Opened 6 months ago

Last modified 6 months ago

## #1107 new defect

# Doubts about Onion Doc

Reported by: | Joachim Wuttke | Owned by: | |
---|---|---|---|

Priority: | minor | Milestone: | SasView 4.3.0 |

Component: | sasmodels | Keywords: | |

Cc: | Work Package: | SasView Bug Fixing |

### Description

quite generally:

to facilitate citation and discussion, I'd suggest to number equations

in doc pages that contain lots of them.

concerning http://marketplace.sasview.org/models/73:

The introduction announces that the SLD of each shell may be »described

by an exponential, linear, or constant function«. In the following,

however, only only the exponential and the constant case are explicitly

covered. For a linear SLD, the reader is left with the hint that

the exponential function with small A is a good approximation.

rho_shell(r) is defined in terms of six parameters. One of them is redundant

since rho_in=B+C. The parameters B and C have no obvious physical meaning,

and they do not appear in the parameter list of Iq. Two equation blocks later,

the paremeter B is defined a second time, now in terms of rho_in, rho_out, and A.

This makes the logic very obscure.

I would suggest that rho_shell(r) be defined in terms of the parameters

A, rho_in, rho_out, r_in, r_out. Then one would introduce Delta t_shell,

B, and C as abbreviations, which makes them categorically distinct from

the API parameters.

- Joachim

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I did work out the equations for sld linear increasing or decreasing spherical shells, so one day we could add them properly.

Richard