10.1. Random Numbers

Generate a vector of standard normal random numbers:

rnorm(10)

A Gaussian random matrix:

> matrix(rnorm(4*3), nrow=4, ncol=3)
           [,1]       [,2]       [,3]
[1,] -1.1436534  0.9533856 -0.6523511
[2,] -1.6479827  2.4177261  0.4608755
[3,] -0.5903960 -0.3371174  0.6652128
[4,]  0.3527609 -0.5014484  0.2769601

Uniformly distributed numbers between 0 and 1:

> runif(4)
[1] 0.8272435 0.9034066 0.5614103 0.1499100

Uniformly distributed numbers between 1 and 4:

> runif(4, min=1, max=4)
[1] 1.788217 3.501510 2.996803 1.741222

Seeding the random number sequence:

> set.seed(10)
> rnorm(10)
 [1]  0.01874617 -0.18425254 -1.37133055 -0.59916772  0.29454513  0.38979430 -1.20807618 -0.36367602
 [9] -1.62667268 -0.25647839
> rnorm(10)
 [1]  1.10177950  0.75578151 -0.23823356  0.98744470  0.74139013  0.08934727 -0.95494386 -0.19515038
 [9]  0.92552126  0.48297852
> set.seed(10)
> rnorm(10)
 [1]  0.01874617 -0.18425254 -1.37133055 -0.59916772  0.29454513  0.38979430 -1.20807618 -0.36367602
 [9] -1.62667268 -0.25647839
> rnorm(10)
 [1]  1.10177950  0.75578151 -0.23823356  0.98744470  0.74139013  0.08934727 -0.95494386 -0.19515038
 [9]  0.92552126  0.48297852