randu {datasets} | R Documentation |

## Random Numbers from Congruential Generator RANDU

### Description

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

### Usage

`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) %% (2^31)
seed/(2^31)
}
myrandu <- matrix(NA_real_, 400, 3, dimnames = list(NULL, c("x","y","z")))
for(i in 1:400) {
U <- c(RANDU(), RANDU(), RANDU(), RANDU(), RANDU())
myrandu[i,] <- round(U[1:3], 6)
}
stopifnot(all.equal(randu, as.data.frame(myrandu), tolerance = 1e-5))
```

[Package

*datasets*version 4.4.0 Index]