function varargout = acsch(varargin)

switch class(varargin{1})

    case 'sdpvar'
        varargout{1} = InstantiateElementWise(mfilename,varargin{:});

    case 'char'

        operator = CreateBasicOperator('callback');
        operator.monotonicity = @(xL,xU)decreasing_except_at(xL,xU,0);
        operator.derivative = @(x)(-1./(abs(x).*sqrt(1 + x.^2)));
        operator.singularity = [0 -inf inf];
        operator.inflection = [-inf -1 0 1];

        varargout{1} = [];
        varargout{2} = operator;
        varargout{3} = varargin{3};

    otherwise
        error(['SDPVAR/' upper(mfilename) ' called with weird argument']);
end
