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1 // Copyright 2011 the V8 project authors. All rights reserved. | 1 // Copyright 2011 the V8 project authors. All rights reserved. |
2 // Redistribution and use in source and binary forms, with or without | 2 // Redistribution and use in source and binary forms, with or without |
3 // modification, are permitted provided that the following conditions are | 3 // modification, are permitted provided that the following conditions are |
4 // met: | 4 // met: |
5 // | 5 // |
6 // * Redistributions of source code must retain the above copyright | 6 // * Redistributions of source code must retain the above copyright |
7 // notice, this list of conditions and the following disclaimer. | 7 // notice, this list of conditions and the following disclaimer. |
8 // * Redistributions in binary form must reproduce the above | 8 // * Redistributions in binary form must reproduce the above |
9 // copyright notice, this list of conditions and the following | 9 // copyright notice, this list of conditions and the following |
10 // disclaimer in the documentation and/or other materials provided | 10 // disclaimer in the documentation and/or other materials provided |
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35 function cosTest() { | 35 function cosTest() { |
36 assertEquals(1, Math.cos(0)); | 36 assertEquals(1, Math.cos(0)); |
37 assertEquals(-1, Math.cos(Math.PI)); | 37 assertEquals(-1, Math.cos(Math.PI)); |
38 } | 38 } |
39 | 39 |
40 sinTest(); | 40 sinTest(); |
41 cosTest(); | 41 cosTest(); |
42 | 42 |
43 // By accident, the slow case for sine and cosine were both sine at | 43 // By accident, the slow case for sine and cosine were both sine at |
44 // some point. This is a regression test for that issue. | 44 // some point. This is a regression test for that issue. |
45 var x = Math.pow(2, 30); | 45 var x = Math.pow(2, 70); |
46 assertTrue(Math.sin(x) != Math.cos(x)); | 46 assertTrue(Math.sin(x) != Math.cos(x)); |
47 | 47 |
48 // Ensure that sine and log are not the same. | 48 // Ensure that sine and log are not the same. |
49 x = 0.5; | 49 x = 0.5; |
50 assertTrue(Math.sin(x) != Math.log(x)); | 50 assertTrue(Math.sin(x) != Math.log(x)); |
51 | |
52 // Test against approximation by series. | |
53 var factorial = [1]; | |
54 var accuracy = 50; | |
55 for (var i = 1; i < accuracy; i++) { | |
56 factorial[i] = factorial[i-1] * i; | |
57 } | |
58 | |
59 // We sum up in the reverse order for higher precision, as we expect the terms | |
60 // to grow smaller for x reasonably close to 0. | |
61 function precision_sum(array) { | |
62 var result = 0; | |
63 while (array.length > 0) { | |
64 result += array.pop(); | |
65 } | |
66 return result; | |
67 } | |
68 | |
69 function sin(x) { | |
70 var sign = 1; | |
71 var x2 = x*x; | |
72 var terms = []; | |
73 for (var i = 1; i < accuracy; i += 2) { | |
74 terms.push(sign * x / factorial[i]); | |
75 x *= x2; | |
76 sign *= -1; | |
77 } | |
78 return precision_sum(terms); | |
79 } | |
80 | |
81 function cos(x) { | |
82 var sign = -1; | |
83 var x2 = x*x; | |
84 x = x2; | |
85 var terms = [1]; | |
86 for (var i = 2; i < accuracy; i += 2) { | |
87 terms.push(sign * x / factorial[i]); | |
88 x *= x2; | |
89 sign *= -1; | |
90 } | |
91 return precision_sum(terms); | |
92 } | |
93 | |
94 function abs_error(fun, ref, x) { | |
95 return Math.abs(ref(x) - fun(x)); | |
96 } | |
97 | |
98 var test_inputs = []; | |
99 for (var i = -10000; i < 10000; i += 177) test_inputs.push(i/1257); | |
100 var epsilon = 0.000001; | |
101 | |
102 test_inputs.push(0); | |
103 test_inputs.push(0 + epsilon); | |
104 test_inputs.push(0 - epsilon); | |
105 test_inputs.push(Math.PI/2); | |
106 test_inputs.push(Math.PI/2 + epsilon); | |
107 test_inputs.push(Math.PI/2 - epsilon); | |
108 test_inputs.push(Math.PI); | |
109 test_inputs.push(Math.PI + epsilon); | |
110 test_inputs.push(Math.PI - epsilon); | |
111 test_inputs.push(- 2*Math.PI); | |
112 test_inputs.push(- 2*Math.PI + epsilon); | |
113 test_inputs.push(- 2*Math.PI - epsilon); | |
114 | |
115 var squares = []; | |
116 for (var i = 0; i < test_inputs.length; i++) { | |
117 var x = test_inputs[i]; | |
118 var err_sin = abs_error(Math.sin, sin, x); | |
119 var err_cos = abs_error(Math.cos, cos, x) | |
120 assertTrue(err_sin < 1E-13); | |
121 assertTrue(err_cos < 1E-13); | |
122 squares.push(err_sin*err_sin + err_cos*err_cos); | |
123 } | |
124 | |
125 // Sum squares up by adding them pairwise, to avoid losing precision. | |
126 while (squares.length > 1) { | |
127 var reduced = []; | |
128 if (squares.length % 2 == 1) reduced.push(squares.pop()); | |
129 // Remaining number of elements is even. | |
130 while(squares.length > 1) reduced.push(squares.pop() + squares.pop()); | |
131 squares = reduced; | |
132 } | |
133 | |
134 var err_rms = Math.sqrt(squares[0] / test_inputs.length / 2); | |
135 assertTrue(err_rms < 1E-14); | |
136 | |
137 assertEquals(-1, Math.cos({ valueOf: function() { return Math.PI; } })); | |
138 assertEquals(0, Math.sin("0x00000")); | |
139 assertTrue(isNaN(Math.sin(Infinity))); | |
140 assertTrue(isNaN(Math.cos("-Infinity"))); | |
141 assertEquals("Infinity", String(Math.tan(Math.PI/2))); | |
142 assertEquals("-Infinity", String(Math.tan(-Math.PI/2))); | |
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