X0=zeros(1,19);
Y0=zeros(1,19);
Z0=zeros(1,19);
i=1;
for t=0:pi/3:6*pi
   X0(i)=cos(t);
   Y0(i)=sin(t);
   Z0(i)=t;
   i=i+1;
end
plot3(X0,Y0,Z0,'k-')
hold on