Ticket #8624 (closed: fixed)

Opened 7 years ago

Last modified 5 years ago

Extent and increase the sampling density of the time domain in the StretchedExFT fitting function

Reported by: Jose Borreguero Owned by: Jose Borreguero
Priority: major Milestone: Release 3.1
Component: Indirect Inelastic Keywords:
Cc: Blocked By:
Blocking: Tester: Roman Tolchenov

Description (last modified by Jose Borreguero) (diff)

The StretchedExFT fitting function calculates the FFT of the stretched exponential using as many time points as bins in the histogram data. This turns out to be insufficient. Many more time points are neccessary to produce a Fourier Transform that can be fitted to the data.

Note to TESTER:

Donwload all attachments and open the python script in the script window of MantidPlot. The header of the script contains the instructions to test the ticket. (the png files are there if you want to take a look at the "experimental" structure factors to be fitted) You can modify the initial guesses for the fitting parameters to see how robust is the fit with respect to the initial guess.

Attachments

lorentzian1.dat​ (11.1 KB) - added by Jose Borreguero 7 years ago.
lorentzian strutcture factor data
lorentzian1.png​ (28.0 KB) - added by Jose Borreguero 7 years ago.
lorentzian structure factor plot
gaussian1.dat​ (17.2 KB) - added by Jose Borreguero 7 years ago.
gaussian structure factor data
gaussian1.png​ (29.0 KB) - added by Jose Borreguero 7 years ago.
gaussian structure factor plot
test_ticket_8624.py​ (1.1 KB) - added by Jose Borreguero 7 years ago.
do fits to lorentzian and gaussian

Change History

Changed 7 years ago by Jose Borreguero

lorentzian strutcture factor data

Changed 7 years ago by Jose Borreguero

lorentzian structure factor plot

Changed 7 years ago by Jose Borreguero

gaussian structure factor data

Changed 7 years ago by Jose Borreguero

gaussian structure factor plot

Changed 7 years ago by Jose Borreguero

do fits to lorentzian and gaussian

comment:1 Changed 7 years ago by Jose Borreguero

  • Status changed from new to inprogress

Refs #8624 improved time domain

both tmin and tmax have been extended to make sure we obtain a sufficiently complete frequency spectrum after doing the fourier transform

modified: StretchedExpFT.py modified: StretchedExpFTTest.py

Changeset: 54c3fefe2e922797bafde3254c78816bec2147ef

comment:2 Changed 7 years ago by Jose Borreguero

Refs #8624 Impose limit on time domain size

Extension of the time domain may create a too large one, thus lengthening the fitting in excess

modified: StretchedExpFT.py modified: StretchedExpFTTest.py

Changeset: 7be194d98f1877296c84f17945947134e786f27a

comment:3 Changed 7 years ago by Jose Borreguero

  • Description modified (diff)

comment:4 Changed 7 years ago by Jose Borreguero

Note to TESTER: please read the tester notes in the Description of the ticket

comment:5 Changed 7 years ago by Jose Borreguero

  • Status changed from inprogress to verify
  • Resolution set to fixed

comment:6 Changed 7 years ago by Jose Borreguero

Notes to tester: Please read the notes for the tester in the description of the ticket

comment:7 Changed 7 years ago by Roman Tolchenov

  • Status changed from verify to verifying
  • Tester set to Roman Tolchenov

comment:8 Changed 7 years ago by Roman Tolchenov

  • Status changed from verifying to closed

Changes make fit better.

comment:9 Changed 7 years ago by Roman Tolchenov

Merge remote-tracking branch 'origin/feature/8624_improve_time_sampling_stExFT'

Full changeset: ​2168e72cb610cb6279f253abae2a8ab3dd631a74

comment:10 Changed 7 years ago by Jose Borreguero

  • Component changed from Framework to Indirect Inelastic

comment:11 Changed 5 years ago by Stuart Campbell

This ticket has been transferred to github issue ​9468

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