Signum

Signum function.

The signum function is defined as

for any real number x.

Installation

npm install @stdlib/math-base-special-signum

Usage

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

signum( x )

Evaluates the signum function for a double-precision floating-point number.

var sign = signum( -5.0 );
// returns -1

sign = signum( 5.0 );
// returns 1

sign = signum( -0.0 );
// returns -0

sign = signum( 0.0 );
// returns 0

sign = signum( NaN );
// returns NaN

Notes

Table of results:

| Value | Sign | | ------- | ----- | | x > 0 | +1 | | x < 0 | -1 | | 0 | 0 | | -0 | -0 | | NaN | NaN |

Examples

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

var sign;
var x;
var i;

for ( i = 0; i < 100; i++ ) {
    x = round( randu()*100.0 ) - 50.0;
    sign = signum( x );
    console.log( 'signum(%d) = %d', x, sign );
}

C APIs

Usage

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

stdlib_base_signum( x )

Evaluates the signum function for a double-precision floating-point number.

double y = stdlib_base_signum( -9.0 );
// returns -1.0

The function accepts the following arguments:

• x: [in] double input value.

double stdlib_base_signum( const double x );

Examples

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

int main( void ) {
    const double x[] = { 3.14, -3.14, 0.0, 0.0/0.0 };

    double y;
    int i;
    for ( i = 0; i < 4; i++ ) {
        y = stdlib_base_signum( x[ i ] );
        printf( "signum(%lf) = %lf\n", x[ i ], y );
    }
}

Notice

This package is part of stdlib, a standard library for JavaScript and Node.js, with an emphasis on numerical and scientific computing. The library provides a collection of robust, high performance libraries for mathematics, statistics, streams, utilities, and more.

For more information on the project, filing bug reports and feature requests, and guidance on how to develop stdlib, see the main project repository.

Community

License

See LICENSE.

Copyright

Copyright © 2016-2024. The Stdlib Authors.