Generate a grid, formatted as a Starlink NDF file, from up to three columns in a catalogue. If one
column is specified the output grid corresponds to a histogram, two columns correspond to a
two-dimensional ’image’ and three columns to a data cube.
The dimensionality of the grid (1, 2 or 3) is specified. Then, for each axis of the grid, the name of the
corresponding column in the catalogue and the number of elements in the grid along the axis are
given. The limits of the grid along each axis correspond to the range of values of the corresponding
catalogue column. The value of each element in grid is set to the number of points which lie within it.
Optionally the grid may be normalised by dividing by the total number of points in the
catalogue.
The grids generated can be displayed and manipulated using Starlink software such as GAIA
(SUN/214), KAPPA (SUN/95) and Figaro (SUN/86) or visualisation packages such as DX (SUN/203
and SC/2).
CATIN = CHARACTER (read)
Name of the input
catalogue.
NDIM = INTEGER (read)
Number of dimensions in the output grid. The
permitted values are 1 - 3.
COLX = CHARACTER (read)
Name of the column to be used for
the X-axis of the grid.
XBINS = INTEGER (read)
Number of bins in the grid along the
X-axis.
COLY = CHARACTER (read)
Name of the column to be used for the Y-axis of the
grid.
YBINS = INTEGER (read)
Number of bins in the grid along the Y-axis.
COLZ =
CHARACTER (read)
Name of the column to be used for the Z-axis of the grid.
ZBINS =
INTEGER (read)
Number of bins in the grid along the Z-axis.
GRID = NDF (Write)
The name of the output data grid or histogram.
NORMAL = LOGICAL (read)
Flag
indicating whether the grid of values is to be normalised or not. If NORMAL is set to TRUE
the grid will be normalised (that is, the value of each grid element will be the number of
points occupying the element divided by the total number of points in the catalogue); if it is
set to FALSE it will not. The default is FALSE.
QUIET = LOGICAL (read)
Operate in
quiet mode where warnings are suppressed. The permitted values are: TRUE - quiet mode,
FALSE - verbose mode.