Compute the double word product of two signed 32-bit integers.
npm install @stdlib/math-base-special-imuldwvar imuldw = require( '@stdlib/math-base-special-imuldw' );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 ]- 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.
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' ) );
}
}@stdlib/math/base/special/imul: perform C-like multiplication of two signed 32-bit integers.@stdlib/math/base/special/uimuldw: compute the double word product of two unsigned 32-bit integers.
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.
See LICENSE.
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