What argument is Missing from this Function?

I'm getting the 'Not Enough Input Arguments' error on my function and I can't for the life of me figure out why? Can someone point out what I'm missing?

function dtheta = nonlin_function(t,t_1,Theta)

if t>=(ceil(t/t_1)-1)*t_1 && t<=(ceil(t/t_1)-1)*t_1+t_1
    F = (5/t_1)*(t-(ceil(t/t_1)-1)*t_1);
elseif t>=(ceil(t/t_1)-1)*t_1
    F = 5;
end

dtheta = zeros(2,1);
dtheta(1) = Theta(2);
dtheta(2) = (666.67*(F-(((1*10^-4)*(cos(Theta(1))*cos(Theta(1)))+(10^-3))*Theta(2))-((0.01)*sin(Theta(1))*cos(Theta(1)))-(0.5*Theta(1))));

[per isakson]

Not without knowing how you call the function. And seeing the full error message would help.

Answer 1

[Walter Roberson]

From the look of that you likely calling this from ode45 . The normal calling sequence for a function called by ode45 is name(t, y) though possibly with different names. In your situation it appears to me that would be nonlin_function(t, Theta) . Notice only two arguments are passed by default -- but your function is expecting three parameters. It appears that t_1 is the extra one that is not normally passed.

You should read http://www.mathworks.com/help/matlab/math/parameterizing-functions.html

However, if I am correct that this is being called from one of the ode* routines, then your function is discontinuous in some circumstances, which is not permitted. For example for t = 0.01 then the function is discontinuous at 0.1 2.06 2.08 2.1 2.12 2.14 2.16 2.18 2.2 2.33 2.35 2.37 2.39 2.41 2.43 2.45 2.58 2.6 2.62 2.64 2.66 2.68 2.7 2.72 2.74 2.83 2.85 2.87 2.89 2.91 2.93 2.95 2.97 2.99 3.1 3.12 3.14 3.16 3.18 3.2 3.22 3.24 3.35 3.37 3.39 3.41 3.43 3.45 3.47 3.49 3.6 3.62 3.64 3.66 3.68 3.7 3.72 3.74 3.85 3.87 3.89 3.91 3.93 3.95 3.97 3.99 4.11 4.15 4.4 4.65 4.9 . You must create an event function to detect the change in smoothness of F and to stop the integration there, and then to restart on the other side of the boundary using the last output of the previous step as the new starting time and new initial conditions.