Bivariate function data objects are functions of two arguments, $f(s,t)$. It can be useful to evaluate the function for argument values satisfying $s=t$, such as evaluating the univariate variance function given the bivariate function that defines the variance-covariance function or surface. A linear differential operator can be applied to function $f(s,t)$ considered as a univariate function of either object holding the other object fixed.
evaldiag.bifd(evalarg, bifdobj, sLfd=int2Lfd(0), tLfd=int2Lfd(0))a vector or matrix of diagonal function values.
a vector of values of $s = t$.
a bivariate functional data object of the bifd class.
either a nonnegative integer or a linear differential operator object.
either a nonnegative integer or a linear differential operator object.
Ramsay, James O., Hooker, Giles, and Graves, Spencer (2009), Functional data analysis with R and Matlab, Springer, New York.
Ramsay, James O., and Silverman, Bernard W. (2005), Functional Data Analysis, 2nd ed., Springer, New York.
Ramsay, James O., and Silverman, Bernard W. (2002), Applied Functional Data Analysis, Springer, New York.
var.fd,
eval.bifd