This function provides a very efficient way to pull an integer random sample sequence from an integer interval.

## Arguments

- low
The lower limit of the interval (inclusive).

- high
The higher limit of the interval (inclusive).

- length
The length of the sample.

## Details

The algorithm runs in `O(length)`

expected time, even if
`high-low`

is big. It is much faster (but of course less general) than
the builtin `sample`

function of R.

## References

Jeffrey Scott Vitter: An Efficient Algorithm for Sequential
Random Sampling, *ACM Transactions on Mathematical Software*, 13/1,
58--67.

## See also

Other other:
`convex_hull()`

,
`running_mean()`

## Author

Gabor Csardi csardi.gabor@gmail.com