Flexible fit functions for can and trans for SANS

[Gesner Passos]

Was agreed to implement an nth order polynomial option in the first instance & to change the GUI to allow different fits for the sample & can.

Alternative fits for transmissions. Log(Trans) can go linearly with wavelength (simple adsorption) or with square of wavelength (strong SANS) or a product of these, it can then also have a wiggle around 6 or 7 angstrom when the wide angle scatter turns off. At present we fit a straight line to Log(trans). Can we have the options to try quadratic or cubic instead of linear, with a separate switch for the sample and the can. Two drop-downs, top right of “reduction settings” tab? Default to linear as now. (I am concerned that letting say a cubic loose on something that only needs a straight line might produce some odd results.) Not sure how to fit the wiggle! Perhaps just try a smoothing function, but keeping those under control at start and end of range may be tricky. Might need two quadratics with a cross-over function in the middle.

[Gesner Passos]

Tester:

Following the complete reduction described in this link, you can change things to test how the new Polynomial method works:

• Changing the UserFile: change in the MaskFile.txt the line FIT/TRANS/YLOG 2.2 10.0 per FIT/TRANS/POLYNOMIAL3 2.2 10, OR FIT/TRANS/CAN/POLYNOMIAL4 2.2 10 and check how the interface changes.
• Change the inferface parameters for fit trans.
• Run the reductions and check that it performs correctly.

[Gesner Passos]

It will be easier to test if you change the variable _VERBOSE_ = True in the ISISCommandInterface.py.

By doing this, you will be able to see the executed command TransFit as for example:

TransFit(LOGARITHMIC, selector="SAMPLE")
TransFit(OFF, selector="CAN")

[Gesner Passos]

Fit options for SANS Reduction transmission

this commit provides a more flexible way to deal with the fit for the transmission for SANS reduction.

Now, you can set the option for the transmission and select a different fit option for the can, or for the sample.

This commit does not change anything. It just rearranges things, to prepare the path to the introduction of more fit options and to use different fit options for each transmission.

re #7733

Changeset: 6d15e0bc0b4cf1017cd3e901ec38eb8222c41f89

[Gesner Passos]

Extending fit/trans to allow selector sample|can

Process user file to allow defining fit/trans/can or fit/trans/sample providing different fit settings for can or sample.

It provides query methods to define fitMethod, lambdaMin and lambdaMax, that will be used by the GUI.

re #7733

Changeset: 4bb6ea549b252c5e3dc33ea24382203820efbaa0

[Gesner Passos]

Extend SANS UI to allow providing different fitting settings

Now, you can provide different options for CAN or SAMPLE when

fitting transmissions.

re #7733

Changeset: bdd54c8873af7a841ffb73b833d6af26f3b7819c

[Gesner Passos]

remove CALC_TRANS_FIT_PARAMS attribute

re #7733

Changeset: 341a836b0d17cd971c51efda354cac8dced6d8f8

[Gesner Passos]

Introduce support for Polynomial fit for calculate transmission

re #7733

Changeset: cce104c641455c8c70dd676b50200046a2a31f74

[Gesner Passos]

Adjust isis_reduction_steps to support polynomial for trans

re #7733

Changeset: 04b93c01553723364d3b567f3736e911e6b8b344

[Gesner Passos]

Extend SANS GUI to support Polynomial

re #7733

Changeset: 41296109248869f1e59b638150cfb877da46e7f4

[Gesner Passos]

Adjust SANS interface to read settings for can and sample

re #7733

Changeset: ec75efd1ef1e5befefc8cad19484ecefc796e12d

[Gesner Passos]

This can only be tested after closing #7734, because, it uses the CalculateTransmission new options.

[Anders Markvardsen]

as discussed

[Gesner Passos]

Correct the label of SANS INTERFACE

Change CAN to Can, to avoid confusion of thinking of acronym CAN.

re #7733

Changeset: 828463cbd4127607396577d15d3131def4dd1ec1

[Anders Markvardsen]

Merge remote-tracking branch 'origin/feature/7733_sans_fit_trans'

[Anders Markvardsen]

tested with changes to userfile and use of the new different polynomial options

[Stuart Campbell]

This ticket has been transferred to github issue ​8578