Active detector length is compared with a coverage floor. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.
highlighted = computed this step
One active cell is below the coverage floor
Active cells 1 with pitch 2 meters give active length 2 meters.
m=Lactive−Lmin=2−4=−2,fail
Two active cells exactly meet the floor
Active cells 2 with pitch 2 meters give active length 4 meters.
m=Lactive−Lmin=4−4=0,pass
Three active cells clear the floor
Active cells 3 with pitch 2 meters give active length 6 meters.