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FITS /BITS

        [VECTOR\]FITS OutputFile.fits FROM InputFile.gdf /BITS Nbit

    The  number  of bits offers two controls: the data size and the encoding
    scheme. This value will be found in the resulting header under the  card
    BITPIX.

    Encoding scheme:
        It is controled by the Nbit sign.
        Positive sign means indexed encoding: the values are scaled as inte-
        gers distributed among the  2**abs(Nbit)  values.  The  forward  and
        back-conversion  from  actual  values to indexed values are based on
        the data extrema. Beware they must be up-to-date in the  GDF  header
        before  converting  a BITPIX>0 FITS (see command V\HEADER /EXTREMA)!
        Blank values are identified as  the  last  integer  of  the  indexed
        scale.
        Negative sign means the actual values are saved "as is" (IEEE float-
        ing point format). Blank values are saved as IEEE NaN.
    Data size:
        It is controled by the Nbit absolute value: 16, 32, or 64 will  con-
        sume  respectively  2, 4 and 8 bytes per value, with a direct impact
        of the file size.

    Nbits=+16 is worth only if the data dynamic (range of  values)  is  low,
    otherwise  value precision loss will happen (2**16 values are not enough
    to cover properly a large range of values). In the other  cases,  Nbit<0
    is  more  modern and should be prefered. The command supports Nbits +16,
    +32, -32, -64.


Gildas manager 2024-03-28