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Re: Piecewise curve fitting in idl [message #61779 is a reply to message #61776]

Thu, 31 July 2008 07:58

jameskuyper
Messages: 79
Registered: October 2007

Member

d.poreh@gmail.com wrote:
> On 31 Jul., 05:39, James Kuyper <jameskuy...@verizon.net> wrote:
...
>> Identifying the different parts is up to you. How do you know that there
>> are 2-3 different trends? Whatever method you use to reach that
>> conclusion will have to be adequate to identify where the different
>> trends start and end. However, once you have identified the different
>> parts you want fit separately, fitting each one separately is trivial:
>> pass x[trend_start[i]:trend_end[i]] and y[trend_start[i]:trend_end[i]]
>> to the curve-fitting routine.
>>
>> If you want a curve fitting routine that automatically figures out where
>> each trend starts and ends, then it gets a LOT more complicated. You
>> could do that by using a non-linear curve fitting routine, and make the
>> transition point between the two trends be one of the parameters of your
>> fitting curve. However, I would strongly recommend trying to understand
>> why you see 2 or 3 different trends, and then try to come up with a
>> single mathematical model for the entire curve that reflects that
>> reason. Then fit that model to your data.- Zitierten Text ausblenden -
>>
>> - Zitierten Text anzeigen -
>
> how we can do this in Iplot?

I don't have any idea. Iplot is a plotting routine, not a curve fitting
routine, so I wouldn't expect it to be possible at all; but I'm not very
familiar with Itools, so I could be mistaken.

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[Message index]

		Re: Piecewise curve fitting in idl By: Wox on Fri, 01 August 2008 01:27
		Re: Piecewise curve fitting in idl By: jameskuyper on Thu, 31 July 2008 07:58
		Re: Piecewise curve fitting in idl By: pgrigis on Thu, 31 July 2008 07:41
		Re: Piecewise curve fitting in idl By: Paul Van Delst[1] on Thu, 31 July 2008 07:31
		Re: Piecewise curve fitting in idl By: David Fanning on Thu, 31 July 2008 07:03
		Re: Piecewise curve fitting in idl By: d.poreh on Thu, 31 July 2008 07:00
		Re: Piecewise curve fitting in idl By: jameskuyper on Thu, 31 July 2008 05:39
		Re: Piecewise curve fitting in idl By: d.poreh on Thu, 31 July 2008 04:54
		Re: Piecewise curve fitting in idl By: Wox on Thu, 31 July 2008 04:21
		Re: Piecewise curve fitting in idl By: Craig Markwardt on Sun, 03 August 2008 21:58

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