Find the value of a and k that minimise RMSE

Hello,I am trying to find the value of a and k that minimise my function RMSE,I have input the following code,can I just asked where have I got wrong since Matlab asked me to have more arguments for some reason?

    %lightprog
    function RMSE=lightprog(V)
    k=V(1);a=V(2)
    stimulus=[2 4 6 8 10 12]
    data=[1.1 1.5 2.1 2.5 2.9 3.2]
    modelS=k*(stimulus.^a);
    RMSE=sqrt(mean(modelS-data).^2)
    return
    [k,a]=fminsearch('lightprog',[0,0])

Answer 1

[Ben Drebing]

The function needs to be defined at the bottom of the file, if you would like to run your code in this way. Try:

 [k,a]=fminsearch(@lightprog,[0,0])
 function RMSE=lightprog(V)
    k=V(1);a=V(2)
    stimulus=[2 4 6 8 10 12]
    data=[1.1 1.5 2.1 2.5 2.9 3.2]
    modelS=k*(stimulus.^a);
    RMSE=sqrt(mean(modelS-data).^2)
    return
 end