double sqrt(), f__cabs();
VOID
z_sqrt(r
, z
) doublecomplex
*r
, *z
;
extern double f__cabs(double, double);
void z_sqrt(doublecomplex
*r
, doublecomplex
*z
)
if( (mag
= f__cabs(z
->r
, z
->i
)) == 0.)
r
->r
= sqrt(0.5 * (mag
+ z
->r
) );
r
->i
= sqrt(0.5 * (mag
- z
->r
) );