A finite damping window uses exact repeated multiplication. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.
highlighted = computed this step
Retention multiplies each cycle
Initial amplitude 8 metres is multiplied by 1/2 for each of 3 cycles.
An=8⋅(21)3
After three cycles, one metre remains
The retained amplitude is 1 metre, so the lost amplitude is 7 metres.