Google Groups no longer supports new Usenet posts or subscriptions. Historical content remains viewable.
Dismiss

LeafCount and ByteCount Lie in Mathematica

42 views
Skip to first unread message

Richard Fateman

unread,
May 4, 2014, 2:28:55 AM5/4/14
to
Mathematica 9.0 .. on a 32 bit windows machine.

f[n_] := Block[{k = f[n - 1]}, {k, k}]
f[0]=x

LeafCount[f[k]] for particular small integers k
returns the number 2^(k+1)-1. e.g. for k=3, it returns 15.

But it returns the same answer for k=30, 31, ....
It returns 2147483647, which, probably not coincidentally, is 2^31-1.

ByteCount has a similar problem in running out of bits in
its counter.

Anyway, ByteCount also lies in a different way...
because it doesn't take into account the
sharing that (say) f[70] has. Without the sharing
implicit in the formula above, I could not compute that --
it has 2.36 X 10^21 leaves. They are just not different leaves.

I would expect that a 64-bit system might work for k=31,
but would conk out somewhere else.

0 new messages