This may not be an easy one to follow, so if you need more information please
let me know!

I have two columns of original data which are linked. Column A is time and B
is acceleration at each time in A. From these two columns of data I need to
calculate new interpolated acceleration data at time points which lie between
the original time points. I need to do this for all (approx 28 data points).
I have written the formulae to calculate the new acceleration data based upon
the new time points, but at the moment I have to identify the original time
points either side of the new time points manually. The two original time
points either side of the new time points are used to calculate the
acceleration. Unfortunately the new time periods are often less than the
original time periods, so I can often have two new interpolated data points
between two original data points. If it was only 1 it would be easy. So I
need something that will identify and return the time value that is
immediately less than the new one, and the value that is immediately greater
than the new value.

I know that this can be done in VBA, but I can not write code at the moment.

Any thoughts?