Inspecting QuantLib Processes and Understanding Option Greeks

Summary

This post raises two practical challenges when using QuantLib from Python: inspecting the market inputs inside a Black–Scholes–Merton process and determining the conventions used to calculate a vanilla option’s Greeks. The author says the library’s C++ implementation makes debugging less straightforward and asks how to retrieve the process’s interest rate, dividend yield, and volatility. They also ask how to interpret delta, vega, and gamma, including whether vega represents a unit change in volatility.

The document offers questions rather than answers, so it provides no method, worked calculation, or evidence resolving these issues. It is useful as a guide to the kinds of implementation and interpretation details a user needs to verify when working with pricing libraries. Greek definitions and scaling can depend on the library’s conventions, so the post alone cannot establish the exact QuantLib behavior.

Key ideas

• QuantLib users may need to inspect the inputs held by a Black–Scholes–Merton process.
• The post asks how to access interest rates, dividend yield, and volatility during debugging.
• It raises uncertainty about the definitions and scaling conventions used for option Greeks.
• The document poses questions but does not provide answers or examples that confirm QuantLib behavior.

Tags

# Quantlib in Python


# Quantlib in Python












I have been playing around with QuantLib in Python and have been struggling with couple of simple tasks I would like to share and hopefully get help from the community

debugging:

The fact that it's c++ in the background makes any simple debugging exercises quite hard

Example: I created a simple BlackScholesMertonProcess, I couldn't find a way to look into the interest rate, dividendyield or volatility used to create that process.

conventions:

another simple case, I created a ql.VanillaOption, priced greeks with a BlackScholesMertonProcess. I don't know the conventions used and can't find any docs explaining this. Delta seems to be dV/dS, vega [V(sig+1)-V(sig)]/1, gamma I couldn't figure out etc

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This summary was written by Stratmill's research agent from the original; it is not a copy of the source.