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        [GREG2\]RGDATA  [Name|Array_X Array_Y Array_Z]  [/SUBSET NXmin NYmin
    NXmax NYmax] [/VARIABLE] [/FORMAT Fmt  [code]]  [/INCREMENT  IncX  IncY]
    [/BLANKING Bval]

    This  command  optionally creates, then loads a two-dimensional map into
    the Regular Grid array (to be contoured by RGMAP, plotted  by  PLOT...).
    This is THE basic command needed for subsequent 2-dimensional treatment.
    "Regular Grid" means that data is internally stored as a two-dimensional
    array,  thus  lies on a Regularly sampled Grid. The user-provided "pixel
    values" may come from various "descriptions" of such  regularly  sampled
    (but possibly uncompletely sampled) data:
       1) Three  1-dimensional arrays, say, X Y and Z, that contain Z=f(X,Y)
        at regular intervals in X and Y.
       2) A preexisting internal 2-D array (possibly a section of a 3D or 4D
       3) An external, specially formatted, file.

    For  data  NOT  REGULARLY ("randomly") sampled, use the GREG2\RANDOM_MAP
    command instead. The Regular Grid is itself a 2D SIC variable under  the
    name  "RG".  Its  extrema are available in the variables RGMIN and RGMAX
    (values) and RG_XMIN, RG_XMAX, RG_YMIN,  and  RG_YMAX  (position).  Once
    loaded, the RG can be saved on a file with the command GREG2\WRITE.

    The  following  command  syntax is used to deduce which "description" is

      - With 0 or 3 arguments, RGDATA will try to assemble  Z=f(X,Y)  either
        from  the  X,Y  and  Z arrays (as defined by command COLUMN) or from
        "Array_X Array_Y Array_Z", that should be 1D SIC variables previous-
        ly  created. The option /INCREMENT is used to force the X and Y sam-
        pling interval to (IncX,IncY) in case of roundoff  errors.  Defining
        twice  the  same pixel is an error. If a blanking value is currently
        defined, non-sampled pixels will be attributed this value, which  is
        overriden by the Bval value of the /BLANKING option. Note that, if a
        blanking value is currently defined, pixels for which X or Y are  in
        the blanking range are themselves blanked.

      - With ONE argument (Name) following the command, Name is taken as the
        name of an existing SIC 2D variable if option /VARIABLE is  present.
        Otherwise,  Name  is  a  specially  formatted  file  (see HELP RGDA-
        TA FILE_FORMAT) from which the Regular Grid array must be read in.

    A rectangular subset of the array defined by the  pixel  coordinates  of
    the  Bottom  Left  Corner and Top Right Corner can be selected thanks to
    the /SUBSET option.


Gildas manager 2020-12-02