%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%
% private_FUNK -- Hey, i didn't name it. J.Chandler did. This is the little
%                 file that provides input as to what function you are 
%                 trying to minimize
% 
%                 -called by STEPIT to compute FOBJ
%
%  Note this is an example file, to be modified with each problem
%
%  This version of FUNK computes the fitted values and the weighted sum
%  of squares for the problem of fitting the model:
%
%  FIT(J) = X(1)/(1.0 + X(2)*T(J,1) + X(3)*T(J,2))
%  
%  to data points (T(J,1),T(J,2),Y(J))
%
%  Modify matrices T or Y or whatever as needed in this file and in STEPITDRIVER2 file
%
%  Ported to Matlab by Jason Lott, University of Alabama at Birmingham
%  CONTACT:hoffa@uab.edu
%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

function a = private_FUNK(b)								


global X
global FOBJ
global NPTS
global Y
global T
global YSIG


FITM = zeros(NPTS,1)	;									%Same size as our number of points

FOBJ = 0.0D0;

for J=1:NPTS
   
   
FITM(J) = X(1)/(1.0D0+X(2)*T(J,1) + X(3)*T(J,2));
FOBJ = FOBJ + ((FITM(J) -Y(J))/YSIG(J))^2;
  
end