clear all;


% orizetai to pedio timon tou x,y
xm=-6;xM=6;
ym=-8;yM=6;
dx=.7;
dy=.7;

%ftiaxnete ta X, Y pinakes me tis antistoixes times (x,y) se kathe stoixeio
%tou
x = xm:dx:xM;
y = ym:dy:yM;
[X,Y] = meshgrid(x,y);


% orizete to dianysmatiko pedio
Xdot =  X - X.*Y;
Ydot = -Y + X.^2;


% zografizete to dianysmatiko pedio me 
% tin entoli quiver
% to scale otan einai >1 megalonei ta veli
scale=1.5

figure(1);hold on;
quiver(X,Y,Xdot,Ydot,scale,'b')

axis([xm xM ym yM])