next, take the union of the run masks

• • next, take the union of the run masks
  • • the mask datasets have values of 0 and 1
    • can take union by computing the mean and comparing to 0.0
    • • other methods exist, but this is done in just two simple commands
      • 3dMean -datum short -prefix rm.mean rm.mask*.HEAD
      • 3dcalc -a rm.mean+orig -expr 'ispositive(a-0)' \
      • -prefix full_mask.$subj
    • -datum short : force full_mask to be of type short
    • rm.* files : these files will be removed later in the script
    • -a rm.mean+orig : specify the dataset used for any 'a' in '-expr'
    • -expr 'ispositive(a-0)': evaluates to 1 whenever 'a' is positive
    • • note that the comparison to 0 can be changed
      • • 0.99 would create an intersection mask
        • 0.49 would mean at least half of the masks are set