Hi, if you don't know the bounds for x and y you don't have enough info to plot some shape, easiest would be to prepare setings of your axis. You can use similar command:
axis([xmin xmax ymin ymax zmin zmax cmin cmax])
so if we use ezplot3 for now instead plot3
figure
ezplot3('sin(t)','cos(t)','t',[0,6*pi])
with what you want, it might be like this:
but we need some real values now, so lets say x=0->1 y=0->2 z=0->3
and we will get: