Hi Huw, This is tricky because in certain situations the cell parameter esds can get lost. For example if best_unit_cell= has been passed during scaling or merging with DIALS. Or, if cell parameter refinement was done using the LFBGS engine, in which case the esds are not calculated.
Cheers David On Fri, 23 Feb 2024, 10:40 Huw Jenkins, < 0000288da93ae744-dmarc-requ...@jiscmail.ac.uk> wrote: > > On 23 Feb 2024, at 09:58, Winter, Graeme (DLSLtd,RAL,LSCI) < > 00006a19cead4548-dmarc-requ...@jiscmail.ac.uk> wrote: > > > > so strictly it is possible and correct - if experimentally unlikely - > to have the situation we are discussing here occur. > > I believe this is only technically possible because the MTZ format does > not store esds on the unit cell parameters? In the thaumatin example > processing the dataset here - https://zenodo.org/records/4916649 - > assuming monoclinic symmetry results in unit cell: > > 58.176(2), 150.543(4), 58.2050(18), 90.0, 90.1058(9), 90.0 > > The situation you describe would result in for example: > > 58.1087(18), 150.543(4), 58.1087(15), 90.0, 90.0000(1), 90.0 > > and the test should really only fail for: > > 58.1087(18), 58.1087(18), 150.400(5), 90.0, 90.0, 90.0 > > i.e. where a=b have same value and esd (as they were constrained to be > identical and esd on beta is 0 as it was constrained to be 90. > > > > > Telling users to “fiddle the parameters” so that the strict test is > satisfied feels like a non-ideal answer: a warning when importing such data > could be legitimate e.g. “hmm I note a = b and al=be=ga=90 _exactly_ this > is unusual, I hope you know what you are doing” rather than a flat out error > > I think you have misunderstood here. I was suggesting telling users to > integrate/scale the data without imposing higher symmetry was the correct > thing to do? I don't see how "fiddling of parameters" is required. > > But I agree i2 should allow an override of this test. > > > Huw > ######################################################################## > > To unsubscribe from the CCP4BB list, click the following link: > https://www.jiscmail.ac.uk/cgi-bin/WA-JISC.exe?SUBED1=CCP4BB&A=1 > > This message was issued to members of www.jiscmail.ac.uk/CCP4BB, a > mailing list hosted by www.jiscmail.ac.uk, terms & conditions are > available at https://www.jiscmail.ac.uk/policyandsecurity/ > ######################################################################## To unsubscribe from the CCP4BB list, click the following link: https://www.jiscmail.ac.uk/cgi-bin/WA-JISC.exe?SUBED1=CCP4BB&A=1 This message was issued to members of www.jiscmail.ac.uk/CCP4BB, a mailing list hosted by www.jiscmail.ac.uk, terms & conditions are available at https://www.jiscmail.ac.uk/policyandsecurity/
