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math-float64-set-high-word

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Readme

Set High Word

$NPM version$ $Build Status$ $Coverage Status$ $Dependencies$

Sets the more significant 32 bits of a double-precision floating-point number.

Installation

$ npm install math-float64-set-high-word

Usage

var setHighWord = require( 'math-float64-set-high-word' );

setHighWord( x, high )

Sets the more significant 32 bits (higher order word) of a double-precision floating-point number x to a bit sequence represented by an unsigned 32-bit integer high. The returned double will have the same less significant 32 bits (lower order word) as x.

var high = 5 >>> 0;
// => 0 00000000000 00000000000000000101

var y = setHighWord( 3.14e201, high );
// returns 1.18350528745e-313 => 0 00000000000 0000000000000000010110010011110010110101100010000010

var pinf = require( 'const-pinf-float64' );
// returns +infinity => 0 11111111111 00000000000000000000 00000000000000000000000000000000

high = 1072693248 >>> 0;
// => 0 01111111111 00000000000000000000

// Set the higher order bits of `+infinity` to return `1`:
y = setHighWord( pinf, high );
// returns 1 => 0 01111111111 0000000000000000000000000000000000000000000000000000

Examples

var pow = require( 'math-power' );
var round = require( 'math-round' );
var setHighWord = require( 'math-float64-set-high-word' );

var MAX_UINT;
var high;
var frac;
var exp;
var x;
var y;
var i;

// Max unsigned 32-bit integer:
MAX_UINT = pow( 2, 32 ) - 1;

// Generate a random double-precision floating-point number:
frac = Math.random() * 10;
exp = -round( Math.random() * 323 );
x = frac * pow( 10, exp );

// Replace the higher order word of `x` to generate new random numbers having the same lower order word...
for ( i = 0; i < 100; i++ ) {
    high = round( Math.random()*MAX_UINT );
    y = setHighWord( x, high );
    console.log( 'x: %d. new high word: %d. y: %d.', x, high, y );
}

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.

math-float64-set-high-word