Dear Karline Soetaert,
I've just returned from a week of travel, so have not had a great deal
of time to look at your request. From a brief rereading of the original
lsoda documentation, it looks as if all I need to do is set a flag to a
different value (jt to 4), and leave it up to the user to construct the
function that calculates the jacobian properly. If you'd contact me
directly, ideally with a test model, I will see if the modification is
really that simple; if so, I'll make the change and release an updated
odesolve to CRAN.
Woody
PS: Thanks, Martin
R. Woodrow Setzer, Jr.
National Center for Computational Toxicology
US Environmental Protection Agency
Mail Drop B205-01/US EPA/RTP, NC 27711
Ph: (919) 541-0128Fax: (919) 541-1194
Martin Maechler
[EMAIL PROTECTED]
ath.ethz.chTo
Soetaert, Karline
11/14/2005 09:46 [EMAIL PROTECTED]
AM cc
R-help@stat.math.ethz.ch, Woodrow
Setzer/RTP/USEPA/[EMAIL PROTECTED]
Please respondSubject
toRe: [R] odesolve with banded
Martin Maechler Jacobian [was no subject]
[EMAIL PROTECTED]
ath.ethz.ch
KSoet == Soetaert, Karline [EMAIL PROTECTED]
on Mon, 14 Nov 2005 13:20:24 +0100 writes:
KSoet Hi, I am trying to solve a model that consists of
KSoet rather stiff ODEs in R.
KSoet I use the package ODEsolve (lsoda) to solve these
KSoet ODEs.
KSoet To speed up the integration, the jacobian is also
KSoet specified.
KSoet Basically, the model is a one-dimensional
KSoet advection-diffusion problem, and thus the jacobian is
KSoet a tridiagonal matrix.
KSoet The size of this jacobian is 100*100.
KSoet In the original package LSODA it is possible to
KSoet specify that the jacobian is banded, which makes its
KSoet inversion very efficient.
KSoet However, this feature seems to have been removed in
KSoet the R version.
KSoet Is there a way to overcome this limitation?
Yes. But probably not a very easy one; maybe even a very
cumbersome one... ;-)
Note however that questions like these should typically be
addressed at the package author - which you can always quickly
find out via
packageDescription(odesolve)
Package: odesolve
Version: 0.5-12
Date: 2004/10/25
Title: Solvers for Ordinary Differential Equations
Author: R. Woodrow Setzer [EMAIL PROTECTED]
Maintainer: R. Woodrow Setzer [EMAIL PROTECTED]
Depends: R (= 1.4.0)
Description: This package provides an interface for the ODE solver
lsoda. ODEs are expressed as R functions or as compiled
code.
...
I've CC'ed this e-mail to Woodrow to help you for once
..
KSoet [[alternative HTML version deleted]]
KSoet __
KSoet .
KSoet PLEASE do read the posting guide!
KSoet http://www.R-project.org/posting-guide.html
if you do read that guide, it will tell you
- why you should always use a 'Subject' for your e-mails
- why HTML-ified e-mails are not much liked and what you can do
about it.
Regards,
Martin Maechler, ETH Zurich
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