Does the add-in assume 365 days in a year, or what?
Yes, it assumes a 365 day year for most option valuation functions but it can be easily changed to any number. Simply convert your number of days to base 365. ie multiply the number of days input to the relevant function (eg number of days to expiration) by 365 and divide by the number of days in your year. For example, if you want to use a 252 day year (eg if your year is measured in trading days) then 504 days (ie exactly two trading years) would be input to all functions as 504*365/252 = 730. Note that this can only be done using the functions which accept days rather than absolute dates as input. ie HoadleyOptions2, HoadleyImpliedVolatility2 etc.
