Using ODE45 to solve Rossler equations

The Rossler equations are defined as

x'(t)=-x(t)-y(t)
y'(t)=ax(t)+y(t)
z'(t)=b+z(t)(x(t)-c) 

and I am trying to use ode45 to solve them

I have so far created a ross function file

function dx = ross(t,x)
%ross: Computes the derivatives involved in solving the
%ross equations.


a=-0.1;
b=2;
c=5.7;
%Right hand sides
dx=zeros(3,1);
dx(1)=-1*x(1)-1*x(2);
dx(2)=a*x(1)+x(2);
dx(3)=b+(x(3)*(x(1)-c));

and I am trying the below code but it doesnt stop running and seems to be stuck in a loop

clear all
      x0=[-8 8 27];
      tspan=[0,20];
     [t,x]=ode45(@ross,tspan,x0)
     %or run
      [t,x]=ode45(@lorenz,tspan,x0)
      %BUT NOT BOTH IN THE SAME CODE (1 OR THE OTHER LORENZ OR ROSS)
     plot3(x(:,1),x(:,2),x(:,3),'b','linewidth',1.5)
     

however if I have instead of @ross but have @lorenz

 [t,x]=ode45(@lorenz,tspan,x0)
 

and try

     function dx = lorenz(t,x)
     % Parameters
     sigma=10;
     beta=8/3;
     rho=28;
     % Differential Equations
     dx=zeros(3,1);
     dx(1)=sigma*(x(2)-x(1));
     dx(2)=rho*x(1)-x(2)-x(1)*x(3);
     dx(3)=x(1)*x(2)-beta*x(3);

it seems to work fine, my question is where am I going wrong with my ross equations

[darova]

Try

tspan = [0 2];

Answer 1

[Jeremy]

You are correct ode45 appears to be stuck. But if you try

ode15s

it appears to work

[Jeremy]

One more thing - are you plotting the equation solutions vs themselves instead of vs. time intentionally?

figure, hold on
plot(t,x(:,1),t,x(:,2),t,x(:,3),'LineWidth',2)

Answer 2

[Tanggo Tang]

Hi you have err in ross attraction

function  dx = ross(t,x)
a = 0.2;
b = 0.2;
c = 5.7 ;

dx=zeros(3,1);
dx(1)=-x(2)-x(3);   %here
dx(2)=x(1)+a*x(2);  %and here
dx(3)=b+(x(3)*(x(1)-c));
end