\name{eval.bifd}
\alias{eval.bifd}
\title{
  Values a Two-argument Functional Data Object
}
\description{
A vector of argument values for the first argument \code{s} of the
functional data object to be evaluated.
}
\usage{
eval.bifd(sevalarg, tevalarg, bifd, sLfd=0, tLfd=0)
}
\arguments{
\item{sevalarg}{
a vector of argument values for the first argument \code{s} of the
functional data object to be evaluated.
}
\item{tevalarg}{
a vector of argument values for the second argument \code{t} of the
functional data object to be evaluated.
}
\item{bifd}{
a two-argument functional data object.
}
\item{sLfd}{
either a nonnegative integer or a linear differential operator object.
If present, the derivative or the value of applying the operator to
the object as a function of the first argument \code{s} is evaluated
rather than the functions themselves.
}
\item{tLfd}{
either a nonnegative integer or a linear differential operator object.
If present, the derivative or the value of applying the operator to
the object as a function of the second argument \code{t} is evaluated
rather than the functions themselves.
}
}
\value{
an array of 2, 3, or 4 dimensions containing the function
values.  The first dimension corresponds to the argument values in sevalarg,
the second to argument values in tevalarg, the third if
present to  replications, and the fourth if present to functions.
}
\examples{
daytime    <- (1:365)-0.5
daybasis   <- create.fourier.basis(c(0,365), 365)
harmLcoef  <- c(0,(2*pi/365)^2,0)
harmLfd    <- vec2Lfd(harmLcoef, c(0,365))
templambda <- 1.0
tempfdPar  <- fdPar(daybasis, harmLfd, templambda)
tempfd     <- smooth.basis(daytime, daily$tempav, tempfdPar)$fd
#    define the variance-covariance bivariate fd object
tempvarbifd <- var.fd(tempfd)
#    evaluate the variance-covariance surface and plot
weektime    <- seq(0,365,len=53)
tempvarmat  <- eval.bifd(weektime,weektime,tempvarbifd)
#    make a perspective plot of the variance function
persp(tempvarmat)
}
\keyword{smooth}
% Converted by Sd2Rd version 1.21.