double mag
, sqrt(), cabs();
if( (mag
= cabs(z
->dreal
, z
->dimag
)) == 0.)
r
->dreal
= r
->dimag
= 0.;
r
->dreal
= sqrt(0.5 * (mag
+ z
->dreal
) );
r
->dimag
= z
->dimag
/ r
->dreal
/ 2;
r
->dimag
= sqrt(0.5 * (mag
- z
->dreal
) );
r
->dreal
= z
->dimag
/ r
->dimag
/ 2;