[Ifeffit] Athena problem

[Elien Lemmens]

Dear,

I was trying to do some linear combination fitting using Athena software. Although the box "All weight between 0 and 1" is ticked I get negative weight results.
I have read the online Athena's User's Guide, but I did not find what the issue can be. Do you have any ideas?
Below you can find some print screens of my actions. I also get an "error" (print screen 2), which I don't understand.

Thanks in advance
Elien

[cid:***@01D46703.6DC31010]

[cid:***@01D46703.6DC31010]

[cid:***@01D46703.6DC31010]

[Christopher Patridge]

Hi Elien,

I might not be correct but are the results you are showing in the 2nd screen shot coming from the combinatorics? That might be different than “fitting the data” since the combinatorics get those results by using each combination of standard and finding the best fits using those are particular standards. So across all the combinations, the D standard fits best by using a negative value which I think might be different. I am not sure but the tick box might not apply to the combinatorics.

Maybe someone else can clarify or correct my interpretation,

Chris

**********************************************
Dr Christopher Patridge
Assistant Professor
Department of Chemistry
SASE 315
D’Youville College
320 Porter Ave.
Buffalo, NY 14201
716-829-8096 / 315-529-0501

Dear,
I was trying to do some linear combination fitting using Athena software. Although the box “All weight between 0 and 1” is ticked I get negative weight results.
I have read the online Athena’s User's Guide, but I did not find what the issue can be. Do you have any ideas?
Below you can find some print screens of my actions. I also get an “error” (print screen 2), which I don’t understand.
Thanks in advance
Elien
<image001.jpg>
<image002.png>
<image003.png>
_______________________________________________
Ifeffit mailing list
http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit <http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit>
Unsubscribe: http://millenia.cars.aps.anl.gov/mailman/options/ifeffit <http://millenia.cars.aps.anl.gov/mailman/options/ifeffit>

[Catalano, Jeff]

Dear Elien and others,

The constraints should apply to all fits, even in combination fitting. I have seen this effect before (negative fit component despite checked box) and found that if I check, uncheck, and recheck each constraint/option box it then works. You might also need to restart Athena, and make sure you have the newest version. I have been too busy to submit a bug report about this.

I also see the popup warning message Elien mentioned but it does not seem to affect the fits. I have also been too busy to submit a bug report about that as well.

Jeff

On 10/18/2018 10:12 AM, Christopher Patridge wrote:
Hi Elien,

I might not be correct but are the results you are showing in the 2nd screen shot coming from the combinatorics? That might be different than “fitting the data” since the combinatorics get those results by using each combination of standard and finding the best fits using those are particular standards. So across all the combinations, the D standard fits best by using a negative value which I think might be different. I am not sure but the tick box might not apply to the combinatorics.

Maybe someone else can clarify or correct my interpretation,

Chris

**********************************************
Dr Christopher Patridge
Assistant Professor
Department of Chemistry
SASE 315
D’Youville College
320 Porter Ave.
Buffalo, NY 14201
716-829-8096 / 315-529-0501
***@dyc.edu<mailto:***@dyc.edu>



On Oct 18, 2018, at 10:55 AM, Elien Lemmens <***@kuleuven.be<mailto:***@kuleuven.be>> wrote:

Dear,

I was trying to do some linear combination fitting using Athena software. Although the box “All weight between 0 and 1” is ticked I get negative weight results.
I have read the online Athena’s User's Guide, but I did not find what the issue can be. Do you have any ideas?
Below you can find some print screens of my actions. I also get an “error” (print screen 2), which I don’t understand.

Thanks in advance
Elien

<image001.jpg>

<image002.png>

<image003.png>


_______________________________________________
Ifeffit mailing list
***@millenia.cars.aps.anl.gov<mailto:***@millenia.cars.aps.anl.gov>
http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit
Unsubscribe: http://millenia.cars.aps.anl.gov/mailman/options/ifeffit




_______________________________________________
Ifeffit mailing list
***@millenia.cars.aps.anl.gov<mailto:***@millenia.cars.aps.anl.gov>
http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit
Unsubscribe: http://millenia.cars.aps.anl.gov/mailman/options/ifeffit

[Matt Noerpel]

Hello Ellen,

You have the "Force Weights Sum to 1" box checked. Uncheck that and it
should work. I think the negative value in the last standard is balancing
out the sum of the other three standards so that the total sum is 1.

Matt

Post by Catalano, Jeff
Dear Elien and others,
The constraints should apply to all fits, even in combination fitting. I
have seen this effect before (negative fit component despite checked box)
and found that if I check, uncheck, and recheck each constraint/option box
it then works. You might also need to restart Athena, and make sure you
have the newest version. I have been too busy to submit a bug report about
this.
I also see the popup warning message Elien mentioned but it does not seem
to affect the fits. I have also been too busy to submit a bug report about
that as well.
Jeff
Hi Elien,
I might not be correct but are the results you are showing in the 2nd
screen shot coming from the combinatorics? That might be different than
“fitting the data” since the combinatorics get those results by using each
combination of standard and finding the best fits using those are
particular standards. So across all the combinations, the D standard fits
best by using a negative value which I think might be different. I am not
sure but the tick box might not apply to the combinatorics.
Maybe someone else can clarify or correct my interpretation,
Chris
**********************************************
Dr Christopher Patridge
Assistant Professor
Department of Chemistry
SASE 315
D’Youville College
320 Porter Ave.
Buffalo, NY 14201
716-829-8096 / 315-529-0501
Dear,
I was trying to do some linear combination fitting using Athena software.
Although the box “All weight between 0 and 1” is ticked I get negative
weight results.
I have read the online Athena’s User's Guide, but I did not find what the
issue can be. Do you have any ideas?
Below you can find some print screens of my actions. I also get an “error”
(print screen 2), which I don’t understand.
Thanks in advance
Elien
<image001.jpg>
<image002.png>
<image003.png>
_______________________________________________
Ifeffit mailing list
http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit
Unsubscribe: http://millenia.cars.aps.anl.gov/mailman/options/ifeffit
_______________________________________________
Unsubscribe: http://millenia.cars.aps.anl.gov/mailman/options/ifeffit
_______________________________________________
Ifeffit mailing list
http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit
Unsubscribe: http://millenia.cars.aps.anl.gov/mailman/options/ifeffit

[Matt Noerpel]

Hello Elien,

You have the "Force Weights Sum to 1" box checked. Uncheck that and it
should work. I think the negative value in the last standard is balancing
out the sum of the other three standards so that the total sum is 1.

Matt

Post by Catalano, Jeff
Dear Elien and others,
The constraints should apply to all fits, even in combination fitting. I
have seen this effect before (negative fit component despite checked box)
and found that if I check, uncheck, and recheck each constraint/option box
it then works. You might also need to restart Athena, and make sure you
have the newest version. I have been too busy to submit a bug report about
this.
I also see the popup warning message Elien mentioned but it does not seem
to affect the fits. I have also been too busy to submit a bug report about
that as well.
Jeff
Hi Elien,
I might not be correct but are the results you are showing in the 2nd
screen shot coming from the combinatorics? That might be different than
“fitting the data” since the combinatorics get those results by using each
combination of standard and finding the best fits using those are
particular standards. So across all the combinations, the D standard fits
best by using a negative value which I think might be different. I am not
sure but the tick box might not apply to the combinatorics.
Maybe someone else can clarify or correct my interpretation,
Chris
**********************************************
Dr Christopher Patridge
Assistant Professor
Department of Chemistry
SASE 315
D’Youville College
320 Porter Ave.
Buffalo, NY 14201
716-829-8096 / 315-529-0501
Dear,
I was trying to do some linear combination fitting using Athena software.
Although the box “All weight between 0 and 1” is ticked I get negative
weight results.
I have read the online Athena’s User's Guide, but I did not find what the
issue can be. Do you have any ideas?
Below you can find some print screens of my actions. I also get an “error”
(print screen 2), which I don’t understand.
Thanks in advance
Elien
<image001.jpg>
<image002.png>
<image003.png>
_______________________________________________
Ifeffit mailing list
http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit
Unsubscribe: http://millenia.cars.aps.anl.gov/mailman/options/ifeffit
_______________________________________________
Unsubscribe: http://millenia.cars.aps.anl.gov/mailman/options/ifeffit
_______________________________________________
Ifeffit mailing list
http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit
Unsubscribe: http://millenia.cars.aps.anl.gov/mailman/options/ifeffit

[Matt Newville]

Hi Elien,

Post by Elien Lemmens
Dear,
I was trying to do some linear combination fitting using Athena software.
Although the box “All weight between 0 and 1” is ticked I get negative
weight results.
I have read the online Athena’s User's Guide, but I did not find what the
issue can be. Do you have any ideas?
Below you can find some print screens of my actions. I also get an “error”
(print screen 2), which I don’t understand.

This is not really an answer for how to do this with Athena, but the Larch
XAS Viewer program can also do such linear combination analysis, and allows
setting an upper and lower limit on each weight and constraining the sum of
weights to be 1.

The GUI interface is slightly different, but the interface should be pretty
familiar to Athena users, and it can read in modern Athena Project files.
That is, it might be worth trying.

--Matt

To download and install, see
https://millenia.cars.aps.anl.gov/xraylarch/installation.html