tgammad32(), tgammad64(), tgammad128() - Calculate gamma function

Standards

Standards / Extensions	C or C++	Dependencies
C/C++ DFP	both	z/OS V1.10

Format

#define __STDC_WANT_DEC_FP__
#include <math.h>

_Decimal32  tgammad32(_Decimal32 x);
_Decimal64  tgammad64(_Decimal64 x);
_Decimal128 tgammad128(_Decimal128 x);
_Decimal32  tgamma(_Decimal32 x);     /* C++ only */
_Decimal64  tgamma(_Decimal64 x);     /* C++ only */
_Decimal128 tgamma(_Decimal128 x);    /* C++ only */

General description

The tgamma() functions compute the gamma function of x.

These functions work in IEEE decimal floating-point format. See IEEE decimal floating-point for more information.

Note: To use IEEE decimal floating-point, the hardware must have the Decimal Floating-Point Facility installed.

Returned value

The tgamma functions return G(x).

A domain error occurs if x is a negative integer or when x is zero and the result cannot be represented. A range error occurs if the magnitude of x is too large or too small.

Example

CELEBT24

⁄* CELEBT24

   This example illustrates the tgammad128() function.

*⁄

#define  __STDC_WANT_DEC_FP__
#include <math.h>
#include <stdio.h>

int main(void)
{
   _Decimal128 x, y;

   x = 5.6DL;
   y = tgammad128(x);

   printf("tgammad128(%DDf) = %DDf\n", x, y);
}

Related information

math.h