Package org.apache.commons.rng.sampling.shape

Class TetrahedronSampler

java.lang.Object

org.apache.commons.rng.sampling.shape.TetrahedronSampler

All Implemented Interfaces:

ObjectSampler<double[]>, SharedStateObjectSampler<double[]>, SharedStateSampler<SharedStateObjectSampler<double[]>>

public class TetrahedronSampler
extends Object
implements SharedStateObjectSampler<double[]>

Generate points uniformly distributed within a tetrahedron.

• Uses the algorithm described in:

  Rocchini, C. and Cignoni, P. (2001)
  Generating Random Points in a Tetrahedron.
  Journal of Graphics Tools 5(4), pp. 9-12.

Sampling uses:

• UniformRandomProvider.nextDouble()

Since:

1.4

See Also:

• Rocchini, C. & Cignoni, P. (2001) Journal of Graphics Tools 5, pp. 9-12

Field Summary

Fields

Modifier and Type	Field	Description
private final double[]	a	The first vertex.
private final double[]	b	The second vertex.
private final double[]	c	The third vertex.
private final double[]	d	The fourth vertex.
private final UniformRandomProvider	rng	The source of randomness.
private static final int	THREE_D	The dimension for 3D sampling.
private static final String	VERTEX_A	The name of vertex a.
private static final String	VERTEX_B	The name of vertex b.
private static final String	VERTEX_C	The name of vertex c.
private static final String	VERTEX_D	The name of vertex d.

Constructor Summary

Constructors

Constructor	Description
TetrahedronSampler(UniformRandomProvider rng, double[] a, double[] b, double[] c, double[] d)
TetrahedronSampler(UniformRandomProvider rng, TetrahedronSampler source)

Method Summary

Modifier and Type	Method	Description
private double[]	createSample(double p1msmtmu, double s, double t, double u)	Creates the sample given the random variates s, t and u in the interval [0, 1] and s + t + u <= 1.
static TetrahedronSampler	of(UniformRandomProvider rng, double[] a, double[] b, double[] c, double[] d)	Create a tetrahedron sampler with vertices a, b, c and d.
double[]	sample()	Create an object sample.
TetrahedronSampler	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 java.lang.Object

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

Methods inherited from interface org.apache.commons.rng.sampling.ObjectSampler

samples, samples

Field Details

THREE_D

private static final int THREE_D

The dimension for 3D sampling.

See Also:

• Constant Field Values

VERTEX_A

private static final String VERTEX_A

The name of vertex a.

See Also:

• Constant Field Values

VERTEX_B

private static final String VERTEX_B

The name of vertex b.

See Also:

• Constant Field Values

VERTEX_C

private static final String VERTEX_C

The name of vertex c.

See Also:

• Constant Field Values

VERTEX_D

private static final String VERTEX_D

The name of vertex d.

See Also:

• Constant Field Values

a

private final double[] a

The first vertex.

b

private final double[] b

The second vertex.

c

private final double[] c

The third vertex.

d

private final double[] d

The fourth vertex.

rng

private final UniformRandomProvider rng

The source of randomness.

Constructor Details

TetrahedronSampler

TetrahedronSampler(UniformRandomProvider rng,
 double[] a,
 double[] b,
 double[] c,
 double[] d)

Parameters:

rng - Source of randomness.

a - The first vertex.

b - The second vertex.

c - The third vertex.

d - The fourth vertex.

TetrahedronSampler

TetrahedronSampler(UniformRandomProvider rng,
 TetrahedronSampler source)

Parameters:

rng - Generator of uniformly distributed random numbers

source - Source to copy.

Method Details

sample

public double[] sample()

Description copied from interface: ObjectSampler

Create an object sample.

Specified by:

sample in interface ObjectSampler<double[]>

Returns:

a random Cartesian point within the tetrahedron.

createSample

private double[] createSample(double p1msmtmu,
 double s,
 double t,
 double u)

Creates the sample given the random variates s, t and u in the interval [0, 1] and s + t + u <= 1. The sum 1 - s - t - u is provided. The sample can be obtained from the tetrahedron abcd using:

 p = (1 - s - t - u)a + sb + tc + ud
 

Parameters:

p1msmtmu - plus 1 minus s minus t minus u (1 - s - t - u)

s - the first variate s

t - the second variate t

u - the third variate u

Returns:

the sample

withUniformRandomProvider

public TetrahedronSampler 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<SharedStateObjectSampler<double[]>>

Parameters:

rng - Generator of uniformly distributed random numbers.

Returns:

the sampler

of

public static TetrahedronSampler of(UniformRandomProvider rng,
 double[] a,
 double[] b,
 double[] c,
 double[] d)

Create a tetrahedron sampler with vertices a, b, c and d. Sampled points are uniformly distributed within the tetrahedron.

No test for a volume is performed. If the vertices are coplanar the sampling distribution is undefined.

Parameters:

rng - Source of randomness.

a - The first vertex.

b - The second vertex.

c - The third vertex.

d - The fourth vertex.

Returns:

the sampler

Throws:

IllegalArgumentException - If the vertices do not have length 3; or vertices have non-finite coordinates