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Re: xerr [message #64272]

Wed, 17 December 2008 14:41

laxsri
Messages: 6
Registered: November 2008

Junior Member

On Dec 18, 9:08 am, Paolo <pgri...@gmail.com> wrote:
> This is discussed for example in
> section 15.3 in edition 3 of the book
> "numerical recipes".
>
Not sure how to constrain the intercept though...
It seemed rather easy to use mpfitfun! Wondering if that is wrong?

Lakshmi

> Ciao,
> Paolo
>
> Vince Hradil wrote:
>> On Dec 17, 2:27 pm, lakshmi <lax...@gmail.com> wrote:
>>> Hi,
>
>>> I've been using mpfitfun to fit measured values of period (y) and
>>> distances (x) in a linear equation y = a + bx.
>>> I would like to know if we can include the measured uncertainties in x
>>> values too?
>
>>> Thanks,
>
>>> Lakshmi
>
>> Well, since it's a linear problem you should probably choose a linear
>> solution, not mpfitfun. Also, you need to take into account the
>> variance and covariance for both x and y, so you need to solve this
>> with care.
>
>> If you google "fitting a straight line when both variables are subject
>> to error" you'll get a lot of info:http://tinyurl.com/54m8l3

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[Message index]

		Re: xerr By: laxsri on Wed, 17 December 2008 14:41
		Re: xerr By: laxsri on Wed, 17 December 2008 14:34
		Re: xerr By: pgrigis on Wed, 17 December 2008 14:08
		Re: xerr By: Vince Hradil on Wed, 17 December 2008 13:29
		Re: xerr By: Craig Markwardt on Thu, 18 December 2008 19:24
		Re: xerr By: Jeremy Bailin on Thu, 18 December 2008 06:49
		Re: xerr By: wlandsman on Thu, 18 December 2008 05:31

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