You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: objfun7.m
    path of file: ./repos/GA-Toolbox/Test_fns
    
    the code of the file until where you have to start completion: % OBJFUN7.M      (OBJective function for schwefel's FUNction)
%
% This function implements the SCHWEFEL function 7.
%
% Syntax:  ObjVal = objfun7(Chrom,rtn_type)
%
% Input parameters:
%    Chrom     - Matrix containing the chromosomes of the current
%                population. Each row corresponds to one
%                individual's string representation.
%                if called with Chrom == [], then boundaries of
%                the function or title for figure will be returned
%    rtn_type  - if Chrom == [] and rtn_type == 1 (or []) then return
%                boundaries, if rtn_type == 2 return title
%
% Output parameters:
%    ObjVal    - Column vector containing the objective values of the
%                individuals in the current population.
%                if called with Chrom == [], then ObjVal contains
%                the matrix with the boundaries of the function or
%                the Text for the title of the graphic output
%                
%
% Author:     Hartmut Pohlheim
% History:    27.11.93     file created
%             30.11.93     show Dim in figure title
%             01.03.94     name changed in obj*
%             14.01.03     updated for MATLAB v6 by Alex Shenfield

function ObjVal 
    
function for schwefel's FUNction)
%
% This function implements the SCHWEFEL function 7.
%
% Syntax:  ObjVal = objfun7(Chrom,rtn_type)
%
% Input parameters:
%    Chrom     - Matrix containing the chromosomes of the current
%                population. Each row corresponds to one
%                individual's string representation.
%                if called with Chrom == [], then boundaries of
%                the function or title for figure will be returned
%    rtn_type  - if Chrom == [] and rtn_type == 1 (or []) then return
%                boundaries, if rtn_type == 2 return title
%
% Output parameters:
%    ObjVal    - Column vector containing the objective values of the
%                individuals in the current population.
%                if called with Chrom == [], then ObjVal contains
%                the matrix with the boundaries of the function or
%                the Text for the title of the graphic output
%                
%
% Author:     Hartmut Pohlheim
% History:    27.11.93     file created
%             30.11.93     show Dim in figure title
%             01.03.94     name changed in obj*
%             14.01.03     updated for MATLAB v6 by Alex Shenfield

function ObjVal = objfun7(Chrom,rtn_type);

% 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 rtn_type == 2
         ObjVal = ['SCHWEFELs function 7-' int2str(Dim)];
      % return value of global minimum
      elseif rtn_type == 3
         xmin = 420.9687;
         ObjVal = Dim * (-xmin * sin(sqrt(abs(xmin))));
      % define size of boundary-matrix and values
      else   
         % lower and upper bound, identical for all n variables        
         ObjVal = [-500; 500];
         ObjVal = ObjVal(1:2,ones(Dim,1));
      end