"Martin Henry H. Stevens" <[EMAIL PROTECTED]> writes: > 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.
One thought: Integrating across input pulses is a known source of "turbulence" in lsoda. You might have better luck integrating over intervals in which the input function is continuous. Tweaking the lsoda tolerances is another thing to try. I haven't seen lsoda fail like that, but it's not too surprising that marginal cases show platform dependency (i.e. the integrator just fails on Mac and barely succeeds on PC). > 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 -- O__ ---- Peter Dalgaard Øster Farimagsgade 5, Entr.B c/ /'_ --- Dept. of Biostatistics PO Box 2099, 1014 Cph. K (*) \(*) -- University of Copenhagen Denmark Ph: (+45) 35327918 ~~~~~~~~~~ - ([EMAIL PROTECTED]) FAX: (+45) 35327907 ______________________________________________ [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
