commons-commits mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From l..@apache.org
Subject [14/22] [math] Reverting commit ca01fdf5808dcaf5bdb6e1c09a7de70a0adc0d28 as per Gilles request.
Date Sun, 17 Jan 2016 10:42:03 GMT
Reverting commit ca01fdf5808dcaf5bdb6e1c09a7de70a0adc0d28 as per Gilles request.

The work on revamping the random packages is perfoemd in the random-ravamp branch.


Project: http://git-wip-us.apache.org/repos/asf/commons-math/repo
Commit: http://git-wip-us.apache.org/repos/asf/commons-math/commit/56888aa6
Tree: http://git-wip-us.apache.org/repos/asf/commons-math/tree/56888aa6
Diff: http://git-wip-us.apache.org/repos/asf/commons-math/diff/56888aa6

Branch: refs/heads/master
Commit: 56888aa666b4997a4eeab7d1044f5358c213a178
Parents: 4abfe08
Author: Luc Maisonobe <luc@apache.org>
Authored: Sun Jan 17 11:35:25 2016 +0100
Committer: Luc Maisonobe <luc@apache.org>
Committed: Sun Jan 17 11:40:27 2016 +0100

----------------------------------------------------------------------
 .../math4/random/BitsStreamGenerator.java       | 218 +++++++++++++++++++
 .../math4/random/BitsStreamGeneratorTest.java   |  86 ++++++++
 2 files changed, 304 insertions(+)
----------------------------------------------------------------------


http://git-wip-us.apache.org/repos/asf/commons-math/blob/56888aa6/src/main/java/org/apache/commons/math4/random/BitsStreamGenerator.java
----------------------------------------------------------------------
diff --git a/src/main/java/org/apache/commons/math4/random/BitsStreamGenerator.java b/src/main/java/org/apache/commons/math4/random/BitsStreamGenerator.java
new file mode 100644
index 0000000..4cf6823
--- /dev/null
+++ b/src/main/java/org/apache/commons/math4/random/BitsStreamGenerator.java
@@ -0,0 +1,218 @@
+/*
+ * 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 org.apache.commons.math4.exception.NotStrictlyPositiveException;
+import org.apache.commons.math4.util.FastMath;
+
+/** Base class for random number generators that generates bits streams.
+ *
+ * @since 2.0
+ */
+public abstract class BitsStreamGenerator
+    implements RandomGenerator,
+               Serializable {
+    /** Serializable version identifier */
+    private static final long serialVersionUID = 20130104L;
+    /** Next gaussian. */
+    private double nextGaussian;
+
+    /**
+     * Creates a new random number generator.
+     */
+    public BitsStreamGenerator() {
+        nextGaussian = Double.NaN;
+    }
+
+    /** {@inheritDoc} */
+    @Override
+    public abstract void setSeed(int seed);
+
+    /** {@inheritDoc} */
+    @Override
+    public abstract void setSeed(int[] seed);
+
+    /** {@inheritDoc} */
+    @Override
+    public abstract void setSeed(long seed);
+
+    /** Generate next pseudorandom number.
+     * <p>This method is the core generation algorithm. It is used by all the
+     * public generation methods for the various primitive types {@link
+     * #nextBoolean()}, {@link #nextBytes(byte[])}, {@link #nextDouble()},
+     * {@link #nextFloat()}, {@link #nextGaussian()}, {@link #nextInt()},
+     * {@link #next(int)} and {@link #nextLong()}.</p>
+     * @param bits number of random bits to produce
+     * @return random bits generated
+     */
+    protected abstract int next(int bits);
+
+    /** {@inheritDoc} */
+    @Override
+    public boolean nextBoolean() {
+        return next(1) != 0;
+    }
+
+    /** {@inheritDoc} */
+    @Override
+    public void nextBytes(byte[] bytes) {
+        // Multiple 4 part of length (i.e. length with two least significant bits unset).
+        final int max = bytes.length & 0x7ffffffc;
+
+        int index = 0;
+        // Start filling in the byte array, 4 bytes at a time.
+        while (index < max) {
+            final int random = next(32);
+            bytes[index++] = (byte) random;
+            bytes[index++] = (byte) (random >>> 8);
+            bytes[index++] = (byte) (random >>> 16);
+            bytes[index++] = (byte) (random >>> 24);
+        }
+
+        // Fill in the remaing bytes.
+        if (index < bytes.length) {
+            int random = next(32);
+            while (true) {
+                bytes[index++] = (byte) random;
+                if (index < bytes.length) {
+                    random >>>= 8;
+                } else {
+                    break;
+                }
+            }
+        }
+    }
+
+    /** {@inheritDoc} */
+    @Override
+    public double nextDouble() {
+        final long high = ((long) next(26)) << 26;
+        final int  low  = next(26);
+        return (high | low) * 0x1.0p-52d;
+    }
+
+    /** {@inheritDoc} */
+    @Override
+    public float nextFloat() {
+        return next(23) * 0x1.0p-23f;
+    }
+
+    /** {@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 next(32);
+    }
+
+    /**
+     * {@inheritDoc}
+     * <p>This default implementation is copied from Apache Harmony
+     * java.util.Random (r929253).</p>
+     *
+     * <p>Implementation notes: <ul>
+     * <li>If n is a power of 2, this method returns
+     * {@code (int) ((n * (long) next(31)) >> 31)}.</li>
+     *
+     * <li>If n is not a power of 2, what is returned is {@code next(31) % n}
+     * with {@code next(31)} values rejected (i.e. regenerated) until a
+     * value that is larger than the remainder of {@code Integer.MAX_VALUE / n}
+     * is generated. Rejection of this initial segment is necessary to ensure
+     * a uniform distribution.</li></ul></p>
+     */
+    @Override
+    public int nextInt(int n) throws IllegalArgumentException {
+        if (n > 0) {
+            if ((n & -n) == n) {
+                return (int) ((n * (long) next(31)) >> 31);
+            }
+            int bits;
+            int val;
+            do {
+                bits = next(31);
+                val = bits % n;
+            } while (bits - val + (n - 1) < 0);
+            return val;
+        }
+        throw new NotStrictlyPositiveException(n);
+    }
+
+    /** {@inheritDoc} */
+    @Override
+    public long nextLong() {
+        final long high  = ((long) next(32)) << 32;
+        final long  low  = (next(32)) & 0xffffffffL;
+        return high | low;
+    }
+
+    /**
+     * Returns a pseudorandom, uniformly distributed {@code long} value
+     * between 0 (inclusive) and the specified value (exclusive), drawn from
+     * this random number generator's sequence.
+     *
+     * @param n the bound on the random number to be returned.  Must be
+     * positive.
+     * @return  a pseudorandom, uniformly distributed {@code long}
+     * value between 0 (inclusive) and n (exclusive).
+     * @throws IllegalArgumentException  if n is not positive.
+     */
+    public long nextLong(long n) throws IllegalArgumentException {
+        if (n > 0) {
+            long bits;
+            long val;
+            do {
+                bits = ((long) next(31)) << 32;
+                bits |= ((long) next(32)) & 0xffffffffL;
+                val  = bits % n;
+            } while (bits - val + (n - 1) < 0);
+            return val;
+        }
+        throw new NotStrictlyPositiveException(n);
+    }
+
+    /**
+     * Clears the cache used by the default implementation of
+     * {@link #nextGaussian}.
+     */
+    public void clear() {
+        nextGaussian = Double.NaN;
+    }
+
+}

http://git-wip-us.apache.org/repos/asf/commons-math/blob/56888aa6/src/test/java/org/apache/commons/math4/random/BitsStreamGeneratorTest.java
----------------------------------------------------------------------
diff --git a/src/test/java/org/apache/commons/math4/random/BitsStreamGeneratorTest.java b/src/test/java/org/apache/commons/math4/random/BitsStreamGeneratorTest.java
new file mode 100644
index 0000000..7f43ccb
--- /dev/null
+++ b/src/test/java/org/apache/commons/math4/random/BitsStreamGeneratorTest.java
@@ -0,0 +1,86 @@
+/*
+ * 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.util.Random;
+
+import org.apache.commons.math4.random.BitsStreamGenerator;
+import org.apache.commons.math4.random.RandomGenerator;
+
+/**
+ * Test cases for the BitStreamGenerator class
+ *
+ */
+
+public class BitsStreamGeneratorTest extends RandomGeneratorAbstractTest {
+
+    public BitsStreamGeneratorTest() {
+        super();
+    }
+
+    @Override
+    protected RandomGenerator makeGenerator() {
+        RandomGenerator generator = new TestBitStreamGenerator();
+        generator.setSeed(1000);
+        return generator;
+    }
+
+    /**
+     * Test BitStreamGenerator using a Random as bit source.
+     */
+    static class TestBitStreamGenerator extends BitsStreamGenerator {
+
+        private static final long serialVersionUID = 1L;
+        private BitRandom ran = new BitRandom();
+
+        @Override
+        public void setSeed(int seed) {
+           ran.setSeed(seed);
+           clear();
+        }
+
+        @Override
+        public void setSeed(int[] seed) {
+            ran.setSeed(seed[0]);
+        }
+
+        @Override
+        public void setSeed(long seed) {
+            ran.setSeed((int) seed);
+
+        }
+
+        @Override
+        protected int next(int bits) {
+            return ran.nextBits(bits);
+        }
+    }
+
+    /**
+     * Extend Random to expose next(bits)
+     */
+    @SuppressWarnings("serial")
+    static class BitRandom extends Random {
+        public BitRandom() {
+            super();
+        }
+        public int nextBits(int bits) {
+            return next(bits);
+        }
+    }
+
+}


Mime
View raw message