To all: After talking to Woody Setzer offline, I ran my "problem" scripts again. I am embarrassed to say that it worked fine for all previously intransigent parameter sets. I compared the results to those of my Windows buddy, and they are essentially identical, with the average absolute difference at each time point is 1.3e-06. I am planning to go back and try to understand what went wrong before. I never used hmin (mistakenly of course, instead of hmax) UNTIL a run with default lsoda argument values failed. Now the default values work! Thus the mistaken use of hmin isn't the entire answer. Thank you for the time and interest, and I apologize for troubling you. I will get back to the list if I can ever repeat the problem or if I can figure out what I did wrong.
Best Regards, Hank On Jul 27, 2005, at 12:36 PM, Martin Henry H. Stevens wrote: > 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 <- as.data.frame(lsoda(xstart,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 > http://www.cas.muohio.edu/botany/bot/henry.html > http://www.muohio.edu/ecology/ > http://www.muohio.edu/botany/ > "E Pluribus Unum" > > ______________________________________________ > [email protected] mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide! > http://www.R-project.org/posting-guide.html > > 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 http://www.cas.muohio.edu/botany/bot/henry.html http://www.muohio.edu/ecology/ http://www.muohio.edu/botany/ "E Pluribus Unum" ______________________________________________ [email protected] mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
