SET FREQUENCY

        LAS\SET FREQUENCY Freq1|* [Freq2|*] [SIGNAL|IMAGE]

    Add a selection by frequency for the command  FIND.  This  criterion  is
    suited only for spectroscopic data.

      - SET FREQUENCY Freq1
          select all observations which frequency range intersects the given
          frequency,
      - SET FREQUENCY Freq1 Freq2
          select all observations which frequency range intersects at  least
          partially the given range,
      - SET FREQUENCY * Freq2
          select all observations which frequency range is at least partial-
          ly under Freq2,
      - SET FREQUENCY Freq1 *
          select all observations which frequency range is at least partial-
          ly above Freq1,
      - SET FREQUENCY *
          select  all  observations i.e. disable the selection by frequency.
          This is the default.

    An optional keyword can be added after the values  to  indicate  whether
    the  selection  should  be performed by SIGNAL or IMAGE frequencies. De-
    fault is SIGNAL.

    Users should be aware that this selection  criterion  requires  to  read
    more  informations in the observation header, and thus has a computation
    cost which can become important for large datasets.