targetD: Computation of the diagonal target D ('diagonal, unequal variances').
Description
The \(p \times p\) diagonal target D is computed from the \(n
\times p\) data matrix. It is defined as follows (\(i,j =
1,...,p\)):
$$t_{ij}=\begin{cases}s_{ii} & \text{ if } i=j \\ 0 & \text{ otherwise }\end{cases}$$
where
\(s_{ij}\) denotes the entry of the unbiased covariance matrix in row
\(i\), column \(j\).
Usage
targetD(x, genegroups)
Value
A \(p \times p\) diagonal matrix.
Arguments
x
A \(n \times p\) data matrix.
genegroups
The genegroups are not used for this target.
Author
Monika Jelizarow and Vincent Guillemot
References
J. Schaefer and K. Strimmer, 2005. A shrinkage approach to
large-scale covariance matrix estimation and implications for functional
genomics. Statist. Appl. Genet. Mol. Biol. 4:32.