1 /*
2 * Copyright (c) 2003, 2012, 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 4074599 4939441
27 * @summary Tests for {Math, StrictMath}.log10
28 * @author Joseph D. Darcy
29 */
30
31 public class Log10Tests {
32 private Log10Tests(){}
33
34 static final double infinityD = Double.POSITIVE_INFINITY;
35 static final double NaNd = Double.NaN;
36 static final double LN_10 = StrictMath.log(10.0);
37
38 // Initialize shared random number generator
39 static java.util.Random rand = new java.util.Random(0L);
40
41 static int testLog10Case(double input, double expected) {
42 int failures=0;
43
44 failures+=Tests.test("Math.log10(double)", input,
45 Math.log10(input), expected);
46
47 failures+=Tests.test("StrictMath.log10(double)", input,
48 StrictMath.log10(input), expected);
49
50 return failures;
51 }
52
53 static int testLog10() {
54 int failures = 0;
55
56 double [][] testCases = {
57 {Double.NaN, NaNd},
58 {Double.longBitsToDouble(0x7FF0000000000001L), NaNd},
59 {Double.longBitsToDouble(0xFFF0000000000001L), NaNd},
60 {Double.longBitsToDouble(0x7FF8555555555555L), NaNd},
61 {Double.longBitsToDouble(0xFFF8555555555555L), NaNd},
62 {Double.longBitsToDouble(0x7FFFFFFFFFFFFFFFL), NaNd},
63 {Double.longBitsToDouble(0xFFFFFFFFFFFFFFFFL), NaNd},
64 {Double.longBitsToDouble(0x7FFDeadBeef00000L), NaNd},
65 {Double.longBitsToDouble(0xFFFDeadBeef00000L), NaNd},
66 {Double.longBitsToDouble(0x7FFCafeBabe00000L), NaNd},
67 {Double.longBitsToDouble(0xFFFCafeBabe00000L), NaNd},
68 {Double.NEGATIVE_INFINITY, NaNd},
69 {-8.0, NaNd},
70 {-1.0, NaNd},
71 {-Double.MIN_NORMAL, NaNd},
72 {-Double.MIN_VALUE, NaNd},
73 {-0.0, -infinityD},
74 {+0.0, -infinityD},
75 {+1.0, 0.0},
76 {Double.POSITIVE_INFINITY, infinityD},
77 };
78
79 // Test special cases
80 for(int i = 0; i < testCases.length; i++) {
81 failures += testLog10Case(testCases[i][0],
82 testCases[i][1]);
83 }
84
85 // Test log10(10^n) == n for integer n; 10^n, n < 0 is not
86 // exactly representable as a floating-point value -- up to
87 // 10^22 can be represented exactly
88 double testCase = 1.0;
89 for(int i = 0; i < 23; i++) {
90 failures += testLog10Case(testCase, i);
91 testCase *= 10.0;
92 }
93
94 // Test for gross inaccuracy by comparing to log; should be
95 // within a few ulps of log(x)/log(10)
96 for(int i = 0; i < 10000; i++) {
97 double input = Double.longBitsToDouble(rand.nextLong());
98 if(! Double.isFinite(input))
99 continue; // avoid testing NaN and infinite values
100 else {
101 input = Math.abs(input);
102
103 double expected = StrictMath.log(input)/LN_10;
104 if( ! Double.isFinite(expected))
105 continue; // if log(input) overflowed, try again
106 else {
107 double result;
108
109 if( Math.abs(((result=Math.log10(input)) - expected)/Math.ulp(expected)) > 3) {
110 failures++;
111 System.err.println("For input " + input +
112 ", Math.log10 was more than 3 ulps different from " +
113 "log(input)/log(10): log10(input) = " + result +
114 "\tlog(input)/log(10) = " + expected);
115 }
116
117 if( Math.abs(((result=StrictMath.log10(input)) - expected)/Math.ulp(expected)) > 3) {
118 failures++;
119 System.err.println("For input " + input +
120 ", StrictMath.log10 was more than 3 ulps different from " +
121 "log(input)/log(10): log10(input) = " + result +
122 "\tlog(input)/log(10) = " + expected);
123 }
124
125
126 }
127 }
128 }
129
130 // Test for accuracy and monotonicity near log10(1.0). From
131 // the Taylor expansion of log,
132 // log10(1+z) ~= (z -(z^2)/2)/LN_10;
133 {
134 double neighbors[] = new double[40];
135 double neighborsStrict[] = new double[40];
136 double z = Double.NaN;
137
138 // Test inputs greater than 1.0.
139 neighbors[0] = Math.log10(1.0);
140 neighborsStrict[0] = StrictMath.log10(1.0);
141
142 double input[] = new double[40];
143 int half = input.length/2;
144
145
146 // Initialize input to the 40 consecutive double values
147 // "centered" at 1.0.
148 double up = Double.NaN;
149 double down = Double.NaN;
150 for(int i = 0; i < half; i++) {
151 if (i == 0) {
152 input[half] = 1.0;
153 up = Math.nextUp(1.0);
154 down = Math.nextDown(1.0);
155 } else {
156 input[half + i] = up;
157 input[half - i] = down;
158 up = Math.nextUp(up);
159 down = Math.nextDown(down);
160 }
161 }
162 input[0] = Math.nextDown(input[1]);
163
164 for(int i = 0; i < neighbors.length; i++) {
165 neighbors[i] = Math.log10(input[i]);
166 neighborsStrict[i] = StrictMath.log10(input[i]);
167
168 // Test accuracy.
169 z = input[i] - 1.0;
170 double expected = (z - (z*z)*0.5)/LN_10;
171 if ( Math.abs(neighbors[i] - expected ) > 3*Math.ulp(expected) ) {
172 failures++;
173 System.err.println("For input near 1.0 " + input[i] +
174 ", Math.log10(1+z) was more than 3 ulps different from " +
175 "(z-(z^2)/2)/ln(10): log10(input) = " + neighbors[i] +
176 "\texpected about = " + expected);
177 }
178
179 if ( Math.abs(neighborsStrict[i] - expected ) > 3*Math.ulp(expected) ) {
180 failures++;
181 System.err.println("For input near 1.0 " + input[i] +
182 ", StrictMath.log10(1+z) was more than 3 ulps different from " +
183 "(z-(z^2)/2)/ln(10): log10(input) = " + neighborsStrict[i] +
184 "\texpected about = " + expected);
185 }
186
187 // Test monotonicity
188 if( i > 0) {
189 if( neighbors[i-1] > neighbors[i] ) {
190 failures++;
191 System.err.println("Monotonicity failure for Math.log10 at " + input[i] +
192 " and prior value.");
193 }
194
195 if( neighborsStrict[i-1] > neighborsStrict[i] ) {
196 failures++;
197 System.err.println("Monotonicity failure for StrictMath.log10 at " + input[i] +
198 " and prior value.");
199 }
200 }
201 }
202
203 }
204
205 return failures;
206 }
207
208 public static void main(String argv[]) {
209 int failures = 0;
210
211 failures += testLog10();
212
213 if (failures > 0) {
214 System.err.println("Testing log10 incurred "
215 + failures + " failures.");
216 throw new RuntimeException();
217 }
218 }
219
220 }