Re: [boost] [mpl][math] double accuracy

From: David Abrahams (dave_at_[hidden])
Date: 2005-09-24 16:37:55

Peder Holt <peder.holt_at_[hidden]> writes:

> What should we do about the accuracy of double_ operations?
>
> The implementation of plus,minus,times and divide mimics the behaviour
> of the runtime equivalent, double. 

On which implementation of C++?

> This means that the mantissa is trunkated from 61 to 52 bit for
> every fundamental operation. The result of this, is that complex
> functions such as sine and exponential will differ from their
> runtime counterpart, unless a specialization is made for
> double_. The problem would disappear if we allow calculations with
> double_ to be more accurate than calculations with double. Is this a
> problem?

It doesn't sound like your correspondence with runtime results can
possibly be portable anyway, can it?

-- 
Dave Abrahams
Boost Consulting
www.boost-consulting.com