WHY do I get this error

function dydt = free25(t,y);

g = 9.81;

l = 1;

dydt = [y(2);-g/l.*sin(y(1))];

end

[t,y]= ode45('free25',[0 10],[0 0.09]);%I typed this in command window

plot(t,y(:,1));

refline([0 0]);

Error using feval Undefined function 'free25' for input arguments of type 'double'.

Error in odearguments (line 87) f0 = feval(ode,t0,y0,args{:}); % ODE15I sets args{1} to yp0.

Error in ode45 (line 115) odearguments(FcnHandlesUsed, solver_name, ode, tspan, y0, options, varargin);

Answer 1

[Mischa Kim]

mahesh, is the above code all in one and the same script? If it is modify like this:

 [t,y]= ode45(@free25,[0 10],[0 0.09]);%I typed this in command window
 plot(t,y(:,1))

 function dydt = free25(t,y)
 g = 9.81;
 l = 1;
 dydt = [y(2);-g/l.*sin(y(1))];
 end

Another option would be to store the first part of the script (first two commands) in one function and the second part in a different function. For this second option make sure you name the file the same way you name the function: free25.m

[mahesh tom]

no..i have saved free25 as a separate .m file

[Mischa Kim]

OK. Name of the file needs to be free25.m. In the command window type

 [t,y] = ode45(@free25,[0 10],[0 0.09]);%I typed this in command window

and make sure the file is in the current folder (see folder window in MATLAB) or on in a folder that is in the MATLAB search path.

[mahesh tom]

Thank you! The problem was that the file was not on the MATLAB search path!

[asavra siddiqui]

I have the same problem with my code how can I put it on MATLAB search path