Re: RFC: Differential Arithmetic Library

From: deane_yang (Deane_Yang_at_[hidden])
Date: 2002-02-12 22:13:13

--- In boost_at_y..., Peter Schmitteckert (boost) <boost_at_s...> wrote:
> Salut,
> 
> How would you implement a recursion for
> differential_number<N, double>::exp( x );
> 
> Currently I do the following for the second order:
> 
> template<class T>
> diff2<T> exp(const diff2<T> a)
> {
> 	const diff<T> r( exp( diff<T>(a.d0(), a.d1() ) ));
> 	return diff2<T>( r.d0() , r.d1(), ( a.d2() + a.d1()*a.d1())
*r.d0() );
> }
> 
> But that does not scale for
> differential_number<N, double>::exp( x );

Good point. And it looks pretty bad, doesn't it?
As it happens, I personally only need the class up to order 2
and have a hard time envisioning anyone needing it for higher
order. Maybe we could just define the interface and leave the
implementation of higher order functions to users who actually
need them?