#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"
#ifdef __cplusplus
extern "C" {
#endif
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;
         }
  }
#ifdef __cplusplus
}
#endif
