As far as I'm aware there is no integration function in Excel. The reason for this may be that in EXCEL it is really easy to integrate the function yourself using any of the standard integration schemes ("Midpoint", "Trapeziodal", etc.). Of course, once the integration procedure is setup in a spreadsheet, you will be able to use this for any subsequent functions you need to integrate.

-- drej --

Integration of a six order polynomial trend line(I am afraid that you will not be happy with the solution )should not be a problem: from algebra lessons we still remember(don't we?) that

integral(X^n* dx)=1/[a*(n+1)]*X^(n+1) for n<>-1; for n=-1 we get 1/a*ln(X)

with some effort you can make a simple Vba code for it.
m777182

awhile back in this forum, IRStuff recommended numerically integerating for another posting.  seems to me that since the equation is available as is the data, numerically integrating is a simple process.  check your math book or a good reference for proper application and check your results - the good old fashion way, by hand.

good luck!
-pmover