Splits a single-precision floating-point number into a normalized fraction and an integer power of two.
$ npm install math-float32-frexp
var frexp = require( 'math-float32-frexp' );
Splits a single-precision floating-point number into a normalized fraction and an integer power of two.
var toFloat32 = require( 'float64-to-float32' );
var out = frexp( toFloat32( 4 ) );
// returns [ 0.5, 3 ]
The first element of the returned array
is the normalized fraction and the second is the exponent. The normalized fraction and exponent satisfy the relation x = frac * 2**exp
.
var toFloat32 = require( 'float64-to-float32' );
var pow = require( 'math-power' );
var x1 = toFloat32( 4 );
var out = frexp( x1 );
// returns [ 0.5, 3 ]
var frac = out[ 0 ];
var exp = out[ 1 ];
var x2 = frac * pow(2,exp);
var bool = ( x1 === x2 );
// returns true
If provided positive or negative zero
, NaN
, or positive or negative infinity
, the function
returns a two-element array
containing the input value and an exponent equal to 0
.
var pinf = require( 'const-pinf-float32' );
var ninf = require( 'const-ninf-float32' );
var out = frexp( 0 );
// returns [ 0, 0 ]
out = frexp( -0 );
// returns [ -0, 0 ]
out = frexp( NaN );
// returns [ NaN, 0 ]
out = frexp( pinf );
// returns [ +infinity, 0 ]
out = frexp( ninf );
// returns [ -infinity, 0 ]
For all other numeric
input values, the absolute value of the normalized fraction resides on the interval [1/2,1)
.
var round = require( 'math-round' );
var pow = require( 'math-power' );
var toFloat32 = require( 'float64-to-float32' );
var frexp = require( 'math-float32-frexp' );
var sign;
var frac;
var exp;
var x;
var f;
var v;
var i;
// Generate random single-precision floating-point numbers and break each into a normalized fraction and an integer power of two...
for ( i = 0; i < 100; i++ ) {
if ( Math.random() < 0.5 ) {
sign = -1;
} else {
sign = 1;
}
frac = Math.random() * 10;
exp = round( Math.random()*64 ) - 38;
x = sign * frac * pow( 10, exp );
x = toFloat32( x );
f = frexp( x );
v = f[ 0 ] * pow( 2, f[ 1 ] );
v = toFloat32( v );
console.log( '%d = %d * 2^%d = %d', x, f[ 0 ], f[ 1 ], v );
}
To run the example code from the top-level application directory,
$ node ./examples/index.js
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.
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
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
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