pxf

Pxf is an acronym used in different technical contexts, and there is no single, universal definition. The most notable uses are in astronomy and data management.

In astronomy, pPXF stands for Penalized Pixel-Fitting. It is a software package used to derive stellar kinematics from galaxy spectra. Developed by Michele Cappellari, pPXF fits the observed spectrum with a combination of template stellar spectra convolved with a parametric line-of-sight velocity distribution. A penalty term is applied to stabilize higher-order moments, reducing the risk of overfitting. The method yields parameters such as the mean velocity and velocity dispersion, and can also recover Gauss-Hermite moments like h3 and h4. pPXF supports multiple stellar libraries (for example MILES) and can model multiple kinematic components or stellar populations. The package is available as Python software, with a computational engine largely implemented in Fortran, and it is widely used in studies of galaxy dynamics and stellar populations.

In data management, Platform Extension Framework (PXF) is a framework for integrating external data sources with Greenplum Database and related products. It provides connectors and adapters that enable SQL queries to read from external systems such as HDFS, Hive, HBase, and cloud storage. PXF is implemented in Java and forms part of the external table infrastructure, offering parallel data access and a pluggable set of data sources to extend data access without moving data into Greenplum storage. It originated with Pivotal and remains part of modern Greenplum deployments in contemporary data architectures.