%POINTFEATURE Constructor function for point feature object.%   P = POINTFEATURE%   Creates a new x,y-point feature object with default values%%   P = POINTFEATURE(P)%   Copies and returns point feature P%%   P = POINTFEATURE(ID,X,C)%   Creates a new point feature object with values%     ID : identifier%      X : 2x1 feature parameter vector, interpreted as [x;y]%      C : 2x2 parameter covariance matrix [sxx,sxy;sxy,syy]%%   The point feature class is a child class of the base class%   entity. %%   Examples:%      p = pointfeature(201,[-1;3],0.001*eye(2));%%   See also ENTITY, CLASS.% v.1.0, Nov. 2003, Kai Arras, CAS-KTHfunction p = pointfeature(varargin)switch nargin,  case 0,    % if no input arguments, create a default object    p.x = [0; 0];    p.C = [0, 0; 0, 0];    e = entity('point feature', 0);    p = class(p,'pointfeature',e);        case 1,    % if single argument of class pointfeature, return it    if (isa(varargin{1},'pointfeature'))      p = varargin{1};     else      error('pointfeature: 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}),      p.x = x;      p.C = C;      e = entity('point feature', varargin{1});      p = class(p,'pointfeature',e);    else      error('pointfeature: Wrong argument syntax');    end;  otherwise    error('pointfeature: Wrong number of input arguments')end