Re: RFC: Arbitrary-precision floats for Guile

[Hans Aberg]

On 1 Feb 2011, at 14:57, Mark H Weaver wrote:

> I want to add arbitrary-precision floats to Guile.
> I'd use the mpf_t type from GNU MP.
>
> There would be a fluid whose value would determine the minimum  
> precision
> to use for inexact operators.  A value of #f (the default) would mean
> that normal floats would be used unless one of the operands was a
> bigfloat.

Only checking takes a lot of time, so it is best to make a new type.  
Same for integral types. So if speed is an issue, Guile ought to have  
C99 integral types.

The name 'floating' seems free for such a type.

> One complication is that we'd have to implement the transcendental
> functions.  However, I already have code to do that, as part of a
> bigfloat library I wrote a while back.

There is already MPFR, which is a package of top of GMP (see the  
manual of the latter).

> I'd also like to add another more general representation of complex
> numbers whose real and imaginary parts are each of type SCM, like the
> way fractions are represented.

One might have a complexification class with one template argument.  
The current Guile 'complex' type is (in my installation) the  
complexification of 64-bit IEEE floats.