I am confused by quantlib
yield
classes: it doesn't make sense to use one interest rate
, e.g., today's rate, for an option chain
that has different expiry
.
Say you have a yield curve
at time t
(today) that goes out from one month to thirty years. If you have several European
equity
options
that expires
in say several possibilities (an option chain): a week, three weeks, one month, three months or six months, to compute the implied volatility
, do you still use for each expiry
, the interest rate
(QuantLib::Rate riskFreeRate
) ;closest to today, or do you use the yield curve
and instead of using FlatForward
use something else?