MATLAB: Index exceeds matrix dimensions when solving for ODE system.

Question

Hi. Im trying to solve this system of equation. But it gives me this error. What does it mean and how to solve this? Thank you.

function dphidz = Pphiode(z,phi,Ro,Eta,Lambda)
Co=2.0-Ro-Ro^2; % Coriolis number
dphidz = [phi(2)
Ro.*(phi(1)^2+phi(2).*phi(5)-phi(3)^2+1)-Co*(phi(3)-1.0)
phi(4)
Ro*(2.0*phi(1)*phi(3) + phi(4)*phi(5))+Co*phi(1)
-2.0*phi(1)];
end

Error:

Trial>> Pphiode(20,2,-1,1,1)
Index exceeds matrix dimensions.
  Error in Pphiode (line 3)
  dphidz = [phi(2)

Let say

z=12, phi=1, R0=-1, Eta=0, Lambda=1

Answer 1

The input

phi = 1 ;

should be a vector with elements 5. Try with:

phi = rand(5,1) ;