 # Boost :

Subject: Re: [boost] [math] Does any one interesting in calculating derivative for a expression automatically?
From: Joel Falcou (joel.falcou_at_[hidden])
Date: 2009-03-04 05:53:21

Dongfei Yin a écrit :
> Hi John,
> 1. I have tried that if you write d(d(d(d(x*x*x*x, x), x), x), x), it
> will take a long compile time without optimized. I have do something
> to optimized it. I need to write a lot of specialized
Can't this be mapped onto a d<N>(f,v) function that is optimized for N =
1,2,3,... ?
I bet that if you use proto, matching d(d(d( ... )))) and repalcing by
d<N>(...) should be easy.

Do you perform your derivation recursively on the derivative degree (ie
d(d(x*x,x),x) is y = d(x*x,x); d(y,x);)
If yes, you may want to use coarser grain. Let's say you specialized d()
d<2>() and d<3>() for ex. Computing d<5>
is d<2>(d<3>()) instead of d(d(d(d(d()))). Of course, using d,d2, d4 is
maybe a better option so you cna use bit representaiton of derivative
degree to find how to combine the derivative.