.. _scan-group:

.. nml:group:: scan

Scan Namelist Group
===================

The :nml:group:`scan` namelist group governs the creation of frequency
grids. The input file can contain one or more, and the points
generated by all (tag-matching) groups are merged together to build a
frequency grid (see the :ref:`freq-grids` section for further
details). The following options are available:

.. nml:option:: grid_type
   :type: string
   :default: 'LINEAR'

   Distribution of frequency points; one of

   - :nml:value:`'LINEAR'` : Uniform in frequency
   - :nml:value:`'INVERSE'` : Uniform in inverse frequency
   - :nml:value:`'FILE'` : Read from file

.. nml:option:: grid_frame
   :type: string
   :default: 'INERTIAL'

   Reference frame in which :nml:option:`grid_type` applies; one of

   - :nml:value:`'INERTIAL'` : Inertial frame
   - :nml:value:`'COROT_I'` : Co-rotating frame at inner boundary
   - :nml:value:`'COROT_O'` : Co-rotating frame at outer boundary

.. nml:option:: freq_min
   :type: real
   :default: 1

   Minimum frequency. Used only when :nml:option:`grid_type` = :nml:valuelist:`'LINEAR' 'INVERSE'`

.. nml:option:: freq_max
   :type: real
   :default: 10

   Maximum frequency. Used only when :nml:option:`grid_type` = :nml:valuelist:`'LINEAR' 'INVERSE'`

.. nml:option:: n_freq
   :type: integer
   :default: 10

   Number of frequency points. Used only when :nml:option:`grid_type` = :nml:valuelist:`'LINEAR' 'INVERSE'`

.. nml:option:: freq_units
   :type: string
   :default: 'NONE'

   Units of :nml:option:`freq_min` and :nml:option:`freq_max`, when
   :nml:option:`grid_type` = :nml:value:`'LINEAR' 'INVERSE'`; or units
   of read frequencies when :nml:option:`grid_type` =
   :nml:value:`'FILE'`

   - :nml:value:`'NONE'` : Dimensionless angular frequency
   - :nml:value:`'HZ'` : Linear frequency in Hz\ [#only-D]_
   - :nml:value:`'UHZ'` : Linear frequency in :math:`\mu`\ Hz\ [#only-D]_
   - :nml:value:`'RAD_PER_SEC'` : Angular frequency in radians per second\ [#only-D]_
   - :nml:value:`'CYC_PER_DAY'` : Linear frequency in cycles per day\ [#only-D]_
   - :nml:value:`'ACOUSTIC_DELTA'` : Fraction of the asymptotic acoustic large frequency separation :math:`\Delta \nu`
   - :nml:value:`'GRAVITY_DELTA'` : Fraction of the asymptotic inverse gravity period separation :math:`(\Delta P)^{-1}`
   - :nml:value:`'UPPER_DELTA'` : Greater of :math:`\Delta \nu` and :math:`(\Delta P)^{-1}`
   - :nml:value:`'LOWER_DELTA'` : Lesser of :math:`\Delta \nu` and :math:`(\Delta P)^{-1}`
   - :nml:value:`'ACOUSTIC_CUTOFF'` : fraction of the acoustic cutoff frequency\ [#only-D]_
   - :nml:value:`'GRAVITY_CUTOFF'` : fraction of the gravity cutoff frequency\ [#only-D]_
   - :nml:value:`'ROSSBY_I'` : fraction of Rossby frequency (see eqn. :eq:`e:ross-freq`) at inner boundary
   - :nml:value:`'ROSSBY_O'` : fraction of Rossby frequency (see eqn. :eq:`e:ross-freq`) at outer boundary

.. nml:option:: freq_min_units
   :type: string
   :default: ''

   Units of :nml:option:`freq_min`; same choices as
   :nml:option:`freq_units` and overrides it if not blank

.. nml:option:: freq_max_units
   :type: string
   :default: ''

   Units of :nml:option:`freq_min`; same choices as
   :nml:option:`freq_units` and overrides it if not blank

.. nml:option:: freq_frame
   :type: string
   :default: 'INERTIAL'

   Reference frame in which :nml:option:`freq_min` and
   :nml:option:`freq_max` are defined; one of

   - :nml:value:`'INERTIAL'` : Inertial frame
   - :nml:value:`'COROT_I'` : Co-rotating frame at inner boundary
   - :nml:value:`'COROT_O'` : Co-rotating frame at outer boundary

   Used only when :nml:option:`grid_type` = :nml:value:`'LINEAR' | 'INVERSE'`

.. nml:option:: file
   :type: string
   :default: ''

   File to read frequencies from. Used only when
   :nml:option:`grid_type` = :nml:value:`'FILE'`

.. nml:option:: axis
   :type: string
   :default: 'REAL'

   Axis that :nml:group:`scan` group applies to; one of

   - :nml:value:`'REAL'` : Real axis
   - :nml:value:`'IMAG'` : Imaginary axis

.. nml:option:: tag_list
   :type: string
   :default: ''

   Comma-separated list of :nml:option:`tag <mode.tag>` values to
   match; matches all if left blank

.. rubric:: Footnotes

.. [#only-D] This option is available only for stellar models with :ref:`D capability <model-caps>`