Duffing Oscillator issue. "Keep getting Unable to perform assignment because the left and right sides have a different number of elements."

The Duffing Oscillator is as follows:

To do this, we have to use the Euler-Cromer method to solve, which follows the following syntax:

and

My code is as follows:

clc;

T=10;

N=1000;

deltat=T/N;

omega=1.2;

alpha=1.5;

beta=0;

delta=0;

gamma=0;

x=[N 1];

y=[N 1];

t=[N 1];

x(1)=0;

y(1)=0;

x2=[N 1];

y2=[N 1];

x2(1)=x(1);

y2(1)=y(1);

t(1)=0;

for n=1:N

x(n+1)=x(n)+y(n)*deltat;

y(n+1)=y(n)+deltat*(gamma*cos(omega*t)-delta*x(n)-alpha*x(n+1)-beta*x(n+1).^3);

x2(n+1)=x2(n)+y2(n)*deltat;

y2(n+1)=y2(n)-k*y2(n)*deltat-(omega^2)*cos(x2(n+1))*deltat;

t(n+1)=t(n)+deltat;

end

figure(1)

plot(t,x);

hold on;

plot(x,y);

I just keep getting "Unable to perform assignment because the left and right sides have a

different number of elements." For the line which I went ahead and bolded

I've never used the Euler-Cromer method before, so maybe I'm doing something wrong, but honestly am not sure. Help would be much appreciated!

Answer 1

[James Tursa]

t is a vector, so your cos(omega*t) is a vector. You need to use cos(omega*t(n)) there.