2.11BSD#431 - /usr/man/cat1/spline.0

SPLINE(1G)	    UNIX Programmer's Manual	       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).

     The following options are recognized, each as a separate
     argument.

     -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


	     (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, i.e. 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).

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

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.


Printed 11/26/99	 April 29, 1985                         1