Re: Problem with singularities in Plot3D

*To*: mathgroup at smc.vnet.net*Subject*: [mg55354] Re: Problem with singularities in Plot3D*From*: Peter Pein <petsie at arcor.de>*Date*: Sun, 20 Mar 2005 04:11:47 -0500 (EST)*References*: <d1gtdv$jh$1@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

Steeve Brechmann (schumi) wrote: > Hi, > > I have a little problem with the Plot3D command of Mathematica. > I want to plot the 3D graphics of : > > eqt[q_,N_,M_]:= - (3*q/(8*Pi))*(Sum[(Cos[4*Pi*n*d]/(2*n*d))-(Sin[4*Pi*n*d]/(8*Pi*(n*d)^2))-(Cos[4*Pi*n*d]/(32*Pi^2*(n*d)^3)),{n,1,N}] - Sum[(Cos[4*Pi*Abs[z0-m*d]]/Abs[z0-m*d])-(Sin[4*Pi*Abs[z0-m*d]]/(4*Pi*Abs[z0-m*d]^2))-(Cos[4*Pi*Abs[z0-m*d]]/(16*Pi^2*Abs[z0-m*d]^3)),{m,-M,M}]) > > Plot3D[Evaluate[eqt[1,10,10]],{z0,0,3},{d,0.1,6},PlotPoints->50]; > > Like you see, my expression eqt[q,N,M] have some singularities at d = 0 and Abs[z0-m*d] = 0. > > How can i say to Mathematica that it must ignore the singularities Abs[z0-m*d] = 0 ? > > Thanks for your help. > > Steeve Brechmann von Brechenmacher > Physics Department, Laval University > steevebrechmann at yahoo.ca > > If it is sufficient, to plot for z0 from 10^-6 to 3, try Plot3D[Evaluate[eqt[1,10,10]],{z0,10^-6,3},{d,1/10,6},PlotPoints->50]; -- Peter Pein Berlin