Get Local Minimum, Maximum Values

I have an application that dynamically downloads a date and a value.

I want to get a local high or low point , followed by the next high or low point .

=min/max(bn:bn) (where n is the cell number) won't work because the there may be
multiple - or no - high or low points within the range.

In effect , I am searching to the next high/low point , then using that as the starting point for
the next search.

John Yard