The comment said internal-to-McStas is 180 degrees about x. It is 180 degrees
about z: internal (a,b,c) maps to McStas (-a,-b,+c), which is what makes the
written vectors correct - internal +y becomes (0,-1,0), the -x of Rx(-rot2)
becomes (1,0,0), and the -z of Rz(-rot3) is unchanged.
180 degrees about x is the internal-to-imgCIF relation, one step further on, and
it is the frame the verification was done in - which is why the vectors are right
and only the prose was wrong. Re-measured after the change: still 1.6e-6 mm over
nine tilt settings.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
leonarski_fandClaude Opus 5
cc334c5c55