gamma(3m)gamma(3m)Name
gamma, lgamma, signgam - log gamma function
Syntax
#include <math.h>
double gamma(x)
double x;
double lgamma(x)
double x;
extern int
Description
The function returns ln |Γ(|x|)|. The sign of Γ(|x|) is returned in
the external integer The following C program might be used to calculate
Γ:
y = gamma(x);
if (y > 88.0)
error();
y = exp(y);
if(signgam)
y = -y;
The function is another name for the gamma function.
Return Values
The and functions return HUGE_VAL and set errno to EDOM when x is an
integer value less than or equal to zero. When the correct value would
overflow they return HUGE_VAL and set errno to ERANGE.
Environment
When your program is compiled using the System V environment for non‐
positive integer values, HUGE is returned, and errno is set to EDOM. A
message indicating DOMAIN error is printed on the standard error out‐
put.
If the correct value would overflow, returns HUGE and sets errno to
ERANGE.
These error-handling procedures may be changed with the function
See Alsomatherr(3m)
VAX gamma(3m)