HELP!!! mapping with matrices

I have a peculiar problem and I've hit a massive wall. I am modeling driveline efficiencies and have a matrix with different engine efficiencies depending on torque and engine speed. I didn't know how to do this so I manually created a matrix with efficiency values for given ranges of torque and speed. For example, one row could be a specific range of speed (100-200 rpm) and each entry in that row is an efficiency corresponding to different ranges of torque (say 40-50 Nm, 50-60 Nm, etc,).

So I have a big bunch of efficiencies in a 21x8 matrix.

Now, I also have arrays for torque (vs. time) and speed (vs. time) and thus for POWER (vs. time). I now need to map each power entry to its corresponding efficiency, which depends on its torque and speed values at that time interval (to a specific entry in the efficiency map matrix). I don't know how to tell MATLAB to do so... Unless I create a massive LOOP with thousands os IFs...)

Please any help appreciated!