[R] calculating std err (SEM)?

[Kirk R. Wythers]

Is there a "canned" function in R for finding the standard error of the
mean? I have tried 

>  sem <- function(x) c(mean =mean(x),
+  SEM = stdev(x)/sqrt(length(x)))
> sem(pnet.lai)
Error in sem(pnet.lai) : couldn't find function "stdev"


It looks like there is no stdev function in R

Thanks,

Kirk



Kirk R. Wythers				email: kwythers at umn.edu
University of Minnesota			tel: 612.625.2261
Department of Forest Resources		fax: 612.625.5212
Saint Paul, MN 55108
					

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