graphics problem

*To*: mathgroup at thnext.mit.edu*Subject*: graphics problem*From*: Robert Singleton <bobs at thnext.mit.edu>*Date*: Wed, 21 Oct 92 19:06:37 PDT

I have a graphics problem of sorts. I want to graph a hyperboloid of one sheet with an arc drawn across it. However, when the arc goes around the hyperboloid I would still like to see it rather than have it eclipsed. How do I do this? There was a similar question the other day about partial transparency. Unfortunately I didn't understand the reply (which was from twj at wri.com -- obviously a Mathematica expert). Here is a little more detail: Define: Z0[tau_,w_]:=-Tan[w] Z1[tau_,w_]:= Sin[tau]/Cos[w] Z2[tau_,w_]:= Cos[tau]/Cos[w] where -Pi<tau<Pi and -Pi/2<w<Pi/2. This alo parametrizes the hyperboloid: grHy=ParametricPlot3D[{Z1[tau,w],Z2[tau,w],Z0[tau,w]}, {tau,-Pi,Pi},{w,-1.,1.}] I can also parametarize the hyperboloid as follows: z0[r_,t_]:=(1 - r^2 + t^2)/(2*r) z1[r_,t_]:=t/r z2[r_,t_]:=(1 + r^2 - t^2)/(2*r) where r,t are any real numbers. (These are lower case z's). I am interested in putting the r=3 curve on "grHy". This is what I do: grArc=ParametricPlot3D[{z1[3.0,t],z2[3.0,t],z0[3.0,t]}, {t,-4.16,4.16}] Show[grHy,grArc,ViewPoint->{2.245, 1.552, 2.000}] This gives me an arc running across the hyperboloid, but unfortunately part of it is eclipsed. What should I do to see the arc on both sides? Thanks very much. Robert Singleton bobs at thnext.mit.edu