| #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; | |
| } | |
| } |