【数学建模】灰色预测程序

clear
syms a b;
c = [a b]';
A = [8,1,2,3,4,5,7,8,9,9]; //1999到2008的数据
B = cumsum(A);
n = length(A);
for i = 1:(n - 1)
    C(i) = (B(i) + B(i + 1)) / 2;
end
D = A; D(1) = [];
D = D';
E = [ -C; ones(1, n - 1)];
c = inv(E * E') * E * D;
c = c';
a = c(1); b = c(2);

F = []; F(1) = A(1);
for i = 2:(n + 10)
    F(i) = (A(1) - b / a) / exp(a * (i - 1)) + b / a;
end
G = []; G(1) = A(1);
for i = 2:(n+10)
    G(i) = F(i) - F(i - 1);
end
t1 = 1999:2008; //这里写原序列
t2 = 1999:2018; // 这里要预测2009~2018年的值
G
plot(t1, A, 'o', t2, G)