spline(x, y, n=3*length(x), xmin=min(x), xmax=max(x),
method="fmm")
splinefun(x, y, method="fmm")
x,y
| vectors giving the coordinates of the points to be interpolated. Alternatively a single plotting structure can be specified. | ||||||
n
|
interpolation takes place at n
equally spaced points spanning the interval |
spline performs cubic spline interpolation of the given data points.
It returns a list containing components
x, and y which give the ordinates where interpolation took
place and the interpolated values.
If method="fmm", the spline used is that of
Forsythe, Malcolm and Moler (an exact cubic is fitted through
the four points at each end of the data, and this is used
to determine the end conditions).
Natural splines are used when
method="natural" and periodic splines when
method="periodic".
splinefun returns a function which will perform
cubic spline interpolation of the given data points.
References
Forsythe, G. E., M. A. Malcolm and C. B. Moler (1977).
Computer Methods for Mathematical Computations.
See Also
approx.
Examples
x <- 1:10
y <- rnorm(10)
plot(x, y)
lines(spline(x, y))
x <- 1:10
y <- rnorm(10)
f <- spline(x, y)
curve(f(x), 1, 10)