*To*: mathgroup@smc.vnet.net*Subject*: [mg10587] Re: [mg10539] Drawing multiple curves with ParametricPlot3D*From*: jpk@max.mpae.gwdg.de*Date*: Mon, 26 Jan 1998 04:42:21 -0500

Hi Volker, > For plotting several objects together, the documentation says: > > ParametricPlot3D[{{fx,fy,fz},{gx,gy,gz},...},...] > > but > > ParametricPlot3D[ > {Evaluate[{r1x[t],r1y[t],r1z[t]}/.%], > Evaluate[{r2x[t],r2y[t],r2z[t]}/.%],{t,0,dt}},{t,0,dt}] > > doesn't work at all. No surprise, suppose You had dsol=NDSolve[some equations ...] the command ParametricPlot3D[ Evaluate[{{r1x[t],r1y[t],r1z[t]}, {r2x[t],r2y[t],r2z[t]}}/.Flatten[dsol]],{t,0,dt}] works. NDSolve ives You a List[] of solutions so that in the case of more than one solution x /. {{x->xs1},{x->xs2}} gives You a list of {xs1,xs2}. So You must flatten out the output of NDSolve. Second Evaluate[] is needed for the whole first argument -- so that the pattern matching for ParametricPlot3D[] can go to the case for more than one curve. Hope that helps. Jens