log1pd32(), log1pd64(), log1pd128() — Natural log of x+1
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 log1pd32(_Decimal32 x);
_Decimal64 log1pd64(_Decimal64 x);
_Decimal128 log1pd128(_Decimal128 x);
_Decimal32 log1p(_Decimal32 x); /* C++ only */
_Decimal64 log1p(_Decimal64 x); /* C++ only */
_Decimal128 log1p(_Decimal128 x); /* C++ only */
General description
Computes
The value of x must be greater than -1.0.
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, log1p() returns the Log (1.0 + x) The value of x must be greater than -1.0.
log1p() will fail under the following
conditions:
- If x is less than -1.0, log1p() will return NaNQ and set errno to EDOM.
- If x is equal to -1.0, log1p() will return -HUGE_VAL_D32, -HUGE_VAL_D64 or -HUGE_VAL_D128 and errno remains unchanged.
Example
/* CELEBL27
This exaxmple illustrates the log1pd128() function.
*/
#define __STDC_WANT_DEC_FP__
#include <math.h>
#include <stdio.h>
void main(void)
{
_Decimal128 x, y;
x = 23.2DL;
y = log1pd128(x);
printf("log1pd128( %DDf ) = %DDf\n", x , y);
}