[Rd] matrix operations

[Melanie Vida]

In R, I'm imported a data frame of  2,321,123 by 4 called "dataF".
I converted the data frame "dataF" to a matrix

dataM <- as.matrix(dataF)

Does R have an efficient routine to treat the special elements that 
contain "inf" in them. For example, can you separate the rows that have 
"inf" elements from the matrix into a separate matrix without iterating 
over the entire matrix?

Also, does R have an efficient way to sort columns in a matrix?

-Melanie