Signum

Signum function.

The signum function is defined as

for any real number x.

Installation

$ npm install math-signum

Usage

var signum = require( 'math-signum' );

signum( x )

Evaluates the signum function.

var sign = signum( -5 );
// returns -1

sign = signum( 5 );
// returns 1

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

sign = signum( 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 signum = require( 'math-signum' );

var sign;
var v;
var i;

for ( i = 0; i < 100; i++ ) {
	v = Math.round( Math.random()*100 ) - 50;
	if ( signum( v ) < 0 ) {
		sign = '-';
	} else {
		sign = '+';
	}
	console.log( 'Value: %d. Sign: %s', v, sign );
}

To run the example code from the top-level application directory,

$ node ./examples/index.js

Tests

Unit

This repository uses tape for unit tests. To run the tests, execute the following command in the top-level application directory:

$ make test

All new feature development should have corresponding unit tests to validate correct functionality.

Test Coverage

This repository uses Istanbul as its code coverage tool. To generate a test coverage report, execute the following command in the top-level application directory:

$ make test-cov

Istanbul creates a ./reports/coverage directory. To access an HTML version of the report,

$ make view-cov

Browser Support

This repository uses Testling for browser testing. To run the tests in a (headless) local web browser, execute the following command in the top-level application directory:

$ make test-browsers

To view the tests in a local web browser,

$ make view-browser-tests

License

MIT license.

Copyright

Copyright © 2016. The Compute.io Authors.