求函数f(x,y)=-((x^2+y-1)+(x+y^2-7)^2)/200+10的最大值，x和y取值区间[-100,100]；经过下面的优化过程，得到结果：x=-2，y=-3，最大值为10。

• 源码

%%%%%%%%%%%%%  离散差分进化算法求函数极值 %%%%%%%%%%%%%
%%%%%%%%%%%%%  初始化 %%%%%%%%%%%%%
clear;clc;
NP = 20;                          % 种群数量
D = 2;                             % 变量维度
G = 200;                           % 最大进化代数
F = 0.5;                           % 初始编译算子
CR = 0.1;                           % 交叉算子
Xs = 100;                             % 上限
Xx = -100;                            % 下限
%%%%%%%%%%%%%  赋初值 %%%%%%%%%%%%%
Ob = zeros(NP, 1);
Ob1 = zeros(NP, 1);
trace = zeros(G + 1, 1);
v = zeros(D, NP);                    % 变异种群
u = zeros(D, NP);                    % 选择种群
x = randi([Xx, Xs], D, NP);  
%%%%%%%%%%%%%  计算目标函数 %%%%%%%%%%%%%
for m = 1:NP
   Ob(m) = func3(x(:, m));
end
trace(1) = min(Ob);
%%%%%%%%%%%%%  差分进化循环 %%%%%%%%%%%%%
for gen = 1:G
   %%%%%%%%%%%%%  变异操作 %%%%%%%%%%%%%
   %%%%%%%%%%  r1、r2、r3和m互不相同 %%%%%%%%%%
   for m = 1:NP
      r1 = randi([1, NP], 1);
      while r1 == m
         r1 = randi([1, NP], 1);
      end
      r2 = randi([1, NP], 1);
      while r2 == m || r2 == r1
         r2 = randi([1, NP], 1);
      end
      r3 = randi([1, NP], 1);
      while r3 == m || r3 == r2 || r3 == r1
         r3 = randi([1, NP], 1);
      end
      v(:, m) = floor(x(:, r1) + F*(x(:, r2) - x(:, r3)));
   end
   %%%%%%%%%%%%%  交叉操作 %%%%%%%%%%%%%
   r = randi([1, D], 1);
   for n = 1:D
      cr = rand;
      if cr <= CR || n == r
         u(n, :) = v(n, :);
      else
         u(n, :) = x(n, :);
      end
   end
   %%%%%%%%%%%%%  边界条件的处理 %%%%%%%%%%%%%
   %%%%%%%%%%%%%  边界吸收 %%%%%%%%%%%%%
   for n = 1:D
      for m = 1:NP
         if u(n, m) < Xx
            u(n, m) = Xx;
         end
         if u(n, m) > Xs
            u(n, m) = Xs;
         end
      end
   end
   %%%%%%%%%%%%%  选择操作 %%%%%%%%%%%%%
   for m = 1:NP
      Ob1(m) = func3(u(:, m));
   end
   for m = 1:NP
      if Ob1(m) > Ob(m)
         x(:, m) = u(:, m);
      end
   end
   for m = 1:NP
      Ob(m) = func3(x(:, m));
   end
   trace(gen + 1) = min(Ob);
end
[SortOb, Index] = sort(Ob);
x = x(:, Index);
X = x(:, 1);                     % 最优变量
Y = min(Ob);                 % 最优值
disp(['最优x：' num2str(X')]);
disp(['最优y：' num2str(Y)]);
plot(trace);
xlabel('迭代次数');
ylabel('目标函数值');
title('DE目标函数曲线');

%%%%%%%%%%%%%  适应度函数 %%%%%%%%%%%%%
function result = func3(x)
result = -((x(1).^2 + x(2) - 1).^2 + (x(1) + x(2).^2 - 7).^2)/200 + 10;