nexttowardd32(), nexttowardd64(), nexttowardd128() — Calculate the next representable value

Standards

Standards / Extensions	C or C++	Dependencies
C/C++ DFP	both	z/OS® V1.8

Format

#define __STDC_WANT_DEC_FP__
#include <math.h>

_Decimal32  nexttowardd32(_Decimal32 x, _Decimal128 y); 
_Decimal64  nexttowardd64(_Decimal64 x, _Decimal128 y); 
_Decimal128 nexttowardd128(_Decimal128 x, _Decimal128 y);
_Decimal32  nexttoward(_Decimal32 x, _Decimal128 y); /*C++ only*/
_Decimal64  nexttoward(_Decimal64 x, _Decimal128 y); /*C++ only*/
_Decimal128 nexttoward(_Decimal128 x, _Decimal128 y);/*C++ only*/

General description

The nexttoward() family of functions compute the next representable decimal floating-point value following x in the direction of y.

Notes:

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

Returned value

If successful, they return the next representable value in the specified format after x in the direction of y.

If...	Then...
x equals y	y (of type x) is returned.
x is less than y	the next representable value after x is returned.
x is greater than y	the largest representable decimal floating-point number less than x is returned.
x is finite and the correct function value would overflow	a range error occurs and ±HUGE_VAL_D32, ±HUGE_VAL_D64, or ±HUGE_VAL_D128 (with the same sign as x) is returned by nexttowardd32(), nexttowardd64() or nexttowardd128(), respectively.
x does not equal y and the correct subroutine value is subnormal, 0, or underflows	a range error occurs and either the correct function value (if representable) or 0.0 is returned.
x or y is a NaN	a NaN is returned.

Example

/* CELEBN08

   This example illustrates the nexttowardd32() function.

*/

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


static void try_nt(_Decimal32 x, _Decimal128 y)
{
  _Decimal32 r = nexttowardd32(x, y);
  printf("nexttowardd32(%12.12HG, %12.12DDG) = % 12.12HG\n", x, y, r);
  return;
}


int main(void)
{
  try_nt( 2.000000DF    ,  2.00000001DL    );
  try_nt(-2.000000DF    , -2.00000001DL    );
  try_nt( 2.000000DF    ,  2.00000000DL    );
  try_nt( 2.000000DF    ,  1.99999999DL    );
  try_nt(-2.000000DF    , -1.99999999DL    );
  try_nt( 9.999999E+96DF,  9.99999999E+96DL);
  try_nt( 1.000000E-95DF,  0.99999999E-95DL);

  return 0;
}