spline(1g)
NAME
spline − interpolate smooth curve
SYNTAX
spline [ option... ]
DESCRIPTION
The spline command takes pairs of numbers from the standard input as abcissas and ordinates of a function. It produces a similar set, which is approximately equally spaced and includes the input set, on the standard output. The cubic spline output has two continuous derivatives, and sufficiently many points to look smooth when plotted by graph(1g), for example.
OPTIONS
−a Supply abscissas automatically (they are missing from the input); spacing is given by the next argument, or is assumed to be 1 if next argument is not a number.
−k The constant k used in the boundary value computation
y′′0=ky′′1,y′′n=ky′′n−1
is set by the next argument. By default k = 0.
−n Space output points so that approximately n intervals occur between the lower and upper x limits. (Default n = 100.)
−p Make output periodic, that is match derivatives at ends. First and last input values should normally agree.
−x Next 1 (or 2) arguments are lower (and upper) x limits. Normally these limits are calculated from the data. Automatic abcissas start at lower limit (default 0).
RESTRICTIONS
Limits input points to 1000.
DIAGNOSTICS
When data is not strictly monotone in x, spline reproduces the input without interpolating extra points.