randu                  package:base                  R Documentation

Random Numbers from Congruential Generator

Description:

     400 triples of successive random numbers were taken from the VAX
     FORTRAN function RANDU running under VMS 1.5.

Usage:

     data(randu)

Format:

     A data frame with 400 observations on 3 variables named `x', `y'
     and `z' which give the first, second and third random number in
     the triple.

Details:

     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, ..., 399), and
     they are rounded to 6 decimal places.

     Under VMS versions 2.0 and higher, this problem has been fixed.

Source:

     David Donoho

Examples:

     ## We could re-generate the dataset by the following R code
     seed <- as.double(1)
     RANDU <- function() {
         seed <<- ((2^16 + 3) * seed) 
         seed/(2^31)
     }
     for(i in 1:400) {
         U <- c(RANDU(), RANDU(), RANDU(), RANDU(), RANDU())
         print(round(U[1:3], 6))
     }

