From abb67df4b77364b20a64b43ee3e427cacd60e22f Mon Sep 17 00:00:00 2001 From: Thomas White Date: Thu, 11 Nov 2010 17:51:49 +0100 Subject: Update docs --- doc/process_hkl.txt | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) diff --git a/doc/process_hkl.txt b/doc/process_hkl.txt index 601bcaa2..3c5e40f9 100644 --- a/doc/process_hkl.txt +++ b/doc/process_hkl.txt @@ -26,5 +26,21 @@ somewhat different to the conventional use of the term. In these cases, you will need to merge according to the point group corresponding holohedral Laue class. +You can also tell process_hkl the "apparent" symmetry, which is the symmetry as +far as whatever produced the stream was concerned. In the case of most indexing +algorithms, this will be the corresponding holohedral point group (not the +Laue class nor the holohedral Laue class). If you use the "-a" option to give +this information, process_hkl will try to resolve the remaining orientational +ambiguities to get from the apparent symmetry to the true symmetry (given with +"-y"). Currently, it won't do a very good job of it. + +Commit number 5cdcaad6277c on the 13th of October 2010 altered indexamajig such +that it always finds a right-handed unit cell. That means that no ambiguity due +to inversion exists in streams produced by versions later than that. For +streams produced by copies of indexamajig older than that, you DO need to use +the corresponding holohedral Laue class (not point group) as the apparent +symmetry (with -a). However, since the ambiguity resolution used by process_hkl +doesn't really work, this detail is somewhat academic. + The document twin-calculator.pdf contains more detailed information about this issue, as well as tables which contain all the required information. -- cgit v1.2.3