29 lines
832 B
Matlab
29 lines
832 B
Matlab
function G1=inv(G)
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% inv - inverse of a multivariable FOTF system
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%
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% G1=inv(G)
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%
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% G, G1 - an FOTF object and its inverse system
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% not recommended for MIMO FOTFs, use fotf2sym and work the
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% model G under symbolic framework
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% Copyright (c) Dingyu Xue, Northeastern University, China
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% Last modified 28 March, 2017
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% Last modified 18 May, 2022
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[n,m]=size(G);
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if n*m==1
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if G.ioDelay>0, error('Delay terms are not allowed');
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else, G1=fotf(G.num,G.den); end
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elseif n~=m
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error('Error: non-square matrix, not invertible')
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else, G1=fotfinv(G); end
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end
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function G1=fotfinv(G)
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[n,~]=size(G); A1=G; E0=fotf(eye(n)); A3=E0;
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for i=1:n, ij=1:n; ij=ij(ij~=i);
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E=fotf(eye(n)); a0=inv(A1(i,i));
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for k=ij, E(k,i)=-A1(k,i)*a0; end
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E0=E*E0; A1=E*A1; A3(i,i)=a0;
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end, G1=A3*E0;
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end
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