79 lines
2.0 KiB
Mathematica
79 lines
2.0 KiB
Mathematica
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function varargout = det(varargin)
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%DET (overloaded)
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%
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% t = DET(X)
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switch class(varargin{1})
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case 'sdpvar' % Overloaded operator for SDPVAR objects. Pass on args and save them.
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X = varargin{1};
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[n,m] = size(X);
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if n~=m
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error('Matrix must be square.')
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end
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if nargin == 2
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if strcmp(varargin{2},'polynomial')
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varargout{1} = polynomialform(X);
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return
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else
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error('If you use two arguments in @sdpvar/det, the second should be ''polynomial''');
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end
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end
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if n==1
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varargout{1} = X;
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return
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else
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y = yalmip('define','det_internal',reshape(X,[],1));
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end
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varargout{1} = y;
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otherwise
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end
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function d = polynomialform(X)
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n = X.dim(1);
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m = X.dim(2);
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if n~=m
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error('Matrix must be square.');
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else
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switch n
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case 1
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d = X;
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case 2
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% Freakin overloading on multiplication doesn't work. Probalby
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% stupid code...
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Y1.type = '()';
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Y2.type = '()';
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Y3.type = '()';
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Y4.type = '()';
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Y1.subs = {1,1};
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Y2.subs = {2,2};
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Y3.subs = {1,2};
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Y4.subs = {2,1};
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d = subsref(X,Y1)*subsref(X,Y2)-subsref(X,Y3)*subsref(X,Y4);
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otherwise
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d = 0;
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Y.type = '()';
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for i = 1:n
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Y.subs = {i,1};
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xi = subsref(X,Y);
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if ~isequal(xi,0)
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Y.subs = {[1:1:i-1 i+1:1:n],2:n};
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subX = subsref(X,Y);
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if isa(subX,'sdpvar')
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d = d + (-1)^(i+1)*xi*polynomialform(subX);
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else
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d = d + (-1)^(i+1)*xi*det(subX);
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end
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end
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end
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end
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end
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% Reset info about conic terms
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if isa(d,'sdpvar')
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d.conicinfo = [0 0];
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end
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