55 lines
1.3 KiB
Mathematica
55 lines
1.3 KiB
Mathematica
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function varargout = chebyball(F,ops)
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%CHEBYBALL Computes Chebyshev ball of a constraint object
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%
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% If two outputs are requested, the numerical data is returned
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% [xc,R] = chebyball(F)
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%
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% If three outputs are requrested, the symbolic model (x-xc)'(x-xc)<R^2 is
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% appended
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% [xc,R,C] = chebyball(F)
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%
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% If only one output is requested, only the symbolic constraint is returned
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% C = chebyball(F)
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% Author Johan L<EFBFBD>fberg
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% $Id: chebyball.m,v 1.1 2004-12-08 00:07:15 johanl Exp $
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[model,recoverdata,diagnostic,p] = export(F,[],[],[],[],0);
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if p.K.q(1) > 0 | p.K.s(1) > 0 | any(p.variabletype) | ~isempty(p.binary_variables) | ~isempty(p.integer_variables)
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error('Polytope can only be applied to linear elementwise constraints.')
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end
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A = -p.F_struc(:,2:end);
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b = p.F_struc(:,1);
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x = recover(p.used_variables);
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r = sdpvar(1);
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if nargin < 2
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ops = sdpsettings('verbose',0);
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end
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sol = solvesdp(A*x+r*sqrt(sum(A.^2,2))<=b,-r,ops);
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xc = double(x);
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R = double(r);
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C = (x-xc)'*(x-xc) <= R^2;
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if sol.problem == 1;
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R = 0;
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elseif sol.problem == 2
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R = inf;
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end
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switch nargout
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case 0
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case 1
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varargout{1} = C;
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case 2
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varargout{1} = xc;
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varargout{2} = R;
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case 3
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varargout{1} = xc;
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varargout{2} = R;
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varargout{3} = C;
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otherwise
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end
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