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Create a Periodic Interpolation Spline
Usage
periodicSpline(obj1, obj2, knots, period, ord)
Arguments
obj1
|
Either a numeric vector of x values or a formula.
|
obj2
|
If obj1 is numeric this should be a numeric vector
of the same length. If obj1 is a formula this can be an
optional data frame in which to evaluate the names in the formula.
|
knots
|
An optional numeric vector of knot positions.
|
period
|
A positive numeric value giving the period for the
periodic spline. Defaults to 2 * pi .
|
ord
|
A positive integer giving the order of the spline. Defaults
to 4. See ?splineOrder for a definition of the order of a spline.
|
Description
Create a periodic interpolation spline, either from x
and
y
vectors, or from a formula/data.frame combination.
Value
An object that inherits from class spline
. The object can be in
the B-spline representation, in which case it will be a
pbSpline
object, or in the piecewise polynomial representation
(a ppolySpline
object).
Author(s)
Douglas Bates and Bill VenablesSee Also
splineKnots
,
interpSpline
,
periodic.spline
Examples
xx <- seq( -pi, pi, len = 16 )
yy <- sin( xx )
frm <- data.frame( xx, yy )
pispl <- periodicSpline( xx, yy, period = 2 * pi )
pispl2 <- periodicSpline( yy ~ xx, data = frm, period = 2 * pi )
# pispl and pispl2 should be the same
plot( predict( pispl, seq(-3*pi, 3*pi, len = 101) ) )
plot( pispl )