Re: Problem with initial values of the omega matrix with nonmem 7.6

On 2026-03-18 05:57 AM, Sebastiaan Sassen wrote: > Dear colleagues, > > I ran into a problem with the omega matrix in nonmem 7.6 for a model > I received (simple FOCE+I advan3 trans4 nothing special). > > In the model file it is specified like this (I tried different > notations as simple decimals, scientific notation etc. to no avail): > > $OMEGA BLOCK(3) >   0.107               ; CL >   0.48E-1 0.11          ; V1 >   0.42E-1 0.56E-1 0.084  ; V2 > > However, with nonmem 7.6 I get a problem with the initial estimates > of omega. If I look at the list file I see that it is due to my omega > block, which makes sense as the correlations between these values used > as initial values of etas are not valid (outside of -1,1). However, > these initial estimates are not the ones I provided. Compare this to > the same exact model ran on nonmem 7.4.4. Here the initial omega > estimates are as described in the model and it runs well. > > Even in a clean folder without any files other than the dataset (csv) > and the model file (mod). > Am I doing something wrong or is this something else? > > Nonmem 7.6: > > INITIAL ESTIMATE OF OMEGA HAS A NONZERO BLOCK WHICH IS NUMERICALLY > NOT POSITIVE DEFINITE > > 0INITIAL ESTIMATE OF OMEGA: > BLOCK SET NO. BLOCK > FIXED > 1 > NO > 0.1000E+01 > 0.4000E+01 0.1000E+01 > 0.4000E+01 0.5000E+01 0.8000E+01 > > Compared to nonmem 7.4.4, which seems to do this correctly: >      > 0INITIAL ESTIMATE OF OMEGA: > BLOCK SET NO. BLOCK > FIXED > 1 > NO > 0.1070E+00 > 0.4800E-01 0.1100E+00 > 0.4200E-01 0.5600E-01 0.8400E-01 > > Best regards, > > Sebastiaan