solving systems of differential equations

How can I solve a system of 27 differential equations? in fact the equations are related to each other and I want t solve it in parameteric way. it means all the constants and variables in my equations are unknown. so i can not use ODE45 for example. regards

Answer 1

[Alberto]

I give you an example to solve a system of 2 differential equations:

syms f(t) g(t) % one for every function

S = dsolve(diff(f) == 3*f + 4*g, diff(g) == -4*f + 3*g)

The functions can be extracted using:

S.f, S.g

[zarifeh HD]

Thanks I know how to use dsolve and syms. But actually the problem is large number of parameters in my question and it will take long hours too solve it. Is there a way to solve this large system of equations appropriately and in short time? regards

[Alberto]

With undefined parameters you have to use symbolic methods, and you are right, it takes time.

The only advice i can give you is trying to reduce your system to smaller problems than can be solved in 'finite' time.

Maybe combining some functions in just one or something ( can´t say without watching the equations), but I`m sure you tried that.