bigfloat

[Walter Bright]

Paul D. Anderson wrote:
> I'm not sure I can sign up for ALL of std.math. I'm sure I'll need
> help.  I can do roots, powers and transcendental functions, though.
> Maybe not very efficiently (power series).

It's not necessary to come out of the starting gate with them all 
implemented to arbitrary precision. A workable first version can just 
call the std.math real versions, and note in the documentation as a bug 
that the precision is limited to real precision.

The various constants, like std.math.E and PI should also be there. They 
can be lazily evaluated.

I also suggest that the type be a template parameterized with the 
exponent bits and mantissa bits. float, double and real would then be 
specializations of them.

> (If very high precision numbers are questionable, how valuable are
> high precision sine and cosine??)

If one accepts the utility of high precision numbers, then one must also 
accept the utility of high precision math functions!