Opened 8 years ago
Closed 8 years ago
#604 closed defect (fixed)
pringle model questions
Reported by: | pkienzle | Owned by: | ajj |
---|---|---|---|
Priority: | critical | Milestone: | SasView 4.0.0 |
Component: | SasView | Keywords: | |
Cc: | Work Package: | SasView Bug Fixing |
Description
(1) Sasmodels pringle does not match sasview pringle when polydispersity is present. Sasview does not seem to be using the usual volume normalization; the numerator is not sum(weight * form * volume), but the denominator is sum(weight * volume). Sasmodels is setting volume to 1.
(2) The SasView 3.1.2 model docs define:
Cn = integral from 0 to R r cos(…) Jn(…) J2n(…)
but the code includes an additional scaling by 1/R^{2}.
The equations in the docs and the code need to be consistent. Should the docs be updated with the 1/R^{2} factor?
(3) The normalization in (2) uses the final point r from the gaussian quadrature, which is a tiny bit less than R. Should it use R^{2} instead?
Change History (4)
comment:1 Changed 8 years ago by ajj
- Owner set to ajj
- Status changed from new to assigned
comment:2 Changed 8 years ago by butler
- Priority changed from major to critical
comment:3 Changed 8 years ago by ajj
comment:4 Changed 8 years ago by ajj
- Resolution set to fixed
- Status changed from assigned to closed
(1)&(2) The normalisation here is a bit odd. The derivation I was given for the model did not include any normalisation (mathematicians!) so I had to try to work it out and mostly did it by empirical comparison with the limiting case of a cylinder. I need to work through it again and check.
(3) Yes it should
I will sort these out before release.