disp('>> % |');     % |     disp('>> % |  THE DERIVATIVE OF A SPINOR');     % |  THE DERIVATIVE OF A SPINOR     disp('>> % |');     % |     i = unit(e1^(e2/2+e3/3)); %/  % rotation plane      n = 16;                   %/  % number of rotation steps     phi = i*2*pi/n;           %/  % rotation angle bivector     R = gexp(-phi/2); %/     disp('>> a = e1-e2+e3;              % vector to be rotated');     a = e1-e2+e3;              % vector to be rotated     clf; %/     draw(i,'y'); %/     draw(a,'r'); GAtext(1.1*a,'a'); %/     axis off; %/     GAview([-30 30]); %/     axis([-1.1 1.1 -1.7 0.7 -0.5 2]) %/     disp('>> % |  Vector a and spinor plane ');     % |  Vector a and spinor plane      disp('>> % |');     % |     GAprompt; %/     disp('>> % |  Derivative is vector proportional to x.i');     % |  Derivative is vector proportional to x.i     disp('>> % |');     % |     title('constant i, then   \partial_t(e^{-i\phi/2} a e^{i\phi/2}) = (a \bullet i) \partial_t\phi'); %/     draw(inner(a,phi),'b'); %/     axis([-1.1 1.1 -1.7 0.7 -0.5 2]) %/     GAprompt; %/     disp('>> % |');     % |     disp('>> % |  Capable of locally rotating the vector a.');     % |  Capable of locally rotating the vector a.     for j=1:n %/        anow = a; %/        adernow = inner(anow,phi);  % derivative formula %/        draw(anow,'r'); %/        draw(adernow,'b'); %/        DrawPolyline({anow-adernow/2,anow+adernow/2},'b'); %/        axis([-1.1 1.1 -1.7 0.7 -0.5 2]) %/     	drawnow; %/        a = R*anow/R; %/     end %/     GAorbiter(-360,10); %/     disp('>> % |');     % |