DMS has published a set of macros for use in Excel or OpenCalc for interpolation and extrapolation of datasets. This can be very useful when developing loading conditions for hydrostatic calculations. But once you think about it, there are hundreds of cases where you need to interpolate / extrapolate within data sets. All macros are implemented just like any other spreadsheet function. It is entered as a formula into a cell.
You can view further details and download the macros under: