From LIAO@cosmos.prius.jnj.com Tue Apr 16 09:17:38 1996
Subject: Exp function MATH overflow
Hi dear NONMEM users:
I got this error msg "Exp function MATH overflow" when I used ADVAN2 for a 1-compartment open medel with first-order input.
I believe this might be due to the fact that I have PK sampling time up to 120 DAYS. I tried to use $PRED to define the same model and try to use a conditional statement to set the exp function to
zero when Ka*T get >175. However, I got an error msg saying I can not use conditional statement involving the time. Any suggestions will be greatly appreciated. My $PREP is listed below.
___________________________________________________________
$PRED
CL =THETA(1)*EXP(ETA(1))
V2 =THETA(2)*EXP(ETA(2))
KA =THETA(3)*EXP(ETA(3))
K=CL/V2
D1=AMT/V2
A1=KA*D1/(KA-K)
EINA = 0.
T2=K*TIME
IF (-T2 .GT. -175) EINA=DEXP(-K*TIME)
EINB = 0.
T2=KA*TIME
IF (-T2 .GT. -175) EINB=DEXP(-KA*TIME)
F= A1*(EINA - EINB)
YCAL=F
Y=F*(1 + ERR(1))