the logic to find peak and bottoms explain:

when  Low of candle(i) bigger than maximum of (Lips , Jaws , Teeth)  we get peak

when High of candle(i) lower than minimum of (Lips , Jaws , Teeth)  we get bottom

then we calculate highest high and lowest low to draw zigzag

it is accurate for calculate fibo , harmonic pattern and find trend direction

regards