fabs

Floating-point absolute value function

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Contents

Interface
Description
Special Values
See Also
Standards
Page Comments

Interface

#include <math.h>double  fabs (double x)
long  fabsl (long double x)
float  fabsf (float x)

Description

The fabs functions compute the absolute value of a floating-point number x, which is given by:

$\mathrm{fabs}(x) :=\begin{cases} x, & x \geq 0 \\ -x, & x < 0 \end{cases}$

(2)

Example:

Example - Floating-point absolute value function

Workings

#include <stdio.h>
#include <math.h>
int main(void)
{
  float number = -1234.0;
  printf("number: %.2f   absolute value: %.2f\n", number, fabs(number));
  return 0;
}

Solution

Output:

number: -1234.00   absolute value: 1234.00

Special Values

fabs ( ±0 ) returns 0.

fabs ( ±∞ ) returns +∞.

Standards

The fabs functions conform to ISO/IEC 9899:1999(E).

double	`fabs` (double x)
long	`fabsl` (long double x)
float	`fabsf` (float x)