#copy-pasta in i Octave utan denna rad
function flot(x,y)
u = x;
v = y;	
for t = 1:length(x)
u(t) = (x(t)-y(t))/sqrt(2);
v(t) = (x(t)+y(t))*sqrt(2);
endfor
plot(u,v);
endfunction

hold;
x = (-5:0.1:5);
for k = -10:10
flot(x, x - k);
flot(x, -2*x + k);
flot(x, (-x+k)/2);
flot(0*x + k/3, x);
flot(x, 0*x + k/3);
flot(x, -x-k/3);
endfor