Re: [R] odesolve/lsoda differences on Windows and Mac

From: <>
Date: Thu 28 Jul 2005 - 23:14:01 EST

I've been talking offline with Hank Stephens about this; note that in the example he quotes, he set hmin = 0.1, and the quoted error message says that the stepsize had reached hmin with no convergence. I believe that he intended to set hmax (because of the pulsed input). Then, Peter Dalgaard's explanation would make sense -- the PPC platform just needs a smaller stepsize than does the PC to achieve convergence.

R. Woodrow Setzer, Jr.
National Center for Computational Toxicology US Environmental Protection Agency
Mail Drop B305-03/US EPA/RTP, NC 27711
Ph: (919) 541-0128 Fax: (919) 541-4284

             "Martin Henry H.                                           
             <HStevens@MUOhio                                        To 
             .edu>                    "'R-Help'"                        
             07/27/2005 12:36                                        cc 
             PM                       Thomas Petzoldt                   
                                      Woodrow Setzer/RTP/USEPA/US@EPA   
                                      odesolve/lsoda differences on     
                                      Windows and Mac                   

Hi -
I am getting different results when I run the numerical integrator function lsoda (odesolve package) on a Mac and a PC. I am trying to simulating a system of 10 ODE's with two exogenous pulsed inputs to the system, and have had reasonably good success with many model parameter sets. Under some parameter sets, however, the simulations fail on the Mac (see error message below). The same parameter sets, however, appear to run fine for our computational technician on his PC, generating apparently very reasonable data.

Our tech is successfully running
Dell Latitude D810, Windows XP Pro (Service Pack 2), 1Gb RAM. RGUI 2.1.1 I am running:
  R Version 2.1.1 (2005-06-20) on a
Mac OS 10.3.9

   Machine Model:        Power Mac G5
   CPU Type:             PowerPC 970  (2.2)
   Number Of CPUs:             2
   CPU Speed:            2 GHz
   L2 Cache (per CPU):         512 KB
   Memory:         1.5 GB
   Bus Speed:            1 GHz
   Boot ROM Version:           5.0.7f0
   Serial Number:        XB3472Q1NVS

My Error Message
> system.time(

+ outAc2 <-,times, pondamph, parms, tcrit=170*730, hmin=.1))
+ )
[1] 0.02 0.01 0.04 0.00 0.00
Warning messages:

1: lsoda--  at t (=r1) and step size h (=r2), the
2:       corrector convergence failed repeatedly
3:       or with abs(h) = hmin
4: Returning early from lsoda.  Results are accurate, as far as they go

Thanks for any input.

Hank Stevens

Dr. Martin Henry H. Stevens, Assistant Professor 338 Pearson Hall
Botany Department
Miami University
Oxford, OH 45056

Office: (513) 529-4206
Lab: (513) 529-4262
FAX: (513) 529-4243

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