Hunter wrote:
The following formula was given to me earlier on this forum and it
works great...thanks.

=SUMPRODUCT(--($A$1:$A4<A4),--($A$1:$A4=A4-365),$B$1:$B4)

Now I need to understand how it works. What is the signfigance of
the --?

The formula is summing data in column B for dates found in colun A
for the previous 365 days from the date found in cell A4. I thought
that sumproduct only multiplied the sums of arrays. How does this
work?

Thanks in advance.

Hi Hunter,

I think this link from Bob Phillips' site will be useful for you:

http://www.xldynamic.com/source/xld.SUMPRODUCT.html


--
Hope I helped you.

Thanks in advance for your feedback.

Ciao

Franz Verga from Italy