NONMEM Users Network Archive

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Re: inexplicit equations in PRED

From: Ekaterina Gibiansky <EGibiansky>
Date: Thu, 24 Sep 2009 12:02:44 -0400

Robert,

You can do it using ADVAN9 with NEQUILIBRIUM option in $MODEL, and $AESINITIAL
and $AES blocks. E.g. (where A(13) is what is F in your example) :

$SUBROUTINES ADVAN9 TOL=4
$MODEL NEQUILIBRIUM=1
  COMP(COMP1)
....
  COMP(COMP13)

$PK
   ...

$AESINITIAL
   INIT = 0; 0=APPROXIMATE, 1=EXACT
   A(13)=0.001
$AES
    E(13)=A(9)-A(13)-A(13)*A(10)/(KSS+A(13))-A(13)*A(12)/(KSS2+A(13))

$DES
...

$ERROR
   Y = A(13)+EPS(1)

Regards,
Katya

--------------------------
Ekaterina Gibiansky, Ph.D.
CEO&CSO, QuantPharm LLC
Web: www.quantpharm.com
Email: EGibiansky
Tel: (301)-717-7032


Robert Kalicki wrote:
> Dear NMusers,
>
> Most of the models are pre-defined (ADVANx), expressed as a system of
> differential equations or provided in the form of an explicit
> mathematical equation (PRED).
>
> Is it possible to deal with nonlinear inexplicit equations like y =
> f(x,y) where both differential equations and explicit solution equation
> are not known or not obvious.
>
>
>
> Concretely, using PRED, one would find F on the both sides:
>
> F = f(X) + g(F)
>
> Y = F+EPS(1)
>
>
>
> Many thanks in advance
>
>
>
> Best regards,
>
> Robert
>
>
>
>
>
> ___________________________________________
> Robert M. Kalicki, MD
>
> Postdoctoral Fellow
>
> Department of Nephrology and Hypertension
>
> Inselspital
>
> University of Bern
>
> Switzerland
>
>
>
> Address:
>
> Klinik und Poliklinik für Nephrologie und Hypertonie
>
> KiKl G6
>
> Freiburgstrasse 15
>
> CH-3010 Inselspital Bern
>
>
>
> Tel +41(0)31 632 96 63
>
> Fax +41(0)31 632 14 58
>
>
>
Received on Thu Sep 24 2009 - 12:02:44 EDT

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