# Configuration Options#

NetKet exposes a few configuration options which can be set through environment variables by doing something like

# without exporting it
NETKET_DEBUG=1 python ...

# by exporting it
export NETKET_DEBUG=1
python ...

# by setting it within python
python
>>> import os
>>> os.environ["NETKET_DEBUG"] = "1"
>>> import netket as nk
>>> print(netket.config.netket_debug)
True


Some configuration options can also be changed at runtime by setting it as:

>>> import netket as nk
>>> nk.config.netket_debug = True
>>> ...


You can always query the value of an option by accessing the nk.config module:

>>> import netket as nk
>>> print(nk.config.netket_debug)
False
>>> nk.config.netket_debug = True
>>> print(nk.config.netket_debug)
True


Please note that not all configurations can be set at runtime, and some will raise an error.

Options are used to activate experimental or debug functionalities or to disable some parts of netket. Please keep in mind that all options related to experimental or internal functionalities might be removed in a future release.

# List of configuration options#

Name

Values [default]

Changeable

Description

NETKET_DEBUG

True/[False]

yes

Enable debug logging in many netket functions.

NETKET_EXPERIMENTAL

True/[False]

yes

Enable experimental features such as gradients of non-hermitian operators.

NETKET_MPI_WARNING

[True]/False

no

Raise a warning when running python under MPI without mpi4py and other mpi dependencies installed.

NETKET_MPI

[True]/False

no

When true, NetKet will always attempt to load (and initialize) MPI. If this flag is 0 mpi4py and mpi4jax will not be imported. This can be used to prevent crashes with some MPI variants such as Cray which cannot be initialised when not running under mpirun.

NETKET_USE_PLAIN_RHAT

[True]/False

yes

By default, NetKet uses the split-R̂ Gelman-Rubin diagnostic in netket.stats.statistics, which detects non-stationarity in the MCMC chains (in addition to the classes of chain-mixing failures detected by plain R) since version 3.4. Enabling this flag restores the previous behavior of using plain (non-split) Rhat.

NETKET_EXPERIMENTAL_FFT_AUTOCORRELATION

True/[False]

yes

The integrated autocorrelation time $$\tau_c$$ is computed separately for each chain $$c$$. To summarize it for the user, Stats.tau_corr is changed to contain the average over all chains and a new field Stats.tau_corr_max is added containing the maximum autocorrelation among all chains (which helps to identify outliers). Using the average $$\tau$$ over all chains seems like a good choice as it results in a low-variance estimate (see here for a good discussion).

NETKET_EXPERIMENTAL_DISABLE_ODE_JIT

True/[False]

yes

Disables the jitting of the whole ode solver, mainly used within TDVP solvers. The jitting is sometimes incompatible with GPU-based calculations, and on large calculations it gives negligible speedups so it might be beneficial to disable it.

NETKET_SPHINX_BUILD

True/[False]

no

Set to True when building documentation with Sphinx. Disables some decorators. This is for internal use only.