% CRTRP.M        (CReaTe an initial (Real-value) Population)
%
% This function creates a population of given size of random real-values. 
%
% Syntax:       Chrom = crtrp(Nind,FieldDR);
%
% Input parameters:
%    Nind      - A scalar containing the number of individuals in the new 
%                population.
%
%    FieldDR   - A matrix of size 2 by number of variables describing the
%                boundaries of each variable. It has the following structure:
%                [lower_bound;   (vector with lower bound for each veriable)
%                 upper_bound]   (vector with upper bound for each veriable)
%                [lower_bound_var_1  lower_bound_var_2 ... lower_bound_var_Nvar;
%                 upper_bound_var_1  upper_bound_var_2 ... upper_bound_var_Nvar]
%                example - each individuals consists of 4 variables:
%                FieldDR = [-100 -50 -30 -20;   % lower bound
%                            100  50  30  20]   % upper bound
%              
% Output parameter:
%    Chrom     - A matrix containing the random valued individuals of the
%                new population of size Nind by number of variables.
%
% Author:     Hartmut Pohlheim
% History:    23.11.93     file created
%             25.02.94     clean up, check parameter consistency
%             20.01.03     tested under MATLAB v6 by Alex Shenfield

function Chrom = crtrp(Nind,FieldDR);

% Check parameter consistency
   if nargin < 2, error('parameter FieldDR missing'); end
   if nargin > 2, nargin = 2; end

   [mN, nN] = size(Nind);
   [mF, Nvar] = size(FieldDR);

   if (mN ~= 1 & nN ~= 1), error('Nind has to be a scalar'); end
   if mF ~= 2, error('FieldDR must be a matrix with 2 rows'); end

% Compute Matrix with Range of variables and Matrix with Lower value
   Range = rep((FieldDR(2,:)-FieldDR(1,:)),[Nind 1]);
   Lower = rep(FieldDR(1,:), [Nind 1]);

% Create initial population
% Each row contains one individual, the values of each variable uniformly
% distributed between lower and upper bound (given by FieldDR)
   Chrom = rand(Nind,Nvar) .* Range + Lower;


% End of function