.. _sec-fitters:

Fitters
=======

Two-dimensional datasets can be opened in available **Fitters**. These GUI
applications contain standard data processing technics and constitute
additional utility allowing for more detailed inspection and quantitative
analysis of investigated data.

Two, :ref:`MDC <sec-mdc-fitter>` and :ref:`EDC <sec-edc-fitter>` **Fitters**
are implemented within :mod:`piva`, including methods useful when dealing
with *momentum* and *energy distribution curves*, respectively.


.. _sec-mdc-fitter:

MDC Fitter
----------

**MDC Fitter** allows to investigate *momentum distribution curves* (MDCs)
across available energy range. User interactively can perform subtraction of
polynomial background and fit (asymmetric) Lorentzian line shape within
selected fitting range.

Its layout is shown and described below.

.. figure:: ../img/fitters_plottool/fitters-mdc-main.png
   :alt: Image not found.

=====   =======================================================================
**a**   **Utilities panel**, see description :ref:`below <sec-mdc-util-panel>`.
**b**   **Main data panel** showing investigated 2D dataset. Contains sliders
        allowing to slice through data.
**c**   **MDC panel** extracted at the energy selected with a slider in
        **main data panel**.
=====   =======================================================================


.. _sec-mdc-util-panel:

MDC Fitter's Utilities Panel
^^^^^^^^^^^^^^^^^^^^^^^^^^^^

**Utilities panel** contains all image processing and analysis features.

Image tab
"""""""""

Combines widgets and functionalities of
:ref:`volume <sec-utilities-panel-volume>` and
:ref:`image <sec-utilities-panel-image>` tabs of the
:ref:`DataViewers <sec-viewers>`.


Fitting tab
"""""""""""

Contains all widgets useful for interactive fitting of MDCs.

.. figure:: ../img/fitters_plottool/fitters-mdc-fitting_tab.png
   :alt: Image not found.

=======================     ===================================================
Lorentzian's parameters     - :math:`\mu` - expected value,
                            - :math:`\Gamma` - full width at half maximum,
                            - :math:`\alpha, \beta` - asymmetry factors of
                              fitted line shape,
                            - :math:`a` - normalization factor.

                            Box at the bottom displays fit results.
fit range                   Set fitting range, displayed as a grey shadow on
                            **MDC panel**.
bgr range                   Set background range, indicated with two vertical
                            dashed lines on **MDC panel**. The region between
                            the lines (which supposed to contain entire peak)
                            will be excluded during background fitting.
bgr poly                    Select order of the background polynomial.
results                      - *append* fit results (expected value) on the
                               **Main data panel** and store results in
                               **Fitters** memory.
                             - *edit* collected results; opens ``txt``
                               file with saved parameters.
                             - *load* saved or *update* edited parameters.
                             - *save* fitted parameters to ``txt`` file.
=======================     ===================================================



.. _sec-edc-fitter:

EDC Fitter
----------

**EDC Fitter** allows to investigate *energy distribution curves* (EDCs) and
perform gap analysis.

Its layout is shown and described below.

.. figure:: ../img/fitters_plottool/fitters-edc-main.png
   :alt: Image not found.

=====   =======================================================================
**a**   **Utilities panel**, see description :ref:`below <sec-mdc-util-panel>`.
**b**   **Main data panel** showing investigated 2D dataset. Contains sliders
        allowing to slice through data.
**c**   **EDC panel** extracted at the momentum selected with a slider in
        **main data panel**.
=====   =======================================================================


.. _sec-edc-util-panel:

EDC Fitter's Utilities Panel
^^^^^^^^^^^^^^^^^^^^^^^^^^^^

I addition to basic functionalities of :ref:`volume
<sec-utilities-panel-volume>` and :ref:`image <sec-utilities-panel-image>`
tabs of the :ref:`DataViewers <sec-viewers>`, **EDC Fitter** allows to narrow
energy range and symmetrize EDCs around the Fermi level.



Development
-----------

At the moment only basic methods are implemented within :mod:`piva`
**Fitters**, leaving a large playground for improvement. Users are highly
encouraged to contribute and extend their capabilities or implement
:ref:`entirely new plugins <sec-custom_plugins>`. This can be done directly
through `github  <https://github.com/pudeIko/piva>`_ or alternatively by
contacting the development team:

.. include:: contact.rst