afni.nimh.nih.gov

HI Brian,

If you don't want to threshold dataset A at all, then you can use an expression like:

-expr 'a*step(b)'

and for case 2:

-expr 'a*step(b)*step(c)'

Though if your mask datasets B and C consist of only zeros and ones, then you
don't need the step function:

-expr 'a*b'
-expr 'a*b*c'

Also, note that step() is the same function as ispositive(), but ispositive() might
be more descriptive.

- rick