Hi all-- I'm trying to figure out how to orthogonalize symmetry operators given a unit cell, which doesn't seem to be something we have code for. These appear in PDB files in the REMARK 290 section but I haven't been able to find any other software that generates them, and the relationship between the symops and the real-space equivalents is unclear. I assume this is conceptually similar to orthogonalizing fractional coordinates, but unit_cell.orthogonalize() does not quite do what I wanted. In the PDB, for P63 it has this (excerpted): REMARK 290 2555 -Y,X-Y,Z ... REMARK 290 SMTRY1 2 -0.500000 -0.866025 0.000000 0.00000 REMARK 290 SMTRY2 2 0.866025 -0.500000 0.000000 0.00000 REMARK 290 SMTRY3 2 0.000000 0.000000 1.000000 0.00000 which looks like it should be relatively straightforward, but I'm not very good with matrices. Does anyone know the correct math for this? The corresponding rt_mx object from sgtbx looks like this: r=(0.0, -1.0, 0.0, 1.0, -1.0, 0.0, 0.0, 0.0, 1.0) t=(0.0, 0.0, 0.0) (Yes, I realize that there are much easier ways to apply symmetry operators to coordinates, but I want to limit the number of matrix multiplications involved when starting from Cartesian coordinates.) thanks, Nat