I agree will all that Jon tells you.
Why not get the values of the trendline equation into cells?
See http://people.stfx.ca/bliengme/ExcelTips/Polynomial.htm

Do not always assume there is a bug - we ALL make mistakes and the problem
could be yours (as it is here)

best wishes
--
Bernard V Liengme
Microsoft Excel MVP
http://people.stfx.ca/bliengme
remove caps from email


"Heatjer Mayes" wrote in message
...
I also have trouble with the formula from adding a trendline to a 4th
order polynomial. I graphed data in both 2003 and 2007 and added a 4th
order trendline and displayed the formula on the graph. In both versions,
I got the same formula, specifically, y = 0.00000095x4 - 0.00753977x3 +
22.51174905x2 - 29,872.75x + 14,865,177. This yielded 46690 for my text x
value of 1980, but I expected a number less than 1.

The formula using linest was: y
= -3.3105E-10x^4+1.77394E-06x^3+-0.002673x^2+0x+1798.06, which yields the
expected 0.0065 for the x value of 1980.

Quite a bug!

Note: I also tried a 2nd order polynomial. The results were the same
using linest and using the formula on the chart from the treadline. No
bugs.





Martin Brown wrote:

Excel 2007 Polynomial Order Incorrect
14-Dec-07

If you run the same dataset under 2003 do you get the roughly the same
coefficients for a 4th order fit as are displayed in 2007 but with one
value hidden. Or is 2007 actually doing a 3rd order fit wh

Previous Posts In This Thread:

On Wednesday, December 12, 2007 9:36 AM
Darre wrote:

Excel 2007 Polynomial Order Incorrect
We recently upgraded to Office 2007. When we attempt to do a trendline in
Excel, the order of polynomials is always one below what it is stated to
be
and the highest ordered polynomial is always wrong

On Wednesday, December 12, 2007 4:31 PM
Bernard Liengme wrote:

Have your downloaded Office 2007 SP1 and tried trendlines again?
Have your downloaded Office 2007 SP1 and tried trendlines again?
Download info: http://support.microsoft.com/kb/936982

I was unable to get to your file - my email address was rejected
best wishes
--

On Wednesday, December 12, 2007 4:44 PM
Darre wrote:

Excel 2007 Polynomial Order Incorrect
SP1 did not fix the problem.

"Bernard Liengme" wrote:

On Thursday, December 13, 2007 9:10 AM
Darre wrote:

Excel 2007 Polynomial Order Incorrect
Martin,

Here is a link to the file: http://www.mediafire.com/?7g4abmw30wn

In 2003 we were getting the correct values. 2007 is doing a 3rd order fit
when we click 4th order (and the 3rd order is wron

On Friday, December 14, 2007 2:58 AM
Martin Brown wrote:

Excel 2007 Polynomial Order Incorrect
If you run the same dataset under 2003 do you get the roughly the same
coefficients for a 4th order fit as are displayed in 2007 but with one
value hidden. Or is 2007 actually doing a 3rd order fit wh

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