How to solve this error

To estimate parameter values for my model, fit program was used in model analyzer (Simbiology).

Parameter was successfully estimated when I choosed uniform weght ([]) in the program. However, if I changed weight option (e.g. 1/[DV1 DV2]), program didn't work and got an error message ("All values in the weights matrix must be positive, real, and finite.").

I'd like to know how to solve this problem (which is the problem model or data?)

[Walter Roberson]

If DV1 or DV2 are 0 then 1 divided by them would be infinite which would be a problem.

[Yosuke Nakatani]

Hi Walter,

Thank you. I input zero for DV1 at time 0. I could use other weighting option.

Answer 1

[Arthur Goldsipe]

(Copying answer from comments.) The problem was that one value of DV1 was 0, so the resulting weight was infinite.

One thing I would add to the above answer is that it often doesn't make sense to use this value of 0 during fitting, since the initial conditions of the model are usually guaranteed to provide a value of 0. So you could replace the value of 0 with NaN to indicate that there is no measured data for fitting.