Need to fix error "index exceeds the number of array elements"

Dear friends, please guide me to solve the following problem

function xdot=func(t,w,x)
xdot(1)=x(2);
xdot(2)=-(w^2)*x(1);
xdot=xdot';

i need to code this differential equation and obtain solution and plot a graph of it. But the most common error i get is "index exceeds the number of array elements" which appears after i try to execute the following command:

[t,w,x]=ode45(@(t,x) func(t,w,x), tspan, x0);  

please note w is a parameter in this system and i have already given values of w, tspan and x0.

it also says:

Error in func (line 2)

xdot(1)=x(2);

Thats all, I would appreciate if someone can help me out on this. Thanks

Answer 1

[Image Analyst]

Your x is probably a scalar, not a two element array. If, before that line you put

whos x

what does it show in the command window?

Answer 2

[Star Strider]

The added parameter must be the third (or greater) argument:

function xdot=func(t,x,w)

and the ode45 call will then be:

[t,x]=ode45(@(t,x) func(t,x,w), tspan, x0);

I did not run your code because I am not certain what ‘w’ is. (It appears to ba a scalar.)