[R] simple questions about R

Ross Ihaka ihaka at stat.auckland.ac.nz
Wed Nov 4 20:53:24 CET 1998

Francisco Cribari writes:
 > A few simple questions from a novice R user. (I am running
 > R version 0.62.3 Beta (Sept 8, 1998) under Windows NT.)
 > 1) How do I time the execution of a function/program in R
 >    for Windows? Is there the equivalent of a dos.time function?

I'm not sure about this one.  One of those doing the Windows port will
probably reply.

 > 2) Can anyone send me details on the random number generator
 >    used by R (period, etc.). Also, why is it different from
 >    the SuperDuper RNG in S?

It used to be SuperDuper (some years ago), but was replaced by a
version of Wichmann-Hill generator (Applied Statistics Algorithm AS183)
which claims a period of > 6.95 * 10^12.  By default, a random seed is
chosen using the system clock, but you can initialize the generator
with a particular seed using an expression like
	.Random.seed <- c(1000, 2000, 3000)
The manual entry obtained with ?Random has more details.
(It would be nice to offer users a choice, but what should the choices be?).

 > 3) Will there be an  l1fit  function in future releases
 >    of R?

As with most R code, this depends on someone taking an interest and
providing the code.  There are a number of published algorithms for l1
fitting so it is just a matter of grabbing one of these and following
the way that "lm" builds the design matrix and does the fitting.
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