Date: Tue, 19 Oct 2004 07:34:29 -0700

Author: Eric Ayars

Subject: Re: Curve-Fitting Software



It's free, open-source, scriptable, works on all platforms, and I have
not yet needed anything it doesn't do. "Simple" stuff like what you're
asking for is as easy as (assuming your data is in {x,y} columns in the
text file "data.txt")

y(x) = A*exp(-ax) + B*x**2
A = (insert initial guesses here)
a = (...)
B = (...)
fit y(x) "data.txt" via A,a,B
plot "data.txt", y(x)

I (and my students) use it almost exclusively in the senior lab here at
CSUC. There are numerous short tutorials on the 'net (google "gnuplot
tutorial") and if you wish I can also send you the materials I used for
a half-hour introductory mini-lecture in the lab course.


On Oct 18, 2004, at 2:54 PM, Jason St. John wrote:

> Hello, you wonderful people.
> We're looking for software which can fit curves obtained by the
> classical mechanics lab students. Excel won't do; we want to fit to
> A*exp(-ax) + B*x^2
> with best-fit values for A,a, and B. Any reccomendations? We'd like
> it easy and cheap, but I'd be willing to settle for easy.
> best regards,
> -jmsj
> ____________________________________________________
> Jason St. John 617.353.5980
> Boston University Physics Department
> Room 255, 590 Commonwealth Ave. Boston, MA 02215
Dr. Eric Ayars
Assistant Professor of Physics
California State University, Chico
From Tue Oct 19 07:43:14 2004