[r6rs-discuss] [Formal] NaN is not a real number.

From: John Cowan <cowan>
Date: Sun Sep 24 21:35:54 2006

Aubrey Jaffer scripsit:

> The term flonum doesn't seem to be defined by R5.91RS.

Flonums are an implementation-defined subset of the inexact real numbers;
see p. 39. Furthermore, an external representation of a number that
contains a decimal point or an 'e', but not an 's', 'd', 'f', or 'l',
represents a flonum, as do inf.0 and nan.0 with or without signs (p. 15).

> If it means floating-point numbers, then most flonums are real, but
> flonum NaNs are not. The flonums including NaNs are closed under fl-,
> fl*, fl+, etc. Thus your example code will be completely unaffected
> by the realness of NaNs.

Flonums may, but need not, be represented using floating-point numbers.
The set of inexact real numbers explicitly includes infinities and NaNs.

-- 
John Cowan  <cowan_at_ccil.org>  http://www.ccil.org/~cowan
        Raffiniert ist der Herrgott, aber boshaft ist er nicht.
                --Albert Einstein
Received on Sun Sep 24 2006 - 21:35:48 UTC

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