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 failures += lowPrecisionPerjectSquares();
43
44 // Add trickier rounding cases -- try to find examples of
45
46 // Add direct testing of definition of rounding...
47 // result should be closer than result+ulp or result - ulp,
48 // depending on rounding mode, etc.
49
50 if (failures > 0 ) {
51 throw new RuntimeException("Incurred " + failures + " failures" +
52 " testing BigDecimal.sqrt().");
53 }
54 }
55
56 private static int negativeTests() {
57 int failures = 0;
58
59 for (long i = -10; i < 0; i++) {
60 for (int j = -5; j < 5; j++) {
61 try {
62 BigDecimal input = BigDecimal.valueOf(i, j);
63 BigDecimal result = input.sqrt(MathContext.DECIMAL64);
64 System.err.println("Unexpected sqrt of negative: (" +
65 input + ").sqrt() = " + result );
66 failures += 1;
67 } catch (ArithmeticException e) {
68 ; // Expected
69 }
70 }
71 }
72
73 return failures;
74 }
75
76 private static int zeroTests() {
77 int failures = 0;
78
79 for (int i = -100; i < 100; i++) {
80 BigDecimal expected = BigDecimal.valueOf(0L, i/2);
81 // These results are independent of rounding mode
82 failures += compare(BigDecimal.valueOf(0L, i).sqrt(MathContext.UNLIMITED),
83 expected, true, "zeros");
84
85 failures += compare(BigDecimal.valueOf(0L, i).sqrt(MathContext.DECIMAL64),
86 expected, true, "zeros");
87 }
88
89 return failures;
90 }
91
92 /**
93 * sqrt(10^2N) is 10^N
94 * Both numerical value and representation should be verified
95 */
96 private static int evenPowersOfTenTests() {
97 int failures = 0;
98 MathContext oneDigitExactly = new MathContext(1, RoundingMode.UNNECESSARY);
99
100 for (int scale = -100; scale <= 100; scale++) {
101 BigDecimal testValue = BigDecimal.valueOf(1, 2*scale);
102 BigDecimal expectedNumericalResult = BigDecimal.valueOf(1, scale);
103
104 BigDecimal result;
105
106
107 failures += equalNumerically(expectedNumericalResult,
108 result = testValue.sqrt(MathContext.DECIMAL64),
109 "Even powers of 10, DECIMAL64");
110
111 // Can round to one digit of precision exactly
112 failures += equalNumerically(expectedNumericalResult,
113 result = testValue.sqrt(oneDigitExactly),
114 "even powers of 10, 1 digit");
115 if (result.precision() > 1) {
116 failures += 1;
117 System.err.println("Excess precision for " + result);
118 }
119
120
121 // If rounding to more than one digit, do precision / scale checking...
122
123 }
124
125 return failures;
126 }
127
128 private static int squareRootTwoTests() {
129 int failures = 0;
130 BigDecimal TWO = new BigDecimal(2);
131
132 // Square root of 2 truncated to 65 digits
133 BigDecimal highPrecisionRoot2 =
134 new BigDecimal("1.41421356237309504880168872420969807856967187537694807317667973799");
135
136
137 RoundingMode[] modes = {
138 RoundingMode.UP, RoundingMode.DOWN,
139 RoundingMode.CEILING, RoundingMode.FLOOR,
140 RoundingMode.HALF_UP, RoundingMode.HALF_DOWN, RoundingMode.HALF_EVEN
141 };
142
143 // For each iteresting rounding mode, for precisions 1 to, say
144 // 63 numerically compare TWO.sqrt(mc) to
145 // highPrecisionRoot2.round(mc)
146
147 for (RoundingMode mode : modes) {
148 for (int precision = 1; precision < 63; precision++) {
149 MathContext mc = new MathContext(precision, mode);
150 BigDecimal expected = highPrecisionRoot2.round(mc);
151 BigDecimal computed = TWO.sqrt(mc);
152
153 equalNumerically(expected, computed, "sqrt(2)");
154 }
155 }
156
157 return failures;
158 }
159
160 // When setting the precision to use inside the loop, take
161 // care to avoid the case where the precision of the input
162 // exceeds the requested precision and rounding the input
163 // value too soon.
164 // For example sqrt(16) rounded to one digit should be 4 not
165 // 3; if 16 was rounded down to one digit first, the the returned value might be 3
166 // Similar case for 25, 36, 49, 64, 81,
167
168 private static int lowPrecisionPerfectSquares() {
169 int failures = 0;
170
171 return failures;
172 }
173
174 private static int compare(BigDecimal a, BigDecimal b, boolean expected, String prefix) {
175 boolean result = a.equals(b);
176 int failed = (result==expected) ? 0 : 1;
177 if (failed == 1) {
178 System.err.println("Testing " + prefix +
179 "(" + a + ").compareTo(" + b + ") => " + result +
180 "\n\tExpected " + expected);
181 }
182 return failed;
183 }
184
185 private static int equalNumerically(BigDecimal a, BigDecimal b,
186 String prefix) {
187 return compareNumerically(a, b, 0, prefix);
188 }
189
190
191 private static int compareNumerically(BigDecimal a, BigDecimal b,
192 int expected, String prefix) {
193 int result = a.compareTo(b);
194 int failed = (result==expected) ? 0 : 1;
195 if (failed == 1) {
196 System.err.println("Testing " + prefix +
197 "(" + a + ").compareTo(" + b + ") => " + result +
198 "\n\tExpected " + expected);
199 }
200 return failed;
201 }
202
203 }