Error returned when extrapolating cross section values about xraylib HOT 5 CLOSED

Hi Dean,

I am well and hope that the same goes for you.

What you have run into is not a bug and is in fact intended behaviour. Before 4.0.0 I allowed users querying lower and higher energies than were available in the energy range of the dataset. There wouldn't be any real extrapolation happening though, just the cross section for the lowest/highest available energy would be returned, which didn't feel right.

The CS_Photo function only has data starting at 100 eV, which is why you are now getting that error. Basically xraylib doesn't have any data available for the soft X-ray energy range, mainly because it's not available, and would have large uncertainties if it did.

Hope this helps!

from xraylib.

Ah - I see. I suppose that sounds like a more reasonable approach than returning knowingly wrong answers!

Is the raw data exposed anywhere through the python bindings, so I when I catch a ValueError I can implement the behaviour I want? Or are all of cross section data over the same range (I'm afraid our library does not give me access to the paper where I may well find this information - sorry!)

from xraylib.

The raw data is not exposed, not even in the core C library.

I am not sure that the cross section data has the same range across types and atomic numbers.

Let me know If you'd like a copy of the xraylib manuscript (even though it's outdated).

from xraylib.

I am not sure that the cross section data has the same range across types and atomic numbers

Ok, thanks - this is what I was thinking. At the moment CP_Photo(10,0.00001) raises the same exception as CP_Photo(10,100000) but since I can assume that they all work at 1 keV I can catch the ValueError and sort out the logic at my end.

from xraylib.

Thanks for the answer. This was also my question

from xraylib.