c/numeric/math/lgamma

@1-3@ Computes the natural logarithm of the absolute value of the of. @4@ Type-generic macro: If has type,  is called. Otherwise, if has integer type or the type,  is called. Otherwise, is called.

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.

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.