An example of a sparse matrix for which
to be difficult, an unscaled version of this has been posted to the
web, accompanying an E-mail to R-help
Casper J Albers, Open University, UK.
This is a 72 * 72 symmetric matrix with 216
non-zero entries in five bands, stored as sparse matrix of class
Historical note (2006-03-30):
In earlier versions of R,
eigen(CAex) fell into an
infinite loop whereas
eigen(CAex, EISPACK=TRUE) had been okay.
1 2 3 4 5 6 7 8 9 10 11
data(CAex) str(CAex) # of class "dgCMatrix" image(CAex)# -> it's a simple band matrix with 5 bands ## and the eigen values are basically 1 (42 times) and 0 (30 x): zapsmall(ev <- eigen(CAex, only.values=TRUE)$values) ## i.e., the matrix is symmetric, hence sCA <- as(CAex, "symmetricMatrix") ## and stopifnot(class(sCA) == "dsCMatrix", as(sCA, "matrix") == as(CAex, "matrix"))
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