Re: problem with finding equilibrium points of nonlinear system

On 3/8/2013 1:56 PM, gilraen wrote:
> Hi all,
>
> I need to find equilibrium points of nonlinear system which consist of 9 equations.
>It is complicated system, so when I tried find equilibrium points in this way:
>
> syms x1 x2
> solve(x*2+3,x2^3-2, x3-2*x2); (it is just example)
>
> it give warning:
>
> Warning: The solutions are parametrized by the symbols
>
> It means it cannot be solve analytically. I try to solve this problem numerically but I am stuck.
>
> Is there any method how can I find equillibrium points in matlab numerically?
>
> Any help will be appreciated.
>


You should post complete example, and not bits and pieces. The above could
not have worked as x is not defined, and x3 is not defined.

But it works for me:

----------------------------
syms x1 x2 x x3
sol=solve(x*2+3,x2^3-2, x3-2*x2);

EDU>> sol.x
  -3/2
  -3/2
  -3/2
  
EDU>> sol.x2
  
                             16^(1/3)/2
    (3^(1/2)*16^(1/3)*i)/4 - 16^(1/3)/4
  - (3^(1/2)*16^(1/3)*i)/4 - 16^(1/3)/4
  
EDU>> sol.x3
                               16^(1/3)
    (3^(1/2)*16^(1/3)*i)/2 - 16^(1/3)/2
  - (3^(1/2)*16^(1/3)*i)/2 - 16^(1/3)/2
-------------------------

--Nasser