SPLINE(1G)                           BSD                            SPLINE(1G)



NAME
     spline - interpolate smooth curve

SYNOPSIS
     spline [ option ] ...

DESCRIPTION
     spline 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 (R. W. Hamming, Numerical Methods for
     Scientists and Engineers, 2nd ed., 349ff) has two continuous derivatives,
     and sufficiently many points to look smooth when plotted, for example by
     graph(1G).

OPTIONS
     spline recognizes the following options, each as a separate argument.

     -a [ space ]
               Supply abscissas automatically (they are missing from the
               input); spacing is given by the next argument, or is assumed to
               be 1 if the next argument is not a number.

     -k [ n ]  The constant k used in the boundary value computation


                      (2nd deriv. at end) = k*(2nd deriv. next to end)


               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 [ l[ u ] ]
               Next one (or two) arguments are lower (and upper) x limits.
               Normally these limits are calculated from the data.  Automatic
               abcissas start at lower limit (default 0).

DIAGNOSTICS
     When data is not strictly monotone in x, spline reproduces the input
     without interpolating extra points.

BUGS
     A limit of 1000 input points is enforced silently.

SEE ALSO
     graph(1G), plot(1G)