Please some one should help me traces this error in my code of system of o.d.e. The Matlab give me these error ''Error using kennie>loren Too many input arguments. '''

 function kennie
 global a k
 a=4;
 k=4;
y0=[0 1 0 0];
[T,Y]=ode45(@loren,[0,10],y0,0.01,0.1);
disp([T,Y])

figure(1); plot(T,Y)

function dy=loren(t,y)
 global a k
 dy=zeros(4,1);
for j=1:k
    for i=1:a

dy(1)=y(2);
dy(2)=y(3);
dy(3)=y(4);
dy(4)=(1/(k(j)+a(i)).^4)*y(3)-(2/(k(j)+a(i)))*y(4)-(1/(k(j)+a(i)).^3).*y(2)+(k(j)./(k(j)+a(i)).^3).*y(1).*y(2)-(k(j)./(k(j)+a(i))).*y(1).*y(4)+((k(j)./(k(j)+a(i)))).*y(2).*y(3)-(k(j)./(k(j)+a(i))).*y(1).*y(3)+(k(j)./(k(j)+a(i)).^2).*(y(2)).^2;

      end
  end

[Torsten]

a(i) and k(j) are not defined because a and k are scalars in your code (a=4 and k=4), not arrays.

Best wishes

Torsten.

[Abdulaziz Garba Ahmad]

I try but still did not work out for me.

function kennie
 global a k
 a=0:10;
 k=0:10:50;
y0=[0 1 0 0];
[T,Y]=ode45(@loren,[0,10],y0);
%disp([T,Y]);

figure(1); plot(T,Y,'-.')

function dy=loren(t,y)
 global a k

   dy=zeros(4,1);
   for j=0:length(k)
      for i=0:length(a)
  dy(1)=y(2);
  dy(2)=y(3);
  dy(3)=y(4);
  dy(4)=(1./(k(j)+a(i)).^2).*y(3)-(2./(k(j)+a(i))).*y(4)-(1./((k(j)+a(i))).^3).*y(2)+(k(j)./(k(j)+a(i)).^3).*y(1).*y(2)-(k(j)./(k(j)+a(i))).*y(1).*y(4)+((k(j)./(k(j)+a(i)))).*y(2).*y(3)-(k(j)./(k(j)+a(i)).^2).*y(1).*y(3)+(k(j)./(k(j)+a(i)).^2).*y(2).^2;

      end

   end

[Walter Roberson]

Your code starts j at 0, and uses k(j) which is an attempt to access k(0) which is not permitted in MATLAB.

Remember, 0:length(k) is length(k)+1 total values so if you are using that as a subscript you need to expect you are going to be trying to index either before the beginning of k or after the end of k.

[Abdulaziz Garba Ahmad]

Thank you very much

[Stephen23]

@Abdulaziz Garba Ahmad: Note that using global variables is not recommended (they are slow, and increase the risk of bugs). To parametrize a function you should use either an anonymous function or nested functions, as described in the MATLAB documentation:

https://www.mathworks.com/help/matlab/math/parameterizing-functions.html

Both of these would be faster and less buggy than using global:

https://blogs.mathworks.com/videos/2010/03/08/top-10-matlab-code-practices-that-make-me-cry/

In your case you can easily change the function definition (removing global):

function dy = loren(t,y,a,k)
dy = zeros(4,1);
for j=0:length(k)
    for i=0:length(a)
        ...
    end
end

and then call it with

a = 4;
k = 4;
[T,Y] = ode45(@(t,y)loren(t,y,a,k), [0,10], y0, 0.01, 0.1);

Thus you easily avoid ugly and buggy globals!

[Torsten]

Why do you use the loop in function "loren" ?

You permanently overwrite the setting for dy(4) until in the end, you use k(length(k)) and a(length(a)) in its definition.

Best wishes

Torsten.

[Abdulaziz Garba Ahmad]

Thank you