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Re: comparison operators and *typos

This page is part of the web mail archives of SRFI 70 from before July 7th, 2015. The new archives for SRFI 70 contain all messages, not just those from before July 7th, 2015.

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.