delta.sci

基于SCILAB的The Genetic Algorithm Toolbox for SCILAB (GATS)工具箱

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));
end
change = y*(rand()*(1-r))^b;