Jeff, the "smooth" curve that Excel uses actually goes through each point
so the sum of the offsets is always zero.
The TREND function simply draws the best straight line. Although trend lines
other than straight lines can be drawn using the least squares method, you
must always first guess the form of the equation (linear, log, exponential,
x-order polynomial, etc.).
If the "smooth" line is indeed found using the least squares method then
what is the form of the equation it uses.

Fred



"Jeff Standen" wrote in message
...
If it's the same as the TREND function, it's the least squares method.

http://mathworld.wolfram.com/LeastSquaresFitting.html

Or any other Google result you like :)

Cheers,
Jeff

"fred" wrote in message
...
Can anyone tell me the equation of the line the excel uses to show a
"smooth" line between points on a scatter chart?

Thanks
Fred