From: HOLLADAYL@aol.com
  To  : rasmb@alpha.bbri.org
  Date: Fri, 12 May 2000 20:33:21 EDT

who has a good fitting function with which to compute Mw(r,app)?

HI all your gurus,  wizards, and elves...

I'm searching for a function with which to fit A vs. r^2 with the aim of 
computing pointwise Mw estimates from absorbance scans.  Now I want to avoid 
a sliding fit of any kind in favor of a single function for the entire scan 
that replicates the essential features of the A vs. r^2 curve without 
introducing artifacts.  

Ages ago Jim Osborne used (I believe) a fitting function that was a quadratic 
in r^2 divided by a linear function of r^2.   I've tried Dierckx's 
interpolated cubic spline method, but find it is numerically problematical in 
that deleting a few points drastically alters the results.

Now please do not tell me that this is a bad thing to do, and that it is not 
the best way to analyze sed equil data.  I know this already.  But a friend 
desperately needs a reliable way to do this, and I solicit any ideas, advice, 
or suggestions you might have as to fitting functions.

I promise to put at rasmb any resulting software with a variety of fitting 
options.

thanks all...

Les Holladay