Dear Colleagues,
I am encountering the following error when I run a model that includes
plasma and urine data and SS data column =1.
When I remove the urine data (modelling only the plasma data), the model
runs without any error.
When I drop the SS column (run a single dose or even with additional
doses), the model runs without any error.
When I have both the urine data and SS assigned as 1 or 3, I face the
following error :
MONITORING OF SEARCH:
0THE INPUT MATRIX IS SINGULAR. SOME OF THE DIAGONAL ELEMENTS OF THE UPPER
TRIANGULAR MATRIX U OF THE LU FACTORIZATION ARE CLOSE TO ZERO.
0THE INPUT MATRIX IS SINGULAR. SOME OF THE DIAGONAL ELEMENTS OF THE UPPER
TRIANGULAR MATRIX U OF THE LU FACTORIZATION ARE CLOSE TO ZERO.
0PRED EXIT CODE = 1
0INDIVIDUAL NO. 1 ID= 3.00200000000000E+03 (WITHIN-INDIVIDUAL)
DATA REC NO. 1
THETA=
8.60E+00 1.39E+01 1.78E+02 1.33E-01 1.00E+00
OCCURS DURING SEARCH FOR ETA AT INITIAL VALUE, ETA=0
NUMERICAL DIFFICULTIES WITH INITIAL ESTIMATE OF STEADY-STATE SOLUTION.
DA MATRIX IS NOT INVERTIBLE AT A ZERO STATE VECTOR.
TRY SETTING INITIAL ESTIMATE USING SS=3.
I appreciate your help with interpreting and fixing this error.
Thanks,
--
*Abdelrahman Saqr *
MS. Experimental and Clinical Pharmacology | University of Minnesota
PhD Candidate | Department of Experimental and Clinical Pharmacology
College of Pharmacy | University of Minnesota
www.linkedin.com/in/abdelrahman-saqr
