*
* The extra number of words required as scratch space by the Karatsuba
* routines. This is a (generous) guess, since the actual amount of space
* required is proportional to the recursion depth.
*/
*
* The extra number of words required as scratch space by the Karatsuba
* routines. This is a (generous) guess, since the actual amount of space
* required is proportional to the recursion depth.
*/