function plot_line(A,B)
%
%  plot_line(A,B) plots a line,
%  starting at position A and ending at B.
%
%  ON ENTRY:
%    A     x and y coordinates of start position;
%    B     x and y coordinates of end position.
%
%  EXAMPLE:
%    plot_line([1,1],[2,2])
%    axis([0 3  0 3])
%
plot([A(1),B(1)],[A(2),B(2)]);