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Re: Piecewise curve fitting in idl [message #61901 is a reply to message #61793]

Sun, 03 August 2008 21:58

Craig Markwardt
Messages: 1869
Registered: November 1996

Senior Member

d.poreh@gmail.com writes:

> On Jul 31, 1:21ï¿½pm, Wox <nom...@hotmail.com> wrote:
>> On Thu, 31 Jul 2008 03:30:22 -0700 (PDT), d.po...@gmail.com wrote:
>>> Folks
>>> How we can do the piecewise curve fitting in idl. Say we have an array
>>> that this array has got 2 or 3 trends in data and we want to fit a
>>> liner curve for each trends. In MATLAB curve fitting tool, we can
>>> easily exclude or include a part of data and then fit a curve. How we
>>> can do this in IDL
>>> Cheers
>>> Dave
>>
>> Euhm, just do the fitting on the different parts? Or do you mean
>> fitting with a piecewise polynomial (i.e. spline: see e.g. IMSL_BSLSQ
>> or IMSL_CONLSQ)
>
> just doing the fitting on the difrent part. how we can select this
> parts and how we can fit a curve to these parts separatly?

I realize I'm coming into this discussion late. However, the IDL
Astronomy library has a nice procedure LINTERP which would be very
useful for an application like this. It would still need to be
interfaced to a fitting function. It would allow you to fit the
tabulated Y values, and in principle even the tabulated-X positions,
although I would NOT advise that.

For a graphical interface, IDL is probably not the best application
unless you want to write the whole program yourself.

Craig

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Craig B. Markwardt, Ph.D. EMAIL: craigmnet@REMOVEcow.physics.wisc.edu
Astrophysics, IDL, Finance, Derivatives | Remove "net" for better response
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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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