Exp function MATH overflow

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))