54 lines
1.5 KiB
Mathematica
54 lines
1.5 KiB
Mathematica
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function sys = unblkdiag(F)
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% UNBLOCKDIAG Extracts diagonal blocks
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%
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% G = unblkdiag(F) Detects and converts block diagonal SDP.
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%
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% See also DISSECT
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switch class(F)
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case 'lmi'
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sys = ([]);
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for i = 1:length(F)
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if is(F(i),'sdp') % SDP
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Z = sdpvar(F(i));
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X = spy(Z);
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[v,dummy,r,dummy2]=dmperm(X);
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if v==dummy & length(r)>2
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linearblocks = []; % Simple diagonal terms;
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for blocks = 1:length(r)-1
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r1 = r(blocks);
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r2 = r(blocks+1)-1;
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if r2>r1
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sys = sys + (Z(v(r1:r2),v(r1:r2))>=0);
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else
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linearblocks = [linearblocks v(r1)];
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end
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end
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if ~isempty(linearblocks)
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D=diag(Z);
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sys = sys+(D(linearblocks)>=0);
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end
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else
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sys = sys + F(i);
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end
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else
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sys = sys + F(i);
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end
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end
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case 'sdpvar'
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sys = {};
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Z = F;
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X = spy(Z);
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[v,dummy,r,dummy2]=dmperm(X);
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if v==dummy & length(r)>2
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for blocks = 1:length(r)-1
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r1 = r(blocks);
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r2 = r(blocks+1)-1;
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sys{end+1} = Z(v(r1:r2),v(r1:r2));
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end
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else
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sys{1} = Z;
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end
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otherwise
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error('Heh')
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end
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