[Ifeffit] Artemis fit error - chi-square and R-factors are always equal to 0
bravel at bnl.gov
Fri Mar 26 12:29:40 CDT 2021
I'm sure it's that Artemis is retrieving the information incorrectly
from the fit object in Larch. That is, I imagine the fit is running
correctly and the stats are being evaluated correctly, but Artemis
failing to report correctly.
I will try to find some time t olook into it....
On 3/26/21 1:13 PM, Matt Newville wrote:
> Hi Ava,
> Sorry for the trouble. It looks to me like the fit actually ran.
> Like, getting non-trivial and non-starting values and uncertainties for
> 'ss_Cu1', 'dr_Cu1', etc tells me that many parts of the fit and code
> worked. I'm not at all sure why Chi-square and R-factor would report 0.
> Do you get a plot of the fit, and if so, does it look reasonable?
> Can you send any additional information about how the fit is being
> defined - like data file (or is this one of the example Cu data sets?)
> and feff.dat file used?
> On Fri, Mar 26, 2021 at 6:32 AM Ava Rajh <ava.rajh at ijs.si
> <mailto:ava.rajh at ijs.si>> wrote:
> I have recently installed Demeter suite on my LinuxMint 20 machine with
> all required dependencies met. Athena works well and Demeter passed all
> tests during installation. When running Artemis however, there is an
> issue with fits that persists with provided examples any any other
> projects I open (including the ones done by colleagues and just re-run
> on my machine).
> After the fit (which completes fine and returns expected fit that looks
> ok when comparing it to experiment), when inspecting the log file,
> chi-square, reduced chi-square and R values are equal to 0 (example log
> file attached bellow). No errors accompany the fit.
> I am using Larch installed with anaconda, and Artemis uses Feff6
> executable. I have re-installed Demeter and tried to get it to work
> Ifeffit but the error persists. I have found an existing git hub thread
> dealing with similar issue
> <https://github.com/bruceravel/demeter/issues/62>) but no solution
> that I
> could discern. Could it be an issue with my perl version (5.30.0)?
> Maybe. That issue seemed to start with a problem of not being able to
> find and run Feff.
> I don't know if that is relevant for you - it sure seems like Feff6 ran
> for you - can you verify that?
> I'm also not sure if that issue ever got resolved. I was sure confused
> about what was going on there.
> For sure, it is much easier for me to support and help folks using
> Larch. Can you verify that the example fitting scripts for Larch (see
> <https://github.com/xraypy/xraylarch/tree/master/examples/feffit> ) work
> for you?
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Bruce Ravel ------------------------------------ bravel at bnl.gov
National Institute of Standards and Technology
Synchrotron Science Group at NSLS-II
Lead Beamline Scientist, 6BM (BMM)
Building 743, Room 114
Upton NY, 11973
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