Barton Willis wrote:
> -----Richard Fateman wrote: -----
>
>
>>I believe the commercial Macsyma has a sophisticated program
>>involved in this, courtesy of Bill Gosper, which allows the system
>>to decide how much precision is required to determine the
>>sign of (or,especially, the zeroness of ..) an expression.
>
>
> Too bad we don't have the source -- with Macysma 2.2, it's
> easy to break 'floor':
If you had the sources, you couldn't legally look at them :(
>
> (c1) p : sqrt(5) * (sqrt(5) - 1/sqrt(5))$ /* p = 4 */
>
> (c2) floor(p);
> (d2) 3 <--- bogus
>
>
> (c3) floor(expand(p));
> (d3) 4 <--- OK
>
> Maybe this was fixed in later versions.
>
>
Commercial macsyma gives 4.