[R] sparseM and kronecker product_R latest version

[Martin Maechler]

>>>>> "am" == alessia matano <alexis.rtd at gmail.com>
>>>>>     on Mon, 11 Jan 2010 16:20:57 +0100 writes:

    am> Many thanks for it.
    am> However it is strange that when I put the numbers rather than ncol(R)
    am> (a matrix with ncol=36698) it worked. Look below

    >> dim(res2)
    am> [1] 170471  25822
    >> D<- as.matrix.csr(0,nrow(tmpb),25822)
    >> D<- as.matrix.csr(0,nrow(tmpb),ncol(res2))
    am> Error in if (length(x) == nrow * ncol) x <- matrix(x, nrow, ncol) else { :
    am> missing value where TRUE/FALSE needed
    am> In addition: Warning message:
    am> In nrow * ncol : NAs produced by integer overflow

    am> But probably it is true what you said, anyway.

yes, it is true.
The clue is that  typeof(25822)   is "double" and not "integer".

    am> So, do you suggest me to use directly the simple matrix command? or a
    am> kind of sparse matrix within your package?!? 

the latter, e.g.,

 library(Matrix)
 D <- Matrix(0, nrow = 113289, ncol=36698)
 ## or
 D. <- sparseMatrix(x=double(0), i=integer(0), j=integer(0),
		    dims = c(113289,36698))
 identical(D, D.) ##--> TRUE

## and, e.g.,

> Dk <- kronecker(D, Diagonal(x=5:2))
> identical(Dk, D %x% Diagonal(x = 5:2))
[1] TRUE
> dim(D)
[1] 113289  36698
> dim(Dk)
[1] 453156 146792
> 

Regards,
Martin Maechler, ETH Zurich