c/numeric/complex/ctanh

@1-3@ Computes the complex hyperbolic tangent of. @4@ Type-generic macro: If has type,  is called. if has type,  is called, if  has type ,  is called. If is real or integer, then the macro invokes the corresponding real function. If is imaginary, then the macro invokes the corresponding real version of the function tan, implementing the formula $tanh(iy) = i tan(y)$, and the return type is imaginary.

Return value
If no errors occur, complex hyperbolic tangent of is returned

Error handling and special values
Errors are reported consistent with math_errhandling

If the implementation supports IEEE floating-point arithmetic,
 * If is, the result is
 * If is  (for any finite x), the result is  and fe_invalid is raised
 * If is  (for any finite x), the result is  and fe_invalid may be raised
 * If is  (for any finite positive y), the result is
 * If is, the result is  (the sign of the imaginary part is unspecified)
 * If is, the result is  (the sign of the imaginary part is unspecified)
 * If is, the result is
 * If is  (for any non-zero y), the result is  and fe_invalid may be raised
 * If is, the result is
 * If is  (for any non-zero y), the result is  and fe_invalid may be raised
 * If is, the result is