spline(1) manual page
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spline - interpolate smooth curve
spline [ -aknpx ] ...
SUNWesu
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(1)
.
- -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, 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).
graph(1)
R. W. Hamming, Numerical
Methods for Scientists and Engineers, 2nd ed.
When data is not
strictly monotonic in x, spline reproduces the input without interpolating
extra points.
A limit of 1000 input points is enforced silently.
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