Problem in ode15s, undefined function for input arguments of type double

I am trying to use ode15s on a time-variant dynamic system. When i try to run my script i get the following error:

Error using feval

Undefined function 'leading_vehicle.m' for input arguments of type 'double'.

Error in odearguments (line 88)

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

Error in ode15s (line 149)

[neq, tspan, ntspan, next, t0, tfinal, tdir, y0, f0, odeArgs, odeFcn, ...

Error in simulation (line 3)

[t, q_i_1]=ode15s('leading_vehicle.m', tspan, leading_initial);

The function leading_vehicle.m is in the current directory of matlab, so thats definitely not the case of my problem. My code is the following:

function Dq = leading_vehicle( t, q )
  Dq=[u(t)*cos(q(3)); u(t)*sin(q(3)); (1/a)*tan(g(t))*u(t)];
end

    function fa=u(t)
        fa=t;
    end

    function fb=g(t)
        fb=0*t;
    end

tspan=[0 20];

leading_initial=[3; 0; 0]; %initial conditions of leading vehicle

[t, q_i_1]=ode15s('leading_vehicle.m', tspan, leading_initial);

[David Goodmanson]

Hi John, aside from a possible misspelling error, looks like Matlab can't find the function either on the Matlab path or in the current directory. Have you tried, just before your ode15s call, "cd" and "dir *.m" ?

Answer 1

[James Tursa]

Try giving a function handle to oce15s instead of a character string file name. E.g.,

[t, q_i_1]=ode15s(@leading_vehicle, tspan, leading_initial);

Answer 2

[Walter Roberson]

Do not include the .m in the string.

[t, q_i_1]=ode15s('leading_vehicle', tspan, leading_initial);