
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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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/* 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 aux_blas */
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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 3/93 to return if incx .le. 0. */
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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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integer idamax_(integer *n, doublereal *dx, integer *incx)
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{
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/* System generated locals */
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integer ret_val, i__1;
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doublereal d__1;
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/* Local variables */
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integer i__, ix;
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doublereal dmax__;
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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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--dx;
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/* Function Body */
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ret_val = 0;
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if (*n < 1 || *incx <= 0) {
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return ret_val;
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}
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ret_val = 1;
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if (*n == 1) {
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return ret_val;
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}
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if (*incx == 1) {
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/* code for increment equal to 1 */
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dmax__ = abs(dx[1]);
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i__1 = *n;
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for (i__ = 2; i__ <= i__1; ++i__) {
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if ((d__1 = dx[i__], abs(d__1)) > dmax__) {
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ret_val = i__;
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dmax__ = (d__1 = dx[i__], abs(d__1));
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}
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}
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} else {
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/* code for increment not equal to 1 */
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ix = 1;
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dmax__ = abs(dx[1]);
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ix += *incx;
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i__1 = *n;
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for (i__ = 2; i__ <= i__1; ++i__) {
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if ((d__1 = dx[ix], abs(d__1)) > dmax__) {
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ret_val = i__;
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dmax__ = (d__1 = dx[ix], abs(d__1));
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}
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ix += *incx;
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}
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}
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return ret_val;
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/* End of IDAMAX */
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} /* idamax_ */
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#ifdef __cplusplus
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}
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#endif
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