Ticket #6016 (closed: wontfix)
Implement mutliple step fit in LeBailFit and more
| Reported by: | Wenduo Zhou | Owned by: | Wenduo Zhou |
|---|---|---|---|
| Priority: | major | Milestone: | Release 2.4 |
| Component: | Mantid | Keywords: | |
| Cc: | Blocked By: | ||
| Blocking: | Tester: | Nick Draper |
Description (last modified by Wenduo Zhou) (diff)
Implement multiple step fit in LeBailFit to increase the computation efficiency. If in one step, the minimizer uses differential of the function and the covariance between any 2 parameters, do the fitting again by using 'simplex' as the minimizer.
Add property "DampingFactor" if the user specifies the minimizer as "Damping".
Change History
comment:2 Changed 8 years ago by Wenduo Zhou
- Status changed from new to accepted
- Description modified (diff)
- Summary changed from Implement mutliple step fit in LeBailFit to Implement mutliple step fit in LeBailFit and more
comment:3 Changed 8 years ago by Wenduo Zhou
Use numerical derivative. Refs #6016.
Changeset: 3fe0fc3b82ff4a95098d46d9d9fc8ae1dc225ae6
comment:4 Changed 8 years ago by Wenduo Zhou
More choice to set peak height explicitly. Refs #6016.
Changeset: 0a8ac0aacfe4951ca62cc2ac9ed53825e1ed6a91
comment:5 Changed 8 years ago by Wenduo Zhou
Fix the build. Refs #6016.
Changeset: ac859c3e83a4f70cf02afd21eddfe2f392c3279e
comment:6 Changed 8 years ago by Wenduo Zhou
Use numerical derivative. Refs #6016.
Changeset: 3fe0fc3b82ff4a95098d46d9d9fc8ae1dc225ae6
comment:7 Changed 8 years ago by Wenduo Zhou
More choice to set peak height explicitly. Refs #6016.
Changeset: 0a8ac0aacfe4951ca62cc2ac9ed53825e1ed6a91
comment:8 Changed 8 years ago by Wenduo Zhou
Fix the build. Refs #6016.
Changeset: ac859c3e83a4f70cf02afd21eddfe2f392c3279e
comment:9 Changed 8 years ago by Wenduo Zhou
- Status changed from accepted to verify
- Resolution set to wontfix
The peak function (thermal neutron back to back exponential convoluted with pseudo-voigt) has parameters strongly correlated. In real application, fitting with regular minimizer, such as Simplex and Levenberg-Marquardt, is very unstable. Alternatively, the Monte Carlo algorithm is robust and able to obtain a good result. Therefore, the effort on doing Le Bail fit with multiple step fit with regular minimizer is given up.
comment:10 Changed 8 years ago by Nick Draper
- Status changed from verify to verifying
- Tester set to Nick Draper
work continued in #6019
comment:12 Changed 5 years ago by Stuart Campbell
This ticket has been transferred to github issue 6862
