system.time executes a function and then reports how long it took to execute it. system.time(cat("\nHello World\n"))
# Hello World
# user system elapsed
# 0 0 0
cat ("\n\n")
set.seed(17)
nof_columns = 120
nof_rows = 4500
m <- matrix( rnorm (nof_columns * nof_rows), nrow = nof_rows)
system.time( dist(m) )
# user system elapsed
# 7.55 0.02 7.61