Hello,

To do the symbolic differentiation, I created a new class, that store the dependencies with respect to a symbol (or many) and the degree of differentiation. 

Then I can differentiate the symbol (add 1 to the degree). and at the end I can make the substitution and the real differentiation.

 I'm not sure that is the correct approach, but it works for me.

Felipe.


Le 22 juil. 12 à 19:29, Martin Ettl a écrit :

Hello,

i have a question regarding symbolic differentiation with GiNAC.

Here is what i am trying to do:

I have to variables a(t) and b(t), both are dependent from time (t). 
Suppose, this two variables are multiplied liked this:

             a(t) * b(t)

Is it possible to derive this expression (a(t)*b(t)) according time with ginac.

The only function i found in the manual is usefull for partial derivation, which does not help me here.


Here is some example code:

 symbol a("a"), b("b");  // <-- how to tell ginac that variable a and b is dependant from variable t
 expression f = a*b;
 std::cout << f.diff(t,1) << std::endl;


Many thanks in advance and best regards

Martin Ettl 



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