lagged concentrations

From: BellyGom@aol.com Subject: [NMusers] lagged concentrations Date: 10/29/2003 2:36 PM Dear All, I have a coding problem and hope that someone can kindly enlighten me! I have a PKPD model (a zero-order one compartment model for PK: fixed), and a part of the model requires concentration estimates from different time point: $PK ~ ~ ~ S1 = V S2 = V S3 = V K = CL/V ALAG2 = THETA() ALAG3 = THETA() $DES DADT(1) = -K*A(1) DADT(2) = -K*A(2) DADT(3) = -K*A(3) C1=A(1)/S1 C2=A(2)/S2 C3=A(3)/S3 I did not initialise compartment 2 and 3 since the corresponding amount should be 0 at the beginning anyway. Note that neither comp. 2 or comp.3 is the output. Now, the above code does not work and I am not sure why... Please help! Sincerely, In-Sun Nam