OK, I think I've seen this before, but I can't recall how it's done. So, if I
have a table with dates as headers, and a particular row may have, say:


0 0 0 1 0 0 0 0 0 0 2 0 0 1 0 0 0 4 0 0 0 0 0 1

As individual values.


I would like a formula that tells me that the longest time frame between
non-zero fields was 6 days. The actual value of the nonzero cells can vary.