Re: Restriction on the domain of Plot3D

• To: mathgroup at smc.vnet.net
• Subject: [mg55402] Re: [mg55385] Restriction on the domain of Plot3D
• From: yehuda ben-shimol <bsyehuda at gmail.com>
• Date: Tue, 22 Mar 2005 03:50:53 -0500 (EST)
• References: <200503210801.DAA07886@smc.vnet.net>
• Reply-to: yehuda ben-shimol <bsyehuda at gmail.com>
• Sender: owner-wri-mathgroup at wolfram.com

```Hi,
One way that I could think of, is to multiply your function with an
appropriate UnitStep function. I'm not sure that this is efficient or
even what you had in mind but it will make the plot at zero level for
following

eqt1[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}])UnitStep[d - 2z0]
Plot3D[Evaluate[eqt1[1, 10, 10]], {z0, 10^-6, 3}, {d, 1/10, 6}, PlotPoints ->
50];

By the way, did you used the ViewPoint option to rotate the graph

yehuda

On Mon, 21 Mar 2005 03:01:52 -0500 (EST), Steeve Brechmann (schumi)
<steevebrechmann at yahoo.ca> wrote:
>
> Hi everyone,
>
> I want to plot the following function with Plot3D :
>
> 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]],{z0,10^ - 6,3},{d,1/10,6},PlotPoints->50];
>
> But, how can i specify to Mathematica, that i want just the plot for 2*zz0 < dd ?
>
> Thanks for the help !
>
> Steeve Brechmann
> Physics Department, Laval University
> steevebrechmann at yahoo.ca
>
>

```

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