fastKronEye_crossprod: Fast kronecker product of crossproduct matrix
Description
This is a c++ implementation of the fast kronecker product
t(X)
Usage
fastKronEye_crossprod(XtX, Sigma, pvec, n, J)
Arguments
XtX
a matrix that is crossprod((X1, ..., XJ)) in R
pvec
J-dimensional vector giving number of observations for each endpoint
Value
matrix
result of \(X' (\Sigma \otimes I_n) X\)