Opened 3 months ago

Last modified 2 months ago

#1152 new defect

document limits on parameter ranges for Hayter-Penfold structure factor

Reported by: pkienzle Owned by:
Priority: trivial Milestone: SasView 4.3.0
Component: SasView Keywords:
Cc: Work Package: SasView Bug Fixing

Description

Setting the charge to 204 in the following parameter set breaks the Hayter_MSA model:

sasview_parameter_values:scale,False,1,0,inf
:background,False,0.001,-inf,inf
:sld,False,3.5,-inf,inf
:sld_solvent,False,6.3,-inf,inf
:radius,False,300,0,inf
:volfraction,False,0.2,0,0.74
:charge,False,204,0,250
:temperature,False,293,0,450
:concentration_salt,False,0.02,0,inf
:dielectconst,False,78,-inf,inf

The docs don't say anything about it.

Change History (2)

comment:1 Changed 3 months ago by pkienzle

Note that the default parameter range is limited to 200, so this isn't a problem in practice.

comment:2 Changed 2 months ago by richardh

This ticket is perhaps really part of #859

The Hayter-Penfold rmsa S(Q) has a lot of "instabilities" which may be due to the physical limitations and/or numerical approximations used in generating it. Paul Butler and Richard had some discussions by email with Paul Fitzgerald in Sydney in Feb & March 2017 regarding issues he had seen. Jeff Penfold's view is that this S(Q) should not be pushed too far. For the record, an editied version of the email string is about to be included on #859

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