plesty.fss.energy
=================

.. py:module:: plesty.fss.energy

.. autoapi-nested-parse::

   A line's position as a photon-energy shift, which is what a splitting is.

   A fine-structure splitting is an energy, and the wavelengths it separates
   differ in the fourth decimal place: 775.2000 nm and 775.2013 nm are 2.7 µeV
   apart. Plotted in nanometres that is a flat line; plotted as a shift from the
   line's mean position, in µeV, it is the measurement.

   Both the report figures (:mod:`plesty.fss.plot`) and the live views
   (:mod:`plesty.fss.monitor`) draw that shift, so the conversion lives here
   rather than in either of them.



Attributes
----------

.. autoapisummary::

   plesty.fss.energy.MICRO


Functions
---------

.. autoapisummary::

   plesty.fss.energy.energy_shift_uev
   plesty.fss.energy.energy_error_uev


Module Contents
---------------

.. py:data:: MICRO
   :value: 1000000.0


.. py:function:: energy_shift_uev(centers: numpy.ndarray, mean: float, to_nm: float = 1.0) -> numpy.ndarray

   Photon-energy shifts in µeV of line positions from a mean position.

   :param centers: Fitted line positions.
   :param mean: The position they are measured from, in the same unit.
   :param to_nm: Factor converting that unit to nanometres — 1.0 when the
                 positions are already in nm.

   :returns: One shift per position; positive where the line sits at higher energy
             (shorter wavelength) than *mean*.


.. py:function:: energy_error_uev(errors: numpy.ndarray, centers: numpy.ndarray, to_nm: float = 1.0) -> numpy.ndarray

   One-sigma energy errors in µeV of line positions with wavelength errors *errors*.

   :param errors: One-sigma error of each fitted position.
   :param centers: The fitted positions themselves, in the same unit.
   :param to_nm: Factor converting that unit to nanometres.

   :returns: One error per position.