| Re: Gauss2DFit question [message #19927] |
Tue, 09 May 2000 00:00  |
Craig Markwardt
Messages: 1869
Registered: November 1996
|
Senior Member |
|
|
"Kenneth P. Bowman" <kbowman@null.net> writes:
> [[ This message was both posted and mailed: see
> the "To," "Cc," and "Newsgroups" headers for details. ]]
>
> In article <on3dnrl7o9.fsf@cow.physics.wisc.edu>, Craig Markwardt
> <craigmnet@cow.physics.wisc.edu> wrote:
>
>> http://cow.physics.wisc.edu/~craigm/idl/idl.html
>
> Thanks, Craig. I greatly appreciate the help.
>
> I was thinking of writing a GAUSS2DFIT replacement using the built-in
> Levenberg-Marquardt algorithm, LMFIT. Have you compared the built-in
> function with your LM algorithm? (For speed, accuracy, etc.?)
I haven't done any direct comparisons, but I would expect any better.
In the speed category it will definitely be a loser, since it does a
function call for *each* data point. For images that's a lot of
points!
MPFIT is based on MINPACK-1 which which was designed to handle more
difficult problems. I believe that LMFIT is descends from Numerical
Recipes which doesn't have that reputation.
Craig
P.S. MPFIT is not the end-all, be-all. It fails this problem
miserably, <http://www.maxthis.com/curviex.htm>, but I believe this is
because the initial trial function spans about 8 orders of magnitude.
--
------------------------------------------------------------ --------------
Craig B. Markwardt, Ph.D. EMAIL: craigmnet@cow.physics.wisc.edu
Astrophysics, IDL, Finance, Derivatives | Remove "net" for better response
------------------------------------------------------------ --------------
|
|
|
|
comp.lang.idl-pvwave archive
Members
Search
Help
Login
Home
