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Calculate derivatives in a non-uniform grid |
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August 1, 2019, 08:08 |
Calculate derivatives in a non-uniform grid
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#1 |
Senior Member
Join Date: Jan 2018
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I have a non-uniform 2D grid (non-equal intervals between nodes). [x,y]
I also have the data (U) calculated on this grid. I want to calculate the derivatives of U with respect to y and then x. How can I do this? (Specially using MATLAB) |
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August 1, 2019, 08:17 |
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#2 |
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Svetlana Tkachenko
Join Date: Oct 2013
Location: Australia, Sydney
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Is it rectangular grid?
You could just use matrix operations ie dmyfdx = (myf(2:end)-myf(1:end-1)) / (coordx(2:end)-coordx(1:end-1)) where myf is your variable and coordx is the x coordinate in the grid. If this is not sufficiently helpful then please create a small test case demonstrating the data format in a small example. Thanks. |
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August 1, 2019, 08:45 |
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#3 | |
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Quote:
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August 1, 2019, 18:17 |
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#4 |
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Svetlana Tkachenko
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I think you can view the formulas here
http://web.media.mit.edu/~crtaylor/calculator.html Vary the number of input points to get the desired order of accuracy. |
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August 1, 2019, 18:39 |
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#5 | |
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Filippo Maria Denaro
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Quote:
For example, you have the value f1,f2,f3 at x1,x2,x3. Then you can define a lagrangian second degree polynomial and compute analytically the derivative. More nodes allow you to increase the degree of the polynomial and the accuracy of the derivative. Have also a look to the textbook of Peric & Ferziger |
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August 2, 2019, 02:23 |
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#6 | |
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Quote:
Last edited by Moreza7; August 2, 2019 at 04:37. |
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Tags |
derivatives, non-uniform grid |
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