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% OBJFUN1.M      (OBJective function for De Jong's FUNction 1) 
% 
% This function implements the De Jong function 1. 
% 
% Syntax:  ObjVal = objfun1(Chrom,switch) 
% 
% Input parameters: 
%    Chrom     - Matrix containing the chromosomes of the current 
%                population. Each row corresponds to one individual's 
%                string representation. 
%                if Chrom == [], then special values will be returned 
%    switch    - if Chrom == [] and 
%                switch == 1 (or []) return boundaries 
%                switch == 2 return title 
%                switch == 3 return value of global minimum 
% 
% Output parameters: 
%    ObjVal    - Column vector containing the objective values of the 
%                individuals in the current population. 
%                if called with Chrom == [], then ObjVal contains 
%                switch == 1, matrix with the boundaries of the function 
%                switch == 2, text for the title of the graphic output 
%                switch == 3, value of global minimum 
%                 
 
% Author:     Hartmut Pohlheim 
% History:    26.11.93     file created 
%             27.11.93     text of title and switch added 
%             30.11.93     show Dim in figure title 
%             16.12.93     switch == 3, return value of global minimum 
%             01.03.94     name changed in obj* 
 
function ObjVal = objfun1(Chrom,switch); 
 
% Dimension of objective function 
   Dim = 20; 
    
% Compute population parameters 
   [Nind,Nvar] = size(Chrom); 
 
% Check size of Chrom and do the appropriate thing 
   % if Chrom is [], then define size of boundary-matrix and values 
   if Nind == 0 
      % return text of title for graphic output 
      if switch == 2 
         ObjVal = ['DE JONG function 1-' int2str(Dim)]; 
      % return value of global minimum 
      elseif switch == 3 
         ObjVal = 0; 
      % define size of boundary-matrix and values 
      else    
         % lower and upper bound, identical for all n variables         
         ObjVal = 100*[-5.12; 5.12]; 
         ObjVal = ObjVal(1:2,ones(Dim,1)); 
      end 
   % if Dim variables, compute values of function 
   elseif Nvar == Dim 
      % function 1, sum of xi^2 for i = 1:Dim (Dim=30) 
      % n = Dim, -5.12 <= xi <= 5.12 
      % global minimum at (xi)=(0) ; fmin=0 
      ObjVal = sum((Chrom .* Chrom)')'; 
      % ObjVal = diag(Chrom * Chrom');  % both lines produce the same 
   % otherwise error, wrong format of Chrom 
   else 
      error('size of matrix Chrom is not correct for function evaluation'); 
   end    
 
 
% End of function