extern
int
signgam
;
double
lgamma(
double x
)
float
lgammaf(
float x
)
double
lgamma_r(
double x
, int *sign
)
float
lgammaf_r(
float x
, int *sign
)
double
gamma(
double x
)
float
gammaf(
float x
)
double
gamma_r(
double x
, int *sign
)
float
gammaf_r(
float x
, int *sign
)
x
)
returns ln|(x)|.
The external integer
signgam
returns the sign of (x).
lgamma_r()
is a reentrant interface that performs identically to
lgamma(
),
differing in that the sign of (x) is stored in the location
pointed to by the
sign
argument and
signgam
is not modified.
signgam*exp(lgamma(x))
''
to compute g := (x).
Instead use a program like this (in C):
lg = lgamma(x); g = signgam*exp(lg);
Only after
lgamma()
has returned can signgam be correct.
)
returns appropriate values unless an argument is out of range.
Overflow will occur for sufficiently large positive values, and
non-positive integers.
On the
VAX,
the reserved operator is returned,
and
errno
is set to
ERANGE
.