Minimizing Chi-Squared Function in MATLAB

[aymer]

Homework Statement

I am using MATLAB to minimize a sum of squares (chi-squared) function. My model has a definite integral (from zero to data values).The model has three parameters w.r.t which I need to minimize.

2. relevant equations
*I need to integrate (1+x).^(b-a-2).* exp(-b.*x) from zero to z(i), where a and b *are parameters.

The Attempt at a Solution

I make a function handle
>> modelfun1=@ (y,a,b,c) (978.4./c).*int( (1+x).^(b-a-2).* exp(-b.*x),0,y)
and then a sum of squares function as
>> sum1=@(a,b,c,data) sum(((data.ydata-modelfun1(data.xdata,a,b,c)).^2)./data.zdata.^2);
where data.xdata has all the z values,data.ydata are the observed values and data.zdata are the variances.
when I minimize this function using fminsearch
>> [tmin,ssmin]=fminsearch(sum1,[-0.1;0.06;70],[],data)
i get the following error

Error using @(a,b,c,data)sum(((data.ydata-modelfun1(data.xdata,a,b,c)).^2)./data.zdata.^2)
Not enough input arguments.

Error in fminsearch (line 191)
fv(:,1) = funfcn(x,varargin{:});

can someone please point out what I am doing wrong. I have tried many more things but this seems to be the most recurring error.

thankyou

 

[Mindscrape]

Is data a structure with vectors or are they symbols? I'm guessing your problem is with your structure either way.

 

[aymer]

The data is a vector of observed values at different z's. All the three data vectors i.e data.xdata, data.ydata and data.zdata are 32X1 matrices