[Ifeffit] Plot multiple fits in (D)Artemis and statistical errors

[Christopher Patridge]

Hello Nilmar,

You mention floating the so2 value between two values?  Can you constrain
that value and completely remove it from the fit?  It can usually be
reasonably determined by standards. You might also take a look at the
correlations in your fit.  As another general guideline, when posting
issues you come across, a very helpful step is to find and attach the log
file in the Demeter folder after the error occurs, such as the program
closing, which gives detailed information of the problem.  I don't remember
the exact location for the file but if you search the mailing list for the
DArtemislog or artemis log file, you should be able to find it.

You also have many parameters that you are fitting.  Could you establish
any sorts of relationships or approximations between them in order to
reduce the number?  You have ss for In and Ir which are quite close in
value as well as delrIn11           =   0.00235278 and  delrIn12
=   0.00255704    # +/-   0.00000000     [0] .  You could set them equal to
each other and this can reduce the uncertainty of the fit.

buena salud,

Chris

On Fri, Oct 26, 2012 at 8:42 AM, Nilmar Camilo <nilmar at fis.ufu.br> wrote:

> Dear Bruce,****
>
> ** **
>
> I am new in the list and really don’t know if the points raised below were
> already discussed.****
>
> In the (D)Artemis (Demeter version 0.9.13) how may I:****
>
> **-          **Plot different fits with the experimental data (to
> visually compare the results)****
>
> **-          **I don’t know if this is a (new) bug of the program but
> when I try to restore a fit the program closes. In the log file the
> following line is written: “Can't use an undefined value as a HASH
> reference at C:/Strawberry/perl/site/lib/Demeter/Fit.pm line 1558.”****
>
> Obs.:  I am running Demeter in Windows 7 (Pro).****
>
> ** **
>
> Another problem is related to the statistical errors when constraining the
> S0^2 parameter to float between two limits.  The program doesn’t return the
> error for all others parameters (but just zero as the error value) as you
> can see below:****
>
> ** **
>
> guess parameters:
>                        ****
>
>   amp                =   0.79284158    # +/-   0.00000000     [0.95]****
>
>   enot               =   5.29826510    # +/-   0.00000000     [0]****
>
>   delrIn11           =   0.00235278    # +/-   0.00000000     [0]****
>
>   ssIn11             =   0.00155959    # +/-   0.00000000     [0.00300]***
> *
>
>   delrCe1            =  -0.00231455    # +/-   0.00000000     [0]****
>
>   ssCe1              =   0.00192778    # +/-   0.00000000     [0.00300]***
> *
>
>   delrIn11In11       =   0.02070081    # +/-   0.00000000     [0]****
>
>   delrIr1            =  -0.00435502    # +/-   0.00000000     [0]****
>
>   ssIr1              =   0.00386517    # +/-   0.00000000     [0.00300]***
> *
>
>   delrIn31           =   0.00648507    # +/-   0.00000000     [0]****
>
>   ssIn31             =   0.00669602    # +/-   0.00000000     [0.00300]***
> *
>
>   delrIn12           =   0.00255704    # +/-   0.00000000     [0]****
>
>   ssIn12             =   0.00305432    # +/-   0.00000000     [0.00300]***
> *
>
> ** **
>
> def
> parameters:
> ****
>
>   b                  =   0.80000000    # [min(max(0.8,amp),1.0)]****
>
> ** **
>
> ** **
>
> Thanks so much in advance.****
>
> Nilmar****
>
> ** **
>
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>
>


-- 
Christopher J. Patridge PhD.
Contact: (315)-529-0501
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