cpp/numeric/special functions/beta

@1-3@ Computes the of  and.

@A@ Additional overloads are provided for all other combinations of arithmetic types.

Return value
If no errors occur, value of the beta function of and, that is , or, equivalently,  is returned.

Error handling
Errors may be reported as specified in math_errhandling
 * If any argument is NaN, NaN is returned and domain error is not reported
 * The function is only required to be defined where both and  are greater than zero, and is allowed to report a domain error otherwise.