Re: [Scheme-reports] Numerical example (real? -2.5+0.0i)

[Jussi Piitulainen <jpiitula@x>]

Andre van Tonder writes:
> On Mon, 15 Aug 2011, Jussi Piitulainen wrote:
> 
> > An example in July draft 6.2.5 shows (real? -2.5+0.0i) as #t. The text
> > above the examples says (real? z) if and only if (zero? (imag-part z))
> > and (exact? (imag-part z)). The imag-part is clearly not exact.
> 
> Just off the cuff I thought fully known concrete finite-recision reals
> such as 0.0 were exact.  How is it not?  There is no uncertainty (no
> hashes indicated), so it is mathematically equal to an exact rational
> number.

6.2.4 Syntax of numerical constants, latter half of third para:

    If the written representation of a number has no exactness prefix,
    ... [the constant] is inexact if it _contains a decimal point_, an
    exponent, or a "#" character in the place of a digit [my emphasis]

For what it's worth:

guile> (exact? 0.0)
#f


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