AT&T UNIX™PC Unix System V Users Manual - tenox

GAMMA ( 3M ) GAMMA ( 3M )
NAME
gamma - log gamma function
SYNOPSIS
#include < math.h >
extern int signgam;
double gamma (x)
double x;
DESCRIPTION
Gamma returns ln( I r( x ) I ), where r( x ) IS defined as
00
Je-t t" -l dt . The sign of r( x ) is returned m the external
0
integer sign gam. The argument x may not be a non-negative
integer.
The following C program fragment might be used to calculate r:
if ((y = gamma(x)) > LOGHUGE)
error( );
y = signgam * exp(y );
where LOGHUGE is the least value that causes exp (3M) to return a
range error.
DIAGNOSTICS
For non-negative integer arguments HUGE is returned, and errno
is set to EDOM. A message indicating DOMAIN error is printed on
the standard error output.
If the correct value would overflow, gamma returns HUGE and
sets errno to ERANGE.
These error-handling procedures may be changed with the function
matherr(3M).
SEE ALSO
exp(3M), matherr(3M).
- 1 -