20.3.6  Generating random matrices

The randmatrix or ranm or randMat command produces random vectors and matrices. (See also Section 11.1.28 and Section 20.3.5.)

• randmatrix takes one mandatory argument and three optional arguments:
  • n, an integer.
  • Optionally, p, an integer.
  • Optionally, a, an integer.
  • Optionally, a..b, a range.
  • Optionally, distr, a distribution, which can be one of:
    • ’rand(n)’ (see Section 20.3.2).
    • ’binomial(n,p)’, ’binomial,n,p’ or ’randbinomial(n,p)’, for a binomial distribution (see Section 20.4.3 and Section 20.3.3).
    • ’multinomial(P,K)’, ’multinomial,P,K’ or ’randmultinomial(P,K)’ for a multinomial distribution (see Section 20.4.5 and Section 20.3.3).
    • ’poisson(λ)’, ’poisson, λ’ or ’randpoisson(λ)’ for a Poisson distribution (see Section 20.4.6 and Section 20.3.3).
    • ’normald(µ,σ)’, ’normald,µ,σ’ or ’randnorm(µ,σ)’ for a normal distribution (see Section 20.4.7 and Section 20.3.3).
    • ’exp(a)’, ’exp,a’ or ’randexp(a)’ for an exponential distribution (see Section 20.4.15 and Section 20.3.3).
    • ’fisher(n,m)’, ’fisher,n,m’ or ’randfisher(n,m)’ for a Fisher-Snédécor distribution (see Section 20.4.10 and Section 20.3.3).
    Note that distr is in quotes.
• randmatrix(n) returns a vector of length n whose elements are integers chosen randomly from {−99,−98,…,98,99} with equal probability.
• randmatrix(n,p) returns an n× p matrix whose elements are integers chosen randomly from {−99,…,99} with equal probability.
• randmatrix(n,p,a) returns an n× p matrix whose elements are integers chosen randomly from [0,a) (or (a,0] is a is negative) with equal probability.
• randmatrix(n,p,a..b) returns an n× p matrix whose elements are real numbers chosen randomly from [a,b) with equal probability.
• randmatrix(n,p,distr) returns an n× p matrix whose elements are numbers chosen randomly according to distribution distr.

Examples