sum in vector

Hi all,

On Sun, Nov 14, 2010 at 10:06 PM, Henrique Dallazuanna <wwwhsd at gmail.com> wrote:

Try this:

?rowsum(price, market)

?does it work ?with multiple factors/groups ?
 ?using multiple factors such as c(factor1,factor2,factor3,...) as
second arg with ?rowsum() doesnt seem to work!
 ?am i missing something ?
 ?regards
 ?KM