downProbability function

double downProbability(
  1. PricerInputs inputs,
  2. double strike
)

P(settle < strike) — the DOWN digital. Exactly 1 − up, matching the chain's range_price(-inf, strike] = up(-inf) − up(strike) = 1 − up.

Implementation

double downProbability(PricerInputs inputs, double strike) =>
    1 - upProbability(inputs, strike);