%ARLINEFEATURE Constructor function for alpha,r-line feature object.%   L = ARLINEFEATURE%   Creates a new alpha,r-line feature object with default values%%   L = ARLINEFEATURE(L)%   Copies and returns alpha,r-line feature L%%   L = ARLINEFEATURE(ID,X,C)%   Creates a new alpha,r-line feature object with values%     ID : identifier%      X : 2x1 feature parameter vector, interpreted as [alpha;r]%      C : 2x2 parameter covariance matrix [saa,sar;sar,srr]%%   The line feature class is a child class of the base class%   entity. %%   Examples:%      l = arlinefeature(10,[-pi/3;2],0.001*eye(2));%%   See also ENTITY, CLASS.% v.1.0, Dec. 2003, Kai Arras, CAS-KTHfunction l = arlinefeature(varargin)switch nargin,  case 0,    % if no input arguments, create a default object    l.x = [0; 0];    l.C = [0, 0; 0, 0];    e = entity('alpha,r line feature', 0);    l = class(l,'arlinefeature',e);        case 1,    % if single argument of class pointfeature, return it    if (isa(varargin{1},'arlinefeature'))      l = varargin{1};     else      error('arlinefeature: Input argument is not a pointfeature object')    end  case 3,    % create object using specified values    x = varargin{2};    C = varargin{3};    if isnumeric(x) & (prod(size(x)) == 2) & isnumeric(C) & ...       (size(C) == [2,2]) & isnumeric(varargin{1}),      l.x = x;      l.C = C;      e = entity('alpha,r line feature', varargin{1});      l = class(l,'arlinefeature',e);    else      error('arlinefeature: Wrong argument syntax');    end;  otherwise    error('arlinefeature: Wrong number of input arguments')end