Pro Gurus:
Thank you all for your time and help.
The relation sdx=100+SIN(TRAJPAR*360*8)*20 suggested in #1 works for
me. I can control the taper angle by constraining the line profile
either at its midpoint or at its end point to the trajectory origin
and by varying the 100 value.
The relation suggested in #2 doesn't seem to work for me.
As for Relation 3 & 4 I don't know how to create Curves from equation
yet. So I leave them as "pieces de resistance".
Frank