Disable stop criteria (x tolerance) do not work for Sbplx

[sgherrero]

Hello,
I am using the algorithm Sbplx (LN_SBPLX). I have disabled the stop criteria based on the x tolerance (relative and absolute) using the (C++) methods set_xtol_rel(value) and set_xtol_abs(value) with a negative value. Indeed, I have read that the stop criterias are disabled by default but I have explicitely disabled. However, the algorithm stops and it returns the code NLOPT_XTOL_REACHED = 4. Could you expain me this behaviour?
A reason could be that the Subplex is necessary this stop criteria but I have not found it in the documentation.
Thanks in advance for the help.

Sara

[UnixJunkie]

I think I observe the same problem with auglag (global) parameterized by sbplx (local).
Optimization stops with NLOPT_FTOL_REACHED while I have called both

  Nlopt.set_ftol_abs local (-1.0)
  Nlopt.set_ftol_abs global (-1.0)

[UnixJunkie]

I am using libnlopt-dev version 2.7.1-3build1 on Ubuntu Linux.
I wonder if this is a bug affecting several of the optimization algorithms.

[jschueller]

can you provide a minimal reproducer example please ?

[UnixJunkie]

By default, those values are all 0s:

15:34:05.32|I: local_ftol_abs before: 0.000000
15:34:05.32|I: local_ftol_rel before: 0.000000
15:34:05.32|I: global_ftol_abs before: 0.000000
15:34:05.32|I: global_ftol_rel before: 0.000000

but the optimization still stops w/ NLOPT_FTOL_REACHED.

[UnixJunkie]

I am using the OCaml interface and working on a large unpublished program, the behavior I observe is not easy to replicate/minimize.