RE: NONMEM ODE solver
Benjamin,
According the comments in the code in version VI (imagine that -
comments in code)
ADVAN6 (DVERK1.for) is originally from IMSL, and is RUNGE KUTTA-VERNER
FIFTH AND SIXTH ORDER METHOD.
ADVAN8, (DGEAR1.for) is VARIABLE ORDER ADAMS PREDICTOR CORRECTOR METHOD
OR GEARS METHOD
and
ADVAN9 is: the Livermore solver, from the ODEPACK.
and, no, I'm pretty sure there is no switching between algorithms. (does
any software do this??)
BTW, no one ever answered my question from 2 years ago.
Mark Sale
Next Level Solutions, LLC
www.NextLevelSolns.com
Quoted reply history
> -------- Original Message --------
> Subject: [NMusers] NONMEM ODE solver
> From: Benjamin Ribba <[EMAIL PROTECTED]>
> Date: Sun, May 27, 2007 12:53 pm
> To: <[email protected]>
>
> Dear NMusers,
>
> 1. I have some difficulties to find information on the ODE solver
> implemented in NONMEM.
> Can anyone tell me about the numerical integrator(s) implemented when
> using
> ADVAN6 (recommended for non-stiff) and ADVAN8 (stiff problems)? In
> particular, is the integrator able to switch automatically between
> stiff and
> non-stiff resolution techniques?
>
> 2. Then, still related to the ODE solver, I was also interested in a
> message
> I¹ve picked up from the archive (from Mark Sale, posted January 2005,
> see
> below), for which I couldn¹t find any answer from the group. Additional
> information on these items would be greatly appreciated.
> _______________________________________________________
>
> From: [EMAIL PROTECTED]
> Subject: [NMusers] questions on ODE solver errors
> Date: Wed, January 26, 2005 4:40 pm
>
> If the NOABORT option is used for the ODE solvers, and the
> ODE solver has "numerical difficulties", giving the message:
>
> NUMERICAL DIFFICULTIES WITH INTEGRATION ROUTINE.
> MAXIMUM NO. OF EVALUATIONS OF DIFFERENTIAL EQUATIONS, 100000, EXCEEDED.
> 0END OF PRED EXIT CODE MESSAGES FROM THE ESTIMATION STEP
>
> But, NONMEM continues to plod along.
> Does anyone know what NONMEM does instead? I assume that the OBJ
> contribution for that subject cannot be calculated, so, the gradient
> for the dimension(s) requiring that OBJ cannot be calculated. Seems
> like an error to simply ignore the OBJ contribution from that person
> (resulting in a lower OBJ for that function evaluation, and a bad
> gradient and Hessian). Is that function evaluation discarded, and
> no gradient is generated for that dimension/iteration? But I don't
> see a 0 gradient anywhere in the output (I know, in NONMEM V, it
> isn't as simple as one function evaluation per dimension (+1))
>
> Thanks
>
>
> Mark Sale M.D.
> Global Director, Research Modeling and Simulation
> GlaxoSmithKline
> 919-483-1808
> Mobile
> 919-522-6668
> _______________________________________________________
>
>
> Thanks for your help in this matter.
>
> Benjamin Ribba
>
> Therapeutic Targeting in Oncology (EA3738)
> University Claude Bernard Lyon 1
> Faculty of Medicine Lyon-Sud
> 165, chemin du grand revoyet
> 69921 Oullins cedex
>
> Tel: +33 4 26 23 59 57 / +33 6 66 06 15 21