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I am trying to do a vector plot of a given vector field for which I wrote following code

f[x_, y_, z_] := 1/Sqrt[x^2 + y^2 + z^2] + 1/Sqrt[(x - 1)^2 + y^2 + z^2] + 1/Sqrt[(x - 1)^2 + (y -1)^2 + z^2] + 1/Sqrt[x^2 + (y - 1)^2 + z^2] + 1/Sqrt[x^2 + y^2 + (z - 1)^2] + 1/Sqrt[(x - 1)^2 + y^2 + (z - 1)^2] + 1/Sqrt[(x - 1)^2 + (y - 1)^2 + (z - 1)^2] + 1/Sqrt[x^2 + (y - 1)^2 + (z - 1)^2]
VectorPlot3D[Grad[f[x, y, z], {x, y, z}], {x, -1, 1}, {y, -1, 1}, {z, -1, 1}]

But I'm getting following output enter image description here

Where am I making the mistake and I have also tried restarting the kernel?

Edit: I got around the problem by going through the method of tables. The code is:

f[x_, y_, z_] := 1/Sqrt[x^2 + y^2 + z^2] + 1/Sqrt[(x - 1)^2 + y^2 + z^2] + 1/Sqrt[(x - 1)^2 + (y -1)^2 + z^2] + 1/Sqrt[x^2 + (y - 1)^2 + z^2] + 1/Sqrt[x^2 + y^2 + (z - 1)^2] + 1/Sqrt[(x - 1)^2 + y^2 + (z - 1)^2] + 1/Sqrt[(x - 1)^2 + (y - 1)^2 + (z - 1)^2] + 1/Sqrt[x^2 + (y - 1)^2 + (z - 1)^2]
h = Grad[f[x, y, z], {x, y, z}];
vectors = Table[-h, {x, -0.13, 1.13, 0.05}, {y, -.13, 1.13, 0.05}, {z, -.13, 1.13, 0.05}];
ListVectorPlot3D[vectors, VectorScale -> {Small, 0.6, Automatic}, VectorColorFunction -> "Rainbow", PerformanceGoal -> "Quality"]

and the output looks like: c

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1 Answer 1

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Try

VectorPlot3D[Evaluate@Grad[f[x, y, z], {x, y, z}], 
      {x, -1, 1}, {y, -1, 1}, {z, -1,1}]

enter image description here

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3
  • $\begingroup$ Nope I'm still getting the same single vector in the output. $\endgroup$
    – aitfel
    Commented Apr 3, 2020 at 5:38
  • $\begingroup$ @aitfel I am sorry to hear that. But as you can see, it works for me. May be version difference. I could try on what I have, which is V 12.1 $\endgroup$
    – Nasser
    Commented Apr 3, 2020 at 5:50
  • $\begingroup$ I did get the result but by using ListVectorPlot3D $\endgroup$
    – aitfel
    Commented Apr 3, 2020 at 6:26

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