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        [GREG2\]RANDOM_MAP [Arg1 [Arg2]] [/NEIGHBOURS Nb] [/TRIANGLES] [/EX-

    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.

    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.


Gildas manager 2014-07-01