#include "f2c.h" | |
#ifdef KR_headers | |
extern double sqrt(), f__cabs(); | |
VOID c_sqrt(r, z) complex *r, *z; | |
#else | |
#undef abs | |
#include "math.h" | |
extern double f__cabs(double, double); | |
void c_sqrt(complex *r, complex *z) | |
#endif | |
{ | |
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; | |
} | |
} |