@stdlib/math-base-special-imuldw NPM

imuldw

$NPM version$ $Build Status$ $Coverage Status$ $dependencies$

Compute the double word product of two signed 32-bit integers.

Installation

npm install @stdlib/math-base-special-imuldw

Usage

var imuldw = require( '@stdlib/math-base-special-imuldw' );

imuldw( [out,] a, b )

Multiplies two signed 32-bit integers and returns an array of two signed 32-bit integers which represents the signed 64-bit integer product.

var v = imuldw( 1, 10 );
// returns [ 0, 10 ]

v = imuldw( 0x80000000|0, 0x40000000|0 ); // -(2^31) * 2^30 = -2305843009213694000 => 32-bit integer overflow
// returns [ -536870912, 0 ]

Notes

When computing the product of 32-bit integer values in double-precision floating-point format (the default JavaScript numeric data type), computing the double word product is necessary in order to avoid exceeding the maximum safe double-precision floating-point integer value.

Examples

var lpad = require( '@stdlib/string-left-pad' );
var imuldw = require( '@stdlib/math-base-special-imuldw' );

var i;
var j;
var y;

for ( i = 0x7FFFFFF0; i < 0x7FFFFFFF; i++ ) {
    for ( j = i; j < 0x7FFFFFFF; j++) {
        y = imuldw( i|0, j|0 );
        console.log( '%d x %d = 0x%s%s', i|0, j|0, lpad( ( y[0] >>> 0 ).toString( 16 ), 8, '0'), lpad( ( y[1] >>> 0 ).toString( 16 ), 8, '0' ) );
    }
}

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.