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KevinW
 
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Default Increaseing Precision in polynomial trendline equations


As Previously mentioned in this thread, I was having difficulty with the
LINEST function in Excel 2004 for Mac (OSX) Ver11.2

I couldn't get it to return the coefficients for even a simple
quadratic equation, let alone the 6th order polynomial I was using to
describe my line.

After opening my file at my office, I was able to get LINEST to perform
correctly for my 6th order polynomial as well as reproduce the example
at http://www.stfx.ca/people/bliengme/E...Polynomial.htm no
problem.

At work I am running Excel 2002 on Windows XP.

Since I didn't make any mods to my spreadsheet from my home computer,
I'd have to say that LINEST doesn't work for Excel 2004 for Mac.

Thanks
Kevin

P.S. With regards to Jerry’s suggestion on fitting multiple curves etc-
I could probably increase the accuracy of reproducing the best fit line
that I digitize, however the underlying scatter in the raw data that
curve was created from is huge. The Excel polynomial fit is good enough
for my needs. Generally, the Larson Miller Parameter is reported with
zero decimal places (ie for a given design stress the corresponding
LMP=29 or 30).


--
KevinW
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