function[change] = delta(ct,mt,y,b)// The delta function is the non-uniform distributions used by the nonUniform// mutations.  This function returns a change based on the current gen, the// max gen and the amount of possible deviation.//// function[change] = delta(ct,mt,y,b)// ct - current generation// mt - maximum generation// y  - maximum amount of change, i.e. distance from parameter value to bounds// b  - shape parameter// Binary and Real-Valued Simulation Evolution for Matlab // Copyright (C) 1996 C.R. Houck, J.A. Joines, M.G. Kay //// C.R. Houck, J.Joines, and M.Kay. A genetic algorithm for function// optimization: A Matlab implementation. ACM Transactions on Mathmatical// Software, Submitted 1996.//// This program is free software; you can redistribute it and/or modify// it under the terms of the GNU General Public License as published by// the Free Software Foundation; either version 1, or (at your option)// any later version.//// This program is distributed in the hope that it will be useful,// but WITHOUT ANY WARRANTY; without even the implied warranty of// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the// GNU General Public License for more details. A copy of the GNU // General Public License can be obtained from the // Free Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.r=ct/mt;if(r>1)  r=.99;  // disp(sprintf('max gen %d < current gen %d setting ratio = 1',mt,ct));endchange = y*(rand()*(1-r))^b;