Finite-difference vanilla options

The Black-Scholes finite-difference engine prices European, American and Bermudan vanilla options. It reports NPV, delta, gamma and theta on the same option object.

from itofin import Settings
from itofin.instruments import OptionType, VanillaOption
from itofin.pricingengines import FdBlackScholesVanillaEngine
from itofin.processes import BlackScholesProcess
from itofin.time import Date, DayCounter

today = Date(15, 1, 2025)
expiry = Date(15, 1, 2026)
settings = Settings()
settings.set_evaluation_date(today)
process = BlackScholesProcess(
    80.0, 0.05, 0.0, 0.25, today, DayCounter.actual365_fixed()
)
option = VanillaOption.american(OptionType.Put, 100.0, today, expiry, settings)
engine = FdBlackScholesVanillaEngine(process, t_grid=200, x_grid=200)
value = option.price_fd(engine)
print(value, option.delta(), option.gamma(), option.theta())

The example returns approximately 20.357667204554883 for the American put. option.set_fd_engine(engine) also attaches the engine for later option.npv() calls. The option retains its engine, and the engine retains the process.

The default grid is 100 time steps by 100 spatial nodes, with zero damping steps and FdScheme.Douglas. FdScheme.ImplicitEuler is the other supported rollback scheme. Time steps must be positive and spatial nodes at least three. Cash dividends, quanto and local-volatility settings are outside this API.

For the equivalent Go constructor and configuration, see the Go SDK FD example.