# imuldw
> Compute the double word product of two signed 32-bit integers.
## Usage
```javascript
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.
```javascript
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][@stdlib/constants/float64/max-safe-integer].
## Examples
```javascript
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/constants/float64/max-safe-integer]: https://www.npmjs.com/package/@stdlib/constants-float64-max-safe-integer