Bug in Plot3D?

*To*: mathgroup at smc.vnet.net*Subject*: [mg105217] Bug in Plot3D?*From*: SixWingedSeraph <wellsoberlin at gmail.com>*Date*: Tue, 24 Nov 2009 05:51:44 -0500 (EST)

The two plot commands in the notebook below should give identical outputs, but they don't. The notebook is posted at http://abstractmath.org/MM/MmaBugQ.nb a := 9; b := 18; ff[x_, y_, z_] := x + y + z gg[x_, y_, z_] := 2*x - 2*y - z f[x_, y_] := z /. Solve[ff[x, y, z] == a, z] f[x, y] g[x_, y_] := z /. Solve[gg[x, y, z] == b, z] g[x, y] Plot3D[{-x - y + 9, 2*(x - y - 9)}, {x, 6, 10}, {y, -5, 1}, BoxRatios -> {4, 6, 24}, ViewPoint -> {4.5, 3, 20}, MeshStyle -> Gray, AxesLabel -> {x, y, z}, PlotStyle -> {{Red, Opacity[0.7]}, {Green, Opacity[0.7]}}, ColorFunction -> White] Plot3D[{f[x, y], g[x, y]}, {x, 6, 10}, {y, -5, 1}, BoxRatios -> {4, 6, 24}, ViewPoint -> {4.5, 3, 20}, MeshStyle -> Gray, AxesLabel -> {x, y, z}, PlotStyle -> {{Red, Opacity[0.7]}, {Green, Opacity[0.7]}}, ColorFunction -> White]