@BeginModule
@NewPage
@Name      = Smooth9
@Title     = 9 point smoothing
@Section   = Miscellaneous
@Arguments = ifile ofile
@Operators = smooth9
@EndModule


@BeginOperator_smooth9
@Title     = 9 point smoothing

@BeginDescription
Performs a 9 point smoothing on all fields with a regular quadrilateral grid.
The result at each grid point is a weighted average of the grid point plus
the 8 surrounding points. The center point receives a weight of 1.0, the 
points at each side and above and below receive a weight of 0.5, and corner 
points receive a weight of 0.3.
All 9 points are multiplied by their weights and summed, then divided by 
the total weight to obtain the smoothed value. Any missing data points are 
not included in the sum; points beyond the grid boundary are considered to 
be missing. Thus the final result may be the result of an averaging with less 
than 9 points.
@EndDescription
@EndOperator
