RE: On Arnold's challenge & Paul's Observation...
Can you clarify this example? We are replacing an expression with an
equal Single-Use expression -- for which (modulo rounding errors)
straightforward interval computations produce the exact range, what is
wrong with this transformation?
> -----Original Message-----
> From: stds-1788@xxxxxxxx [mailto:stds-1788@xxxxxxxx] On Behalf Of Dan
Zuras Intervals
> (3) There are other, perhaps more powerful re-arrangements
> (mostly algebraic in nature) that help even more but should
> be forbidden to compilers on the grounds that they change
> the calculation. These appear to be equivalent to the so-
> called 'value changing optimizations' in 754.
> Then, those things in point (3), say replacing an expression
> like (x^2 - y^2)/x^2 with 1 - (y/x)^2, should also be listed
> but, as they are value changing, reserved to the programmer
> to use or not, as the problem warrents.