function array_product ( input ) {	// Calculate the product of values in an array
	// 
	// +   original by: _argos

	var Index = 0, Product = 1;
	if ( input instanceof Array ) {
		while ( Index < input.length ) {
			Product *= ( !isNaN ( input [ Index ] ) ? input [ Index ] : 0 );
			Index++;
		}
	} else {
		Product = null;
	}

	return Product;
}