Re: [femm] Re: number of points in material defintion

["Robert Macy" <macy@xxxxxxxxxxxxxx>]

My concern is that the "curve fitting" process puts me into very incorrect
territory with regard to actual permeability vs A/m field strengths.
Probably too small to be significant, but still doesn't represent the
material anymore.

- Robert -


----- Original Message -----
From: mailto:David Meeker <dmeeker@xxxxxxxx
To: femm@xxxxxxxxxxxxxxx
Sent: Wednesday, February 05, 2003 7:07 AM
Subject: [femm] Re: number of points in material defintion


--- In femm@xxxxxxxxxxxxxxx, "Robert Macy" <macy@xxxx> wrote:
> I took points from manufacturer's data curve. When femm
> plotted the data, the curve did not follow the data points.
>
> Yet, the original data was monotonic and "made sense". Please explain.
>
> - Robert -

Even when you enter in a lot of data points, your selection of points
could be such that the program can't fit a "good" cubic spline through
the points. The program fits a cubic spline and then checks if there
are any extremas anywhere in the fit, which is the definition of a
"bad" fit. If there are any extremas, the program smooths the entered
data points using a three-point moving average algorithm. The process
is repeated until a "good" fit is obtained.

Dave.
--
David Meeker
http://femm.berlios.de/dmeeker