stats::hypergeometricRandom

Generate a random number generator for hypergeometric deviates

Use only in the MuPAD Notebook Interface.

This functionality does not run in MATLAB.

Syntax

stats::hypergeometricRandom(N, X, n, <Seed = s>)

Description

stats::hypergeometricRandom(N, X, n) returns a procedure that produces hypergeometric-deviates (random numbers) with population size N, success population size X and sample size n.

The procedure f:=stats::hypergeometricRandom(N, X, n) can be called in the form f().

The return value of f(x) is either an integer between max(0, X + n - N) and min(X, n) or a symbolic expression:

If N is a positive integer and both X and n are nonnegative integers, then an explicit numerical value is returned.

If any of the parameters is symbolic, then in some cases numerical or symbolic result will be returned:

0 will be returned if either n or X is zero, n will be returned if N = X and X will be returned if N = n.

The symbolic call stats::hypergeometricRandom(N, X, n)() is returned in all other cases.

Numerical values for N are only accepted if they are positive integers.

Numerical values for X and n are only accepted if they are integers that satisfy 0 ≤ X, nN.

The values R = f() are distributed randomly according to the hypergeometric distribution with poupulation size N, success population size X and sample size n.

For any max(0, X + n - N) ≤ xmin(X, n), the probability of Rx is given by

.

Without the option Seed = s, an initial seed is chosen internally. This initial seed is set to a default value when MuPAD® is started. Thus, each time MuPAD is started or re-initialized with the reset function, random generators produce the same sequences of numbers.

    Note:   With this option, the parameters N, X and n must evaluate to suitable numerical values at the time, when the generator is created.

    Note:   In contrast to the function random, the generators produced by stats::hypergeometricRandom do not react to the environment variable SEED.

For efficiency, it is recommended to produce sequences of K random numbers via

f := stats::hypergeometricRandom(N, X, n): f() $k = 1..K;

rather than by

stats::hypergeometricRandom(N, X, n)() $k = 1..K;

The latter call produces a sequence of generators each of which is called once. Also note that

stats::hypergeometricRandom(N, X, n, Seed = s)() $k = 1..K;

does not produce a random sequence, because a sequence of freshly initialized generators would be created each of them producing the same number.

Environment Interactions

The function is sensitive to the environment variable DIGITS which determines the numerical working precision.

Examples

Example 1

We generate hypergeometric deviates with parameters N = 100, X = 30, and n = 7:

f := stats::hypergeometricRandom(100, 30, 7): f() $ k = 1..10

delete f:

Example 2

With symbolic parameters, no random numbers can be produced:

f := stats::hypergeometricRandom(N, X, n): f()

When N, X and n evaluate to suitable numbers, the generator starts to produce random numbers:

N := 200: X := 80: n := 20: f() $ k= 1..10

delete f, N, X, n:

Example 3

We use the option Seed = s to reproduce a sequence of random numbers:

f := stats::hypergeometricRandom(500, 100, 50, Seed = 1):
f() $ k = 1..10

g := stats::hypergeometricRandom(500, 100, 50, Seed = 1):
g() $ k = 1..10

f() = g(), f() = g()

delete f, g:

Parameters

N

The "population size": an arithmetical expression representing a positive integer

X

The "success population size": an arithmetical expression representing a nonnegative integer

n

The "sample size": an arithmetical expression representing a nonnegative integer

Options

Seed

Option, specified as Seed = s

Initializes the random generator with the integer seed s. s can also be the option CurrentTime, to make the seed depend on the current time.

This option serves for generating generators that return predictable sequences of pseudo-random numbers. The generator is initialized with the seed s which may be an arbitrary integer. Several generators with the same initial seed produce the same sequence of numbers.

When this option is used, the parameters N, X and n must be numerical values at the time when the random generator is generated.

Return Values

procedure.

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