Set the Optimizer using umx_set_optimizer

As of version 2.0, OpenMx has 3 optimizers: NPSOL, CSOLNP, and SLSQP (the default).

NPSOL doesn’t ship on the CRAN version of OpenMx (it’s proprietary). It is, however, highly optimized and works well with the vast majority of models. If you’re having hassles with mxRun, or CIs, NPSOL might help.

CSOLNP can work well for ordinal models. SLSQP has the benefit of working out of the box from CRAN, and is often as good or better than NPSOL.

You can see what optimizer is being used by calling umx_set_optimizer with no parameters.


Set the optimizer by name:


See all options by asking for something that doesn’t exist:

# The Optimizer 'tinkerbell' is not legal. Legal values (from mxAvailableOptimizers() ) are:'CSOLNP' and 'SLSQP'

If, as above, you don’t see NPSOL as an option and want to use it (or parallel processing), grab the custom UVA version of OpenMx

How to enable NPSOL

  1. Grab the NPSOL version of OpemMx with this command:

That’s it :-)