| dCholCMatrix-class {Matrix} | R Documentation |
"dCholCMatrix" is class of Cholesky decompositions
of symmetric, sparse, compressed, column-oriented matrices (the
"dsCMatrix" class). "lCholCMatrix" is class showing the
logical structure (positions of the non-zeros) of these Cholesky decompositions.
Objects can be created by calls of the form new("dCholCMatrix", ...)
but are more commonly created from chol applied to
dsCMatrix or lsCMatrix objects.
perm:"integer" giving the
permutation of the rows and columns chosen to minimize fill-in.
If pivoting has not been applied this will be an integer vector of
length 0.diag:"dtCMatrix" class. It is always "N" for this class.uplo:"U" or "u") or the lower triangle
("L" or "l") is stored. At present only the lower
triangle form is allowed.p:"integer" of pointers, one
for each column, to the initial (zero-based) index of elements in
the column.i:"integer" of length nnzero
(number of non-zero elements). These are the row numbers for
each non-zero element in the matrix.x:"numeric" - the non-zero
elements of the matrix. Present only in the "dCholCMatrix"
class.factors:"list" - a list
of factorizations of the matrix. Dim:"integer" - the dimensions
of the matrix - must be an integer vector with exactly two
non-negative values.Dimnames:"Matrix" class, see Matrix.D:"numeric" - the diagonal
elements of the matrix D in the LDL' decomposition. Present only
in the "dCholCMatrix" class.Parent:"integer" - the
elimination tree of the (possibly permuted) symmetric matrix.
Class "dtCMatrix", directly.
Class "dgCMatrix", by class "dtCMatrix".
No methods defined with class "dCholCMatrix" in the signature.
Class dgCMatrix
data(KNex)
xpx <- with(KNex, crossprod(mm))
str(xpx)
str(ch <- chol(xpx))
## Visualize the sparseness:
dq <- function(ch) paste('"',ch,'"', sep="") ## dQuote(<UTF-8>) gives bad plots
image(xpx, main=paste("crossprod(mm) : Sparse", dq(class(xpx))))
image(ch, main= paste("chol (crossprod(mm)) : Sparse", dq(class(ch))))