151 lines
3.8 KiB
C++
151 lines
3.8 KiB
C++
/* fortran/dlapy2.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 DLAPY2 returns sqrt(x2+y2). */
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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 DLAPY2 + dependencies */
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/* > <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dlapy2.
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f"> */
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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/dlapy2.
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f"> */
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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/dlapy2.
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f"> */
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/* > [TXT]</a> */
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/* > \endhtmlonly */
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/* Definition: */
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/* =========== */
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/* DOUBLE PRECISION FUNCTION DLAPY2( X, Y ) */
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/* .. Scalar Arguments .. */
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/* DOUBLE PRECISION X, Y */
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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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/* > DLAPY2 returns sqrt(x**2+y**2), taking care not to cause unnecessary */
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/* > overflow and unnecessary underflow. */
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/* > \endverbatim */
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/* Arguments: */
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/* ========== */
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/* > \param[in] X */
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/* > \verbatim */
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/* > X is DOUBLE PRECISION */
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/* > \endverbatim */
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/* > */
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/* > \param[in] Y */
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/* > \verbatim */
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/* > Y is DOUBLE PRECISION */
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/* > X and Y specify the values x and y. */
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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 OTHERauxiliary */
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/* ===================================================================== */
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doublereal dlapy2_(doublereal *x, doublereal *y)
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{
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/* System generated locals */
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doublereal ret_val, d__1;
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/* Builtin functions */
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double sqrt(doublereal);
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/* Local variables */
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logical x_is_nan__, y_is_nan__;
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doublereal w, z__, xabs, yabs;
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extern doublereal dlamch_(char *, ftnlen);
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extern logical disnan_(doublereal *);
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doublereal hugeval;
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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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/* ===================================================================== */
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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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x_is_nan__ = disnan_(x);
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y_is_nan__ = disnan_(y);
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if (x_is_nan__) {
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ret_val = *x;
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}
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if (y_is_nan__) {
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ret_val = *y;
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}
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hugeval = dlamch_((char *)"Overflow", (ftnlen)8);
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if (! (x_is_nan__ || y_is_nan__)) {
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xabs = abs(*x);
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yabs = abs(*y);
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w = max(xabs,yabs);
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z__ = min(xabs,yabs);
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if (z__ == 0. || w > hugeval) {
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ret_val = w;
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} else {
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/* Computing 2nd power */
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d__1 = z__ / w;
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ret_val = w * sqrt(d__1 * d__1 + 1.);
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}
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}
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return ret_val;
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/* End of DLAPY2 */
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} /* dlapy2_ */
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#ifdef __cplusplus
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}
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#endif
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