cpp/numeric/complex/cosh

Computes complex hyperbolic cosine of a complex value.

Return value
If no errors occur, complex hyperbolic cosine 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, the result is  (the sign of the imaginary part is unspecified) and fe_invalid is raised
 * If is, the result is  (the sign of the imaginary part is unspecified)
 * If is  (for any finite non-zero x), the result is  and fe_invalid is raised
 * If is  (for any finite non-zero x), the result is  and fe_invalid may be raised
 * If is, the result is
 * If is  (for any finite non-zero y), the result is
 * If is, the result is  (the sign of the real part is unspecified) and fe_invalid is raised
 * If is, the result is
 * If is, the result is  (the sign of the imaginary part is unspecified)
 * If is  (for any finite non-zero y), the result is  and fe_invalid may be raised
 * If is, the result is
 * If is  (for any finite non-zero y), the result is  and fe_invalid may be raised
 * If is, the result is

where $cis(y)$ is $cos(y) + i sin(y)$.