(maxima.info)Functions and Variables for discrete distributions


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52.3 Functions and Variables for discrete distributions
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 -- Function: pdf_general_finite_discrete (<x>,<v>)
     Returns the value at <x> of the probability function of a general
     finite discrete random variable, with vector probabilities v, such
     that 'Pr(X=i) = v_i'.  Vector v can be a list of nonnegative
     expressions, whose components will be normalized to get a vector of
     probabilities.  To make use of this function, write first
     'load("distrib")'.

          (%i1) load ("distrib")$
          (%i2) pdf_general_finite_discrete(2, [1/7, 4/7, 2/7]);
                                          4
          (%o2)                           -
                                          7
          (%i3) pdf_general_finite_discrete(2, [1, 4, 2]);
                                          4
          (%o3)                           -
                                          7

 -- Function: cdf_general_finite_discrete (<x>,<v>)
     Returns the value at <x> of the distribution function of a general
     finite discrete random variable, with vector probabilities v.

     See 'pdf_general_finite_discrete' for more details.

          (%i1) load ("distrib")$
          (%i2) cdf_general_finite_discrete(2, [1/7, 4/7, 2/7]);
                                          5
          (%o2)                           -
                                          7
          (%i3) cdf_general_finite_discrete(2, [1, 4, 2]);
                                          5
          (%o3)                           -
                                          7
          (%i4) cdf_general_finite_discrete(2+1/2, [1, 4, 2]);
                                          5
          (%o4)                           -
                                          7

 -- Function: quantile_general_finite_discrete (<q>,<v>)
     Returns the <q>-quantile of a general finite discrete random
     variable, with vector probabilities v.

     See 'pdf_general_finite_discrete' for more details.

 -- Function: mean_general_finite_discrete (<v>)
     Returns the mean of a general finite discrete random variable, with
     vector probabilities v.

     See 'pdf_general_finite_discrete' for more details.

 -- Function: var_general_finite_discrete (<v>)
     Returns the variance of a general finite discrete random variable,
     with vector probabilities v.

     See 'pdf_general_finite_discrete' for more details.

 -- Function: std_general_finite_discrete (<v>)
     Returns the standard deviation of a general finite discrete random
     variable, with vector probabilities v.

     See 'pdf_general_finite_discrete' for more details.

 -- Function: skewness_general_finite_discrete (<v>)
     Returns the skewness coefficient of a general finite discrete
     random variable, with vector probabilities v.

     See 'pdf_general_finite_discrete' for more details.

 -- Function: kurtosis_general_finite_discrete (<v>)
     Returns the kurtosis coefficient of a general finite discrete
     random variable, with vector probabilities v.

     See 'pdf_general_finite_discrete' for more details.

 -- Function: random_general_finite_discrete (<v>)
          random_general_finite_discrete (<v>,<m>)

     Returns a general finite discrete random variate, with vector
     probabilities v.  Calling 'random_general_finite_discrete' with a
     second argument <m>, a random sample of size <m> will be simulated.

     See 'pdf_general_finite_discrete' for more details.

          (%i1) load ("distrib")$
          (%i2) random_general_finite_discrete([1,3,1,5]);
          (%o2)                          4
          (%i3) random_general_finite_discrete([1,3,1,5], 10);
          (%o3)           [4, 2, 2, 3, 2, 4, 4, 1, 2, 2]

 -- Function: pdf_binomial (<x>,<n>,<p>)
     Returns the value at <x> of the probability function of a
     Binomial(n,p) random variable, with 0 \leq p \leq 1 and n a
     positive integer.  To make use of this function, write first
     'load("distrib")'.

 -- Function: cdf_binomial (<x>,<n>,<p>)
     Returns the value at <x> of the distribution function of a
     Binomial(n,p) random variable, with 0 \leq p \leq 1 and n a
     positive integer.

          (%i1) load ("distrib")$
          (%i2) cdf_binomial(5,7,1/6);
                                      7775
          (%o2)                       ----
                                      7776
          (%i3) float(%);
          (%o3)               .9998713991769548

 -- Function: quantile_binomial (<q>,<n>,<p>)
     Returns the <q>-quantile of a Binomial(n,p) random variable, with 0
     \leq p \leq 1 and n a positive integer; in other words, this is the
     inverse of 'cdf_binomial'.  Argument <q> must be an element of
     [0,1].  To make use of this function, write first
     'load("distrib")'.

 -- Function: mean_binomial (<n>,<p>)
     Returns the mean of a Binomial(n,p) random variable, with 0 \leq p
     \leq 1 and n a positive integer.  To make use of this function,
     write first 'load("distrib")'.

 -- Function: var_binomial (<n>,<p>)
     Returns the variance of a Binomial(n,p) random variable, with 0
     \leq p \leq 1 and n a positive integer.  To make use of this
     function, write first 'load("distrib")'.

 -- Function: std_binomial (<n>,<p>)
     Returns the standard deviation of a Binomial(n,p) random variable,
     with 0 \leq p \leq 1 and n a positive integer.  To make use of this
     function, write first 'load("distrib")'.

 -- Function: skewness_binomial (<n>,<p>)
     Returns the skewness coefficient of a Binomial(n,p) random
     variable, with 0 \leq p \leq 1 and n a positive integer.  To make
     use of this function, write first 'load("distrib")'.

 -- Function: kurtosis_binomial (<n>,<p>)
     Returns the kurtosis coefficient of a Binomial(n,p) random
     variable, with 0 \leq p \leq 1 and n a positive integer.  To make
     use of this function, write first 'load("distrib")'.

 -- Function: random_binomial (<n>,<p>)
          random_binomial (<n>,<p>,<m>)

     Returns a Binomial(n,p) random variate, with 0 \leq p \leq 1 and n
     a positive integer.  Calling 'random_binomial' with a third
     argument <m>, a random sample of size <m> will be simulated.

     The implemented algorithm is based on the one described in
     Kachitvichyanukul, V. and Schmeiser, B.W. (1988) <Binomial Random
     Variate Generation>.  Communications of the ACM, 31, Feb., 216.

     To make use of this function, write first 'load("distrib")'.

 -- Function: pdf_poisson (<x>,<m>)
     Returns the value at <x> of the probability function of a
     Poisson(m) random variable, with m>0.  To make use of this
     function, write first 'load("distrib")'.

 -- Function: cdf_poisson (<x>,<m>)
     Returns the value at <x> of the distribution function of a
     Poisson(m) random variable, with m>0.

          (%i1) load ("distrib")$
          (%i2) cdf_poisson(3,5);
          (%o2)       gamma_incomplete_regularized(4, 5)
          (%i3) float(%);
          (%o3)               .2650259152973623

 -- Function: quantile_poisson (<q>,<m>)
     Returns the <q>-quantile of a Poisson(m) random variable, with m>0;
     in other words, this is the inverse of 'cdf_poisson'.  Argument <q>
     must be an element of [0,1].  To make use of this function, write
     first 'load("distrib")'.

 -- Function: mean_poisson (<m>)
     Returns the mean of a Poisson(m) random variable, with m>0.  To
     make use of this function, write first 'load("distrib")'.

 -- Function: var_poisson (<m>)
     Returns the variance of a Poisson(m) random variable, with m>0.  To
     make use of this function, write first 'load("distrib")'.

 -- Function: std_poisson (<m>)
     Returns the standard deviation of a Poisson(m) random variable,
     with m>0.  To make use of this function, write first
     'load("distrib")'.

 -- Function: skewness_poisson (<m>)
     Returns the skewness coefficient of a Poisson(m) random variable,
     with m>0.  To make use of this function, write first
     'load("distrib")'.

 -- Function: kurtosis_poisson (<m>)
     Returns the kurtosis coefficient of a Poisson random variable
     Poi(m), with m>0.  To make use of this function, write first
     'load("distrib")'.

 -- Function: random_poisson (<m>)
          random_poisson (<m>,<n>)

     Returns a Poisson(m) random variate, with m>0.  Calling
     'random_poisson' with a second argument <n>, a random sample of
     size <n> will be simulated.

     The implemented algorithm is the one described in Ahrens, J.H. and
     Dieter, U. (1982) <Computer Generation of Poisson Deviates From
     Modified Normal Distributions>.  ACM Trans.  Math.  Software, 8, 2,
     June,163-179.

     To make use of this function, write first 'load("distrib")'.

 -- Function: pdf_bernoulli (<x>,<p>)
     Returns the value at <x> of the probability function of a
     Bernoulli(p) random variable, with 0 \leq p \leq 1.

     The Bernoulli(p) random variable is equivalent to the
     Binomial(1,p).

          (%i1) load ("distrib")$
          (%i2) pdf_bernoulli(1,p);
          (%o2)                           p

 -- Function: cdf_bernoulli (<x>,<p>)
     Returns the value at <x> of the distribution function of a
     Bernoulli(p) random variable, with 0 \leq p \leq 1.  To make use of
     this function, write first 'load("distrib")'.

 -- Function: quantile_bernoulli (<q>,<p>)
     Returns the <q>-quantile of a Bernoulli(p) random variable, with 0
     \leq p \leq 1; in other words, this is the inverse of
     'cdf_bernoulli'.  Argument <q> must be an element of [0,1].  To
     make use of this function, write first 'load("distrib")'.

 -- Function: mean_bernoulli (<p>)
     Returns the mean of a Bernoulli(p) random variable, with 0 \leq p
     \leq 1.

     The Bernoulli(p) random variable is equivalent to the
     Binomial(1,p).

          (%i1) load ("distrib")$
          (%i2) mean_bernoulli(p);
          (%o2)                           p

 -- Function: var_bernoulli (<p>)
     Returns the variance of a Bernoulli(p) random variable, with 0 \leq
     p \leq 1.

     The Bernoulli(p) random variable is equivalent to the
     Binomial(1,p).

          (%i1) load ("distrib")$
          (%i2) var_bernoulli(p);
          (%o2)                       (1 - p) p

 -- Function: std_bernoulli (<p>)
     Returns the standard deviation of a Bernoulli(p) random variable,
     with 0 \leq p \leq 1.

     The Bernoulli(p) random variable is equivalent to the
     Binomial(1,p).

          (%i1) load ("distrib")$
          (%i2) std_bernoulli(p);
          (%o2)                           sqrt((1 - p) p)

 -- Function: skewness_bernoulli (<p>)
     Returns the skewness coefficient of a Bernoulli(p) random variable,
     with 0 \leq p \leq 1.

     The Bernoulli(p) random variable is equivalent to the
     Binomial(1,p).

          (%i1) load ("distrib")$
          (%i2) skewness_bernoulli(p);
                                              1 - 2 p
          (%o2)                           ---------------
                                          sqrt((1 - p) p)

 -- Function: kurtosis_bernoulli (<p>)
     Returns the kurtosis coefficient of a Bernoulli(p) random variable,
     with 0 \leq p \leq 1.

     The Bernoulli(p) random variable is equivalent to the
     Binomial(1,p).

          (%i1) load ("distrib")$
          (%i2) kurtosis_bernoulli(p);
                                   1 - 6 (1 - p) p
          (%o2)                    ---------------
                                      (1 - p) p

 -- Function: random_bernoulli (<p>)
          random_bernoulli (<p>,<n>)

     Returns a Bernoulli(p) random variate, with 0 \leq p \leq 1.
     Calling 'random_bernoulli' with a second argument <n>, a random
     sample of size <n> will be simulated.

     This is a direct application of the 'random' built-in Maxima
     function.

     See also 'random'.  To make use of this function, write first
     'load("distrib")'.

 -- Function: pdf_geometric (<x>,<p>)
     Returns the value at <x> of the probability function of a
     Geometric(p) random variable, with 0 < p <= 1.

     The probability function is defined as p (1 - p)^x.  This is
     interpreted as the probability of x failures before the first
     success.

     'load("distrib")' loads this function.

 -- Function: cdf_geometric (<x>,<p>)
     Returns the value at <x> of the distribution function of a
     Geometric(p) random variable, with 0 < p <= 1.

     The probability from which the distribution function is derived is
     defined as p (1 - p)^x.  This is interpreted as the probability of
     x failures before the first success.

     'load("distrib")' loads this function.

 -- Function: quantile_geometric (<q>,<p>)
     Returns the <q>-quantile of a Geometric(p) random variable, with 0
     < p <= 1; in other words, this is the inverse of 'cdf_geometric'.
     Argument <q> must be an element of [0,1].

     The probability from which the quantile is derived is defined as p
     (1 - p)^x.  This is interpreted as the probability of x failures
     before the first success.

     'load("distrib")' loads this function.

 -- Function: mean_geometric (<p>)
     Returns the mean of a Geometric(p) random variable, with 0 < p <=
     1.

     The probability from which the mean is derived is defined as p (1 -
     p)^x.  This is interpreted as the probability of x failures before
     the first success.

     'load("distrib")' loads this function.

 -- Function: var_geometric (<p>)
     Returns the variance of a Geometric(p) random variable, with 0 < p
     <= 1.

     The probability from which the variance is derived is defined as p
     (1 - p)^x.  This is interpreted as the probability of x failures
     before the first success.

     'load("distrib")' loads this function.

 -- Function: std_geometric (<p>)
     Returns the standard deviation of a Geometric(p) random variable,
     with 0 < p <= 1.

     The probability from which the standard deviation is derived is
     defined as p (1 - p)^x.  This is interpreted as the probability of
     x failures before the first success.

     'load("distrib")' loads this function.

 -- Function: skewness_geometric (<p>)
     Returns the skewness coefficient of a Geometric(p) random variable,
     with 0 < p <= 1.

     The probability from which the skewness is derived is defined as p
     (1 - p)^x.  This is interpreted as the probability of x failures
     before the first success.

     'load("distrib")' loads this function.

 -- Function: kurtosis_geometric (<p>)
     Returns the kurtosis coefficient of a geometric random variable
     Geometric(p), with 0 < p <= 1.

     The probability from which the kurtosis is derived is defined as p
     (1 - p)^x.  This is interpreted as the probability of x failures
     before the first success.

     'load("distrib")' loads this function.

 -- Function: random_geometric (<p>)
          random_geometric (<p>,<n>)

     'random_geometric(<p>)' returns one random sample from a
     Geometric(p) distribution, with 0 < p <= 1.

     'random_geometric(<p>, <n>)' returns a list of <n> random samples.

     The algorithm is based on simulation of Bernoulli trials.

     The probability from which the random sample is derived is defined
     as p (1 - p)^x.  This is interpreted as the probability of x
     failures before the first success.

     'load("distrib")' loads this function.

 -- Function: pdf_discrete_uniform (<x>,<n>)
     Returns the value at <x> of the probability function of a Discrete
     Uniform(n) random variable, with n a strictly positive integer.  To
     make use of this function, write first 'load("distrib")'.

 -- Function: cdf_discrete_uniform (<x>,<n>)
     Returns the value at <x> of the distribution function of a Discrete
     Uniform(n) random variable, with n a strictly positive integer.  To
     make use of this function, write first 'load("distrib")'.

 -- Function: quantile_discrete_uniform (<q>,<n>)
     Returns the <q>-quantile of a Discrete Uniform(n) random variable,
     with n a strictly positive integer; in other words, this is the
     inverse of 'cdf_discrete_uniform'.  Argument <q> must be an element
     of [0,1].  To make use of this function, write first
     'load("distrib")'.

 -- Function: mean_discrete_uniform (<n>)
     Returns the mean of a Discrete Uniform(n) random variable, with n a
     strictly positive integer.  To make use of this function, write
     first 'load("distrib")'.

 -- Function: var_discrete_uniform (<n>)
     Returns the variance of a Discrete Uniform(n) random variable, with
     n a strictly positive integer.  To make use of this function, write
     first 'load("distrib")'.

 -- Function: std_discrete_uniform (<n>)
     Returns the standard deviation of a Discrete Uniform(n) random
     variable, with n a strictly positive integer.  To make use of this
     function, write first 'load("distrib")'.

 -- Function: skewness_discrete_uniform (<n>)
     Returns the skewness coefficient of a Discrete Uniform(n) random
     variable, with n a strictly positive integer.  To make use of this
     function, write first 'load("distrib")'.

 -- Function: kurtosis_discrete_uniform (<n>)
     Returns the kurtosis coefficient of a Discrete Uniform(n) random
     variable, with n a strictly positive integer.  To make use of this
     function, write first 'load("distrib")'.

 -- Function: random_discrete_uniform (<n>)
          random_discrete_uniform (<n>,<m>)

     Returns a Discrete Uniform(n) random variate, with n a strictly
     positive integer.  Calling 'random_discrete_uniform' with a second
     argument <m>, a random sample of size <m> will be simulated.

     This is a direct application of the 'random' built-in Maxima
     function.

     See also 'random'.  To make use of this function, write first
     'load("distrib")'.

 -- Function: pdf_hypergeometric (<x>,<n1>,<n2>,<n>)
     Returns the value at <x> of the probability function of a
     Hypergeometric(n1,n2,n) random variable, with <n1>, <n2> and <n>
     non negative integers and n<=n1+n2.  Being <n1> the number of
     objects of class A, <n2> the number of objects of class B, and <n>
     the size of the sample without replacement, this function returns
     the probability of event "exactly <x> objects are of class A".

     To make use of this function, write first 'load("distrib")'.

 -- Function: cdf_hypergeometric (<x>,<n1>,<n2>,<n>)
     Returns the value at <x> of the distribution function of a
     Hypergeometric(n1,n2,n) random variable, with <n1>, <n2> and <n>
     non negative integers and n<=n1+n2.  See 'pdf_hypergeometric' for a
     more complete description.

     To make use of this function, write first 'load("distrib")'.

 -- Function: quantile_hypergeometric (<q>,<n1>,<n2>,<n>)
     Returns the <q>-quantile of a Hypergeometric(n1,n2,n) random
     variable, with <n1>, <n2> and <n> non negative integers and
     n<=n1+n2; in other words, this is the inverse of
     'cdf_hypergeometric'.  Argument <q> must be an element of [0,1].
     To make use of this function, write first 'load("distrib")'.

 -- Function: mean_hypergeometric (<n1>,<n2>,<n>)
     Returns the mean of a discrete uniform random variable
     Hyp(n1,n2,n), with <n1>, <n2> and <n> non negative integers and
     n<=n1+n2.  To make use of this function, write first
     'load("distrib")'.

 -- Function: var_hypergeometric (<n1>,<n2>,<n>)
     Returns the variance of a hypergeometric random variable
     Hyp(n1,n2,n), with <n1>, <n2> and <n> non negative integers and
     n<=n1+n2.  To make use of this function, write first
     'load("distrib")'.

 -- Function: std_hypergeometric (<n1>,<n2>,<n>)
     Returns the standard deviation of a Hypergeometric(n1,n2,n) random
     variable, with <n1>, <n2> and <n> non negative integers and
     n<=n1+n2.  To make use of this function, write first
     'load("distrib")'.

 -- Function: skewness_hypergeometric (<n1>,<n2>,<n>)
     Returns the skewness coefficient of a Hypergeometric(n1,n2,n)
     random variable, with <n1>, <n2> and <n> non negative integers and
     n<=n1+n2.  To make use of this function, write first
     'load("distrib")'.

 -- Function: kurtosis_hypergeometric (<n1>,<n2>,<n>)
     Returns the kurtosis coefficient of a Hypergeometric(n1,n2,n)
     random variable, with <n1>, <n2> and <n> non negative integers and
     n<=n1+n2.  To make use of this function, write first
     'load("distrib")'.

 -- Function: random_hypergeometric (<n1>,<n2>,<n>)
          random_hypergeometric (<n1>,<n2>,<n>,<m>)

     Returns a Hypergeometric(n1,n2,n) random variate, with <n1>, <n2>
     and <n> non negative integers and n<=n1+n2.  Calling
     'random_hypergeometric' with a fourth argument <m>, a random sample
     of size <m> will be simulated.

     Algorithm described in Kachitvichyanukul, V., Schmeiser, B.W.
     (1985) <Computer generation of hypergeometric random variates.>
     Journal of Statistical Computation and Simulation 22, 127-145.

     To make use of this function, write first 'load("distrib")'.

 -- Function: pdf_negative_binomial (<x>,<n>,<p>)
     Returns the value at <x> of the probability function of a Negative
     Binomial(n,p) random variable, with 0 < p \leq 1 and n a positive
     number.  To make use of this function, write first
     'load("distrib")'.

 -- Function: cdf_negative_binomial (<x>,<n>,<p>)
     Returns the value at <x> of the distribution function of a Negative
     Binomial(n,p) random variable, with 0 < p \leq 1 and n a positive
     number.

          (%i1) load ("distrib")$
          (%i2) cdf_negative_binomial(3,4,1/8);
                                      3271
          (%o2)                      ------
                                     524288

 -- Function: quantile_negative_binomial (<q>,<n>,<p>)
     Returns the <q>-quantile of a Negative Binomial(n,p) random
     variable, with 0 < p \leq 1 and n a positive number; in other
     words, this is the inverse of 'cdf_negative_binomial'.  Argument
     <q> must be an element of [0,1].  To make use of this function,
     write first 'load("distrib")'.

 -- Function: mean_negative_binomial (<n>,<p>)
     Returns the mean of a Negative Binomial(n,p) random variable, with
     0 < p \leq 1 and n a positive number.  To make use of this
     function, write first 'load("distrib")'.

 -- Function: var_negative_binomial (<n>,<p>)
     Returns the variance of a Negative Binomial(n,p) random variable,
     with 0 < p \leq 1 and n a positive number.  To make use of this
     function, write first 'load("distrib")'.

 -- Function: std_negative_binomial (<n>,<p>)
     Returns the standard deviation of a Negative Binomial(n,p) random
     variable, with 0 < p \leq 1 and n a positive number.  To make use
     of this function, write first 'load("distrib")'.

 -- Function: skewness_negative_binomial (<n>,<p>)
     Returns the skewness coefficient of a Negative Binomial(n,p) random
     variable, with 0 < p \leq 1 and n a positive number.  To make use
     of this function, write first 'load("distrib")'.

 -- Function: kurtosis_negative_binomial (<n>,<p>)
     Returns the kurtosis coefficient of a Negative Binomial(n,p) random
     variable, with 0 < p \leq 1 and n a positive number.  To make use
     of this function, write first 'load("distrib")'.

 -- Function: random_negative_binomial (<n>,<p>)
          random_negative_binomial (<n>,<p>,<m>)

     Returns a Negative Binomial(n,p) random variate, with 0 < p \leq 1
     and n a positive number.  Calling 'random_negative_binomial' with a
     third argument <m>, a random sample of size <m> will be simulated.

     Algorithm described in Devroye, L. (1986) <Non-Uniform Random
     Variate Generation>.  Springer Verlag, p.  480.

     To make use of this function, write first 'load("distrib")'.


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