[R] The match of "ave()" for "FUN=SD"

[Felix Wave]

Hello,
I have many subsets of x. I want to get the standard deviation
for each subset with the same factor levels. For "FUN=mean" and
"FUN=median" I am using "ave()". 
Can anybody tell me the match of "ave()" for using "FUN=SD"?

At the beginning I used aggregate(), also for mean and median. But 
aggregegate make ""arithmetical errors"" in computing huge records.


Thank's a lot. 

Felix



R-CODE:
-------
MEAN   <- ave(INPUT[,3], INPUT[,1], INPUT[,2], FUN = mean)
mMEAN  <- matrix( c(INPUT[,1], INPUT[,2], MEAN), ncol=3, byrow=FALSE)


SD      <- na.omit( aggregate(INPUT[,3], by=list(INPUT[,2],INPUT[,1] ), FUN=sd ) ) 
mSD         <- matrix( c(     SD[,2],    SD[,1],      SD[,3]), ncol=3, byrow=FALSE)
mSD[,1]     <- (mSD[,1] - 1 )        #eleminate the converting-fault list-> matrix
mSD[,2]     <- (mSD[,2] - 1 ) / 10   #eleminate the converting-fault list-> matrix



the arithmetical errors:
------------------------
list -> matrix
0	-> 1	1
1	-> 2
2.1	-> 22
3.5	-> 36