44 lines
1.5 KiB
Mathematica
44 lines
1.5 KiB
Mathematica
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function varargout = lambda_min(varargin)
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% LAMBDA_MIN Returns largest eigenvalue of Hermitian matrix.
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%
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% r = LAMBDA_MIN(X)
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%
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% See also LAMBDA_MAX
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switch class(varargin{1})
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case 'double' % What is the numerical value of this argument (needed for displays etc)
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error(nargchk(1,1,nargin));
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X = varargin{1};
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[n,m] = size(X);
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if ~ishermitian(X)
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error('LAMBDA_MIN can only be applied on Hermitian matrices');
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else
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varargout{1} = min(real(eig(X)));
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end
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case 'sdpvar' % Overloaded operator for SDPVAR objects. Pass on args and save them.
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error(nargchk(1,1,nargin));
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X = varargin{1};
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[n,m] = size(X);
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if ~ishermitian(X)
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error('LAMBDA_MIN can only be Hermitian matrices');
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else
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varargout{1} = yalmip('define',mfilename,varargin{:});
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end
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case 'char' % YALMIP sends 'model' when it wants the epigraph or hypograph
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if isequal(varargin{1},'graph')
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t = varargin{2}; % Second arg is the extended operator variable
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X = varargin{3}; % Third arg and above are the args user used when defining t.
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varargout{1} = (t*eye(size(X,1)) <= X);
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varargout{2} = struct('convexity','concave','monotonicity','none','definiteness','none','model','graph');
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varargout{3} = X;
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else
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varargout{1} = [];
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varargout{2} = [];
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varargout{3} = [];
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end
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otherwise
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end
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