1 /*
2 * Copyright (c) 2016, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 */
23
24 /*
25 * @test
26 * @bug 4851777
27 * @summary Tests of BigDecimal.sqrt().
28 */
29
30 import java.math.*;
31 import java.util.*;
32
33 public class SquareRootTests {
34
35 public static void main(String... args) {
36 int failures = 0;
37
38 failures += negativeTests();
39 failures += zeroTests();
40 failures += evenPowersOfTenTests();
41 failures += squareRootTwoTests();
42
43 // Add trickier rounding cases -- try to find examples of
44
45 // When setting the precision to use inside the loop, take
46 // care to avoid the case where the precision of the input
47 // exceeds the requested precision and rounding the input
48 // value too soon.
49
50
51 if (failures > 0 ) {
52 throw new RuntimeException("Incurred " + failures + " failures" +
53 " testing BigDecimal.sqrt().");
54 }
55 }
56
57 private static int negativeTests() {
58 int failures = 0;
59
60 for (long i = -10; i < 0; i++) {
61 for (int j = -5; j < 5; j++) {
62 try {
63 BigDecimal input = BigDecimal.valueOf(i, j);
64 BigDecimal result = input.sqrt(MathContext.DECIMAL64);
65 System.err.println("Unexpected sqrt of negative: (" +
66 input + ").sqrt() = " + result );
67 failures += 1;
68 } catch (ArithmeticException e) {
69 ; // Expected
70 }
71 }
72 }
73
74 return failures;
75 }
76
77 private static int zeroTests() {
78 int failures = 0;
79
80 for (int i = -100; i < 100; i++) {
81 BigDecimal expected = BigDecimal.valueOf(0L, i/2);
82 // These results are independent of rounding mode
83 failures += compare(BigDecimal.valueOf(0L, i).sqrt(MathContext.UNLIMITED),
84 expected, true, "zeros");
85
86 failures += compare(BigDecimal.valueOf(0L, i).sqrt(MathContext.DECIMAL64),
87 expected, true, "zeros");
88 }
89
90 return failures;
91 }
92
93 /**
94 * sqrt(10^2N) is 10^N
95 * Both numerical value and representation should be verified
96 */
97 private static int evenPowersOfTenTests() {
98 int failures = 0;
99 MathContext oneDigitExactly = new MathContext(1, RoundingMode.UNNECESSARY);
100
101 for (int scale = -100; scale <= 100; scale++) {
102 BigDecimal testValue = BigDecimal.valueOf(1, 2*scale);
103 BigDecimal expectedNumericalResult = BigDecimal.valueOf(1, scale);
104
105 BigDecimal result;
106
107
108 failures += equalNumerically(expectedNumericalResult,
109 result = testValue.sqrt(MathContext.DECIMAL64),
110 "Even powers of 10, DECIMAL64");
111
112 // Can round to one digit of precision exactly
113 failures += equalNumerically(expectedNumericalResult,
114 result = testValue.sqrt(oneDigitExactly),
115 "even powers of 10, 1 digit");
116 if (result.precision() > 1) {
117 failures += 1;
118 System.err.println("Excess precision for " + result);
119 }
120
121
122 // If rounding to more than one digit, do precision / scale checking...
123
124 }
125
126 return failures;
127 }
128
129 private static int squareRootTwoTests() {
130 int failures = 0;
131 BigDecimal TWO = new BigDecimal(2);
132
133 // Square root of 2 truncated to 65 digits
134 BigDecimal highPrecisionRoot2 =
135 new BigDecimal("1.41421356237309504880168872420969807856967187537694807317667973799");
136
137
138 RoundingMode[] modes = {
139 RoundingMode.UP, RoundingMode.DOWN,
140 RoundingMode.CEILING, RoundingMode.FLOOR,
141 RoundingMode.HALF_UP, RoundingMode.HALF_DOWN, RoundingMode.HALF_EVEN
142 };
143
144 // For each iteresting rounding mode, for precisions 1 to, say
145 // 63 numerically compare TWO.sqrt(mc) to
146 // highPrecisionRoot2.round(mc)
147
148 for (RoundingMode mode : modes) {
149 for (int precision = 1; precision < 63; precision++) {
150 MathContext mc = new MathContext(precision, mode);
151 BigDecimal expected = highPrecisionRoot2.round(mc);
152 BigDecimal computed = TWO.sqrt(mc);
153
154 equalNumerically(expected, computed, "sqrt(2)");
155 }
156 }
157
158 return failures;
159 }
160
161
162
163 private static int compare(BigDecimal a, BigDecimal b, boolean expected, String prefix) {
164 boolean result = a.equals(b);
165 int failed = (result==expected) ? 0 : 1;
166 if (failed == 1) {
167 System.err.println("Testing " + prefix +
168 "(" + a + ").compareTo(" + b + ") => " + result +
169 "\n\tExpected " + expected);
170 }
171 return failed;
172 }
173
174 private static int equalNumerically(BigDecimal a, BigDecimal b,
175 String prefix) {
176 return compareNumerically(a, b, 0, prefix);
177 }
178
179
180 private static int compareNumerically(BigDecimal a, BigDecimal b,
181 int expected, String prefix) {
182 int result = a.compareTo(b);
183 int failed = (result==expected) ? 0 : 1;
184 if (failed == 1) {
185 System.err.println("Testing " + prefix +
186 "(" + a + ").compareTo(" + b + ") => " + result +
187 "\n\tExpected " + expected);
188 }
189 return failed;
190 }
191
192 }