#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;

  if((mag = f__cabs(z->r, z->i)) == 0.)
    r->r = r->i = 0.;
  else if(z->r > 0)
  {
    r->r = t = sqrt(0.5 * (mag + z->r));
    t = z->i / t;
    r->i = 0.5 * t;
  }
  else
  {
    t = sqrt(0.5 * (mag - z->r));
    if(z->i < 0)
      t = -t;
    r->i = t;
    t = z->i / t;
    r->r = 0.5 * t;
  }
}
