灰色模型

zhang6880258

我在matlab中用GM（1,1）模型预测，可是误差太大了。请高手指点~~~~~~~~~~

1. clear
   # V: _8 ]\" g0 g* M: e+ v! z! z
2. syms a b;3 _+ y\" @7 C9 r/ s
   
3. c=[a b]';
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4. A=[539.658590944408,544.467335019023,543.118901615168,541.395536784412,539.719603563031,538.320685053971,536.799895148485,539.869612431029,534.915223499512,544.533125668254];
   1 I: p# u, a1 A
5. B=cumsum(A);
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6. n=length(A);4 }9 P; x9 ?7 [( k( f, l
   
7. for m=1:(n-1)) z/ \1 p# C& h3 x
   
8.     C(m)=(B(m)+B(m+1))/2;# N8 S/ t8 K* i4 F: S& B% h
   
9. end! K! `% b2 s) P7 F! y
   
10. D=A;
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11. D(1)=[];
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12. D=D';! N: q+ t\" Z: ?/ k7 d5 I6 o5 o
    
13. E=[-C;ones(1,n-1)];; j3 A) b6 |5 Z( Z* |
    
14. c=inv(E*E')*E*D;
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15. c=c';
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16. a=c(1);0 w# ]3 N2 q& ]$ l, w7 ~
    
17. b=c(2);
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18. F=[];
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19. F(1)=A(1);
    ; A# G3 r* S. _2 I6 f
20. for m=2:(n+10)
    % ^+ |  `3 F1 [: \
21.     F(m)=(A(1)-b/a)/exp(a*(m-1))+b/a;
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22. end
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23. G=[];
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24. G(1)=A(1);
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25. for m=2:(n+2)$ F7 o; [/ k* g' }6 k7 }& d# D3 }, ^
    
26.     G(m)=F(m)-F(m-1);* e7 h: \$ `$ _% v! v% ?
    
27. end1 E, r$ @% v$ E% N
    
28. t1=1:10;
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29. t2=1:12;
    9 @% c: p; ~7 `8 X) J
30. plot(t1,A,'r',t2,G,'g')
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