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

tgamma, tgammaf, tgammal - compute gamma function

c99 [flag... ]file...-lm[library... ] #include <math.h>doubletgamma(doublex);

floattgammaf(floatx);

long doubletgammal(long doublex);

These functions compute the **gamma()** function of
*x*.

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.

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.

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.

See attributes(7) for descriptions of the following attributes:

ATTRIBUTE TYPE | ATTRIBUTE VALUE |

Interface Stability | Standard |

MT-Level | MT-Safe |

math.h(3HEAD), feclearexcept(3M), fetestexcept(3M), lgamma(3M), attributes(7), standards(7)

July 12, 2006 | SunOS 5.11 |