184 lines
4.3 KiB
C++
184 lines
4.3 KiB
C++
/* fortran/dznrm2.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 DZNRM2 */
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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 DZNRM2(N,X,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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/* COMPLEX*16 X(*) */
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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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/* > DZNRM2 returns the euclidean norm of a vector via the function */
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/* > name, so that */
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/* > */
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/* > DZNRM2 := sqrt( x**H*x ) */
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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] X */
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/* > \verbatim */
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/* > X is COMPLEX*16 array, dimension (N) */
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/* > complex vector with N elements */
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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 X */
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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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/* > \date December 2016 */
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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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/* > -- This version written on 25-October-1982. */
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/* > Modified on 14-October-1993 to inline the call to ZLASSQ. */
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/* > Sven Hammarling, Nag Ltd. */
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/* > \endverbatim */
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/* > */
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/* ===================================================================== */
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doublereal dznrm2_(integer *n, doublecomplex *x, integer *incx)
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{
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/* System generated locals */
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integer i__1, i__2, i__3;
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doublereal ret_val, d__1;
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/* Builtin functions */
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double d_imag(doublecomplex *), sqrt(doublereal);
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/* Local variables */
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integer ix;
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doublereal ssq, temp, norm, scale;
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/* -- Reference BLAS level1 routine (version 3.7.0) -- */
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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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/* December 2016 */
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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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/* .. Intrinsic Functions .. */
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/* .. */
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/* Parameter adjustments */
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--x;
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/* Function Body */
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if (*n < 1 || *incx < 1) {
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norm = 0.;
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} else {
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scale = 0.;
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ssq = 1.;
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/* The following loop is equivalent to this call to the LAPACK */
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/* auxiliary routine: */
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/* CALL ZLASSQ( N, X, INCX, SCALE, SSQ ) */
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i__1 = (*n - 1) * *incx + 1;
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i__2 = *incx;
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for (ix = 1; i__2 < 0 ? ix >= i__1 : ix <= i__1; ix += i__2) {
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i__3 = ix;
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if (x[i__3].r != 0.) {
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i__3 = ix;
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temp = (d__1 = x[i__3].r, abs(d__1));
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if (scale < temp) {
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/* Computing 2nd power */
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d__1 = scale / temp;
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ssq = ssq * (d__1 * d__1) + 1.;
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scale = temp;
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} else {
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/* Computing 2nd power */
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d__1 = temp / scale;
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ssq += d__1 * d__1;
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}
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}
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if (d_imag(&x[ix]) != 0.) {
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temp = (d__1 = d_imag(&x[ix]), abs(d__1));
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if (scale < temp) {
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/* Computing 2nd power */
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d__1 = scale / temp;
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ssq = ssq * (d__1 * d__1) + 1.;
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scale = temp;
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} else {
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/* Computing 2nd power */
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d__1 = temp / scale;
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ssq += d__1 * d__1;
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}
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}
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/* L10: */
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}
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norm = scale * sqrt(ssq);
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}
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ret_val = norm;
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return ret_val;
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/* End of DZNRM2. */
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} /* dznrm2_ */
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#ifdef __cplusplus
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}
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#endif
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