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 }