Dear AFNI users-

We are very pleased to announce that the new AFNI Message Board framework is up! Please join us at:

https://discuss.afni.nimh.nih.gov

Existing user accounts have been migrated, so returning users can login by requesting a password reset. New users can create accounts, as well, through a standard account creation process. Please note that these setup emails might initially go to spam folders (esp. for NIH users!), so please check those locations in the beginning.

The current Message Board discussion threads have been migrated to the new framework. The current Message Board will remain visible, but read-only, for a little while.

Sincerely, AFNI HQ

# get approximate rotation part of affine file AFF, and invert it
cat_matvec   \
    -ONELINE \
    AFF -IP  \
    > AFF_IP

-P = Do a polar decomposition on the 3x3 matrix part 
       of the mfile. This would result in an orthogonal
       matrix (rotation only, no scaling) Q that is closest,
       in the Frobenius distance sense, to the input matrix A.