Solvers

A Solver is a Python class that connects hklpy2 with a backend library providing diffractometer capabilities, including:

• definition(s) of physical diffractometer geometries

  • axes (angles and reciprocal space)

  • operating modes for the axes

• calculations that convert:

  • forward: reciprocal space coordinates into diffractometer angles

  • inverse: diffractometer angles into reciprocal space coordinates

• support blocks include:

  • calculate the UB matrix

  • refine the crystal lattice

  • sample definition (name, lattice parameters, orientation reflections)

A Solver class is written as a plugin for hklpy2 and is connected by an entry point using the "hklpy2.solver" group.

Solvers provided with hklpy2:

Name	Description
hkl_soleil	Hkl/Soleil backend (Linux 64-bit only). Supports many geometry types.
no_op	No-op solver for testing. Provides no useful geometries.
th_tth	Pure-Python minimal solver: \(\theta, 2\theta\) geometry with \(Q\) pseudo axis. Runs on any OS.

A Solver is not needed to:

• define subclass of DiffractometerBase() and create instance

• create instance of Sample()

• create instance of Lattice()

• create instance of _WavelengthBase() subclass

• create instance of SolverBase() subclass

• set wavelength

• list available solvers: (solvers())

• review saved orientation details

A Solver is needed to:

• list available Solver geometries

• list a Solver geometry’s required pseudo_axis_names, real_axis_names, extra_axis_names, modes

• create instance of Reflection()

• define or compute a \(UB\) matrix (calc_UB(), calc_UB())

• forward() and inverse()

• determine the diffractometer position

• save or restore orientation details

• refine lattice parameters

See also

Solvers Guide for how to list, select, and instantiate solvers.

How to write a new Solver for how to write a new solver plugin.