function PlotLine(x,y,s,c,n,t)
% PLOTLINE plots a line through a set of points
%   PlotLine(x,y,s,c,n,t) plots the set of points (x,y) using the
%   symbol s and plots the line c+n1*x+n2*y=0 using the line type
%   defined by t

plot(x,y,s)
xrange=[min(x) max(x)]; yrange=[min(y) max(y)];
if n(1)==0,                                  % c+n2*y=0  => y=-c/n(2)
  x1=xrange(1); y1=-c/n(2);
  x2=xrange(2); y2=y1
elseif n(2)==0,                              % c+n1*x=0  => x=-c/n(1)
  y1=yrange(1); x1=-c/n(1);
  y2=yrange(2); x2=x1;
elseif xrange(2)-xrange(1)>yrange(2)-yrange(1),
  x1=xrange(1); y1=-(c+n(1)*x1)/n(2);
  x2=xrange(2); y2=-(c+n(1)*x2)/n(2);
else
  y1=yrange(1); x1=-(c+n(2)*y1)/n(1);
  y2=yrange(2); x2=-(c+n(2)*y2)/n(1);
end
plot([x1,x2],[y1,y2],t)
