%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 
% function sample_half() : Reduces a matrix by 1/2.
%			   Odd columns are removed.
% INPUT : m x n matrix.
% OUTPUT: m x n/2 matrix
% 
% Author: Jason Tate June 10, 1998
%         tate@edcenter.sdsu.edu
%
% Educational Center for Computational Science & Engineering
% http://www.edcenter.sdsu.edu
%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

function sampled = sample_half(ElevationMatrix)

 % DETERMINE DIMENSIONS OF MATRIX
	Dimensions =  size(ElevationMatrix);
	numRows = Dimensions(1);
	numColumns = Dimensions(2);

 % INIT 'SAMPLED' MATRIX	
	sampled = zeros(numRows,floor(numColumns/2) );

 sampled_index = 1;

 % GO THRU EVERY COLUMN OF ELEVATIONMATRIX AND... 
 for j = 1:numColumns
	% SAMPLE EVEN NUMBERED COLUMNS ONLY
	if (mod(j,2) == 0)
	  sampled(:,sampled_index) = ElevationMatrix(:,j);
          sampled_index = sampled_index + 1;
	end	
 end