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imuldw

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

Installation

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

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

imuldw( 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 ]

imuldw.assign( a, b, out, stride, offset )

Multiplies two signed 32-bit integers and assigns results representing the signed 64-bit integer product to a provided output array.

var out = [ 0, 0 ];

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

var bool = ( v === out );
// returns true

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-ops-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' ) );
    }
}

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See Also

• @stdlib/math-base/ops/imul: perform C-like multiplication of two signed 32-bit integers.

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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 © 2016-2024. The Stdlib Authors.