gcc/libf2c/libF77/z_sqrt.c

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#include "f2c.h"
#ifdef KR_headers
double sqrt(), f__cabs();
VOID z_sqrt(resx, z) doublecomplex *resx, *z;
#else
#undef abs
#include <math.h>
extern double f__cabs(double, double);
void z_sqrt(doublecomplex *resx, doublecomplex *z)
#endif
{
double mag;
doublecomplex res;
if( (mag = f__cabs(z->r, z->i)) == 0.)
res.r = res.i = 0.;
else if(z->r > 0)
{
res.r = sqrt(0.5 * (mag + z->r) );
res.i = z->i / res.r / 2;
}
else
{
res.i = sqrt(0.5 * (mag - z->r) );
if(z->i < 0)
res.i = - res.i;
res.r = z->i / res.i / 2;
}
resx->r = res.r;
resx->i = res.i;
}