Excel trendline

[David Love]

The trendline function is more than a "rounding off" of values.  It uses
various mathematical formulas (your choice) that describe different types of
curves to find a best fit for the data you have.  The point here was to
determine the Y values of the curve at specific points on the X axis.  

David Love
davidlovepianos at comcast.net 

-----Original Message-----
From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On Behalf
Of John Fortiner
Sent: Sunday, May 14, 2006 10:12 PM
To: 'Pianotech List'
Subject: RE: Excel trendline

Ron:  The "smoothing" is simply a "rounding off" of values.  Sometimes it
rounds up and sometimes down depending on settings.  Sort of like saying the
over tension is "about" 40k lbs on a piano.  That is a "smoothed" figure.
It is totally impossible to derive an "exact" from that.  To derive the
"exact" a person would have to have all the raw data to recalculate
again.....
I'm sure this isn't what you wanted to hear, but that's the way it is. ;-{

John Fortiner
Billings, MT. 

-----Original Message-----
From: Ron Nossaman [mailto:rnossaman at cox.net] 
Sent: Sunday, May 14, 2006 12:25 PM
To: Pianotech
Subject: Excel trendline


Brain pool - help!

Excel has a trendline feature in it's charting system, to visually smooth
the data. Does anyone know a way to get the set of smoothed data point
values BACK from the second degree polynomial trendline routine, or how to
use the trendline's Y and R^2 formulas to reconstruct the smoothed set in a
column?

Yes, it's piano related.

Thanks,
Ron N