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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.


Gildas manager 2018-05-24