Re: Corrupt graphics output

*To*: mathgroup at smc.vnet.net*Subject*: [mg90697] Re: Corrupt graphics output*From*: "David Park" <djmpark at comcast.net>*Date*: Sat, 19 Jul 2008 04:52:08 -0400 (EDT)*References*: <g5pj0s$qbg$1@smc.vnet.net>

If you are using Version 6 you don't need a lot of PlotPoints. You can control things better using MaxRecursion. The following gives a fairly decent representation: Plot3D[Abs[Gamma[x + I y]], {x, -5.5, 5}, {y, -2, 2}, PlotPoints -> {20, 5}, MaxRecursion -> 4, PlotRange -> {0, 10}, BoxRatios -> {10.5, 4, 8}, AxesLabel -> {Re[z], Im[z], Abs[Gamma[z]]}] Each of the poles should have infinite height but instead they have smaller height for the more negative poles. One method to supplement the graphic is to add a table of the residues obtained by integrating around each pole. poles = {0, -1, -2, -3, -4, -5}; Table[{z0, With[{\[CapitalDelta] = .05}, NIntegrate[ Gamma[z], {z, z0 - \[CapitalDelta] - I \[CapitalDelta], z0 + \[CapitalDelta] - I \[CapitalDelta], z0 + \[CapitalDelta] + I \[CapitalDelta], z0 - \[CapitalDelta] + I \[CapitalDelta], z0 - \[CapitalDelta] - I \[CapitalDelta]}] // Abs]}, {z0, poles}] // TableForm 0 6.28319 -1 6.28319 -2 3.14159 -3 1.0472 -4 0.261799 -5 0.0523599 -- David Park djmpark at comcast.net http://home.comcast.net/~djmpark/ "Paul M" <paul at somewhere.com> wrote in message news:g5pj0s$qbg$1 at smc.vnet.net... > Hello, > > I was playing around with Mathematica the other day and was attempting > to graph the modulus of the complex-valued gamma function. When I use > a PlotPoints value of 120 the graph looks fine. However, the > following command yields a corrupt graph (PlotPoints value of 150). > > Plot3D[Abs[Gamma[x + I y]], {x, -5, 5}, {y, -5, 5}, > PlotPoints -> {150, 150}, PlotRange -> {0, 10}, > BoxRatios -> {1, 1, 0.8}, AxesLabel -> {x, I y, Abs[Gamma[z]]}] > > Anyone know the reason for this and possible solutions? > > Thank you, > Paul >