% point
 line([3],[7])      % point
% line from  x1 y1 to x2 y2
 line([3.1 ,4.1], [7,8])  
%   where  x=  [ 3.1       y=  [ 7
%                4.1 ]           8 ]
 line([ 1,2,3 ], [1,10,1])  
%  polyline
%
% x:  x1      y:   y1
%     x2           y2
%     x3           y3