[Ifeffit] Athena and "norm" file groups

[Mike Massey]

Thanks for the response! 

For clarification, I'm not really trying to re-normalize the normalized data, which is flattened in this case. However, I'm having (terminal) difficulty extracting the EXAFS from the normalized groups, because I can't seem to get the program to pass a spline through it (even though the spline will pretty much be a straight line) and gimme my EXAFS!

All caution will of course be applied in the use of said EXAFS, if I can get that far...!


Cheers, thanks again,


Mike




> On Oct 15, 2016, at 1:25 PM, Anatoly Frenkel <anatoly.frenkel at stonybrook.edu> wrote:
> 
> I would try to rename .norm by .xmu and see if it will be able to do what you want.
> I would still be cautious doing it because .norm means that the raw data was already altered (pre-edge function was subtrated and slope changed).
> Doing anything like that is possible but not wise because it is not guaranteed that you would obtain the same result as when you start from the raw data directly.
> 
> For example, suppose "norm1" is normalization operation with one set of parameters, and "norm2" - with another. Xmu is the raw absorption coefficient data (obtained from the ratio of detector signals).
> It is not likely that norm2 (xmu) will give the same results as norm2(norm1(xmu)), although the differences may be small. That is the reason, I think, Athena does not allow any ex post factum normalization to the normalized data.
> 
> Anatoly Frenkel
> Stony Brook University
> 
> 
>> On Oct 15, 2016 4:10 PM, "Mike Massey" <mmassey at gmail.com> wrote:
>> Hi everyone,
>> 
>> 
>> Apologies if this has been covered before, I'm just getting around to upgrading to Demeter. I have a bunch of old project files with a mishmash of data from different sources, and I'm having trouble getting them to work fully with the new software.
>> 
>> Any group with a data type of "xmu" (energy space) seems to work as expected, but any group with a data type of "norm" (normalized data) doesn't seem to work properly when it comes to spline or post-edge background subtraction (which is handy if I want to do LCF, for example). Is this a bug or a feature? Has anybody yet developed a workaround?
>> 
>> Any thoughts or advice would be greatly appreciated. The ultimate workaround is to use different data, but I'd like to use existing projects if possible (saves a lot of time and brain damage).
>> 
>> 
>> Cheers, and thanks!
>> 
>> 
>> Mike
>> 
>> 
>> 
>> 
>> 
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