SRS1 Cubic Spline for Excel is free software that adds cubic and other spline functions as well as linear interpolation to Microsoft Excel. The cubic spline function smoothly interpolates between given data points. It is possible to provide a more constrained smooth fit to data with the help of Bessel and OneWay (monotonic) spline functions. The integration is seamless, you access these added functions same way as with Excel built-in functions. This current version of the program works with Excel 2007 or later, including both 32 and 64 bit versions. Operating systems this is compatible with is Windows versions right up to Windows 8. The downloaded package includes a sample workbook showing how SRS1 Cubic Spline for Excel functions work. This workbook shows examples of how to use the functions provided in this tool in your Excel analysis scenarios.
There is a workbook included that illustrate interpolation of monthly economic values from quarterly data. This real life example demonstrates how the cubic spline functions can be used to interpolate monthly values from a set of economic values that are given on a quarterly basis. Other examples are provided. For regular users of Excel, this tool just adds additional functions; there is no change in how you use the spreadsheet. When you want to add the functions provided by this plug-in, you simply pick off the functions from the list of functions provided by the Excel. This is a very good tool.