\name{int2Lfd}
\alias{int2Lfd}
\title{
Convert Integer to Linear Differential Operator
}
\description{
This function turns an integer specifying an order of a derivative
into the equivalent linear differential operator object. It is also
useful for checking that an object is of the "Lfd" class.
}
\usage{
int2Lfd(m=0)
}
\arguments{
\item{m}{
either a nonnegative integer or a linear differential operator
object.
}
}
\details{
Smoothing is achieved by penalizing the integral of the square of the
derivative of order \code{m} over \code{rangeval}:
m = 0 penalizes the squared difference from 0 of the function
1 = penalize the square of the slope or velocity
2 = penalize the squared acceleration
3 = penalize the squared rate of change of acceleration
4 = penalize the squared curvature of acceleration?
}
\value{
a linear differential operator object of the "Lfd" class that is
equivalent to the integer argument.
}
\examples{
# Lfd to penalize the squared acceleration
# typical for smoothing a cubic spline (order 4)
int2Lfd(2)
# Lfd to penalize the curvature of acceleration
# used with splines of order 6
# when it is desired to study velocity and acceleration
int2Lfd(4)
}
\keyword{smooth}