71 lines
1.8 KiB
Mathematica
71 lines
1.8 KiB
Mathematica
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function Y=diff(varargin)
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%DIFF (overloaded)
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X = varargin{1};
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n = X.dim(1);
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m = X.dim(2);
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Y = X;
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x_lmi_variables = X.lmi_variables;
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lmi_variables = [];
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% Fast diff of large matrices. Convert to optmized case
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switch nargin
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case 1
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if (min([n m]) > 1)
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Y = diff(X',1,2)';
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return
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end
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case 2
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if varargin{2} == 1 & (min([n m]) > 1)
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Y = diff(X',1,2)';
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return
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end
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case 3
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if varargin{2}==1 & varargin{3} == 2 & (min([n m]) > 1)
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shift = [-speye(m-1) spalloc(m-1,1,0)] + [spalloc(m-1,1,0) speye(m-1)];
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% shift = shift(1:m-1,1:m);
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shift = kron(shift,speye(n));
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Y.basis = shift*X.basis;
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Y.dim(1) = n;
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Y.dim(2) = m - 1;
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% Reset info about conic terms
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Y.conicinfo = [0 0];
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Y = clean(Y);
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return
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elseif varargin{2}==1 & varargin{3} == 1 & (min([n m]) > 1)
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Y = diff(X',1,2)';
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return
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end
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otherwise
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error('To many input arguments.')
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end
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% Slow but safe case. Used for higher order diff
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try
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j = 1;
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diffX = diff(reshape(X.basis(:,1),n,m),varargin{2:end});
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Y.basis=diffX(:);
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for i = 1:length(x_lmi_variables)
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diffX = diff(reshape(X.basis(:,i+1),n,m),varargin{2:end});
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if (norm(diffX,inf)>0)
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Y.basis(:,j+1) = diffX(:);
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lmi_variables = [lmi_variables x_lmi_variables(i)];
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j = j+1;
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end
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end
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if j~=1
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Y.lmi_variables = lmi_variables;
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else
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Y = full(reshape(Y.basis(:,1),size(diffX,1),size(diffX,2)));
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return
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end
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catch
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error(lasterr)
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end
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Y.dim(1) = size(diffX,1);
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Y.dim(2) = size(diffX,2);
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% Reset info about conic terms
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Y.conicinfo = [0 0];
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