c/numeric/math/tanh

@1-3@ Computes the hyperbolic tangent of. @4@ Type-generic macro: If the argument has type, is called. Otherwise, if the argument has integer type or the type, is called. Otherwise, is called. If the argument is complex, then the macro invokes the corresponding complex function.

Return value
If no errors occur, the hyperbolic tangent of ($tanh(arg)$, or $$) is returned.

If a range error occurs due to underflow, the correct result (after rounding) is returned.

Error handling
Errors are reported as specified in math_errhandling.

If the implementation supports IEEE floating-point arithmetic (IEC 60559),
 * if the argument is ±0, ±0 is returned
 * If the argument is ±∞, ±1 is returned
 * if the argument is NaN, NaN is returned