% RECOMBIN.M       (RECOMBINation high-level function)
%
% This function performs recombination between pairs of individuals
% and returns the new individuals after mating. The function handles
% multiple populations and calls the low-level recombination function
% for the actual recombination process.
%
% Syntax:  NewChrom = recombin(REC_F, OldChrom, RecOpt, SUBPOP)
%
% Input parameters:
%    REC_F     - String containing the name of the recombination or
%                crossover function
%    Chrom     - Matrix containing the chromosomes of the old
%                population. Each line corresponds to one individual
%    RecOpt    - (optional) Scalar containing the probability of 
%                recombination/crossover occurring between pairs
%                of individuals.
%                if omitted or NaN, 1 is assumed
%    SUBPOP    - (optional) Number of subpopulations
%                if omitted or NaN, 1 subpopulation is assumed
%
% Output parameter:
%    NewChrom  - Matrix containing the chromosomes of the population
%                after recombination in the same format as OldChrom.
%
%  Author:    Hartmut Pohlheim
%  History:   18.03.94     file created
%             22.01.03     tested under MATLAB v6 by Alex Shenfield
%                          (NOTE : doesn't work with low level recmut.m)

function NewChrom = recombin(REC_F, Chrom, RecOpt, SUBPOP);

% Check parameter consistency
   if nargin < 2, error('Not enough input parameter'); end

   % Identify the population size (Nind)
   [Nind,Nvar] = size(Chrom);
 
   if nargin < 4, SUBPOP = 1; end
   if nargin > 3,
      if isempty(SUBPOP), SUBPOP = 1;
      elseif isnan(SUBPOP), SUBPOP = 1;
      elseif length(SUBPOP) ~= 1, error('SUBPOP must be a scalar'); end
   end

   if (Nind/SUBPOP) ~= fix(Nind/SUBPOP), error('Chrom and SUBPOP disagree'); end
   Nind = Nind/SUBPOP;  % Compute number of individuals per subpopulation

   if nargin < 3, RecOpt = 0.7; end
   if nargin > 2,
      if isempty(RecOpt), RecOpt = 0.7;
      elseif isnan(RecOpt), RecOpt = 0.7;
      elseif length(RecOpt) ~= 1, error('RecOpt must be a scalar');
      elseif (RecOpt < 0 | RecOpt > 1), error('RecOpt must be a scalar in [0, 1]'); end
   end

% Select individuals of one subpopulation and call low level function
   NewChrom = [];
   for irun = 1:SUBPOP,
      ChromSub = Chrom((irun-1)*Nind+1:irun*Nind,:);  
      NewChromSub = feval(REC_F, ChromSub, RecOpt);
      NewChrom=[NewChrom; NewChromSub];
   end

% End of function