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gcd

Compute the greatest common divisor (gcd).

The greatest common divisor (gcd) of two non-zero integers a and b is the largest positive integer which divides both a and b without a remainder. The gcd is also known as the greatest common factor (gcf), highest common factor (hcf), highest common divisor, and greatest common measure (gcm).

Usage

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

gcd( a, b )

Computes the greatest common divisor (gcd).

var v = gcd( 48, 18 );
// returns 6

If both a and b are 0, the function returns 0.

var v = gcd( 0, 0 );
// returns 0

Both a and b must have integer values; otherwise, the function returns NaN.

var v = gcd( 3.14, 18 );
// returns NaN

v = gcd( 48, 3.14 );
// returns NaN

v = gcd( NaN, 18 );
// returns NaN

v = gcd( 48, NaN );
// returns NaN

Examples

var discreteUniform = require( '@stdlib/random/array/discrete-uniform' );
var logEachMap = require( '@stdlib/console/log-each-map' );
var gcd = require( '@stdlib/math/base/special/gcd' );

var opts = {
    'dtype': 'float64'
};
var a = discreteUniform( 100, 0, 50, opts );
var b = discreteUniform( a.length, 0, 50, opts );

logEachMap( 'gcd(%d,%d) = %d', a, b, gcd );

C APIs

Usage

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

stdlib_base_gcd( a, b )

Computes the greatest common divisor (gcd).

double v = stdlib_base_gcd( 48.0, 18.0 );
// returns 6.0

The function accepts the following arguments:

  • a: [in] double input value.
  • b: [in] double input value.
double stdlib_base_gcd( const double a, const double b );

Examples

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

int main( void ) {
    const double a[] = { 24.0, 32.0, 48.0, 116.0, 33.0 };
    const double b[] = { 12.0, 6.0, 15.0, 52.0, 22.0 };

    double out;
    int i;
    for ( i = 0; i < 5; i++ ) {
        out = stdlib_base_gcd( a[ i ], b[ i ] );
        printf( "gcd(%lf, %lf) = %lf\n", a[ i ], b[ i ], out );
    }
}

References

  • Stein, Josef. 1967. "Computational problems associated with Racah algebra." Journal of Computational Physics 1 (3): 397–405. doi:10.1016/0021-9991(67)90047-2.

See Also