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/* zrotg.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"
/* Subroutine */ int zrotg_(doublecomplex *ca, doublecomplex *cb, doublereal *
c__, doublecomplex *s)
{
/* System generated locals */
doublereal d__1, d__2;
doublecomplex z__1, z__2, z__3, z__4;
/* Builtin functions */
double z_abs(doublecomplex *);
void z_div(doublecomplex *, doublecomplex *, doublecomplex *);
double sqrt(doublereal);
void d_cnjg(doublecomplex *, doublecomplex *);
/* Local variables */
doublereal norm;
doublecomplex alpha;
doublereal scale;
/* .. Scalar Arguments .. */
/* .. */
/* Purpose */
/* ======= */
/* determines a double complex Givens rotation. */
/* .. Local Scalars .. */
/* .. */
/* .. Intrinsic Functions .. */
/* .. */
if (z_abs(ca) != 0.) {
goto L10;
}
*c__ = 0.;
s->r = 1., s->i = 0.;
ca->r = cb->r, ca->i = cb->i;
goto L20;
L10:
scale = z_abs(ca) + z_abs(cb);
z__2.r = scale, z__2.i = 0.;
z_div(&z__1, ca, &z__2);
/* Computing 2nd power */
d__1 = z_abs(&z__1);
z__4.r = scale, z__4.i = 0.;
z_div(&z__3, cb, &z__4);
/* Computing 2nd power */
d__2 = z_abs(&z__3);
norm = scale * sqrt(d__1 * d__1 + d__2 * d__2);
d__1 = z_abs(ca);
z__1.r = ca->r / d__1, z__1.i = ca->i / d__1;
alpha.r = z__1.r, alpha.i = z__1.i;
*c__ = z_abs(ca) / norm;
d_cnjg(&z__3, cb);
z__2.r = alpha.r * z__3.r - alpha.i * z__3.i, z__2.i = alpha.r * z__3.i +
alpha.i * z__3.r;
z__1.r = z__2.r / norm, z__1.i = z__2.i / norm;
s->r = z__1.r, s->i = z__1.i;
z__1.r = norm * alpha.r, z__1.i = norm * alpha.i;
ca->r = z__1.r, ca->i = z__1.i;
L20:
return 0;
} /* zrotg_ */
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