Package org.apache.commons.rng.sampling.distribution

Class ContinuousUniformSampler

java.lang.Object

org.apache.commons.rng.sampling.distribution.SamplerBase

org.apache.commons.rng.sampling.distribution.ContinuousUniformSampler

All Implemented Interfaces:

ContinuousSampler, SharedStateContinuousSampler, SharedStateSampler<SharedStateContinuousSampler>

Direct Known Subclasses:

ContinuousUniformSampler.OpenIntervalContinuousUniformSampler

public class ContinuousUniformSampler
extends SamplerBase
implements SharedStateContinuousSampler

Sampling from a uniform distribution.

Sampling uses UniformRandomProvider.nextDouble().

Since:

1.0

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
private static class	ContinuousUniformSampler.OpenIntervalContinuousUniformSampler	Specialization to sample from an open interval (lo, hi).

Field Summary

Fields

Modifier and Type	Field	Description
private double	hi	Higher bound.
private double	lo	Lower bound.
private static int	MIN_ULP_OPPOSITE_SIGN	The minimum ULP gap for the open interval when the doubles have the opposite sign.
private static int	MIN_ULP_SAME_SIGN	The minimum ULP gap for the open interval when the doubles have the same sign.
private UniformRandomProvider	rng	Underlying source of randomness.

Constructor Summary

Constructors

Constructor	Description
ContinuousUniformSampler(UniformRandomProvider rng, double lo, double hi)	Create an instance.

Method Summary

Modifier and Type	Method	Description
(package private) double	getHi()	Gets the higher bound.
(package private) double	getLo()	Gets the lower bound.
private static boolean	lessThanUnsigned(long x, long y)	Compares two long values numerically treating the values as unsigned to test if the first value is less than the second value.
static SharedStateContinuousSampler	of(UniformRandomProvider rng, double lo, double hi)	Creates a new continuous uniform distribution sampler.
static SharedStateContinuousSampler	of(UniformRandomProvider rng, double lo, double hi, boolean excludeBounds)	Creates a new continuous uniform distribution sampler.
double	sample()	Creates a double sample.
java.lang.String	toString()
private static boolean	validateOpenInterval(double lo, double hi)	Check that the open interval is valid.
SharedStateContinuousSampler	withUniformRandomProvider(UniformRandomProvider rng)	Create a new instance of the sampler with the same underlying state using the given uniform random provider as the source of randomness.

Methods inherited from class org.apache.commons.rng.sampling.distribution.SamplerBase

nextDouble, nextInt, nextInt, nextLong

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Methods inherited from interface org.apache.commons.rng.sampling.distribution.ContinuousSampler

samples, samples

Field Detail

MIN_ULP_SAME_SIGN

private static final int MIN_ULP_SAME_SIGN

The minimum ULP gap for the open interval when the doubles have the same sign.

See Also:

Constant Field Values

MIN_ULP_OPPOSITE_SIGN

private static final int MIN_ULP_OPPOSITE_SIGN

The minimum ULP gap for the open interval when the doubles have the opposite sign.

See Also:

Constant Field Values

lo

private final double lo

Lower bound.

hi

private final double hi

Higher bound.

rng

private final UniformRandomProvider rng

Underlying source of randomness.

Constructor Detail

ContinuousUniformSampler

public ContinuousUniformSampler(UniformRandomProvider rng,
                                double lo,
                                double hi)

Create an instance.

Parameters:

rng - Generator of uniformly distributed random numbers.

lo - Lower bound.

hi - Higher bound.

Method Detail

sample

public double sample()

Creates a double sample.

Specified by:

sample in interface ContinuousSampler

Returns:

a sample.

getLo

double getLo()

Gets the lower bound. This is deliberately scoped as package private.

Returns:

the lower bound

getHi

double getHi()

Gets the higher bound. This is deliberately scoped as package private.

Returns:

the higher bound

toString

public java.lang.String toString()

Overrides:

toString in class SamplerBase

withUniformRandomProvider

public SharedStateContinuousSampler withUniformRandomProvider(UniformRandomProvider rng)

Create a new instance of the sampler with the same underlying state using the given uniform random provider as the source of randomness.

Specified by:

withUniformRandomProvider in interface SharedStateSampler<SharedStateContinuousSampler>

Parameters:

rng - Generator of uniformly distributed random numbers.

Returns:

the sampler

Since:

1.3

of

public static SharedStateContinuousSampler of(UniformRandomProvider rng,
                                              double lo,
                                              double hi)

Creates a new continuous uniform distribution sampler.

Parameters:

rng - Generator of uniformly distributed random numbers.

lo - Lower bound.

hi - Higher bound.

Returns:

the sampler

Since:

1.3

of

public static SharedStateContinuousSampler of(UniformRandomProvider rng,
                                              double lo,
                                              double hi,
                                              boolean excludeBounds)

Creates a new continuous uniform distribution sampler.

The bounds can be optionally excluded to sample from the open interval (lower, upper). In this case if the bounds have the same sign the open interval must contain at least 1 double value between the limits; if the bounds have opposite signs the open interval must contain at least 2 double values between the limits excluding -0.0. Thus the interval (-x,x) will raise an exception when x is Double.MIN_VALUE.

Parameters:

rng - Generator of uniformly distributed random numbers.

lo - Lower bound.

hi - Higher bound.

excludeBounds - Set to true to use the open interval (lower, upper).

Returns:

the sampler

Throws:

java.lang.IllegalArgumentException - If the open interval is invalid.

Since:

1.4

validateOpenInterval

private static boolean validateOpenInterval(double lo,
                                            double hi)

Check that the open interval is valid. It must contain at least one double value between the limits if the signs are the same, or two double values between the limits if the signs are different (excluding -0.0).

Parameters:

lo - Lower bound.

hi - Higher bound.

Returns:

false is the interval is invalid

lessThanUnsigned

private static boolean lessThanUnsigned(long x,
                                        long y)

Compares two long values numerically treating the values as unsigned to test if the first value is less than the second value.

See Long.compareUnsigned(long, long) in JDK 1.8.

Parameters:

x - the first value

y - the second value

Returns:

true if x < y