灰色预测
format long;X0=[357.35
653.91
1123.29
1601.79
1952.05
1977.59
1964.89
1856.72
1869.67
1984.31
2158.41
2828.87
];
n=length(X0);
X1=[];
X1(1)=X0(1);
for i=2:n
X1(i)=X1(i-1)+X0(i);
end
for i=1:n-1
B(i,1)=-0.5*(X1(i)+X1(i+1));
B(i,2)=1;
Y(i)=X0(i+1);
end
alpha=(B'*B)^(-1)*B'*Y';
a=alpha(1,1);
b=alpha(2,1);
d=b/a;
c=X1(1)-d;
X2(1)=X0(1);
X(1)=X0(1);
for i=1:n-1
X2(i+1)=c*exp(-a*i)+d;
X(i+1)=X2(i+1)-X2(i);
end
for i=1:n
error(i)=X(i)-X0(i);
error1(i)=abs(error(i));
error2(i)=error1(i)/X0(i);
end
g=std(error1)/std(X0)
e=c-c*exp(a)
for i=1:18
X2(i+1)=c*exp(-a*i)+d;
X(i+1)=X2(i+1)-X2(i);
end
X(19)=[];
plot(1992:2009,X,'b*-')
hold on
X0=[
357.35
653.91
1123.29
1601.79
1952.05
1977.59
1964.89
1856.72
1869.67
1984.31
2158.41
2828.87
3084.66
3542.55
3925.09
4458.61
4829.45
5273.3
];
plot(1992:2009,X0,'g+-')
for k=2:18
l(k)=(X0(k)-X0(k-1))/(X(k)-X(k-1));
end
l
ylabel('投资/亿元');
xlabel('上海 时间/年');
legend('预测值',' 实际值 ' ,'Location','NorthWest')
%legend('预测值')
{:3_41:}{:3_41:}
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