identifying which column/row is passed in calls to apply()

["Schwarz,Paul" <PSchwarz@gcrinsight.com>]

S-News readers,

How would I identify which column (or row) is being operated on in a
call to the function specified in apply()? That is, if I wanted to
perform some column-specific (or row-specific) operation, how do I
identify which column/row is being passed to the function that's
specified in the call to apply(), where the number of columns ranges
from 1 to ncol(mymat)?

apply( mymat, 2, function(x){ ? } )


I suspect that this is easy, but I'm drawing a blank on how to do this.

Thanks a lot everyone.

-Paul