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