\Header{randu}{Random Numbers from Congruential Generator RANDU}
\keyword{datasets}{randu}
\begin{Description}\relax
400 triples of successive random numbers were taken from the VAX
FORTRAN function RANDU running under VMS 1.5.
\end{Description}
\begin{Usage}
\begin{verbatim}data(randu)\end{verbatim}
\end{Usage}
\begin{Format}\relax
A data frame with 400 observations on 3 variables named \code{x},
\code{y} and \code{z} which give the first, second and third random
number in the triple.
\end{Format}
\begin{Details}\relax
In three dimensional displays it is evident that the triples fall on
15 parallel planes in 3-space. This can be shown theoretically to be
true for all triples from the RANDU generator.

These particular 400 triples start 5 apart in the sequence, that is
they are ((U[5i+1], U[5i+2], U[5i+3]), i= 0, \dots, 399), and they
are rounded to 6 decimal places.

Under VMS versions 2.0 and higher, this problem has been fixed.
\end{Details}
\begin{Source}\relax
David Donoho
\end{Source}
\begin{Examples}
\begin{ExampleCode}
## Not run: 
## We could re-generate the dataset by the following R code
seed <- as.double(1)
RANDU <- function() {
    seed <<- ((2^16 + 3) * seed) %% (2^31)
    seed/(2^31)
}
for(i in 1:400) {
    U <- c(RANDU(), RANDU(), RANDU(), RANDU(), RANDU())
    print(round(U[1:3], 6))
}
## End(Not run)
\end{ExampleCode}
\end{Examples}

