       Re: Re: Re: 3D plotting problem

• To: mathgroup at smc.vnet.net
• Subject: [mg51784] Re: [mg51771] Re: [mg51743] Re: 3D plotting problem
• From: DrBob <drbob at bigfoot.com>
• Date: Tue, 2 Nov 2004 02:05:04 -0500 (EST)
• References: <200411010753.CAA06509@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

```Documentation is unclear on what ContourPlot3D actually does--until you get to the example.

You also get an empty box if you replace Cos[...] with 1-Cos[...], simply because 1-Cos[...] is never zero in the range. But this gives a surface:

ContourPlot3D[3 - Cosh[Sqrt[
x^2 + y^2 + z^2]], {x, -2, 2}, {y, 0, 2}, {z, -2, 2}]

and so does this:

ContourPlot3D[1.01 - Cosh[Sqrt[x^2 + y^2 +
z^2]], {x, -2, 2}, {y, 0, 2}, {z, -2, 2}]

That's a weird one.

Bobby

On Mon, 1 Nov 2004 02:53:19 -0500 (EST), Henning Heiberg-Andersen <Henning.Heiberg-Andersen at fi.uib.no> wrote:

>
>
>
> I am sorry that I was not clear enough about the nature of my problem,
> which I will try to illustrate by the following example:
>
> If 'Cos' is replaced by 'Cosh' in the command
>
> ContourPlot3D[Cos[Sqrt[x^2+y^2+z^2]],{x,-2,2},{y,0,2},{z,-2,2}]
>
> an empty plot box appears.
>
> It seems to me that it is problematic to make 3D contour plots
> involving exponential functions, and I hope somebody can suggest
> a remedy for this.
>
> Best regards,
> Henning Heiberg-Andersen
>
> On Sun, 31 Oct 2004, Bill Rowe wrote:
>
>> On 10/30/04 at 3:47 AM, Henning.Heiberg-Andersen at fi.uib.no (Henning
>> Heiberg-Andersen) wrote:
>>
>> >I find myself unable to make a 3D plot of the atomic 2p orbital
>>
>> >f_z(2p,x,y,z;a)=z*Exp[-a*Sqrt[x^2+y^2+z^2]].
>>
>> >As far as I can understand, 'ContourPlot3D' is the only option, but
>> >it gives either an empty plot box or a flat sheet.
>>
>> >Can anyone suggest a way out?
>>
>> You did not make it clear exactly what you tried to plot. If it was the expression you posted, then try re-writting your function as
>>
>> f[x_, y_, z_, a_] := z*Exp[-a*Sqrt[x^2 + y^2 + z^2]]
>>
>> Here, I've eliminated the _z from the function name as Mathematica doesn't allow underscore characters in function names f_z is interpeted by Mathematica to be any expression with Head z given a name f, not what you want.
>>
>> Changed the "(" to "[" to corespond to proper Mathematica syntax
>>
>> dropped 2p from the arguements since it does not appear on the rhs
>>
>> added a underscore to all of the other arguments. Using x_ is interpreted by Mathematica as being any valid expression and is given a local name of x
>>
>> Replaced Set ("=") with DelayedSet (":=")
>> --
>> To reply via email subtract one hundred and four
>>
>>
>
>
>
>

--
DrBob at bigfoot.com
www.eclecticdreams.net

```

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