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I'm running the following function

 vzz = DerivativeFilter[z["Path"][[All, 2]], {1}];

But if I then integrate vzz the output z is about 100 smaller than the original z.

Why is this so? I thought DerivativeFilter would provide an alternative to a finite difference scheme but the magnitude of the output is just wrong.


marked as duplicate by MarcoB, user9660, b.gates.you.know.what, Bob Hanlon, Jens Feb 15 '16 at 7:10

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  • 2
    $\begingroup$ If you read the docs for DerivativeFilter, you will see that it applies a spline interpolation and an optional Gaussian-like filter to the data, so it is not really much like a direct finite difference. $\endgroup$ – bill s Feb 10 '16 at 20:47
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    $\begingroup$ Try DerivativeFilter[{{a, b}, {c, d}}, {1}] $\endgroup$ – Dr. belisarius Feb 10 '16 at 21:19
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    $\begingroup$ Potentially related: mathematica.stackexchange.com/q/85212/280 $\endgroup$ – Alexey Popkov Feb 11 '16 at 7:35
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    $\begingroup$ Confirmed as a bug in this answer: (85214) $\endgroup$ – Mr.Wizard Feb 14 '16 at 16:06
  • $\begingroup$ thanks guys! I guess we'll have to wait for an update. $\endgroup$ – MD Coen Feb 16 '16 at 16:14