spline(1G) DG/UX 5.4R3.00 spline(1G)
NAME
spline - interpolate smooth curve
SYNOPSIS
spline [-a [spc]] [-k const] [-n interval] [-p] [-x [lower [upper]]]
where:
spc Horizontal spacing; default = 1
const A numeric constant
interval Number of intervals between lower and upper limits
lower Lower limit of the abscissa; default = 0
upper Upper limit of the abscissa
DESCRIPTION
Spline takes pairs of numbers from the standard input as abscissas
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.
Options are:
-a Supply abscissas automatically (they are missing from the
input); spacing is given by the next argument, or is assumed to
be 1.0 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. If n is less then 1, or n
is not integral, the default value is used. (Default n = 100)
-p Make output periodic, i.e. match derivatives at ends. First and
last input values should normally agree.
-x The arguments, if present, represent the lower and upper x
limits, respectively. Normally these limits are calculated from
the data. If both are given, the lower limit must be less than
the upper limit or the option is ignored. Automatic generation
of the abscissas start at the lower limit.
DIAGNOSTICS
When data is not strictly monotone in x, spline reproduces the input
without interpolating extra points. In the absence of the -a option,
if the last abscissa supplied does not have a corresponding ordinate,
it is ignored.
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spline(1G) DG/UX 5.4R3.00 spline(1G)
BUGS
A limit of 1000 input points is enforced silently.
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