MODEL
Keywords: class

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##
MODEL

            ANALYSE\MODEL Y_Variable [X_Variable] [/BLANK Bval] [/REGULAR  [Xref
        Xval  RestFreq]]  [/FREQUENCY  LineName RestFreq] [/XAXIS Xref Xval Xinc
        Unit]

        Generates a CLASS spectrum from a 1D SIC  variable.  Note  that  the  1D
        variable  can be (and frequently is) a subset of a higher dimensionality
        variable. This command is typically used either to generate  test  data,
        or  more  frequently  to  transfer data from outside world through ASCII
        files.

        A second variable, if present, is interpreted as an  associated  X  axis
        scale for a presumably non linear or irregularly sampled frequency axis,
        as can occur for non resampled data from AOS backends (or optical  spec-
        tra).  Please  note  however that non linear axes are a largely untested
        feature in CLASS, you should avoid this solution when possible.

        There are three (exclusive) ways to define the X axis: provide a  X  ar-
        ray,  /XAXIS  option, /REGULAR option (see below). The model header will
        have a minimal values set, you should update it with SET VARIABLE  used,
        the  command will copy RX and header from the previous R buffer in memo-
        ry.

            MODEL Y                                ! No X array
                Velocity and frequency axes description is copied from the  pre-
                vious R buffer in memory.

            MODEL Y X                              ! With an X array
                If  the  X  array  is regularly sampled, it behaves as MODEL Y X
                /REGULAR.  Otherwise the spectroscopic axis values are taken "as
                is" from the X variable and saved as an irregular axis.

            MODEL Y X /REGULAR                     ! With an X array
                Velocity axis is read from the X variable, and checked for regu-
                lar spacing. The reference channel  and  velocity  at  reference
                channel  (velocity  offset) are taken at the middle of the X ar-
                ray.

            MODEL Y X /REGULAR Xref Xval RestFreq  ! With an X array
                Velocity axis is read from the X variable, and checked for regu-
                lar  spacing.  Velocity  spacing  is taken from the X array. The
                reference channel, the velocity at reference  channel  (velocity
                offset), and the frequency at reference channel (rest frequency)
                are passed as arguments to the option.

            MODEL Y /XAXIS Xref Xval Xinc Unit     ! No X array
                Define the X axis with its reference channel (Xref),  its  value
                at  reference  channel  (Xval),  and  the  increment per channel
                (Xinc). Units are km/s or MHz if Unit is VELOCITY  or  FREQUENCY
                respectively.  If  Unit is FREQUENCY, Xval is expected to be the
                rest frequency.

        Additional options:

            /FREQUENCY LineName RestFreq
                Indicate line name and the rest frequency. Default rest frequen-
                cy is 300000 MHz.

            /BLANK Bval
                Allow the user to provide the blanking value. Default is -1000.