Linear Interpolate

Here is a Linear Interpolation using An Excel VBA UDF

This UDF provides Linear Interpolation of missing buckets by coearsing the first and last buckets to 1 if they are missing and/or they are negative or zero (0)

This Interpolation routine uses a Slope and Intercept calculation to Interpolate between any Series of 'Known_ys' against any Series of 'Known_xs', meaning it can fit the Interpolation values for sequential or disparate periods, for example, given Known_ys of '2, 0 and 4' and 'Known_xs' periods of '7, 12 and 20' the period '12' of the 'Known_xs' for the value '0' will be interpolated to '2.77'. This Interpolation routine will inflate the final values as it does not rebalance the weightings of the values following Interpolation

Three Examples are demonstrated