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Re: [Scheme-reports] result of (infinite? +nan.0+inf.0i)

Per Bothner scripsit:

> What should be the result of (infinite? +nan.0+inf.0i)?  The report
> says #t but that seems undesirable, because it would mean that
> finite?/infinite?/nan? would no longer be a partitioning of the
> complex numbers,

It never has been.  If you look at R6RS, you'll see that these predicates
are defined on real numbers only; the extension to complex numbers is
new in R7RS.  The WG decided that the convention that a partly-infinite
complex number is an infinity and that a partly-NaN complex number is
a NaN was more important than extending the trichotomy.

There was some sentiment for declaring that any complex operation
that generated a partial NaN should generate a NaN, pure and simple,
but there were strong objections from the users of complex numbers,
who expected to be able to extract meaningful results from a partial NaN.

Winter:  MIT,                                   John Cowan
Keio, INRIA,                                    cowan@x
Issue lots of Drafts.                           http://www.ccil.org/~cowan
So much more to understand!
Might simplicity return?                        (A "tanka", or extended haiku)

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