tgamma, tgammaf, tgammal

Artikel
08/03/2021
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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, see Global state in the CRT.

Requirements

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

For additional compatibility information, see Compatibility.