www.pudn.com > GA_Toolbar.rar > GADEMO1.M, change:1997-04-07,size:3954b

% GADEMO1 clf; figure(gcf); more on echo on clc % ========================================================== % GADEMO 1 % ========================================================== % INITIALIZE - Initialize a populutaton of solutions % GA - Simulates evolution pause % Strike any key for the introduction to Genetic Algorithms clc % Genetic algorithms % A genetic algorithm is a simulation of evolution where the % rule of survival of the fittest is applied to a population % of individuals. % The basic genetic algorithm is as follows: % 1. Create an initial population (usually a randomly % generated string) % 2. Evaluate all of the individuals (apply some function % or formula to the individuals) % 3. Select a new population from the old population based % on the fitness of the individuals as given by the % evaluation function. % 4. Apply some genetic operators (mutation & crossover) % to members of the population to create new solutions. % 5. Evaluate these newly created individuals. % 6. Repeat steps 3-6 (one generation) until the % termination criteria has been satisfied (usually % perform for a certain fixed number of generations) % % Let's look at an example pause % Strike any key to define the problem... clc % Let's consider the maximization of the following function: % f(x) = x + 10*sin(5*x)+7*cos(4*x) over the interval (0,9) % This may take several minutes... fplot('x + 10*sin(5*x)+7*cos(4*x)',[0 9]) % Done! % Now, let's set up a genetic algorithm to find the maximum % of this problem. First, we need to create the evaluation % function .m file, here is gademo1eval1.m pause % Strike any key to look at gademo1eval1.m % type gademo1eval1.m pause % Strike any key to continue clc % Note that the evaluation function must take two parameters, % sol and options. Sol is a row vector of n+1 elements where % the first n elements are the parameters of interest. The % n+1'th element is the value of this solution. The options % matrix is a row matrix of % [current generation, eval options] % The eval function must return both the value of the sting, % val and the string itself, sol. This is done so that % your evaluation can repair and/or improve the string. pause % Strike any key to continue clc % Now that we have defined the evaluation function, we now % have to create an initial population. The most common way % to generate an initial population is to randomly generate % solutions within the range of interest, in this case 0-9. % The initialize routine will do this for you. pause % Strike any key for help on initialize clc help initialize pause % Strke any key to continue. clc % Let's create a random starting popluation of size 10. initPop=initialize(10,[0 9],'gademo1eval1'); pause % Strike any key to continue. % We can now take a look at this population. hold on plot (initPop(:,1),initPop(:,2),'g+') pause % Strike any key to continue clc % We can now run the evolutionary procedure on this % population. help ga pause % Strike any key to continue % Now let's run the ga for one generation. [x endPop] = ga([0 9],'gademo1eval1',[],initPop,[1e-6 1 1],'maxGenTerm',1,... 'normGeomSelect',[0.08],['arithXover'],[2],'nonUnifMutation',[2 1 3]); x %The best found %And plot the resulting the resulting population plot (endPop(:,1),endPop(:,2),'ro') pause % Strike any key to continue % Now let's run the ga for 25 generations [x endPop] = ga([0 9],'gademo1eval1',[],initPop,[1e-6 1 1],'maxGenTerm',25,... 'normGeomSelect',[0.08],['arithXover'],[2],'nonUnifMutation',[2 1 3]); x %The best found % And plot the resulting the resulting population plot (endPop(:,1),endPop(:,2),'y*') % End of gademo1