Changeset 96153e4 in sasmodels for sasmodels/models/parallelepiped.py
 Timestamp:
 May 20, 2018 11:22:28 PM (4 years ago)
 Branches:
 master, core_shell_microgels, magnetic_model, ticket1257vesicleproduct, ticket_1156, ticket_1265_superball, ticket_822_more_unit_tests
 Children:
 fc7bcd5
 Parents:
 c64a68e
 File:

 1 edited
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sasmodels/models/parallelepiped.py
rb343226 r96153e4 19 19 20 20 The 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 MonteCarlo 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. 21 given in *any* size order as long as the particles are randomly oriented (i.e. 22 take on all possible orientations see notes on 2D below). To avoid multiple fit 23 solutions, especially with MonteCarlo fit methods, it may be advisable to 24 restrict their ranges. There may be a number of closely similar "best fits", so 25 some trial and error, or fixing of some dimensions at expected values, may 26 help. 25 27 26 28 The form factor is normalized by the particle volume and the 1D scattering … … 80 82 of the calculation and angular dispersions see :ref:`orientation` . 81 83 82 .. Comment by Miguel Gonzalez:83 The following text has been commented because I think there are two84 mistakes. Psi is the rotational angle around C (but I cannot understand85 what it means against the q plane) and psi=0 corresponds to ax and by.86 87 The angle $\Psi$ is the rotational angle around the $C$ axis against88 the $q$ plane. For example, $\Psi = 0$ when the $B$ axis is parallel89 to the $x$axis of the detector.90 91 84 The angle $\Psi$ is the rotational angle around the $C$ axis. 92 85 For $\theta = 0$ and $\phi = 0$, $\Psi = 0$ corresponds to the $B$ axis … … 97 90 of the particle to obtain the final orientation of the parallelepiped. 98 91 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 99 97 .. _parallelepipedorientation: 100 98
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