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Re: How can one improve the derivative? [message #86667 is a reply to message #86664]

Wed, 27 November 2013 06:46

wlandsman
Messages: 743
Registered: June 2000

Senior Member

You might look at the SAVGOL function which gets rid of the high-frequency signal (noise) while preserving the lower-frequency signals. (Smooth() suppresses both high and low frequencies.) The documentation for SAVGOL() says

"Tip: You can use this function in conjunction with the CONVOL function for smoothing and optionally for numeric differentiation."

On Wednesday, November 27, 2013 8:26:08 AM UTC-5, David Fanning wrote:
> g.nacarts@gmail.com writes:
>
>
>
>> I had to differentiate noisy data - which is a problem. I was wondering, how can one improve the derivative?
>
>> I read on a blog that one way is to make a Fourier filtering afterwards and another way is to apply a "smoothed" or "filtered" gradient. But I had no idea how to do this in IDL. Can anyone help?
>
>
>
> I think I would just apply the SMOOTH function to your data before you
>
> differentiate it.
>
>
>
> Cheers,
>
>
>
> David
>
> --
>
> David Fanning, Ph.D.
>
> Fanning Software Consulting, Inc.
>
> Coyote's Guide to IDL Programming: http://www.idlcoyote.com/
>
> Sepore ma de ni thue. ("Perhaps thou speakest truth.")

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[Message index]

		How can one improve the derivative? By: g.nacarts on Wed, 27 November 2013 04:25
		Re: How can one improve the derivative? By: David Fanning on Wed, 27 November 2013 05:26
		Re: How can one improve the derivative? By: wlandsman on Wed, 27 November 2013 06:46
		Re: How can one improve the derivative? By: lecacheux.alain on Wed, 27 November 2013 06:50
		Re: How can one improve the derivative? By: g.nacarts on Thu, 28 November 2013 04:28
		Re: How can one improve the derivative? By: lecacheux.alain on Thu, 28 November 2013 05:06
		Re: How can one improve the derivative? By: g.nacarts on Thu, 28 November 2013 05:27
		Re: How can one improve the derivative? By: David Fanning on Thu, 28 November 2013 05:35
		Re: How can one improve the derivative? By: g.nacarts on Thu, 28 November 2013 06:22
		Re: How can one improve the derivative? By: David Fanning on Thu, 28 November 2013 06:27
		Re: How can one improve the derivative? By: g.nacarts on Thu, 28 November 2013 06:42
		Re: How can one improve the derivative? By: David Fanning on Thu, 28 November 2013 06:48
		Re: How can one improve the derivative? By: g.nacarts on Thu, 28 November 2013 07:08
		Re: How can one improve the derivative? By: David Fanning on Thu, 28 November 2013 07:12
		Re: How can one improve the derivative? By: lecacheux.alain on Thu, 28 November 2013 08:53

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