optim() error about animotum

[ianjonsen]

Thanks for the reprex.

It looks like the psi parameter (which rescales the semi-minor axis length to account for potential under-estimation of location error by the CLS Argos KF algorithm) is either not identifiable or doesn't have a sensible starting value for your data - default is log(1). If you fix psi = 1 via:

# generate fit
fit <- foieGras::fit_ssm(
  m1,
  model = "crw",
  time.step = p1,
  map = list(psi = factor(NA))
)

then the model converges.

foieGras v 0.2.2 uses the nlminb() optimizer by default and, for some reason, there is no crash but the model does not converge. v 0.4.0 now uses optim() as the default.

[williamcioffi]

Thanks for the reply, that's very helpful! I'll look into it in my data.