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.numbers.examples.jmh.core;
18
19 import org.apache.commons.rng.UniformRandomProvider;
20
21 /** Class containing utility methods for working with doubles.
22 */
23 final class DoubleUtils {
24
25 /** No instantiation. */
26 private DoubleUtils() {}
27
28 /** Create a random double value with exponent in the range {@code [minExp, maxExp]}.
29 * @param minExp minimum exponent; must be less than {@code maxExp}
30 * @param maxExp maximum exponent; must be greater than {@code minExp}
31 * @param rng random number generator
32 * @return random double
33 */
34 static double random(final int minExp, final int maxExp, final UniformRandomProvider rng) {
35 // Create random doubles using random bits in the sign bit and the mantissa.
36 final long mask = ((1L << 52) - 1) | 1L << 63;
37 final long bits = rng.nextLong() & mask;
38 // The exponent must be unsigned so + 1023 to the signed exponent
39 final long exp = rng.nextInt(maxExp - minExp + 1) + minExp + 1023;
40 return Double.longBitsToDouble(bits | (exp << 52));
41 }
42
43 /** Create an array with the given length containing random doubles with exponents in the range
44 * {@code [minExp, maxExp]}.
45 * @param len array length
46 * @param minExp minimum exponent; must be less than {@code maxExp}
47 * @param maxExp maximum exponent; must be greater than {@code minExp}
48 * @param rng random number generator
49 * @return array of random doubles
50 */
51 static double[] randomArray(final int len, final int minExp, final int maxExp,
52 final UniformRandomProvider rng) {
53 final double[] arr = new double[len];
54 for (int i = 0; i < arr.length; ++i) {
55 arr[i] = random(minExp, maxExp, rng);
56 }
57 return arr;
58 }
59
60 /** Return a new array containing each element of {@code v} multiplied by {@code s}.
61 * @param v input array
62 * @param s scale factor
63 * @return new array containing each element of {@code v} multiplied by {@code s}
64 */
65 static double[] scalarMultiply(final double[] v, final double s) {
66 final double[] sv = new double[v.length];
67 for (int i = 0; i < v.length; ++i) {
68 sv[i] = s * v[i];
69 }
70 return sv;
71 }
72 }