1 /*
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3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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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
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17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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23 
24 /*
25  * @test
26  * @bug 8139688
27  * @key randomness
28  * @library /test/lib
29  * @build jdk.test.lib.RandomFactory
30  * @build Tests
31  * @build FdlibmTranslit
32  * @build ExpTests
33  * @run main ExpTests
34  * @summary Tests specifically for StrictMath.exp
35  */
36 
37 import jdk.test.lib.RandomFactory;
38 
39 /**
40  * The role of this test is to verify that the FDLIBM exp algorithm is
41  * being used by running golden file style tests on values that may
42  * vary from one conforming exponential implementation to another.
43  */
44 
45 public class ExpTests {
ExpTests()46     private ExpTests(){}
47 
main(String [] argv)48     public static void main(String [] argv) {
49         int failures = 0;
50 
51         failures += testExp();
52         failures += testAgainstTranslit();
53 
54         if (failures > 0) {
55             System.err.println("Testing the exponential incurred "
56                                + failures + " failures.");
57             throw new RuntimeException();
58         }
59     }
60 
61     // From the fdlibm source, the overflow threshold in hex is:
62     // 0x4086_2E42_FEFA_39EF.
63     static final double EXP_OVERFLOW_THRESH  = Double.longBitsToDouble(0x4086_2E42_FEFA_39EFL);
64 
65     // From the fdlibm source, the underflow threshold in hex is:
66     // 0xc087_4910_D52D_3051L.
67     static final double EXP_UNDERFLOW_THRESH = Double.longBitsToDouble(0xc087_4910_D52D_3051L);
68 
testExp()69     static int testExp() {
70         int failures = 0;
71 
72         double [][] testCases = {
73             // Some of these could be moved to common Math/StrictMath exp testing.
74             {Double.NaN,                      Double.NaN},
75             {Double.MAX_VALUE,                Double.POSITIVE_INFINITY},
76             {Double.POSITIVE_INFINITY,        Double.POSITIVE_INFINITY},
77             {Double.NEGATIVE_INFINITY,        +0.0},
78             {EXP_OVERFLOW_THRESH,                 0x1.ffff_ffff_fff2ap1023},
79             {Math.nextUp(EXP_OVERFLOW_THRESH),    Double.POSITIVE_INFINITY},
80             {Math.nextDown(EXP_UNDERFLOW_THRESH), +0.0},
81             {EXP_UNDERFLOW_THRESH,                +Double.MIN_VALUE},
82         };
83 
84         for(double[] testCase: testCases)
85             failures+=testExpCase(testCase[0], testCase[1]);
86 
87         return failures;
88     }
89 
testExpCase(double input, double expected)90     static int testExpCase(double input, double expected) {
91         int failures = 0;
92 
93         failures+=Tests.test("StrictMath.exp(double)", input,
94                              StrictMath.exp(input), expected);
95         return failures;
96     }
97 
98     // Initialize shared random number generator
99     private static java.util.Random random = RandomFactory.getRandom();
100 
101     /**
102      * Test StrictMath.exp against transliteration port of exp.
103      */
testAgainstTranslit()104     private static int testAgainstTranslit() {
105         int failures = 0;
106 
107         double[] decisionPoints = {
108             // Near overflow threshold
109             EXP_OVERFLOW_THRESH - 512*Math.ulp(EXP_OVERFLOW_THRESH),
110 
111             // Near underflow threshold
112             EXP_UNDERFLOW_THRESH - 512*Math.ulp(EXP_UNDERFLOW_THRESH),
113 
114             // Straddle algorithm conditional checks
115             Double.longBitsToDouble(0x4086_2E42_0000_0000L - 512L),
116             Double.longBitsToDouble(0x3fd6_2e42_0000_0000L - 512L),
117             Double.longBitsToDouble(0x3FF0_A2B2_0000_0000L - 512L),
118             Double.longBitsToDouble(0x3e30_0000_0000_0000L - 512L),
119 
120             // Other notable points
121             Double.MIN_NORMAL - Math.ulp(Double.MIN_NORMAL)*512,
122             -Double.MIN_VALUE*512,
123         };
124 
125         for (double decisionPoint : decisionPoints) {
126             double ulp = Math.ulp(decisionPoint);
127             failures += testRange(decisionPoint - 1024*ulp, ulp, 1_024);
128         }
129 
130         // Try out some random values
131         for (int i = 0; i < 100; i++) {
132             double x = Tests.createRandomDouble(random);
133             failures += testRange(x, Math.ulp(x), 100);
134         }
135 
136         return failures;
137     }
138 
testRange(double start, double increment, int count)139     private static int testRange(double start, double increment, int count) {
140         int failures = 0;
141         double x = start;
142         for (int i = 0; i < count; i++, x += increment) {
143             failures += testExpCase(x, FdlibmTranslit.Exp.compute(x));
144         }
145         return failures;
146     }
147 }
148