cpp/numeric/math/lgamma

@1-3@ Computes the natural logarithm of the absolute value of the of. @A@ Additional overloads are provided for all integer types, which are treated as.

Return value
If no errors occur, the value of the logarithm of the gamma function of, that is , is returned.

If a pole error occurs, huge_val,, or is returned.

If a range error due to overflow occurs, huge_val,, or is returned.

Error handling
Errors are reported as specified in math_errhandling.

If is zero or is an integer less than zero, a pole error may occur.

If the implementation supports IEEE floating-point arithmetic (IEC 60559),
 * If the argument is 1, +0 is returned.
 * If the argument is 2, +0 is returned.
 * If the argument is ±0, +∞ is returned and fe_divbyzero is raised.
 * If the argument is a negative integer, +∞ is returned and fe_divbyzero is raised.
 * If the argument is ±∞, +∞ is returned.
 * If the argument is NaN, NaN is returned.