The math rand library

Overview

The rand library supplies a random number generator. It is not cryptographically secure: for that, you should use the crypto/rand package instead.

Types

Exponential = struct

Data structure to pass to get ... from to get a random number with an exponential distribution.

Normal = struct

Data structure to pass to get ... from to get a random number with an exponential distribution.

Random = struct (elements any?)

Data structure to pass to get ... from to get a random value depending on the elements field; see the documentation for get (x ref) from (r Random) for further details.

Seed = struct

Data structure to pass to put ... into when setting the random seed.

Shuffle = struct (elements any?)

Zipf = struct (s float, v float, imax int)

Commands

put(i int) into (seed Seed)

Sets the random seed to i. If unset, the RNG is given a strong random seed on initialization.

get(x ref) from (r Random)

This populates the random value from the range given by the elements field of the Random value, according to the type of elements: - If elements is a list, it selects a random element of the list. E.g: get x from Random ["one", "two", "three]. - If it's an integer i, it selects a random integer in 0::i. - If it's int, it selects a random integer from the whole 64-bit range of integers. - If it's a float x, it selects a random float between 0 and x. - If it's float, it selects a random float between 0 and 1. - If it's bool, it selects randomly from true and false. - If it's the name of an enum type, it selects a random element of the enum. - If it's a pair of integers, it selects a random integer from the range. - If it's a pair of floats, it selects a random float from the range.

get(x ref) from (s Shuffle)

This populates the reference variable with a random permutation of the range given by the elements field of the Shuffle value, according to the type of elements: - If elements is a list, it returns a permutation of the list. - If it's the name of an enum type, it returns a permutation of the elements of the enum. - If it's a pair of integers, if returns a permutation of the integers in that range, e.g. get x from Shuffle 0::10 will get a permutation of the numbers 0 ... 9.

get(x ref) from (n Normal)

This populates the reference variable with a random float with a normal distribution having mean 0 and standard deviation 1.

get(x ref) from (e Exponential)

This populates the reference variable with a random float greater than or equal to 0, with an exponential distribution and mean both equal to 1.

get(x ref) from (z Zipf)

This populates the reference variable with a float chosen from values k ∈ [0, z[imax]] such that P(k) is proportional to (z[v]+k)^(-z[s]). Note that in this one case, the top of the range (z[imax]) is among the possibilities.

---

This page is automatically generated from the Pipefish standard library. Any edits made directly to this wiki page will be overwritten the next time the documentation is regenerated.