freebsd-dev/contrib/libf2c/libF77/c_sqrt.c
2003-07-11 03:42:19 +00:00

31 lines
490 B
C

#include "f2c.h"
#undef abs
#include "math.h"
extern double f__cabs (double, double);
void
c_sqrt (complex * r, complex * z)
{
double mag, t;
double zi = z->i, zr = z->r;
if ((mag = f__cabs (zr, zi)) == 0.)
r->r = r->i = 0.;
else if (zr > 0)
{
r->r = t = sqrt (0.5 * (mag + zr));
t = zi / t;
r->i = 0.5 * t;
}
else
{
t = sqrt (0.5 * (mag - zr));
if (zi < 0)
t = -t;
r->i = t;
t = zi / t;
r->r = 0.5 * t;
}
}