ODE for an AUC compartment

[KevSmart]

Hi!

Ive been playing with assemblerr after the Roche training today. I really like the tool!

Im trying to recreate an existing model, and would like to add a differential equation to allow derivation of AUC - just a normal output we may find useful. Normally, I would code like this:

$DES
CP = A(1)/V1
DADT(1) = K21 * A(2) - (K12 + K10) * A(1)
DADT(2) = K12 * A(1) - K21 * A(2)
DADT(3) = CP
$ERROR
AUC = A(3)

In assembler, I've not found a way to create an empty, user defined ODE, nor have I found a way to add an algebraic equation into the $DES block. To trick it, I have used this:

m_pk_test2<-model()+
...
compartment("auc",volume=1)+
...
algebraic(cp~A(1)/s1)+
...
flow(cp,from="central",to="auc")+
...
algebraic(aucA["auc"])+
obs_proportional(~conc)

When I render, the model looks like this:

CP = A(1)/S1
$DES
DADT(1) = K21 * A(2) - (K12 * A(1) + K10 * A(1) + CP)
DADT(2) = K12 * A(1) - K21 * A(2)
DADT(3) = CP
$ERROR
CONC = A(1)/V1
AUC = A(3)
Y = CONC + CONC * EPS(1)

By removing the + CP from DADT(1) and moving the CP equation into $DES, then things work fine.

I wondered if there is a better way to create a user defined DADT()??

Many thanks in advance!

[sebastianueckert]

Good point; this functionality should undoubtedly be added. It does, unfortunately, require some more extensive changes than it might seem. I'll keep it in mind for the future.