class Random

Random class which contains several static random methods.

Public Methods

static void seed()

Initializes the random number generator with the computer clock

static void manualSeed(unsigned long the_seed_)

Initializes the random number generator with the given long "the_seed_"

static unsigned long getInitialSeed()

Returns the starting seed used

static unsigned long random()

Generates a uniform 32 bits integer

static real uniform()

Generates a uniform random number on [0,1[

static void getShuffledIndices(int* indices, int n_indices)

Returns in indices n_indices shuffled.

static void shuffle(void* tabular, int size_elem, int n_elems)

Shuffles tabular, which contains n_elems of size size_elem

static real boundedUniform(real a, real b)

Generates a uniform random number on [a,b[ (b>a)

static real normal(real mean=0, real stdv=1)

Generates a random number from a normal distribution.

static real exponential(real lambda)

Generates a random number from an exponential distribution.

static real cauchy(real median=0, real sigma=1)

Returns a random number from a Cauchy distribution.

static real logNormal(real mean, real stdv)

Generates a random number from a log-normal distribution.

static int geometric(real p)

Generates a random number from a geometric distribution.

static bool bernouilli(real p=0.5)

Returns true with probability and false with probability (p > 0)

Documentation

Random class which contains several static random methods.

These methods are based on a uniform random generator, named "Mersenne Twister", available at: http://www.math.keio.ac.jp/matumoto/emt.html. Copyright Makoto Matsumoto and Takuji Nishimura. (Have a look inside the implementation file for details).

The random generator can be initialized with the manualSeed() method. Otherwise, it will be automatically initialized with a seed based on the current computer clock.

static void seed()

Initializes the random number generator with the computer clock

static void manualSeed(unsigned long the_seed_)

Initializes the random number generator with the given long "the_seed_"

static unsigned long getInitialSeed()

Returns the starting seed used

static unsigned long random()

Generates a uniform 32 bits integer

static real uniform()

Generates a uniform random number on [0,1[

static void getShuffledIndices(int* indices, int n_indices)

Returns in indices n_indices shuffled. (between 0 and n_indices-1).

static void shuffle(void* tabular, int size_elem, int n_elems)

Shuffles tabular, which contains n_elems of size size_elem

static real boundedUniform(real a, real b)

Generates a uniform random number on [a,b[ (b>a)

static real normal(real mean=0, real stdv=1)

Generates a random number from a normal distribution. (With mean mean and standard deviation stdv >= 0).

static real exponential(real lambda)

Generates a random number from an exponential distribution. The density is , where lambda is a positive number.

static real cauchy(real median=0, real sigma=1)

Returns a random number from a Cauchy distribution. The Cauchy density is

static real logNormal(real mean, real stdv)

Generates a random number from a log-normal distribution. (mean > 0 is the mean of the log-normal distribution and stdv is its standard deviation).

static int geometric(real p)

Generates a random number from a geometric distribution. It returns an integer i, where . p must satisfy .

static bool bernouilli(real p=0.5)

Returns true with probability and false with probability (p > 0)

This class has no child classes.

Author:

Ronan Collobert (collober@idiap.ch)

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