On Sat, Jun 20, 2009 at 4:10 PM, Dr. D. P. Kreil <dpkreil@gmail.com> wrote:

> Ah, that's probably where I went wrong. I thought R would take the
> "0.1", the "0.3", the "3", convert them to extended precision binary
> representations, do its calculations, an the reduction to normal
> double precision binary floats would only happen when the result was
> stored or printed.
>

This proposal is problematic in many ways.  For example, it would *still*
not guarantee that 0.3 - 3*0.1 == 0, since extended-precision floats have
the same characteristics as normal-precision floats.  Would you round to
normal precision when passing arguments?  Then sqrt could not produce
extended-precision results. etc. etc.

I suppose R could support an extended-precision floating-point type, but
that would require that the *user* choose which operations were in
extended-precision and which in normal precision. (And of course it would be
a lot of work to add in a complete and consistent way.)

           -s

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