RANDOM_MAP

##
RANDOM_MAP

            [GREG2\]RANDOM_MAP [Arg1 [Arg2]] [/NEIGHBOURS Nb] [/TRIANGLES] [/EX-
        TRAPOLATE] [/BLANKING Bval] [/VARIABLES Vx Vy Vz] [/SKIP [TRIANGULATION]
        [INTERPOLATION]]

        This command is a general purpose interpolation  task  which  uses  data
        from  the X, Y and Z arrays (or those specified in option /VARIABLES) to
        fill in a Regular Grid array representing the same surface  Z=f(X,Y)  by
        an  interpolation  process.  X, Y and Z are arrays defined by the COLUMN
        command (see HELP COLUMN). It triangulates the data  for  interpolation.
        If  a  triangulation  already  exists,  and  only  the  Z array has been
        changed, RANDOM_MAP does not make a new triangulation.

        Often, the user-provided Z=f(X,Y) surface is REGULARLY SAMPLED, even  if
        NOT  COMPLETELY SAMPLED. In this case, it is recommended to use directly
        the RGDATA command to create a Regular-grid map, since RANDOM  is  known
        to perform awkwardly with regularly sampled data.

        The  interpolated  grid  can  be  defined  by  the arguments. If Arg1 is
        "RGMAP", the interpolated grid will be exactly coincident with the  cur-
        rent  Regular  Grid  array,  else Arg1 and Arg2 are used to indicate the
        number of pixels in X and Y directions and Arg2 = Arg1 if not specified.
        If  no  argument is specified, the previous grid (if any) is reused (see
        also subtopic /SKIP).

        Note that several hypothesis are made about the geometry of triangles in
        the  plot  page space (hence the geometry may be changed by changing the
        LIMIT or the BOX_LOCATION). You should thus use  limits  which  gives  a
        reasonable  representation  of  what  are the neighbours of a given data
        point. Moreover, this is an interpolation process. Hence  if  the  basic
        sampling theory is not respected by your choice of input data points and
        output grid, spurious oscillations may occur in the resulting grid.

Subsections

- RANDOM_MAP /BLANKING
- RANDOM_MAP /EXTRAPOLATE
- RANDOM_MAP /NEIGHBOURS
- RANDOM_MAP /SKIP
- RANDOM_MAP /TRIANGLES
- RANDOM_MAP /VARIABLES