adding subset of interpolating function from a system of ODE

*To*: mathgroup at smc.vnet.net*Subject*: [mg45859] adding subset of interpolating function from a system of ODE*From*: sean_incali at yahoo.com (sean kim)*Date*: Tue, 27 Jan 2004 04:51:17 -0500 (EST)*Sender*: owner-wri-mathgroup at wolfram.com

hello group. Please consider the lorenz system for example. In[2]:= solution=NDSolve[{Derivative[1][x][t]\[Equal]-y[t]-z[t],x[0]\[Equal]-0.04, Derivative[1][y][t]\[Equal]x[t]+0.425*y[t],y[0]\[Equal]-0.3, Derivative[1][z][t]\[Equal]2-(4-x[t])*z[t],z[0]\[Equal]0.52},{x[t], y[t],z[t]},{t,0,25}]; ParametricPlot3D[Evaluate[{x[t],y[t],z[t]}/.solution],{t,0,25}, PlotPoints -> 1000,PlotRange ->All]; above shows a parametric plot of x, y and z. but let's say for some reason I want to plot the following.. x+y vs time x+z vs y how do I achieve this? is this possible in mathematica? as always any and all thoughts are appreciated. thank you all in advance sean