function out=residfn(x)
%This function takes in the guesses for the fitting parameters and returns
%the sum of the square of the residuals.  The data is passed in using the
%global command:

global datapass

data=datapass;
t=data(:,1);
ca=data(:,2);
resid=ca-1.0./(x(1)+x(2)*t);
out=resid'*resid;