math-float64-normalize v1.0.0
Normalize
Returns a normal number
y
and exponentexp
satisfyingx = y * 2^exp
.
Installation
$ npm install math-float64-normalize
Usage
var normalize = require( 'math-float64-normalize' );
normalize( x )
Returns a normal number y
and exponent exp
satisfying x = y * 2^exp
.
var out = normalize( 3.14e-319 );
// returns [ 1.4141234400356668e-303, -52 ]
The first element of the returned array
corresponds to y
and the second to exp
.
var pow = require( 'math-power' );
var y = out[ 0 ];
var exp = out[ 1 ];
var bool = ( y*pow(2,exp) === 3.14e-319 );
// returns true
The function
expects a finite, non-zero numeric
value x
. If x == 0
,
var out = normalize( 0 );
// returns [ 0, 0 ];
If x
is either positive or negative infinity
or NaN
,
var pinf = require( 'const-pinf-float64' );
var ninf = require( 'const-ninf-float64' );
var out = normalize( pinf );
// returns [ pinf, 0 ]
out = normalize( ninf );
// returns [ ninf, 0 ]
out = normalize( NaN );
// returns [ NaN, 0 ]
Examples
var round = require( 'math-round' );
var pow = require( 'math-power' );
var normalize = require( 'math-float64-normalize' );
var frac;
var exp;
var x;
var v;
var i;
// Generate denormalized numbers and then normalize them...
for ( i = 0; i < 100; i++ ) {
// Generate a random fraction:
frac = Math.random() * 10;
// Generate an exponent on the interval (-308,-324):
exp = -309 - round( Math.random()*14 );
// Create a subnormal number (~2.23e-308, ~4.94e-324):
x = frac * pow( 10, exp );
// Determine a `y` and an `exp` to "normalize" the subnormal:
v = normalize( x );
console.log( '%d = %d * 2^%d = %d', x, v[0], v[1], v[0]*pow(2,v[1]) );
}
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
Copyright
Copyright © 2016. The Compute.io Authors.