Hi Daniel,
I tried the method you mentioned, unfortunately, I got another error:
#Script is running (command trimmed):
cat_matvec -ONELINE ./sub04_avg_anat_al_junk_e2a_only_mat.aff12.1D /Volumes/fMRI_Data/AFNI_PROCESSED_DATA/vis_loc/sub04_20170516/xform_test.aff12.1D -I > ./sub04_avg_anat_al_junk_mat.aff12.1D
** FATAL ERROR: File '/Volumes/fMRI_Data/AFNI_PROCESSED_DATA/vis_loc/sub04_20170516/xform_test.aff12.1D' has 4 values per row, which isn't 12
I'm totally confused now.
Sarah