SPLINE(VI) 5/15/74 SPLINE(VI)
NAME
spline - interpolate smooth curve
SYNOPSIS
*spline* [ option ] ...
DESCRIPTION
*Spline* takes pairs of numbers from the standard input as ab-
cissas 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 Engi-*
*neers,* 2nd ed., 349ff) has two continuous derivatives, and
sufficiently many points to look smooth when plotted, for
example by plot(I).
The following options are recognized, each as a separate ar-
gument.
**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* points oc-
cur 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
plot(I)
AUTHOR
M. D. McIlroy
BUGS
A limit of 1000 input points is enforced silently.
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