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Re: comparison operators and *typos
On Wed, 6 Jul 2005, Aubrey Jaffer wrote:
> | Thereby hypothetically: (presuming sufficient numerical precision)
> | (tan pi/2) => 0
>An exact zero? That is just wrong.
No, actually it's more right than we expect computation to
get. If pi/2 can be an exact number in the representation
used by the scheme system, an exact zero is precisely the
correct response to (tan pi/2). That said, tan isn't one
of the functions that is required to return an exact result
given exact arguments, so even if pi/2 is exact in the number
representation, we still aren't *required* to return the
exact zero, even though it's true.
In the usual case, where the numeric representation does
not allow pi/2 to be expressed as an exact number, then we
have an operation on an inexact number and we *must* return
an inexact result.