[boost] [mpl][math] double accuracy

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. 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? Regards Peder