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#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;
}
}
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