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From Binary String

Create a double-precision floating-point number from a literal bit representation.

Installation

npm install @stdlib/number-float64-base-from-binary-string

Alternatively,

• To load the package in a website via a script tag without installation and bundlers, use the ES Module available on the esm branch (see README).
• If you are using Deno, visit the deno branch (see README for usage intructions).
• For use in Observable, or in browser/node environments, use the Universal Module Definition (UMD) build available on the umd branch (see README).

The branches.md file summarizes the available branches and displays a diagram illustrating their relationships.

To view installation and usage instructions specific to each branch build, be sure to explicitly navigate to the respective README files on each branch, as linked to above.

Usage

var fromBinaryString = require( '@stdlib/number-float64-base-from-binary-string' );

fromBinaryString( bstr )

Creates a double-precision floating-point number from a literal bit representation.

var bstr = '0100000000010000000000000000000000000000000000000000000000000000';
var val = fromBinaryString( bstr );
// returns 4.0

bstr = '0100000000001001001000011111101101010100010001000010110100011000';
val = fromBinaryString( bstr );
// returns 3.141592653589793

bstr = '1111111111100001110011001111001110000101111010111100100010100000';
val = fromBinaryString( bstr );
// returns -1.0e308

The function handles subnormals.

var bstr = '1000000000000000000000000000000000000000000000000001100011010011';
var val = fromBinaryString( bstr );
// returns -3.14e-320

bstr = '0000000000000000000000000000000000000000000000000000000000000001';
val = fromBinaryString( bstr );
// returns 5.0e-324

The function handles special values.

var bstr = '0000000000000000000000000000000000000000000000000000000000000000';
var val = fromBinaryString( bstr );
// returns 0.0

bstr = '1000000000000000000000000000000000000000000000000000000000000000';
val = fromBinaryString( bstr );
// returns -0.0

bstr = '0111111111111000000000000000000000000000000000000000000000000000';
val = fromBinaryString( bstr );
// returns NaN

bstr = '0111111111110000000000000000000000000000000000000000000000000000';
val = fromBinaryString( bstr );
// returns Infinity

bstr = '1111111111110000000000000000000000000000000000000000000000000000';
val = fromBinaryString( bstr );
// returns -Infinity

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 toBinaryString = require( '@stdlib/number-float64-base-to-binary-string' );
var fromBinaryString = require( '@stdlib/number-float64-base-from-binary-string' );

var frac;
var sign;
var exp;
var b;
var x;
var y;
var i;

// Convert random numbers to literal bit representations and then convert them back...
for ( i = 0; i < 100; i++ ) {
    if ( randu() < 0.5 ) {
        sign = -1.0;
    } else {
        sign = 1.0;
    }
    frac = randu() * 10.0;
    exp = round( randu()*100.0 );
    if ( randu() < 0.5 ) {
        exp = -exp;
    }
    x = sign * frac * pow( 2.0, exp );
    b = toBinaryString( x );
    y = fromBinaryString( b );
    console.log( '%d => %s => %d', x, b, y );
    console.log( x === y );
}

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See Also

• @stdlib/number-float32/base/from-binary-string: create a single-precision floating-point number from a literal bit representation.
• @stdlib/number-float64/base/to-binary-string: return a string giving the literal bit representation of a double-precision floating-point number.

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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

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License

See LICENSE.

Copyright

Copyright © 2016-2025. The Stdlib Authors.