fmad32(), fmad64(), fmad128() — Multiply then add

Standards

Standards / Extensions	C or C++	Dependencies
C/C++ DFP	both	z/OS V1.11

Format

#define __STDC_WANT_DEC_FP__
#include <math.h>

_Decimal32  fmad32(_Decimal32 x, _Decimal32 y, _Decimal32 z); 
_Decimal64  fmad64(_Decimal64 x, _Decimal64 y, _Decimal64 z); 
_Decimal128 fmad128(_Decimal128 x, _Decimal128 y, _Decimal128 z); 

_Decimal32  fma(_Decimal32 x, _Decimal32 y, _Decimal32 z);     /* C++ only */
_Decimal64  fma(_Decimal64 x, _Decimal64 y, _Decimal64 z);     /* C++ only */
_Decimal128 fma(_Decimal128 x, _Decimal128 y, _Decimal128 z);    /* C++ only */

General description

The fma() family of functions compute (x * y) + z rounded as one ternary operation: they compute the value to infinite precision and round once to the resulting format according to the current rounding mode.

Notes:

These functions work in IEEE decimal floating-point format. See IEEE decimal floating-pointIEEE Decimal Floating-Point for more information.
To use IEEE decimal floating-point, the hardware must have the Decimal Floating-Point Facility installed.

Returned value

If successful, they return the rounded value of (x * y) + z as one ternary operation.

Example

⁄* CELEBF82

   This example illustrates the fmad64() function.

*⁄

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

void main(void)
{
   _Decimal64 w, x, y, z;

   x = 2.5DD;
   y = 6.7DD;
   z = 1.0DD;
   w = fmad64(x,y,z);

   printf("fmad64( %Df, %Df, %Df ) = %Df\n", x, y, z, w);
}

Related information

math.h