Discrete Uniform

Discrete uniform distribution constructor.

Usage

var DiscreteUniform = require( '@stdlib/math/base/dists/discrete-uniform/ctor' );

DiscreteUniform( [a, b] )

Returns a discrete uniform distribution object.

var discreteUniform = new DiscreteUniform();

var mu = discreteUniform.mean;
// returns 0.5

By default, a = 0 and b = 1. To create a distribution having a different a (minimum support) and b (maximum support), provide parameter values.

var discreteUniform = new DiscreteUniform( 2, 4 );

var mu = discreteUniform.mean;
// returns 3.0

discreteUniform

A discrete uniform distribution object has the following properties and methods...

Writable Properties

discreteUniform.a

Minimum support of the distribution. a must be an integer smaller than or equal to b.

var discreteUniform = new DiscreteUniform( -2, 2 );

var a = discreteUniform.a;
// returns -2

discreteUniform.a = 0;

a = discreteUniform.a;
// returns 0

discreteUniform.b

Maximum support of the distribution. b must be an integer larger than or equal to a.

var discreteUniform = new DiscreteUniform( 2, 4 );

var b = discreteUniform.b;
// returns 4

discreteUniform.b = 3;

b = discreteUniform.b;
// returns 3

Computed Properties

DiscreteUniform.prototype.entropy

Returns the differential entropy.

var discreteUniform = new DiscreteUniform( 4, 12 );

var entropy = discreteUniform.entropy;
// returns ~2.197

DiscreteUniform.prototype.kurtosis

Returns the excess kurtosis.

var discreteUniform = new DiscreteUniform( 4, 12 );

var kurtosis = discreteUniform.kurtosis;
// returns -1.23

DiscreteUniform.prototype.mean

Returns the expected value.

var discreteUniform = new DiscreteUniform( 4, 12 );

var mu = discreteUniform.mean;
// returns 8.0

DiscreteUniform.prototype.median

Returns the median.

var discreteUniform = new DiscreteUniform( 4, 12 );

var median = discreteUniform.median;
// returns 8.0

DiscreteUniform.prototype.skewness

Returns the skewness.

var discreteUniform = new DiscreteUniform( 4, 12 );

var skewness = discreteUniform.skewness;
// returns 0.0

DiscreteUniform.prototype.stdev

Returns the standard deviation.

var discreteUniform = new DiscreteUniform( 4, 12 );

var s = discreteUniform.stdev;
// returns ~2.582

DiscreteUniform.prototype.variance

Returns the variance.

var discreteUniform = new DiscreteUniform( 4, 12 );

var s2 = discreteUniform.variance;
// returns ~6.667

Methods

DiscreteUniform.prototype.cdf( x )

Evaluates the cumulative distribution function (CDF).

var discreteUniform = new DiscreteUniform( 2, 4 );

var y = discreteUniform.cdf( 2.5 );
// returns ~0.333

DiscreteUniform.prototype.logcdf( x )

Evaluates the natural logarithm of the cumulative distribution function (CDF).

var discreteUniform = new DiscreteUniform( 2, 4 );

var y = discreteUniform.logcdf( 2.5 );
// returns ~-1.099

DiscreteUniform.prototype.logpmf( x )

Evaluates the natural logarithm of the probability mass function (PMF).

var discreteUniform = new DiscreteUniform( 2, 4 );

var y = discreteUniform.logpmf( 4.0 );
// returns ~-1.099

DiscreteUniform.prototype.pmf( x )

Evaluates the probability mass function (PMF).

var discreteUniform = new DiscreteUniform( 2, 4 );

var y = discreteUniform.pmf( 3, 0 );
// returns ~0.333

DiscreteUniform.prototype.quantile( p )

Evaluates the quantile function at probability p.

var discreteUniform = new DiscreteUniform( 2, 4 );

var y = discreteUniform.quantile( 0.5 );
// returns 3.0

y = quantile( 1.9 );
// returns NaN

Examples

var DiscreteUniform = require( '@stdlib/math/base/dists/discrete-uniform/ctor' );

var discreteUniform = new DiscreteUniform( -2, 2 );

var mu = discreteUniform.mean;
// returns 0.0

var median = discreteUniform.median;
// returns 0.0

var s2 = discreteUniform.variance;
// returns 2.0

var y = discreteUniform.cdf( 2.5 );
// returns 1.0