NAME
lgamma — log gamma
function
SYNOPSIS
#include <math.h> double lgamma(double x); extern int signgam;
DESCRIPTION
The lgamma() function computes
The sign of is returned in the external integer signgam . The argument x need
not be a non-positive integer, ( is defined over the reals, except the
non-positive integers).
An application wishing to check for error situations should set errno to 0 before calling lgamma(). If errno is non-zero on return, or the return value is NaN, an error has occurred.
This interface need not be reentrant.
RETURN VALUE
Upon successful completion, lgamma() returns the logarithmic gamma of x .
If x is NaN, NaN is returned and errno may be set to [EDOM].
If x is a non-positive integer, either HUGE_VAL or NaN is returned and errno may be set to [EDOM].
If the correct value would cause overflow, lgamma() returns HUGE_VAL and may set errno to [ERANGE].
If the correct value would cause underflow, lgamma() returns 0 and may set errno to [ERANGE].
ERRORS
The lgamma() function may fail if:
- [EDOM]
- The value of x is a non-positive integer or NaN.
- [ERANGE]
- The value to be returned would have caused overflow or underflow.
No other errors will occur.
EXAMPLES
None.
APPLICATION USAGE
None.
FUTURE DIRECTIONS
None.