.. only:: html

    .. note::
        :class: sphx-glr-download-link-note

        Click :ref:`here <sphx_glr_download_modeling_gallery_spectral_plot_piecewise_norm_spectral.py>`     to download the full example code
    .. rst-class:: sphx-glr-example-title

    .. _sphx_glr_modeling_gallery_spectral_plot_piecewise_norm_spectral.py:


.. _piecewise-norm-spectral:

Piecewise  Norm Spectral Model
==============================================

This model parametrises a piecewise spectral correction
with a free norm parameter at each fixed energy node.

Example plot
------------
Here is an example plot of the model:


.. code-block:: default


    from astropy import units as u
    import matplotlib.pyplot as plt
    from gammapy.modeling.models import (
        Models,
        PiecewiseNormSpectralModel,
        PowerLawSpectralModel,
        SkyModel,
    )

    energy_range = [0.1, 100] * u.TeV
    model = PiecewiseNormSpectralModel(
        energy=[0.1, 1, 3, 10, 30, 100] * u.TeV, norms=[1, 3, 8, 10, 8, 2],
    )
    model.plot(energy_range, flux_unit="")
    plt.grid(which="both")





.. image:: /modeling/gallery/spectral/images/sphx_glr_plot_piecewise_norm_spectral_001.png
    :alt: plot piecewise norm spectral
    :class: sphx-glr-single-img





YAML representation
-------------------
Here is an example YAML file using the model:


.. code-block:: default


    model = model * PowerLawSpectralModel()
    model = SkyModel(spectral_model=model, name="piecewise-norm-model")
    models = Models([model])

    print(models.to_yaml())




.. rst-class:: sphx-glr-script-out

 Out:

 .. code-block:: none

    components:
    -   name: piecewise-norm-model
        type: SkyModel
        spectral:
            type: CompoundSpectralModel
            model1:
                type: PiecewiseNormSpectralModel
                parameters:
                -   name: norm_0
                    value: 1.0
                -   name: norm_1
                    value: 3.0
                -   name: norm_2
                    value: 8.0
                -   name: norm_3
                    value: 10.0
                -   name: norm_4
                    value: 8.0
                -   name: norm_5
                    value: 2.0
                energy:
                    data:
                    - 0.1
                    - 1.0
                    - 3.0
                    - 10.0
                    - 30.0
                    - 100.0
                    unit: TeV
            model2:
                type: PowerLawSpectralModel
                parameters:
                -   name: index
                    value: 2.0
                -   name: amplitude
                    value: 1.0e-12
                    unit: cm-2 s-1 TeV-1
                -   name: reference
                    value: 1.0
                    unit: TeV
                    frozen: true
            operator: mul






.. _sphx_glr_download_modeling_gallery_spectral_plot_piecewise_norm_spectral.py:


.. only :: html

 .. container:: sphx-glr-footer
    :class: sphx-glr-footer-example



  .. container:: sphx-glr-download sphx-glr-download-python

     :download:`Download Python source code: plot_piecewise_norm_spectral.py <plot_piecewise_norm_spectral.py>`



  .. container:: sphx-glr-download sphx-glr-download-jupyter

     :download:`Download Jupyter notebook: plot_piecewise_norm_spectral.ipynb <plot_piecewise_norm_spectral.ipynb>`


.. only:: html

 .. rst-class:: sphx-glr-signature

    `Gallery generated by Sphinx-Gallery <https://sphinx-gallery.github.io>`_