Re: Problem with ListPlotVectorField3D

• To: mathgroup at smc.vnet.net
• Subject: [mg56084] Re: Problem with ListPlotVectorField3D
• From: dh <dh at metrohm.ch>
• Date: Fri, 15 Apr 2005 04:47:20 -0400 (EDT)
• References: <d3lrej\$s7d\$1@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

```Hello Alain,
Mathematica version 5.1 shows the same behaviour.
It seems that ListPlotVectorField3D tries to be smart and croppes
peripheral vectors where the vector-density is small.
Interestingly, either setting VectorHeads -> False, or better,
PlotRange->All cures the problem.

If anybody has enough time, he could look at the code in
"ListPlotVectorField3D" and let the group know.

Here, instead of AI I would speak of AS (artificial stupidity)

Sincerely, Daniel

Alain Cochard wrote:
> Mathematica 4.0 for Linux
> Copyright 1988-1999 Wolfram Research, Inc.
>  -- Motif graphics initialized --
>
> In[1]:= <<Graphics`
>
>    Here is a vector field:
>
> In[2]:= vecfield={{{0, 0, 4}, {1, 0, 0}}, {{0, 0, 4}, {1, 0, 0}}, {{0, 0, 4}, {1, 0, 0}},
>  {{0, 0, 4}, {1, 0, 0}}, {{0, 0, 4}, {1, 0, 0}}, {{0, 0, 4}, {1, 0, 0}},
>  {{0, 0, 4}, {1, 0, 0}}, {{4, 0, 0}, {0, 0, 1}},
>  {{2, 2*Sqrt[3], 0}, {0, 0, 1/2}}, {{-2, 2*Sqrt[3], 0}, {0, 0, -1/2}},
>  {{-4, 0, 0}, {0, 0, -1}}, {{-2, -2*Sqrt[3], 0}, {0, 0, -1/2}},
>  {{2, -2*Sqrt[3], 0}, {0, 0, 1/2}}, {{4, 0, 0}, {0, 0, 1}},
>  {{0, 0, -4}, {-1, 0, 0}}, {{0, 0, -4}, {-1, 0, 0}},
>  {{0, 0, -4}, {-1, 0, 0}}, {{0, 0, -4}, {-1, 0, 0}},
>  {{0, 0, -4}, {-1, 0, 0}}, {{0, 0, -4}, {-1, 0, 0}}, {{0, 0, -4}, {-1, 0, 0}}};
>
>    In the following I get only 4 arrows:
>
> In[3]:= ListPlotVectorField3D[vecfield, VectorHeads -> True]
>
> Out[3]= -Graphics3D-
>
>    In the following I get all the expected arrows (but without the
>
> In[4]:= ListPlotVectorField3D[vecfield]
>
> Out[4]= -Graphics3D-
>
>    ... in the following, I do get all the expected arrows with heads,
>    but why?  As I understand, Union is only supposed to sort and
>    remove duplicates, so what difference does it make as far as
>    ListPlotVectorField3D is concerned?  Plus I have experimented with
>    "some amount" of duplication without problem.
>
>   In[5]:= ListPlotVectorField3D[Union[vecfield],
>
> Out[5]= -Graphics3D-
>
>
> Am I doing something wrong?
> Thanks,
> Alain
>

```

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