gcc/libf2c/libF77/z_sqrt.c

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#include "f2c.h"
#undef abs
#include "math.h"
extern double f__cabs (double, double);
void
z_sqrt (doublecomplex * r, doublecomplex * z)
{
double mag, zi = z->i, zr = z->r;
if ((mag = f__cabs (zr, zi)) == 0.)
r->r = r->i = 0.;
else if (zr > 0)
{
r->r = sqrt (0.5 * (mag + zr));
r->i = zi / r->r / 2;
}
else
{
r->i = sqrt (0.5 * (mag - zr));
if (zi < 0)
r->i = -r->i;
r->r = zi / r->i / 2;
}
}