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Mathematics Graphics and Visualization Wolfram Language

Posted 9 years ago

I cannot make ListVectorPlot work. I am using Mathematica 11 on Win 10. I created the following test code: ListVectorPlot[{ { {1, 2}, {3, 4}}, {{5, 6}, {7, 8}} }] data = Table[{{x, -3 x}, {2/7, x/5}}, {x, -2, 2, 1}] ListVectorPlot[data] The data are {{{-2, 6}, {2/7, -(2/5)}}, {{-1, 3}, {2/7, -(1/5)}}, {{0, 0}, {2/7, 0}}, {{1, -3}, {2/7, 1/5}}, {{2, -6}, {2/7, 2/5}}} The pictures that were generated are meaningless - they are copied below as pictures and attached as pdf. The first picture is empty. The second picture contains many more vectors than data. There were no error messages from Mathematica. Any and all help will be appreciated. Chris Attachments:

POSTED BY: Krzysztof Burdzy

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Posted 9 years ago

A `ListVectorPlot` creates a vector field on a grid from the listed vectors through interpolation. Your first example has only two sets of vectors which is not enough to construct a vector field. (Should it give you an error or warning? Probably.) For your second example, again, a vector field is created on a grid by interpolation of the vectors you give and can be denser than the grid of vectors that you give it.

POSTED BY: Jim Baldwin

Posted 9 years ago

It would seem that `ListVectorPlot` only works for vector arrays of at least 3 by 3. For smaller arrays I get the message Visualization`Core`ListVectorPlot::vfldata With[{n = 2}, ListVectorPlot[Table[{1, 1}, {n}, {n}], VectorPoints -> All]] I wonder why the message does not appear with your input ListVectorPlot[{{{1, 2}, {3, 4}}, {{5, 6}, {7, 8}}}] If you want as many vectors as data, just use the option `VectorPoints->All`: With[{n = 3}, ListVectorPlot[Table[{1, 1}, {n}, {n}], VectorPoints -> All]] With[{n = 3}, ListVectorPlot[RandomReal[{0, 1}, {n, n, 2}]]]