I recently presented a webinar called "Effectively Working with Excel", demonstrating some of GoldSim's Excel interface features. In addition to demonstrating how GoldSim can import/export data, I also talked about how GoldSim can dynamically interact with Excel during a simulation. One of the attendees asked me if GoldSim will wait for user-defined functions to be called by external programs, DLLs, or scripts used by Excel before reading in values from Excel. At the time, I didn't have a ready answer because I couldn't think of a time that I've actually seen this done. 
To answer his question, I built a simple GoldSim model that interfaces with an Excel file and this Excel file relies on user-defined functions written in a Python script. I thought this example might also be useful for a wider audience, so I decided to blog about it.
