Reparameterize barbell and capped cylinder (Trac #676)

butlerpd commented 5 years ago

Currently the parameterization of these models require a constraint in the fitting which may do funky things when using polydispersity:

constraint: bell/cap radius >= cylinder radius

Possible replacements:

ratio of bell/cap to cylinder
cylinder to bell/cap

Migrated from http://trac.sasview.org/ticket/676

{
    "status": "new",
    "changetime": "2019-03-03T01:02:50",
    "_ts": "2019-03-03 01:02:50.534611+00:00",
    "description": "Currently the parameterization of these models require a constraint in the fitting which may do funky things when using polydispersity:\n\n    constraint: bell/cap radius >= cylinder radius\n\nPossible replacements:\n* ratio of bell/cap to cylinder\n* cylinder to bell/cap",
    "reporter": "butler",
    "cc": "",
    "resolution": "",
    "workpackage": "SasModels Model Issues",
    "time": "2016-10-01T17:18:46",
    "component": "SasView",
    "summary": "Reparameterize barbell and capped cylinder",
    "priority": "major",
    "keywords": "",
    "milestone": "SasView Next Release +1",
    "owner": "",
    "type": "enhancement"
}

butlerpd commented 5 years ago

Trac update at 2019/03/01 23:52:37: butler changed workpackage from "SasModels Redesign" to "SasModels New Model"

butlerpd commented 5 years ago

Trac update at 2019/03/03 01:02:50: butler changed workpackage from "SasModels New Model" to "SasModels Model Issues"

pkienzle commented 5 years ago

May be addressed by sasview/sasview#501 (PR #211).

butlerpd commented 5 years ago

This is actually a sasmodels question suggesting that the models themselves are poorly written. For those in the know about the problem the reparameterization allowed by PR #211 can help but not for most people. Moving this to sasmodels next release +1

SasView / sasmodels

Reparameterize barbell and capped cylinder (Trac #676) #304