BunchKaufman-methods: Bunch-Kaufman Decomposition Methods
In bedatadriven/renjin-matrix: Sparse and Dense Matrix Classes and Methods

Description Usage Arguments Value Methods References See Also Examples

The Bunch-Kaufman Decomposition of a square symmetric matrix A is A = P LDL' P' where P is a permutation matrix, L is unit-lower triangular and D is block-diagonal with blocks of dimension 1 x 1 or 2 x 2.

1	BunchKaufman(x, ...)

`x`	a symmetric square matrix.
`...`	potentially further arguments passed to methods.

an object of class BunchKaufman, which can also be used as a (triangular) matrix directly.

Currently, only methods for dense numeric symmetric matrices are implemented.

x = "dspMatrix": uses Lapack routine dsptrf,
x = "dsyMatrix": uses Lapack routine dsytrf, computing the Bunch-Kaufman decomposition.

The original LAPACK source code, including documentation; http://www.netlib.org/lapack/double/dsytrf.f and http://www.netlib.org/lapack/double/dsptrf.f

The resulting class, BunchKaufman. Related decompositions are the LU, lu, and the Cholesky, chol (and for sparse matrices, Cholesky).

data(CAex)
dim(CAex)
isSymmetric(CAex)# TRUE
CAs <- as(CAex, "symmetricMatrix")
if(FALSE) # no method defined yet for *sparse* :
   bk. <- BunchKaufman(CAs)
## does apply to *dense* symmetric matrices:
bkCA <- BunchKaufman(as(CAs, "denseMatrix"))
bkCA

image(bkCA)# shows how sparse it is, too
str(R.CA <- as(bkCA, "sparseMatrix"))
## an upper triangular 72x72 matrix with only 144 non-zero entries