Thanks for the answers! For the purpose of my master thesis I am trying to
optimize the simulaion of helicopter dynamics. These dynamics are pretty
complicated, which leads to huge equations for most states. In order to
speed up the calculation I need to detect functions that where already
evaluated. The inner derivative that is produced due to the chain rule is
such a function, that I need to detect.
*factor()* works only for the first derivative unfortunately. In the second
and higher derivatives it does not factorize the inner derivates anymore:
t = sym.symbols('t')
diff( (sin(t)+exp(t))**5 , t )
>> (exp(t) + sin(t))**4*(5*exp(t) + 5*cos(t))
factor(diff( (sin(t)+exp(t))**5 , t ))
>> 5*(exp(t) + sin(t))**4*(exp(t) + cos(t))
factor(diff( (sin(t)+exp(t))**5 , t, t ))
>> 5*(exp(t) + sin(t))**3*(5*exp(2*t) + 8*exp(t)*cos(t) - sin(t)**2 +
4*cos(t)**2)
I think, writing my own differentiation programm will be a little bit to
hard to solve my issue. Is there no other way besides factor() and wiriting
my own programm?
Thank for your help!
Am Mittwoch, 1. Juni 2016 15:34:28 UTC+2 schrieb Michi S:
>
> Hello!
>
> Is there a way to turn off the automatic simplification by calculating the
> derivative of a function? For example
>
> t = sym.symbols('t')
> sym.Derivative( (sin(t)+exp(t))**3 , t ).doit()
>
> gives:
> (exp(t) + sin(t))**2*(3*exp(t) + 3*cos(t))
>
> I need the result without any simplifications (in order to detect the
> inner derivative for further calculations)
>
> Should be:
> (exp(t) + sin(t))**2*3*(exp(t) + cos(t))
>
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