MAP_SMOOTH

        [CLEAN\]MAP_SMOOTH WhichOne Nc [Result] [/ASYMMETRIC]

    Smooth a  3-D data cubes by Nc channels along the velocity axis.
         Nc   number of channels to be averaged in smoothing.
    WhichOne indicates which data cube must be compressed. Allowed values are
         - Built-in buffers DIRTY, CLEAN, SKY, SINGLE or *, which means all
           of the previous existing ones. Smoothing is done in place.
         - Any SIC Image Variable that is not a built-in buffer in IMAGER.
         - A GILDAS data file
    For the two later cases, the Result argument indicates  where  the  smoothed
    data  cube  is stored. Result can be a file name or an existing SIC variable
    of adequate dimensions.

    By default, the smoothing does not  modify  the  spectral  sampling  of  the
    cubes.  While this naturally occurs when the smoothing number Nc is odd, the
    Nc even case requires a specific handling.  For Nc even, the smoothed  chan-
    nel  at  channel "i" sums up half of channel i-Nc/2, half of channels i+Nc/2
    and all channels in between.  Thus for Nc=2, this is a Hanning smoothing.

    Like for UV_SMOOTH, this behaviour can be modified by option /ASYMMETRIC.