Manual page for SPLINE(1G)
spline - interpolate smooth curve
SYNOPSIS
spline
[
-aknpx
] ...
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
- -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
xy''0=ky''1,y''n=ky''n-101
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
-
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
R. W. Hamming,
Numerical Methods for Scientists and Engineers,
2nd ed.
DIAGNOSTICS
When data is not strictly monotonic in
x,
spline
reproduces the input without interpolating extra points.
BUGS
A limit of 1000 input points is enforced silently.
Created by unroff & hp-tools.
© somebody (See intro for details). All Rights Reserved.
Last modified 11/5/97