You'll need to write a function using if...elseif...elseif...else...end or you could be creative and write the function using interp1 if wanted a one-liner.
Actually, I was just kicked in the teeth again by the silly restriction of interp1 that only accepts a scalar extrapolation value instead of a two vector for each end...why, TMW hamstrung it such is a pain for such cases. It seems like I figured out a workaround some years ago, but it doesn't strike me at the moment what it was... :( This may just be enough to submit the enhancement request.
