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
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 __plot__ (I).
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__ points
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
plot (I)
AUTHOR
M. D. McIlroy
BUGS
A limit of 1000 input points is enforced silently.