Syntax:
smooth {unique | frequency | csplines | acsplines | bezier | sbezier}
unique and frequency plot the data after making them monotonic. Each of the other routines uses the data to determine the coefficients of a continuous curve between the endpoints of the data. This curve is then plotted in the same manner as a function, that is, by finding its value at uniform intervals along the abscissa (see set samples (p. )) and connecting these points with straight line segments (if a line style is chosen).
If autoscale is in effect, the ranges will be computed such that the plotted curve lies within the borders of the graph.
If autoscale is not in effect, and the smooth option is either acspline or cspline, the sampling of the generated curve is done across the intersection of the x range covered by the input data and the fixed abscissa range as defined by set xrange.
If too few points are available to allow the selected option to be applied, an error message is produced. The minimum number is one for unique and frequency, four for acsplines, and three for the others.
The smooth options have no effect on function plots.