MATLAB: Fminsearch with part of input function

Question

hello,

i have defined a function that is model, and want to use a fminsearch for a first value for the lsqnonlin,but i get all the time "Assignment has more non-singleton rhs dimensions than non-singleton subscripts" also in the error it says fv(:,1) = funfcn(x,varargin{:}); the model_error is the output to optimise

my code:

        param0=[1, 50];
        param0=fminsearch(@(param) Model(param,t,inlet_signal,outlet_signal),param0);
function [error_model,h]= dispmodel_2param(param,t,x,y)
            theta = t/param(2);
            h = (sqrt(param(1)./(4*pi*theta)).*exp(-param(1)./(theta*4).*(1-theta).^2));
            h(1) = 0;
            y=[y;y(end)*zeros((length(E_theta)+length(x)-1)-length(y),1)];
            error_model= y-conv(h/param(2),x);
end

Answer 1

No matter whether t, inlet_signal and outlet_signal are scalars or vectors, your line

            y=[y;y(end)*zeros((length(E_theta)+length(x)-1)-length(y),1)];

is making y into a vector at that point. Then your error_model would be a vector because it involves y.

When you use fminsearch there is a single output for the function, and it must return a scalar.

The form you are using appears to have been designed for use with lsqnonlin, which expects the individual predictions to be returned rather than a sum-of-squares . lsqnonlin internally does the equivalent of sum( (fun(Param) - y).^2 ) but fminsearch does not.