-1*-1 + -1*1 = 0
axis([-4 8 0 12]) ; axis square
Pl1 = [ 0 1 0 0 0; 0 0 0 0 1; 1 0 0 0 0 ; 0 0 0 0 0; 0 0 0 0 0];
Pr1 = [ 0 0 0 1 0; 0 0 1 0 0; 0 0 0 0 0; 0 0 0 0 0; 0 0 0 0 1]
M= [6 6 4]'
en = [-0.6 0 0.8]
T1 = [1 0 -8; 0 1 -2;0 0 1]; T2 = [0 1 0; -1 0 0 ; 0 0 1]; T3 = [1 0 8; 0 1 2;0 0 1]; TT = T3*T2*T1 % =[0 1 6; -1 0 10 ; 0 0 1]; Q = [8 16 16 8 8; -6 -6 2 2 -6; 1 1 1 1 1]; QT = TT*Q; plot(Q(1,:),Q(2,:)); hold on; plot(QT(1,:),QT(2,:),'r'); axis([-18 18 -18 18]); axis square; hold off
w=(0:0.02:5)*2*pi; z= 5*cos(w); y= -5*sin(w); xr= w*0.8/2/pi; xl = -xr; clf; plot3(xr,y,z); hold on; plot3(xl,y,z,'m'); axis equal; hold off