Dear Moeti NCube
I have read several discussions of
pricing and calibration of Heston model and I am wondering if you have encountered the problems alluded to in the following comments on calibrating Heston and pricing Heston calls given parameters:
(1) pricing the option using Heston' formulas " gives rise to an inherent numerical instability as a
consequence of which most implementations of Heston’s formulæ are not robust for moderate to long dated maturities or strong mean reversion."
(2) the calibration can get bogged down in local minima and can take a long time
In Heston model, If the parameters obey 2*kappa*theta> sig (known as the Feller condition) then the process volatility is strictly positive. When I run your codes even using your marketdata, calibrated parameters violate the feller condition. Could you please explain why it is so and probably fix it if possible.
Thanks in advance