Absolute Value

Compute an absolute value of a signed 32-bit integer.

The absolute value is defined as

StartAbsoluteValue x EndAbsoluteValue equals StartLayout Enlarged left-brace 1st Row 1st Column x 2nd Column if x greater-than-or-equal-to 0 2nd Row 1st Column negative x 2nd Column if x less-than 0 EndLayout

Usage

var labs = require( '@stdlib/math/base/special/labs' );

labs( x )

Computes an absolute value of a signed 32-bit integer.

var v = labs( -1|0 );
// returns 1

v = labs( 2|0 );
// returns 2

v = labs( 0|0 );
// returns 0

Notes

  • The implementation assumes two's complement.

  • In two's complement systems, the absolute value of the minimum signed 32-bit integer is out-of-range. The absolute value for the minimum signed 32-bit integer is thus undefined.

    // -2^31
    var x = -2147483648|0;
    
    var v = labs( x );
    // returns -2147483648
    

Examples

var randu = require( '@stdlib/random/base/randu' );
var round = require( '@stdlib/math/base/special/round' );
var labs = require( '@stdlib/math/base/special/labs' );

var x;
var i;

for ( i = 0; i < 100; i++ ) {
    x = round( randu() * 100.0 ) - 50;
    console.log( 'abs(%d) = %d', x, labs( x|0 ) );
}

C APIs

Usage

#include "stdlib/math/base/special/labs.h"

stdlib_base_labs( x )

Computes the absolute value of a signed 32-bit integer in two's complement format.

#include <stdint.h>

int32_t y = stdlib_base_labs( -5 );
// returns 5

The function accepts the following arguments:

  • x: [in] int32_t input value.
int32_t stdlib_base_labs( const int32_t x );

Examples

#include "stdlib/math/base/special/labs.h"
#include <stdint.h>
#include <stdio.h>

int main() {
    int32_t x[] = { 3, -3, 0, -10 };

    int32_t y;
    int i;
    for ( i = 0; i < 4; i++ ) {
        y = stdlib_base_labs( x[ i ] );
        printf( "|%i| = %i\n", x[ i ], y );
    }
}
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