function varargout = sec(varargin) %SEC (overloaded) switch class(varargin{1}) case 'double' error('Overloaded SDPVAR/SEC CALLED WITH DOUBLE. Report error') case 'sdpvar' varargout{1} = InstantiateElementWise(mfilename,varargin{:}); case 'char' operator = struct('convexity','none','monotonicity','none','definiteness','none','model','callback'); operator.derivative = @(x)(tan(x).*sec(x)); varargout{1} = []; varargout{2} = operator; varargout{3} = varargin{3}; otherwise error('SDPVAR/SEC called with CHAR argument?'); end