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tgamma, tgammaf, tgammal

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Determines the gamma function of the specified value.

Syntax

double tgamma(
   double x
);

float tgammaf(
   float x
);

long double tgammal(
   long double x
);

#define tgamma(X) // Requires C11 or higher

float tgamma(
   float x
); //C++ only

long double tgamma(
   long double x
); //C++ only

Parameters

x
The value to find the gamma of.

Return value

If successful, returns the gamma of x.

A range error may occur if the magnitude of x is too large or too small for the data type. A domain error or range error may occur if x <= 0.

Issue Return
x = ±0 ±INFINITY
x = negative integer NaN
x = -INFINITY NaN
x = +INFINITY +INFINITY
x = NaN NaN
domain error NaN
pole error ±HUGE_VAL, ±HUGE_VALF, or ±HUGE_VALL
overflow range error ±HUGE_VAL, ±HUGE_VALF, or ±HUGE_VALL
underflow range error the correct value, after rounding.

Errors are reported as specified in _matherr.

Remarks

Because C++ allows overloading, you can call overloads of tgamma that take and return float and long double types. In a C program, unless you're using the <tgmath.h> macro to call this function, tgamma always takes and returns a double.

If you use the <tgmath.h> tgamma() macro, the type of the argument determines which version of the function is selected. See Type-generic math for details.

If x is a natural number, this function returns the factorial of (x-1).

By default, this function's global state is scoped to the application. To change this behavior, see Global state in the CRT.

Requirements

Function C header C++ header
tgamma, tgammaf, tgammal <math.h> <cmath>
tgamma macro <tgmath.h>

For more compatibility information, see Compatibility.

See also

Alphabetical function reference
lgamma, lgammaf, lgammal