# 4.2.1.10. Random Number Generator builtins¶

These functions implement random number generators from different probability distributions.

## bernoulli¶

 test bernoulli(float: p)  Return a boolean sample from the Bernoulli distribution defined by probability $${\bf p}$$

## binomial¶

 function int: binomial(int: t, float: p)  Return a sample from the binomial distribution defined by sample number t and probability p

## cauchy¶

 function float: cauchy(float: mean, float: scale) function float: cauchy(int: mean, float: scale)  Return a sample from the cauchy distribution defined by $${\bf mean}, {\bf scale}$$

## chisquared¶

 function float: chisquared(int: n) function float: chisquared(float: n)  Return a sample from the chi-squared distribution defined by the degree of freedom $${\bf n}$$

## discrete_distribution¶

 function int: discrete_distribution(array [int] of int: weights)  Return a sample from the discrete distribution defined by the array of weights $${\bf weights}$$ that assigns a weight to each integer starting from zero

## exponential¶

 function float: exponential(int: lambda) function float: exponential(float: lambda)  Return a sample from the exponential distribution defined by $${\bf lambda}$$

## fdistribution¶

 function float: fdistribution(float: d1, float: d2) function float: fdistribution(int: d1, int: d2)  Return a sample from the Fisher-Snedecor F-distribution defined by the degrees of freedom $${\bf d1}, {\bf d2}$$

## gamma¶

 function float: gamma(float: alpha, float: beta) function float: gamma(int: alpha, float: beta)  Return a sample from the gamma distribution defined by $${\bf alpha}, {\bf beta}$$

## lognormal¶

 function float: lognormal(float: mean, float: std) function float: lognormal(int: mean, float: std)  Return a sample from the lognormal distribution defined by $${\bf mean}, {\bf std}$$

## normal¶

 function float: normal(float: mean, float: std) function float: normal(int: mean, float: std)  Return a sample from the normal distribution defined by $${\bf mean}, {\bf std}$$

## poisson¶

 1. function int: poisson(float: mean) 2. function int: poisson(int: mean)  Return a sample from the poisson distribution defined by mean Return a sample from the poisson distribution defined by an integer mean

## tdistribution¶

 function float: tdistribution(float: n) function float: tdistribution(int: n)  Return a sample from the student’s t-distribution defined by the sample size $${\bf n}$$

## uniform¶

 1. function float: uniform(float: lowerbound, float: upperbound) 2. function int: uniform(int: lowerbound, int: upperbound) 3. function int: uniform(set of int: S)  1, 2. Return a sample from the uniform distribution defined by $${\bf lowerbound}, {\bf upperbound}$$ Return a sample from the uniform distribution defined by S

## weibull¶

 function float: weibull(float: shape, float: scale) function float: weibull(int: shape, float: scale)  Return a sample from the Weibull distribution defined by $${\bf shape}, {\bf scale}$$