\name{sp2d}
\alias{sp2d}
\title{
2-dimentional Radial Spline
}
\description{
2-dimentional radial spline generator used in \code{cpglmm}
}
\usage{
sp2d(x1, x2, k = max(20, min(length(x1)/4, 150)), by = NULL,
allPen = FALSE, varying = NULL, diag = FALSE,
knots1 = quantile(x1, probs = 1:k/(k + 1)),
knots2 = quantile(x1, probs = 1:k/(k + 1)))
}
%- maybe also 'usage' for other objects documented here.
\arguments{
\item{x1}{
the first covariate in the coordinate
}
\item{x2}{
the second covariate in the coordinate
}
\item{k}{
number of knots
}
\item{by}{
not used. This is just for compatibility with \code{amer}.
}
\item{allPen}{
not used. This is just for compatibility with \code{amer}.
}
\item{varying}{
not used. This is just for compatibility with \code{amer}.
}
\item{diag}{
not used. This is just for compatibility with \code{amer}.
}
\item{knots1}{
vector of knot locations for the first covariate in the coordinate
}
\item{knots2}{
vector of knot locations for the second covariate in the coordinate
}
}
\author{
Fabian Scheipl \email{fabian.scheipl@googlemail.com}
}