The package

In PIANISTpy, a model (Model) is the equilibrium of one or more components that share one total potential, untruncated or truncated in phase space. A component (Component) is a density profile, such as a DoublePowerLaw, with a velocity anisotropy (Anisotropy). solve computes a model from one component: the component’s distribution function, and the self-consistent density, mass and potential of the model (Chiang+(2026d)).

Every observable is computed from a model. Sampler draws particles. sigma_r and sigma_t give the radial and the tangential velocity dispersion at 3D radii, sigma_los the line-of-sight velocity dispersion at projected radii, and losvd the line-of-sight velocity distribution. likelihood compares a model with observed data (Data).

A model, a distribution function, a LosTable and a sampler each carry a validation report (pianistpy.validation). The report’s tier, such as model.validation.tier, is the worst band among the relative errors that the report’s checks measured and the tiers of the results it was computed from: "silent" (at most \(10^{-6}\)), "recorded" (at most \(10^{-4}\)), "warned" (at most \(10^{-2}\)) or "refused" (above \(10^{-2}\), or not a number).

>>> import pianistpy as pp
>>> model = pp.solve(pp.Component(pp.DoublePowerLaw.hernquist()))
>>> model.validation.tier
'silent'

Every public class and function of the package is documented on the page of its subpackage (Functions by subpackage).