How to fit my data to interpolated functions

Hi all,

I need to do a complex fit of a power-law plus a few Gaussians (and no problem until here) but I have to add a different function coming from an array of x-y points downloaded from people who made numerical simulations. These five functions are given by the following five x-y couples x1,y1 etc...

This is how my model look like, but I get errors as it seems it can't read the variables x1,y1,x2,y2 etc

It says "??? Unrecognized function or variable 'x1' "

Anyone please know how I can do this?

Thanks in advance

mod=fittype(['F0*x^alpha' ...                                     %powerlaw    
    '+A1b*exp(-((x-c1b)^2)/(2*s1b^2))' ...                        %gauss1b
    '+A1n*exp(-((x-c1n)^2)/(2*s1n^2))' ...                        %gauss1n
    '+A2n*exp(-((x-c2n)^2)/(2*s2n^2))' ...                        %gauss2n
    '+A2o*exp(-((x-c2o)^2)/(2*s2o^2))' ...                        %gauss2out
    '+A3n*exp(-((x-c3n)^2)/(2*s3n^2))' ...                        %gauss3n
    '+A3o*exp(-((x-(c3n-(c2n-c2o)))^2)/(2*s3o^2))'...             %gauss3out
    '+k1*interp1(x1,y1,x)' ...                                    %interpolated func 1
    '+k2*interp1(x2,y2,x)' ...                                    %interpolated func 2
    '+k3*interp1(x3,y3,x)' ...                                    %interpolated func 3
    '+k4*interp1(x4,y4,x)' ...                                    %interpolated func 4
    '+k5*interp1(x5,y5,x)' ...                                    %interpolated func 5
    ],...
    'independent','x', ...
    'coefficients',{'F0','alpha', ...
    'A1b','c1b','s1b',...
    'A1n','c1n','s1n',...
    'A2n','c2n','s2n',...
    'A2o','c2o','s2o',...
    'A3n','c3n','s3n',...
    'A3o','s3o',...
    'k1','k2','k3','k4','k5',...
     });

Answer 1

[Steven Lord]

Rather than defining your function as a large piece of text, I would define it as a function as per the "Fit a Curve Defined by a File" example on the fittype documentation page. I'd also either define your x1, x2, etc. variables inside that function or (if you want to be able to change them without having to modify the code) define them as problem parameters and specify their values in your call to the fit function.

[Roberto Serafinelli]

Thank you! This solution worked!