1.0.0 • Published 10 years ago

math-float64-exponent v1.0.0

Weekly downloads
141
License
MIT
Repository
github
Last release
10 years ago

Exponent

NPM version Build Status Coverage Status Dependencies

Returns an integer corresponding to the unbiased exponent of a double-precision floating-point number.

Installation

$ npm install math-float64-exponent

Usage

var exponent = require( 'math-float64-exponent' );

exponent( x )

Returns an integer corresponding to the unbiased exponent of a double-precision floating-point number.

var exp = exponent( 3.14e307 );
// returns 1021 => 2**1021 ~ 1e307

var exp = exponent( 3.14e-307 );
// returns -1019 => 2**-1019 ~ 1e-307

exp = exponent( -3.14 );
// returns 1

exp = exponent( 0 );
// returns 0

exp = exponent( NaN );
// returns 1024 => 2**1024 ~ infinity

Examples

var round = require( 'math-round' );
var pow = require( 'math-power' );
var exponent = require( 'math-float64-exponent' );

var frac;
var exp;
var x;
var e;
var i;

// Generate random numbers and extract their exponents...
for ( i = 0; i < 100; i++ ) {
	frac = Math.random() * 10;
	exp = round( Math.random()*646 ) - 323;
	x = frac * pow( 10, exp );
	e = exponent( x );
	console.log( 'x: %d. unbiased exponent: %d.', x, e );
}

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.