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Subject: Re: [boost] [math] Does any one interesting in calculating derivative for a expression automatically?
From: Dongfei Yin (yin.dongfei_at_[hidden])
Date: 2009-03-06 08:04:34

Hi Bruno,
    Till now, it can only work with polynomial and trigonometric
functions. and I have a good idea of simplifying a expression.
as you said, if N is compile time known, it should be int_<N>, then the
expression with it can be simplified.

    As the hypersphere talked before, if N=2, and the volume expression
will be simplified from (int_<N>^(int_<N>/int_<2>)*var(r)^int_<N>) /
gamma(int_<N>/int_<2> + int_<1>) to int_<pi>*var(r)^int_<2> if gamma()
has been specialized.

Till now, (_x*_x*_x) is a functor, it can be simplified to something
like pow(_x, int_<3>).
without using d(...), it can be used to simplify expression as we talked
before. this is another use of it.

   You know, there are too many functions in math, so I think I can't
implement all of them, the functions included in standard library is
enough for me. and I will make it easy to be extended. what do you think
about it, I mean how many functions should I implement.

   My main purpose is calculating derivative easily, of course simplify
expression is a important part, I am working on it.


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