|
|
cc [flag ...] file ... -lm [library ...]#include <math.h>
double gamma(double x);
float gammaf(float x);
long double gammal(long double x);
double lgamma(double x);
float lgammaf(float x);
long double lgammal(long double x);
extern int signgam;
double tgamma(double x);
float tgammaf(float x);
long double tgammal(long double x);
(x) is defined as:
The sign of (x) is returned in the
external integer signgam. The argument x
must be positive and greater than zero. A
range error occurs if x is too large.
tgamma, tgammaf and tgammal return the gamma value of x. The argument x must be positive and greater than zero. A range error may occur if the magnitude of x is too large or too small.
, ±0 or a negative
integer, gamma, gammaf, gammal,
lgamma, lgammaf and lgammal return
+HUGE_VAL,
+HUGE_VALF or +HUGE_VALL (respectively)
and errno is set to ERANGE.
If x is -, ±0 or a negative
integer, tgamma, tgammaf and tgammal
return IEEE NaN on systems that support it and raise the invalid
operation exception. Otherwise, they return 0. errno
is set to EDOM.
If x is + tgamma, tgammaf
and tgammal return +HUGE_VAL,
+HUGE_VALF or +HUGE_VALL
and errno
is set to ERANGE.
If the correct value would overflow, all gamma functions return a value that compares equal to +HUGE_VAL, +HUGE_VALF or +HUGE_VALL and set errno to ERANGE.
On systems that support IEEE NaN, if x is a quiet NaN, that value is returned. If x is a signaling NaN, a quiet NaN is returned and the invalid operation exception is raised. In either case, errno is set to EDOM.
If the program was compiled with the -Xt compilation mode, a value that will compare equal to HUGE is returned instead of HUGE_VAL. In addition, for non-positive integer arguments, a message indicating SING error is printed on the standard error output. These error handling procedures may be changed with the function matherr.
X/Open Portability Guide, Issue 3, 1989 .