Abdelrahman Said
150 lines
3.6 KiB
C
150 lines
3.6 KiB
C
/* -- translated by f2c (version 20191129).
|
|
You must link the resulting object file with libf2c:
|
|
on Microsoft Windows system, link with libf2c.lib;
|
|
on Linux or Unix systems, link with .../path/to/libf2c.a -lm
|
|
or, if you install libf2c.a in a standard place, with -lf2c -lm
|
|
-- in that order, at the end of the command line, as in
|
|
cc *.o -lf2c -lm
|
|
Source for libf2c is in /netlib/f2c/libf2c.zip, e.g.,
|
|
|
|
http://www.netlib.org/f2c/libf2c.zip
|
|
*/
|
|
|
|
#include "f2c.h"
|
|
|
|
/* > \brief \b DNRM2
|
|
|
|
=========== DOCUMENTATION ===========
|
|
|
|
Online html documentation available at
|
|
http://www.netlib.org/lapack/explore-html/
|
|
|
|
Definition:
|
|
===========
|
|
|
|
DOUBLE PRECISION FUNCTION DNRM2(N,X,INCX)
|
|
|
|
INTEGER INCX,N
|
|
DOUBLE PRECISION X(*)
|
|
|
|
|
|
> \par Purpose:
|
|
=============
|
|
>
|
|
> \verbatim
|
|
>
|
|
> DNRM2 returns the euclidean norm of a vector via the function
|
|
> name, so that
|
|
>
|
|
> DNRM2 := sqrt( x'*x )
|
|
> \endverbatim
|
|
|
|
Arguments:
|
|
==========
|
|
|
|
> \param[in] N
|
|
> \verbatim
|
|
> N is INTEGER
|
|
> number of elements in input vector(s)
|
|
> \endverbatim
|
|
>
|
|
> \param[in] X
|
|
> \verbatim
|
|
> X is DOUBLE PRECISION array, dimension ( 1 + ( N - 1 )*abs( INCX ) )
|
|
> \endverbatim
|
|
>
|
|
> \param[in] INCX
|
|
> \verbatim
|
|
> INCX is INTEGER
|
|
> storage spacing between elements of DX
|
|
> \endverbatim
|
|
|
|
Authors:
|
|
========
|
|
|
|
> \author Univ. of Tennessee
|
|
> \author Univ. of California Berkeley
|
|
> \author Univ. of Colorado Denver
|
|
> \author NAG Ltd.
|
|
|
|
> \date November 2017
|
|
|
|
> \ingroup double_blas_level1
|
|
|
|
> \par Further Details:
|
|
=====================
|
|
>
|
|
> \verbatim
|
|
>
|
|
> -- This version written on 25-October-1982.
|
|
> Modified on 14-October-1993 to inline the call to DLASSQ.
|
|
> Sven Hammarling, Nag Ltd.
|
|
> \endverbatim
|
|
>
|
|
===================================================================== */
|
|
doublereal igraphdnrm2_(integer *n, doublereal *x, integer *incx)
|
|
{
|
|
/* System generated locals */
|
|
integer i__1, i__2;
|
|
doublereal ret_val, d__1;
|
|
|
|
/* Builtin functions */
|
|
double sqrt(doublereal);
|
|
|
|
/* Local variables */
|
|
integer ix;
|
|
doublereal ssq, norm, scale, absxi;
|
|
|
|
|
|
/* -- Reference BLAS level1 routine (version 3.8.0) --
|
|
-- Reference BLAS is a software package provided by Univ. of Tennessee, --
|
|
-- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
|
|
November 2017
|
|
|
|
|
|
=====================================================================
|
|
|
|
Parameter adjustments */
|
|
--x;
|
|
|
|
/* Function Body */
|
|
if (*n < 1 || *incx < 1) {
|
|
norm = 0.;
|
|
} else if (*n == 1) {
|
|
norm = abs(x[1]);
|
|
} else {
|
|
scale = 0.;
|
|
ssq = 1.;
|
|
/* The following loop is equivalent to this call to the LAPACK
|
|
auxiliary routine:
|
|
CALL DLASSQ( N, X, INCX, SCALE, SSQ ) */
|
|
|
|
i__1 = (*n - 1) * *incx + 1;
|
|
i__2 = *incx;
|
|
for (ix = 1; i__2 < 0 ? ix >= i__1 : ix <= i__1; ix += i__2) {
|
|
if (x[ix] != 0.) {
|
|
absxi = (d__1 = x[ix], abs(d__1));
|
|
if (scale < absxi) {
|
|
/* Computing 2nd power */
|
|
d__1 = scale / absxi;
|
|
ssq = ssq * (d__1 * d__1) + 1.;
|
|
scale = absxi;
|
|
} else {
|
|
/* Computing 2nd power */
|
|
d__1 = absxi / scale;
|
|
ssq += d__1 * d__1;
|
|
}
|
|
}
|
|
/* L10: */
|
|
}
|
|
norm = scale * sqrt(ssq);
|
|
}
|
|
|
|
ret_val = norm;
|
|
return ret_val;
|
|
|
|
/* End of DNRM2. */
|
|
|
|
} /* igraphdnrm2_ */
|
|
|