“Before using the program, please load Excel Add-Ins "Analysis ToolPak VBA" on your computer. The program uses this resource for calculation of Bessel functions. How to load it: 1. Press Office button 2. Choose Excel Options 3. Choose Add-ins bookmark 4. Choose "Excel Add-ins" from "Manage" drop-down menu and click go 5. Check "Analysis ToolPak VBA" option and exit by clicking ok