201 lines
5.2 KiB
C++
201 lines
5.2 KiB
C++
/* fortran/drscl.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 DRSCL multiplies a vector by the reciprocal of a real scalar. */
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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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/* > \htmlonly */
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/* > Download DRSCL + dependencies */
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/* > <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/drscl.f
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"> */
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/* > [TGZ]</a> */
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/* > <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/drscl.f
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"> */
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/* > [ZIP]</a> */
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/* > <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/drscl.f
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"> */
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/* > [TXT]</a> */
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/* > \endhtmlonly */
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/* Definition: */
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/* =========== */
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/* SUBROUTINE DRSCL( N, SA, SX, INCX ) */
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/* .. Scalar Arguments .. */
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/* INTEGER INCX, N */
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/* DOUBLE PRECISION SA */
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/* .. */
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/* .. Array Arguments .. */
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/* DOUBLE PRECISION SX( * ) */
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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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/* > DRSCL multiplies an n-element real vector x by the real scalar 1/a. */
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/* > This is done without overflow or underflow as long as */
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/* > the final result x/a does not overflow or underflow. */
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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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/* > The number of components of the vector x. */
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/* > \endverbatim */
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/* > */
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/* > \param[in] SA */
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/* > \verbatim */
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/* > SA is DOUBLE PRECISION */
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/* > The scalar a which is used to divide each component of x. */
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/* > SA must be >= 0, or the subroutine will divide by zero. */
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/* > \endverbatim */
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/* > */
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/* > \param[in,out] SX */
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/* > \verbatim */
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/* > SX is DOUBLE PRECISION array, dimension */
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/* > (1+(N-1)*abs(INCX)) */
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/* > The n-element 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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/* > The increment between successive values of the vector SX. */
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/* > > 0: SX(1) = X(1) and SX(1+(i-1)*INCX) = x(i), 1< i<= n */
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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 doubleOTHERauxiliary */
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/* ===================================================================== */
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/* Subroutine */ int drscl_(integer *n, doublereal *sa, doublereal *sx,
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integer *incx)
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{
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doublereal mul, cden;
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logical done;
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doublereal cnum, cden1, cnum1;
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extern /* Subroutine */ int dscal_(integer *, doublereal *, doublereal *,
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integer *), dlabad_(doublereal *, doublereal *);
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extern doublereal dlamch_(char *, ftnlen);
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doublereal bignum, smlnum;
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/* -- LAPACK auxiliary routine -- */
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/* -- LAPACK 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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/* .. Parameters .. */
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/* .. */
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/* .. Local Scalars .. */
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/* .. */
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/* .. External Functions .. */
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/* .. */
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/* .. External Subroutines .. */
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/* .. */
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/* .. Intrinsic Functions .. */
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/* .. */
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/* .. Executable Statements .. */
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/* Quick return if possible */
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/* Parameter adjustments */
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--sx;
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/* Function Body */
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if (*n <= 0) {
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return 0;
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}
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/* Get machine parameters */
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smlnum = dlamch_((char *)"S", (ftnlen)1);
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bignum = 1. / smlnum;
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dlabad_(&smlnum, &bignum);
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/* Initialize the denominator to SA and the numerator to 1. */
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cden = *sa;
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cnum = 1.;
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L10:
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cden1 = cden * smlnum;
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cnum1 = cnum / bignum;
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if (abs(cden1) > abs(cnum) && cnum != 0.) {
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/* Pre-multiply X by SMLNUM if CDEN is large compared to CNUM. */
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mul = smlnum;
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done = FALSE_;
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cden = cden1;
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} else if (abs(cnum1) > abs(cden)) {
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/* Pre-multiply X by BIGNUM if CDEN is small compared to CNUM. */
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mul = bignum;
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done = FALSE_;
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cnum = cnum1;
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} else {
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/* Multiply X by CNUM / CDEN and return. */
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mul = cnum / cden;
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done = TRUE_;
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}
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/* Scale the vector X by MUL */
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dscal_(n, &mul, &sx[1], incx);
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if (! done) {
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goto L10;
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}
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return 0;
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/* End of DRSCL */
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} /* drscl_ */
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#ifdef __cplusplus
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}
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#endif
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