你得先给x0赋值，也就是你手上的原始数据，比如
x0=[7.777 7.9726 7.1108 6.6415 6.8747 6.9085 6.7809 6.705 6.6305 6.787 7.2766 6.923 6.6873 7.58 7.21]
网上的GM（1，1）的MATLAB程序很多的，不难找，祝你好运!

给x0赋值，然后利用下面的主程序：
function GM1=GM(x0)%输入原始数据x0
T=input('T=');%从键盘输入从最后一个历史数据算起的第T时点
x1=zeros(1,length(x0));
B=zeros(length(x0)-1,2);
yn=zeros(length(x0)-1,1);
Hatx0=zeros(1,length(x0)+T);
Hatx00=zeros(1,length(x0));Hatx1=zeros(1,length(x0)+T);
epsilon=zeros(length(x0),1);
omega=zeros(length(x0),1);
for i=1:length(x0)
    for j=1:i
        x1(i)=x1(i)+x0(j);
    end
end
for i=1:length(x0)-1
    B(i,1)=(-1/2)*(x1(i)+x1(i+1));
    B(i,2)=1;
    yn(i)=x0(i+1);
end
HatA=(inv(B'*B))*B'*yn
for k=1:length(x0)+T
    Hatx1(k)=(x0(1)-HatA(2)/HatA(1))*exp(-HatA(1)*(k-1))+HatA(2)/HatA(1);
end
Hatx0(1)=Hatx1(1);
for k=2:length(x0)+T
    Hatx0(k)=Hatx1(k)-Hatx1(k-1)
end
for i=1:length(x0)
    epsilon(i)=x0(i)-Hatx0(i);
    omega(i)=(epsilon(i)/x0(i))*100
end
% x0;Hatx0;epsilon;omega;
c=std(epsilon)/std(x0) ;p=0;
for i=1:length(x0)
    if abs(epsilon(i)-mean(epsilon))<0.6745*std(x0)
        p=p+1;
    end
end
p=p/length(x0)
if p>0.95&c<0.35
    disp('The model is good ,and the forecast is:'),disp(Hatx0(length(x0)+T))
elseif p>0.85&c<0.5
    disp('The model is eligibility ,and the forecast is:'),disp(Hatx0(length(x0)+T))
elseif p>0.70&c<0.65
    disp('The model is not good ,and the forecast is:'),disp(Hatx0(length(x0)+T))
else p<=0.70&c>0.65
    disp('The model is bad and try again')
end
for i=1:length(x0)
    Hatx00(i)=Hatx0(i);
end
z=1:length(x0);
plot(z,x0,'-',z,Hatx00,':')
text(2,x0(2),'History data:real line')
text(length(x0)/2,Hatx00(length(x0))/2,'Simulation data :broken line')
end

function函数里面不能赋值。修改代码如下：先把这个存为m文件，然后再命令窗口输入：然后调用函数，GM1_1(X0)，就可以了