Math errors in python

[Tim Peters]

[Paul Rubin]
> I don't know that it's generally tractable to do exact computation on
> constructive reals.  How do you implement comparison (<, >, ==)?

Equality of constructive reals is undecidable.  In practice, CR
packages allow specifying a "number of digits of evidence " parameter
N, so that equality is taken to mean "provably don't differ by more
than a unit in the N'th digit".