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Re: What is the difference between 'curvefit', 'lmfit' and 'svdfit' procudure? [message #52899 is a reply to message #52898]

Wed, 07 March 2007 17:08

duxiyu@gmail.com
Messages: 88
Registered: March 2007

Member

On Mar 7, 10:20 pm, Craig Markwardt
<craigm...@REMOVEcow.physics.wisc.edu> wrote:
> "dux...@gmail.com" <dux...@gmail.com> writes:
>> I have a set of 'x' and 'y', and want to use a special function 'f(x)'
>> to fit it.
>> The function 'f(x)' contains three parameters.
>> But I'm confused by the three different procudure 'curvefit', 'lmfit'
>> and 'svdfit'.
>> It seems that all of them can meet my request, but I don't know the
>> difference between them.
>
> SVDFIT is for fitting linear combinations of basis functions, probably
> not what you wanted. You could use LMFIT or CURVEFIT.
>
> You can also graduate straight to MPFIT and MPFITFUN which are both
> easier to use, and give you more options when you need them.
>
> Good luck!
> Craig
>
> Seehttp://cow.physics.wisc.edu/~craigm/idl/idl.html (under Curve Fitting)
> --
> ------------------------------------------------------------ --------------
> Craig B. Markwardt, Ph.D. EMAIL: craigm...@REMOVEcow.physics.wisc.edu
> Astrophysics, IDL, Finance, Derivatives | Remove "net" for better response
> ------------------------------------------------------------ --------------

Thank you very much!
I have download the MPFIT package.
Now I'm studying it. ^_^
But in your package there is not procedure named 'MPEVALEXPR' which is
in the sentence 'yfit = MPEVALEXPR(expr, x, p) Expression named expr'.

By the way, I wonder the difference between LMFIT and CURVEFIT very
much.
Are their function the same as each other?

Best regards,
Du Jian

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[Message index]

		Re: What is the difference between 'curvefit', 'lmfit' and 'svdfit' procudure? By: Paul Van Delst[1] on Thu, 08 March 2007 07:53
		Re: What is the difference between 'curvefit', 'lmfit' and 'svdfit' procudure? By: Wox on Thu, 08 March 2007 01:53
		Re: What is the difference between 'curvefit', 'lmfit' and 'svdfit' procudure? By: Craig Markwardt on Wed, 07 March 2007 18:07
		Re: What is the difference between 'curvefit', 'lmfit' and 'svdfit' procudure? By: duxiyu@gmail.com on Wed, 07 March 2007 17:19
		Re: What is the difference between 'curvefit', 'lmfit' and 'svdfit' procudure? By: duxiyu@gmail.com on Wed, 07 March 2007 17:08
		Re: What is the difference between 'curvefit', 'lmfit' and 'svdfit' procudure? By: news.qwest.net on Wed, 07 March 2007 07:02
		Re: What is the difference between 'curvefit', 'lmfit' and 'svdfit' procudure? By: Craig Markwardt on Wed, 07 March 2007 06:20

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