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/* ctan.c */
/*
Contributed by Danny Smith
2003-10-20
*/
#include <math.h>
#include <complex.h>
#include <errno.h>
/* ctan (x + I * y) = (sin (2 * x) + I * sinh(2 * y))
/ (cos (2 * x) + cosh (2 * y)) */
double complex ctan (double complex Z)
{
double complex Res;
double two_I = 2.0 * __imag__ Z;
double two_R = 2.0 * __real__ Z;
double denom = cos (two_R) + cosh (two_I);
if (denom == 0.0)
{
errno = ERANGE;
__real__ Res = HUGE_VAL;
__imag__ Res = HUGE_VAL;
}
else if (isinf (denom))
{
errno = ERANGE;
__real__ Res = 0.0;
__imag__ Res = two_I > 0 ? 1.0 : -1.0;
}
else
{
__real__ Res = sin (two_R) / denom;
__imag__ Res = sinh (two_I) / denom;
}
return Res;
}
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