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/* dnrm2.f -- translated by f2c (version 20061008).
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"
#include "blaswrap.h"
doublereal dnrm2_(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;
/* .. Scalar Arguments .. */
/* .. */
/* .. Array Arguments .. */
/* .. */
/* Purpose */
/* ======= */
/* DNRM2 returns the euclidean norm of a vector via the function */
/* name, so that */
/* DNRM2 := sqrt( x'*x ) */
/* -- This version written on 25-October-1982. */
/* Modified on 14-October-1993 to inline the call to DLASSQ. */
/* Sven Hammarling, Nag Ltd. */
/* .. Parameters .. */
/* .. */
/* .. Local Scalars .. */
/* .. */
/* .. Intrinsic Functions .. */
/* .. */
/* 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. */
} /* dnrm2_ */
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