/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.commons.math4.random;
import java.io.Serializable;
import java.io.IOException;
import java.io.ObjectOutputStream;
import java.io.ObjectInputStream;
import org.apache.commons.math4.util.FastMath;
import org.apache.commons.rng.RestorableUniformRandomProvider;
import org.apache.commons.rng.simple.RandomSource;
import org.apache.commons.rng.core.RandomProviderDefaultState;
/**
* Adaptor that delegates to a
* {@link org.apache.commons.rng.UniformRandomProvider} instance.
* <p>
* It is provided for users who wish to test the new RNG implementations
* the <i>current</i> generators (up to version 3.6 of Commons Math) in
* codes that require the {@code RandomGenerator} interface.
* </p>
* <p>
* Applications should upgrade to use the new generators ASAP.
* If problems are found that jeopardize the upgrade, please report them
* on the project's
* <a href="https://issues.apache.org/jira/browse/MATH">
* issue tracking system</a>.
* </p>
*
* <p>
* <b>Notes:</b>
* <ul>
* <li>
* The
* {@link RandomGenerator#setSeed(int) setSeed(int)},
* {@link RandomGenerator#setSeed(int[]) setSeed(int[])} and
* {@link RandomGenerator#setSeed(long) setSeed(long)}
* methods of the {@link RandomGenerator} are not part of the
* {@link org.apache.commons.rng.UniformRandomProvider new API}.
* </li>
* <li>
* The new RNG implementations are not {@code Serializable}.
* Use {@link RestorableUniformRandomProvider#saveState()}
* instead.
* </li>
* <li>
* {@link RandomGenerator#nextGaussian() nextGaussian()} is not
* part of the {@link org.apache.commons.rng.UniformRandomProvider
* new API} as it defines a "post-processing" of the output of a
* <i>uniform</i> RNG in order to follow a different distribution.
* </li>
* </ul>
*
* @since 4.0
*
* @deprecated As of 4.0. This class is made available for testing
* the {@link RandomSource new RNG implementations} in existing
* applications.
* It will be removed in the next major release.
*/
@Deprecated
public final class RngAdaptor
implements RandomGenerator,
Serializable {
/** Serializable version identifier. */
private static final long serialVersionUID = 12345L;
/** Source. */
private final RandomSource source;
/** Delegate. */
private transient RestorableUniformRandomProvider delegate;
/** Next gaussian. */
private double nextGaussian = Double.NaN;
/**
* Creates a new instance.
*
* @param source Source of randomness.
*/
public RngAdaptor(RandomSource source) {
this(source, null);
}
/**
* Creates a new instance.
*
* @param source Source of randomness.
* @param seed Seed. Can be {@code null}.
*/
public RngAdaptor(RandomSource source,
Object seed) {
this.source = source;
delegate = RandomSource.create(source, seed);
}
/** {@inheritDoc} */
@Override
public void setSeed(int seed) {
delegate = RandomSource.create(source, seed);
clear();
}
/** {@inheritDoc} */
@Override
public void setSeed(int[] seed) {
delegate = RandomSource.create(source, seed);
clear();
}
/** {@inheritDoc} */
@Override
public void setSeed(long seed) {
delegate = RandomSource.create(source, seed);
clear();
}
/** {@inheritDoc} */
@Override
public boolean nextBoolean() {
return delegate.nextBoolean();
}
/** {@inheritDoc} */
@Override
public void nextBytes(byte[] bytes) {
delegate.nextBytes(bytes);
}
/** {@inheritDoc} */
@Override
public double nextDouble() {
return delegate.nextDouble();
}
/** {@inheritDoc} */
@Override
public float nextFloat() {
return delegate.nextFloat();
}
/** {@inheritDoc} */
@Override
public double nextGaussian() {
final double random;
if (Double.isNaN(nextGaussian)) {
// generate a new pair of gaussian numbers
final double x = nextDouble();
final double y = nextDouble();
final double alpha = 2 * FastMath.PI * x;
final double r = FastMath.sqrt(-2 * FastMath.log(y));
random = r * FastMath.cos(alpha);
nextGaussian = r * FastMath.sin(alpha);
} else {
// use the second element of the pair already generated
random = nextGaussian;
nextGaussian = Double.NaN;
}
return random;
}
/** {@inheritDoc} */
@Override
public int nextInt() {
return delegate.nextInt();
}
/** {@inheritDoc} */
@Override
public int nextInt(int n) {
return delegate.nextInt(n);
}
/** {@inheritDoc} */
@Override
public long nextLong() {
return delegate.nextLong();
}
/**
* Clears the cache used by the default implementation of
* {@link #nextGaussian}.
*/
private void clear() {
nextGaussian = Double.NaN;
}
/**
* @param out Output stream.
* @throws IOException if an error occurs.
*/
private void writeObject(ObjectOutputStream out)
throws IOException {
// Write non-transient fields.
out.defaultWriteObject();
// Save current state.
out.writeObject(((RandomProviderDefaultState) delegate.saveState()).getState());
}
/**
* @param in Input stream.
* @throws IOException if an error occurs.
* @throws ClassNotFoundException if an error occurs.
*/
private void readObject(ObjectInputStream in)
throws IOException,
ClassNotFoundException {
// Read non-transient fields.
in.defaultReadObject();
// Recreate the "delegate" from serialized info.
delegate = RandomSource.create(source);
// And restore its state.
final RandomProviderDefaultState state = new RandomProviderDefaultState((byte[]) in.readObject());
delegate.restoreState(state);
}
}