Opened 2 years ago

Closed 2 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/R2.

The equations in the docs and the code need to be consistent. Should the docs be updated with the 1/R2 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 R2 instead?

Change History (4)

comment:1 Changed 2 years ago by ajj

  • Owner set to ajj
  • Status changed from new to assigned

comment:2 Changed 2 years ago by butler

  • Priority changed from major to critical

comment:3 Changed 2 years ago by ajj

(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.

comment:4 Changed 2 years ago by ajj

  • Resolution set to fixed
  • Status changed from assigned to closed
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