Tribblix: manual page: tgamma.3m

TGAMMA(3M) Mathematical Library Functions TGAMMA(3M)

NAME

tgamma, tgammaf, tgammal - compute gamma function

SYNOPSIS

c99 [ flag... ] file... -lm [ library... ]
#include <math.h>

double tgamma(double x);

float tgammaf(float x);

long double tgammal(long double x);

DESCRIPTION

These functions compute the gamma() function of x.

RETURN VALUES

Upon successful completion, these functions return gamma(x).

If x is a negative integer, a domain error occurs and a NaN is
returned.

If the correct value would cause overflow, a range error occurs and
tgamma(), tgammaf(), and tgammal() return the value of the macro
+-HUGE_VAL, +-HUGE_VALF, or +-HUGE_VALL, respectively.

If x is NaN, a NaN is returned.

If x is +-Inf, x is returned.

If x is +-0, a pole error occurs and tgamma(), tgammaf(), and
tgammal() return +-HUGE_VAL, +-HUGE_VALF, and +-HUGE_VALL,
respectively.

If x is +Inf, a domain error occurs and a NaN is returned.

ERRORS

These functions will fail if:

Domain Error
The value of x is a negative integer or x is -Inf.

If the integer expression (math_errhandling &
MATH_ERREXCEPT) is non-zero, then the invalid
floating-point exception is raised.

Pole Error
The value of x is zero.

If the integer expression (math_errhandling &
MATH_ERREXCEPT) is non-zero, then the divide-by-zero
floating-point exception is raised.

Range Error
The value overflows.

If the integer expression (math_errhandling &
MATH_ERREXCEPT) is non-zero, then the overflow
floating-point exception is raised.

USAGE

An application wanting to check for exceptions should call
feclearexcept(FE_ALL_EXCEPT) before calling these functions. On
return, if fetestexcept(FE_INVALID | FE_DIVBYZERO | FE_OVERFLOW |
FE_UNDERFLOW) is non-zero, an exception has been raised. An
application should either examine the return value or check the
floating point exception flags to detect exceptions.

ATTRIBUTES