R help - Jul 2006 - Warning while subsetting using Matrix package

Hello,
  Could someone please explain the following warning while subsetting in
the Matrix package?
Thanks,
John Thaden, PhD
U. Arkansas for Med. Sci.
Little Rock AR USA
> # In the Matrix package...
> library("Matrix")
> # ...I had previously created a sparse matrix in triplet form:
> str(x)
Formal class 'dgTMatrix' [package "Matrix"] with 6 slots
  ..@ i       : int [1:923636] 1 2 3 4 5 6 7 8 9 10 ...
  ..@ j       : int [1:923636] 1 1 1 1 1 1 1 1 1 1 ...
  ..@ Dim     : int [1:2] 600 4482
  ..@ Dimnames:List of 2
  .. ..$ : chr [1:601] "50" "51" "52"
"53" ...
  .. ..$ : chr [1:4482] "1" "2" "3" "4"
...
  ..@ x       : num [1:923636] 50.2 51.2 52.2 53.2 54.2 ...
  ..@ factors : list()
>
> # While subsetting x, I was surprised to get this warning: 
> y<-x[1:300,]
Warning message:
number of items to replace is not a multiple of replacement
length
> # I did not get a warning, however, if I were more explicit...
> y <- x[1:300,1:4482]
>
> # Of course with a standard matrix, neither form gives a warning:
> (z <- matrix(1:12,4))
     [,1] [,2] [,3]
[1,]    1    5    9
[2,]    2    6   10
[3,]    3    7   11
[4,]    4    8   12
> z[1:2,]
[1,]    1    5    9
[2,]    2    6   10
> z[1:2,1:4]
[1,]    1    5    9
[2,]    2    6   10
> # I wonder what is going on?
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Sorry, I omitted background information:
  R version: 2.3.0
  OS: Windows XP
  CPU:  Pentium III, 
  RAM:  768 MB

Also, what command-line memory settings might prevent R from crashing
while using the Matrix package to convert my 600 X 4482 dgTMatrix to the
dgCMatrix class or to an expanded Matrix, via the as() function? I can
do this with half of the matrix, 300 x 4482.

Thanks,
John T

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