<html><body><div style="color:#000; background-color:#fff; font-family:Courier New, courier, monaco, monospace, sans-serif;font-size:10pt"><div><span>Hi Emre,</span></div><div><span><br></span></div><div><span>This turns out to be a very long-standing oversight.</span></div><div><span>Could you try again with the next cctbx build?</span></div><div><span>http://cci.lbl.gov/cctbx_build/all.html</span></div><div><span>Wait for build tag 2011_06_03_XXXX or higher.</span></div><div><span>It should give you 2*a,2*b,2*c.</span></div><div><br></div><div>The oversight was in cctbx/sgtbx/space_group_type.cpp, in the</div><div>cmp_change_of_basis_mx class. I was only evaluating "is one the</div><div>unit matrix but not the other". I had to add "is one a diagonal</div><div>matrix and not the other".</div><div><br></div><div>Ralf</div><div><br></div><div>P.S.: If you want to try the new version straightaway, you can</div><div>use the
command</div><div><br></div><div>libtbx/development/cctbx_svn_getting_started.csh</div><div><br></div><div>Then manually build from sources as described here:</div><div><br></div><div>http://cctbx.sourceforge.net/current/installation.html</div><div><br></div><div><blockquote style="border-left: 2px solid rgb(16, 16, 255); margin-left: 5px; padding-left: 5px;"><div style="font-family: Courier New, courier, monaco, monospace, sans-serif; font-size: 10pt;"><div style="font-family: times new roman, new york, times, serif; font-size: 12pt;"><font face="Arial" size="2"><hr size="1"><b><span style="font-weight:bold;">From:</span></b> Emre S. Tasci <emre.tasci@ehu.es><br><b><span style="font-weight: bold;">To:</span></b> cctbx mailing list <cctbxbb@phenix-online.org><br><b><span style="font-weight: bold;">Sent:</span></b> Friday, June 3, 2011 3:49 AM<br><b><span style="font-weight: bold;">Subject:</span></b> Re: [cctbxbb] Introducing arbitrary
translations in symmetry operations<br></font><br>
Dear Ralf,<br><br>Thank you very much for your answer. What we are actually trying to do is to refer to the tables of ITA (2006) 15.2.1.* where you have your space group & additional generators and voila! It's not the normalizers defined as a group but the group+normalizers defined as a new group.. 8)<br><br>Here is yet another question-- I might be missing something obvious here so you got my apologies beforehand if it proves that I do:<br><br>Take for instance SG #16, P222. I add the 3 translation operators<br>x+1/2,y,z<br>x,y+1/2,z<br>x,y,z+1/2<br>plus the inversion:<br>-x,-y,-z<br><br>then I get SG #47, Pmmm with (2*b,2*c,2*a) -- but why not (2*a,2*b,2*c)? As I said, I'm highly suspecting that I'm missing something very very obvious but at this moment I'm baffled.<br><br>With my best regards,<br>Emre<br><br><br>On 06/02/2011 07:32 AM, Ralf W. Grosse-Kunstleve wrote:<br>>> But we couldn't find a way to introduce "x,y,z+t" while we are
"expand_smx"ing the space group with these operators.<br>> <br>> <br>> The space_group class only supports finite groups (and only in settings<br>> that can be represented with integral rotation parts and rational<br>> translation parts).<br>> We have the class cctbx.sgtbx.search_symmetry, which multiplies the<br>> discrete origin shifts into the space group and keeps track<br>> of the continuous allowed origin shifts separately.<br>> <br>> It would need new code to determine a full description of affine<br>> normalizers. (Are they considered space groups?)<br><br><br>-- =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-<br>Emre S. Tasci - http://www.emresururi.com<br>Fisica de la Materia Condensada<br>Facultad de Ciencia y Tecnologia<br>Universidad del Pais Vasco<br>Apartado 644<br>48080 Bilbao / Spain<br>-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=<br>_______________________________________________<br>cctbxbb mailing
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