Changeset 96153e4 in sasmodels for sasmodels/models/parallelepiped.py


Ignore:
Timestamp:
May 20, 2018 11:22:28 PM (4 years ago)
Author:
butler
Branches:
master, core_shell_microgels, magnetic_model, ticket-1257-vesicle-product, ticket_1156, ticket_1265_superball, ticket_822_more_unit_tests
Children:
fc7bcd5
Parents:
c64a68e
Message:

more corrections and normalizations

Addreses #896. Brings parallelepiped and core-shell parallelepiped more
into line with each other and corrects angle definitions refering to
orietnational distribution docs for details. Still need to sort out
with Paul Kienzle the proper order the angles are applied.

File:
1 edited

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  • sasmodels/models/parallelepiped.py

    rb343226 r96153e4  
    1919 
    2020The three dimensions of the parallelepiped (strictly here a cuboid) may be 
    21 given in *any* size order. To avoid multiple fit solutions, especially 
    22 with Monte-Carlo fit methods, it may be advisable to restrict their ranges. 
    23 There may be a number of closely similar "best fits", so some trial and 
    24 error, or fixing of some dimensions at expected values, may help. 
     21given in *any* size order as long as the particles are randomly oriented (i.e. 
     22take on all possible orientations see notes on 2D below). To avoid multiple fit 
     23solutions, especially with Monte-Carlo fit methods, it may be advisable to 
     24restrict their ranges. There may be a number of closely similar "best fits", so 
     25some trial and error, or fixing of some dimensions at expected values, may 
     26help. 
    2527 
    2628The form factor is normalized by the particle volume and the 1D scattering 
     
    8082of the calculation and angular dispersions see :ref:`orientation` . 
    8183 
    82 .. Comment by Miguel Gonzalez: 
    83    The following text has been commented because I think there are two 
    84    mistakes. Psi is the rotational angle around C (but I cannot understand 
    85    what it means against the q plane) and psi=0 corresponds to a||x and b||y. 
    86  
    87    The angle $\Psi$ is the rotational angle around the $C$ axis against 
    88    the $q$ plane. For example, $\Psi = 0$ when the $B$ axis is parallel 
    89    to the $x$-axis of the detector. 
    90  
    9184The angle $\Psi$ is the rotational angle around the $C$ axis. 
    9285For $\theta = 0$ and $\phi = 0$, $\Psi = 0$ corresponds to the $B$ axis 
     
    9790of the particle to obtain the final orientation of the parallelepiped. 
    9891 
     92.. note:: For 2d, constraints must be applied during fitting to ensure that the 
     93   inequality $A < B < C$ is not violated, and hence the correct definition 
     94   of angles is preserved. The calculation will not report an error, 
     95   but the results may be not correct. 
     96    
    9997.. _parallelepiped-orientation: 
    10098 
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