1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17 package org.apache.commons.geometry.examples.jmh;
18
19 import org.apache.commons.rng.UniformRandomProvider;
20
21 /** Class containing static utility methods for performance benchmarks.
22 */
23 public final class BenchmarkUtils {
24
25 /** Default min exponent for random double values. */
26 public static final int DEFAULT_MIN_EXP = -64;
27
28 /** Default max exponent for random double values. */
29 public static final int DEFAULT_MAX_EXP = 64;
30
31 /** Utility class; no instantiation. */
32 private BenchmarkUtils() {}
33
34 /** Creates a random double number with a random sign and mantissa and a large, default
35 * range for the exponent. The numbers will not be uniform over the range.
36 * @param rng random number generator
37 * @return the random number
38 */
39 public static double randomDouble(final UniformRandomProvider rng) {
40 return randomDouble(DEFAULT_MIN_EXP, DEFAULT_MAX_EXP, rng);
41 }
42
43 /** Create a random double value with exponent in the range {@code [minExp, maxExp]}.
44 * @param minExp minimum exponent; must be less than {@code maxExp}
45 * @param maxExp maximum exponent; must be greater than {@code minExp}
46 * @param rng random number generator
47 * @return random double
48 */
49 public static double randomDouble(final int minExp, final int maxExp, final UniformRandomProvider rng) {
50 // Create random doubles using random bits in the sign bit and the mantissa.
51 final long mask = ((1L << 52) - 1) | 1L << 63;
52 final long bits = rng.nextLong() & mask;
53 // The exponent must be unsigned so + 1023 to the signed exponent
54 final long exp = rng.nextInt(maxExp - minExp + 1) + minExp + 1023;
55 return Double.longBitsToDouble(bits | (exp << 52));
56 }
57
58 /** Create an array of doubles populated using {@link #randomDouble(UniformRandomProvider)}.
59 * @param rng uniform random provider
60 * @param len array length
61 * @return array containing {@code len} random doubles
62 */
63 public static double[] randomDoubleArray(final int len, final UniformRandomProvider rng) {
64 return randomDoubleArray(len, DEFAULT_MIN_EXP, DEFAULT_MAX_EXP, rng);
65 }
66
67 /** Create an array with the given length containing random doubles with exponents in the range
68 * {@code [minExp, maxExp]}.
69 * @param len array length
70 * @param minExp minimum exponent; must be less than {@code maxExp}
71 * @param maxExp maximum exponent; must be greater than {@code minExp}
72 * @param rng random number generator
73 * @return array of random doubles
74 */
75 public static double[] randomDoubleArray(final int len, final int minExp, final int maxExp,
76 final UniformRandomProvider rng) {
77 final double[] arr = new double[len];
78 for (int i = 0; i < arr.length; ++i) {
79 arr[i] = randomDouble(minExp, maxExp, rng);
80 }
81 return arr;
82 }
83 }