README
Normalize
Return a normal number
y
and exponentexp
satisfyingx = y * 2^exp
.
Installation
npm install @stdlib/number-float64-base-normalize
Usage
var normalize = require( '@stdlib/number-float64-base-normalize' );
normalize( [out,] 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 ]
By default, the function returns y
and exp
as a two-element array
.
var pow = require( '@stdlib/math-base-special-pow' );
var out = normalize( 3.14e-319 );
// returns [ 1.4141234400356668e-303, -52 ]
var y = out[ 0 ];
var exp = out[ 1 ];
var bool = ( y*pow(2.0, exp) === 3.14e-319 );
// returns true
To avoid unnecessary memory allocation, the function supports providing an output (destination) object.
var Float64Array = require( '@stdlib/array-float64' );
var out = new Float64Array( 2 );
var v = normalize( out, 3.14e-319 );
// returns <Float64Array>[ 1.4141234400356668e-303, -52 ]
var bool = ( v === out );
// returns true
The function expects a finite, non-zero numeric
value x
. If x == 0
,
var out = normalize( 0.0 );
// returns [ 0.0, 0 ];
If x
is either positive or negative infinity
or NaN
,
var PINF = require( '@stdlib/constants-float64-pinf' );
var NINF = require( '@stdlib/constants-float64-ninf' );
var out = normalize( PINF );
// returns [ Infinity, 0 ]
out = normalize( NINF );
// returns [ -Infinity, 0 ]
out = normalize( NaN );
// returns [ NaN, 0 ]
Examples
var randu = require( '@stdlib/random-base-randu' );
var round = require( '@stdlib/math-base-special-round' );
var pow = require( '@stdlib/math-base-special-pow' );
var normalize = require( '@stdlib/number-float64-base-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 = randu() * 10.0;
// Generate an exponent on the interval (-308,-324):
exp = -309 - round( randu()*14.0 );
// Create a subnormal number (~2.23e-308, ~4.94e-324):
x = frac * pow( 10.0, 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(2.0, v[1]) );
}
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 © 2016-2022. The Stdlib Authors.