fabs

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Contents
  1. Interface
  2. Description
  3. Special Values
  4. See Also
  5. Standards

floating-point absolute value function

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Computing C Math.h

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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}
(1)

Example 1

#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;
}

Output:

number: -1234.00   absolute value: 1234.00

Special Values

fabs ( &plusmn;0 ) returns 0.
fabs ( &plusmn;&infin; ) returns +&infin;.

See Also

abs, ceil, floor

Standards

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