Differential equation using ode113

I have made a code for non-linear oscillator and used it solution x(t) in the coupled differential equation.see the code is it right. Some one please help.

[darova]

I reduced you time vector

tx = [0 1];    % Time vector

and succeeded

[abhishek singh]

I written that code from pdf file i have given. I am asking about the code is it right or not and I want to rescale the time is there any way to do that.

[darova]

The code for equations in PDF is correct

[abhishek singh]

sumation of cos(n \Omega t) I have written is correct. I want to rescale time for lage value is it possible.

[abhishek singh]

When I am giving time t=[0:1:20] the value of s1 is different then when I provide t=[0:0.1:20] what is the problem in code.

[abhishek singh]

I have checked the value of s1(:,1)