# initialise phi and r as variables and define x,y and z co-ordinates of helix parametricallyphi,r=var('phi,r')fx=r*cos(phi)fy=r*sin(phi)fz=phi# create plot, with u ranging from 0 to 6*pi and v from 0 to 1# colour is given as RGB values in range 0 to 1 (if you don't want red)helix=parametric_plot3d([fx,fy,fz],(phi,0,6*pi),(r,0,1),plot_points=[250,50],frame=False,color=(1.,0.,0.2))helix.show()
