Re: [Scheme-reports] Strong win later reversed: Real numbers have imaginary part #e0

[Mark H Weaver <mhw@x>]

Alex Shinn <alexshinn@x> writes:

> On Thu, Dec 20, 2012 at 7:19 AM, John Cowan <cowan@x>
> wrote:
>
>     Mark H Weaver scripsit:
>     
>     > My point is that your ComplexRepresentation page states that
>     Guile and
>     > Racket do not support complex numbers of mixed exactness, but
>     that's not
>     > quite true.  There is one important special case of mixed
>     exactness that
>     > *is* supported in Guile, Racket, Ikarus, and perhaps others.
>     
>     In that case, *every* Scheme that supports inexact reals at all, a
>     priori
>     supports complex numbers of mixed exactness such that the
>     imag-part is 0.
>     
> I love this reasoning.  So every Scheme supports mixed exactness
> quaternions.  What a progressive language.

No, several implementations (e.g. SCM, Gauche, Guile before 2.0, and
probably others) do not even support mixed exactness complex numbers of
this special kind, so (imag-part 2.0) => 0.0.  If these implementations
supported quaternions, the natural extrapolation of this policy would be
to return 0.0 for all three imaginary components of an inexact real
number.

     Mark

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