gray3.m

灰色理论认为系统的行为现象尽管是朦胧的

clear all
a=0.5;
c=0.01;
sumc=0;
x=[0.4829	0.4628	0.5066	0.4548	0.4495

];
n=size(x,2);
%求级数比
for i=1:n-1
    y(i)=x(i)/x(i+1);
end
y;
%判断级数范围
while exp(-2/(n+1))>min(y)||exp(2/(n+1))<max(y)
    %平移
for i=1:n
    x(i)=x(i)+c;
end
sumc=sumc+c;
%求级数比
for i=1:n-1
    y(i)=x(i)/x(i+1);
end
y;
end

      

%求x1
sum=0;

for i=1:n
    x1(i)=x(i)+sum;
    sum=sum+x(i);
end
x1;
%求z1
for i=1:n-1
    z1(i)=a*x1(i)+(1-a)*x1(i+1);
end
   z1;
   %生成B
   B=[-z1',ones(n-1,1)];
   %生成Y1
   for i=1:n-1
       y1(i)=x(i+1);
   end
   Y1=y1';
   Y1;
   
   x;
   %求(a,b)
   ab=inv(B'*B)*B'*Y1;
   %求预测值
   for i=1:n
       
       yux1(i)=(x(1)-ab(2)/ab(1))*(exp(-ab(1)*i)-exp(-ab(1)*(i-1)))-sumc;
   end
   sumc
  yux1
  x