Not enough input arguments ode45

Hi all, I have been trying to understand the use of ode solvers in MATLAB. In the process, I started with first order equations and all went well. The moment I started trying out second order systems, the trouble started. When I run the code, it shows 'not enough input arguments'. I thought that it may the problem with my code and then I started trying codes given as example in text books (Otto&Denier etc.). For every code, every time I run, the same issue pops up. And the code seems to be correct. Please help me to sort it out. I have attached the screenshot of the error message.

">> lorenz Error using lorenz (line 5) Not enough input arguments." This was a code I chose from a text book.

    if true
      % code
function dx=lorenz(t,x)
sigma=10;
rho=28;
beta=8/3;
dx=[sigma*(x(2)-x(1));x(1)*(rho-x(3)-x(2));x(1)*x(2)-beta*x(3)];
x0=[0 1 1.05];
tspan=[0,20];
[t,x]=ode45(@lorenz,tspan,x0);
plot(x(:,1),x(:,3))

    end

Answer 1

[Massimo Zanetti]

Separate the funciton from the rest

function dx=lorenz(t,x)
  sigma=10;
  rho=28;
  beta=8/3;
  dx=[sigma*(x(2)-x(1));x(1)*(rho-x(3)-x(2));x(1)*x(2)-beta*x(3)];
end

and invoke ode45 correctly

x0=[0 1 1.05];
tspan=[0,20];
[t,x]=ode45(@(t,x) lorenz(t,x),tspan,x0);
plot(x(:,1),x(:,3))

Does it work now?

[Vipin Padinjarath]

It shows a new error now!

>> lorenz

Error: File: lorenz.m Line: 8 Column: 1 This statement is not inside any function. (It follows the END that terminates the definition of the function "lorenz") Line 8 is the initial condition vector.

[Massimo Zanetti]

The function "lorents" must be into a separate file than the other piece of code....

[Vipin Padinjarath]

Yes! It is running now.Thank you very much.

[Vipin Padinjarath]

I am sorry, I know that I am troubling you. But please help me with the following code. This i wrote by myself. (Rossler equations)

Function definition

if true
  % function dR=RH(t,x,y,z)
dR=zeros(3,1);
dR(1)=-(y+z);
dR(2)=(x+2*y);
dR(3)=(1+z(x-3));
end

end
Solution

        if true
          s0=[1 1 1];
tspan=[0 50];
[t,x,y,z]=ode45(@(t,x,y,z)RH(t,x,y,z),tspan,s0);
plot3(t,x,y,z)

        end