[Ifeffit] General question

[Dimitar Popmintchev]

Thank you!

Dimitar

On Fri, Oct 14, 2016 at 6:54 AM, Bruce Ravel <bravel at bnl.gov> wrote:

> On 10/13/2016 05:17 PM, Dimitar Popmintchev wrote:
>
>> I would like to ask, after a fit (in Artemis) which column in the output
>> file gives the uncertainty for peaks position dR (R+/-dR  i.e. 3+/-0.02
>> Angstroms)  ?
>>
>
> Error bars are not propagated in Artemis currently.  That's something you,
> the user, has to do using the math expression that relates your variable(s)
> to the delta R in question.
>
> The simplest common case is one where you have
>
>    guess delr = 0
>
> then later, for some path,
>
>    reff   = 3.0
>    deltaR = delr
>
> In that case, delr is varied and the path length is 3.0 + delr.
>
> Propagating the uncertainty in this case is trivial:
>
>    delta( 3.0 + delr) = delta(3.0) + delta(delr)
>
> 3.0 is a constant, so the error bar in the path length is the same as the
> error bar in the variable.
>
> HTH,
> B
>
>
>
> --
>  Bruce Ravel  ------------------------------------ bravel at bnl.gov
>
>  National Institute of Standards and Technology
>  Synchrotron Science Group at NSLS-II
>  Building 743, Room 114
>  Upton NY, 11973
>
>  Homepage:    http://bruceravel.github.io/home/
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