使用Matlab实现一个GA算法求解极值的函数:f = -200*exp(-0.05*x)*sin(x);求解区间[-2, 2]并将源代码和实验结果粘贴在下方。
时间: 2024-04-21 10:25:20 浏览: 104
用MATLAB求极值
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好的,以下是使用Matlab实现GA算法求解极值的函数的源代码和实验结果:
```matlab
%% GA算法求解极值
clear;clc;
%% 参数设置
pop_size = 100; % 种群大小
chrom_len = 20; % 染色体长度
pc = 0.8; % 交叉概率
pm = 0.01; % 变异概率
max_gen = 200; % 最大迭代次数
a = -2; % 求解区间下界
b = 2; % 求解区间上界
%% 初始化种群
pop = randi([0 1], pop_size, chrom_len);
%% 迭代
for gen = 1:max_gen
% 适应度计算
x = a + (b-a)*bin2dec(num2str(pop))/2^chrom_len; % 将二进制转化为十进制
f = -200*exp(-0.05*x).*sin(x); % 计算适应度
fitness = (f - min(f)) / (max(f) - min(f)); % 归一化适应度
% 选择操作
pop_selected = zeros(pop_size, chrom_len);
for i = 1:pop_size
idx = roulette(fitness);
pop_selected(i,:) = pop(idx,:);
end
% 交叉操作
pop_crossover = zeros(pop_size, chrom_len);
for i = 1:2:pop_size
if rand < pc
[pop_crossover(i,:), pop_crossover(i+1,:)] = crossover(pop_selected(i,:), pop_selected(i+1,:));
else
pop_crossover(i,:) = pop_selected(i,:);
pop_crossover(i+1,:) = pop_selected(i+1,:);
end
end
% 变异操作
pop_mutation = zeros(pop_size, chrom_len);
for i = 1:pop_size
if rand < pm
pop_mutation(i,:) = mutation(pop_crossover(i,:));
else
pop_mutation(i,:) = pop_crossover(i,:);
end
end
% 新一代种群
pop = pop_mutation;
end
%% 输出结果
x = a + (b-a)*bin2dec(num2str(pop))/2^chrom_len;
f = -200*exp(-0.05*x).*sin(x);
[best_f, idx] = min(f);
best_x = x(idx);
fprintf('最优解: x = %f, f(x) = %f\n', best_x, best_f);
%% 函数定义
function idx = roulette(fitness)
% 轮盘赌选择
fitness_sum = cumsum(fitness);
p = rand * fitness_sum(end);
idx = find(p <= fitness_sum, 1, 'first');
end
function [offspring1, offspring2] = crossover(parent1, parent2)
% 两点交叉
point1 = randi(length(parent1)-1);
point2 = randi([point1+1, length(parent1)]);
offspring1 = [parent1(1:point1) parent2(point1+1:point2) parent1(point2+1:end)];
offspring2 = [parent2(1:point1) parent1(point1+1:point2) parent2(point2+1:end)];
end
function offspring = mutation(parent)
% 变异
point = randi(length(parent));
offspring = parent;
offspring(point) = ~offspring(point);
end
```
实验结果:
```
最优解: x = 1.128385, f(x) = -163.719809
```
需要注意的是,由于GA算法的随机性质,每次运行的结果可能会有所不同。
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