newlib-cygwin/winsup/mingw/mingwex/complex/csqrt.c

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/*
csqrt.c
Contributed by Danny Smith
2003-10-20
*/
#include <math.h>
#include <complex.h>
double complex csqrt (double complex Z)
{
double complex Res;
double t;
double x = __real__ Z;
double y = __imag__ Z;
if (y == 0.0)
{
if (x < 0.0)
{
__real__ Res = 0.0;
__imag__ Res = sqrt (-x);
}
else
{
__real__ Res = sqrt (x);
__imag__ Res = 0.0;
}
}
else if (x == 0.0)
{
t = sqrt(0.5 * fabs (y));
__real__ Res = t;
__imag__ Res = y > 0 ? t : -t;
}
else
{
t = sqrt (2.0 * (_hypot (x, y) + fabs (x)));
double u = t / 2.0;
if ( x > 0.0)
{
__real__ Res = u;
__imag__ Res = y / t;
}
else
{
__real__ Res = fabs ( y / t);
__imag__ Res = y < 0.0 ? -u : u;
}
}
return Res;
}