Definition of Gradients

Hello,

I have computed a velocity vector and the same is given as an input for GradientofUNstructuredDataSets. Here I have used Compute Gradient option which gives me Gradient 0 to Gradient 8. What is the definition of Gradient 0 to Gradient 8.
If I have u, v, w as velocity components and need to compute du/dx, du/dy, du/dz etc.

Regards,

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Gradient 0 to 8 are the 9 components of the gradient of a vector field.
https://math.stackexchange.com/questions/156880/what-does-it-mean-to-take-the-gradient-of-a-vector-field

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Thank you for your reply.
I understand that Gradient 0 to 8 are the components of the gradient of vector field, but i wanted to know that how is Gradient 0, 1, … defined? is it dU/dx, dU/dy,… or something else.

0 to 2 are du/dx , du/dy , du/dz .
3 to 5 are dv/dx , dv/dy , dv/dz .
6 to 8 are dw/dx , dw/dy , dw/dz .
This is the best source I found :
https://gitlab.kitware.com/vtk/vtk/blob/master/Filters/General/vtkGradientFilter.cxx

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Thank you so much Roberto Putzu, this is what I needed.