# Frequency Scan Parameters

The `&scan`

namelist group defines frequency grid parameters, as
follows:

`grid_type`

(default`'LINEAR'`

)Distribution of frequency points; one of:

`'LINEAR'`

: Uniform in frequency`'INVERSE'`

: Uniform in inverse frequency`'FILE'`

: Read from file

`grid_frame`

(default`'INERTIAL'`

)Reference frame in which

`grid_type`

applies; one of:`'INERTIAL'`

: Inertial frame`'COROT_I'`

: Co-rotating frame at inner boundary`'COROT_O'`

: Co-rotating frame at outer boundary

`freq_min`

(default`1`

)Minimum frequency, when

`grid_type`

is`'LINEAR'`

or`'INVERSE'`

`freq_max`

(default`10`

)Maximum frequency, when

`grid_type`

is`'LINEAR'`

or`'INVERSE'`

`n_freq`

(default`10`

)Number of frequency points, when

`grid_type`

is`'LINEAR'`

or`'INVERSE'`

`freq_units`

(default`NONE`

)Units of

`freq_min`

and`freq_max`

, when`grid_type`

is`'LINEAR'`

or`'INVERSE'`

; units of read frequencies when`grid_type`

is`'FILE'`

`'NONE'`

: Dimensionless angular frequency`'HZ'`

: Linear frequency in Hz[1]`'UHZ'`

: Linear frequency in \(\mu\)Hz[1]`'RAD_PER_SEC'`

: Angular frequency in radians per second[1]`'CYC_PER_DAY'`

: Linear frequency in cycles per day[1]`'ACOUSTIC_DELTA'`

: Fraction of the asymptotic acoustic large frequency separation \(\Delta \nu\)`'GRAVITY_DELTA'`

: Fraction of the asymptotic inverse gravity period separation \((\Delta P)^{-1}\)`'UPPER_DELTA'`

: Greater of \(\Delta \nu\) and \((\Delta P)^{-1}\)`'LOWER_DELTA'`

: Lesser of \(\Delta \nu\) and \((\Delta P)^{-1}\)`'ACOUSTIC_CUTOFF'`

: fraction of the acoustic cutoff frequency[1]`'GRAVITY_CUTOFF'`

: fraction of the gravity cutoff frequency[1]`'ROSSBY_I'`

: fraction of Rossby frequency (see eqn. 15) at inner boundary`'ROSSBY_O'`

: fraction of Rossby frequency (see eqn. 15) at outer boundary

`freq_min_units`

(default`''`

)Units of

`freq_min`

; same options as`freq_units`

and overrides it if set`freq_max_units`

(default`''`

)Units of

`freq_max`

; same options as`freq_units`

and overrides it if set`freq_frame`

(default`'INERTIAL'`

)Reference frame in which

`freq_min`

and`freq_max`

are defined, when`grid_type`

is`'LINEAR'`

or`'INVERSE'`

; one of:`'INERTIAL'`

: Inertial frame`'COROT_I'`

: Co-rotating frame at inner boundary`'COROT_O'`

: Co-rotating frame at outer boundary

`file`

File to read frequencies from, when

`grid_type`

is`'FILE'`

`axis`

(default`'REAL`

’)Axis that scan applies to; one of

`'REAL'`

: Real axis`'IMAG'`

: Imaginary axis

`tag_list`

(default`''`

, which matches all)Comma-separated list of

`&mode`

tags to match

An input file can contain one or more `&scan`

namelist group;
the points defined by each (tag-matching) group are merged together to
build the frequency grid. See the Frequency Grids section for
further details.

Footnotes