To whom it may concern (which might be nobody):
I think that one of the 3dWarp help file examples may have a very small error. The section that reads:
####################
Example of warping +tlrc results back to +orig space of some subject
(get xform matrix, apply it, tell dataset it is not in orig space):
cat_matvec subj1_anat+tlrc::WARP_DATA > tlrc_xform.1D
3dWarp -matvec_out2in tlrc_xform.1D -prefix group_warped+tlrc \
-gridset subj1_epi+orig -cubic group_data+tlrc
3drefit -view orig group_warped+tlrc
####################
...should have the 3dWarp -matvec* flag argument as "-matvec_in2out". At least, that's what works, unless I'm quite confused.
Thanks
-Daniel
