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1 // Copyright 2014 the V8 project authors. All rights reserved. | |
2 // Use of this source code is governed by a BSD-style license that can be | |
3 // found in the LICENSE file. | |
4 | |
5 // Flags: --harmony-maths | |
6 | |
7 assertTrue(isNaN(Math.log1p(NaN))); | |
8 assertTrue(isNaN(Math.log1p(function() {}))); | |
9 assertTrue(isNaN(Math.log1p({ toString: function() { return NaN; } }))); | |
10 assertTrue(isNaN(Math.log1p({ valueOf: function() { return "abc"; } }))); | |
11 assertEquals("Infinity", String(1/Math.log1p(0))); | |
12 assertEquals("-Infinity", String(1/Math.log1p(-0))); | |
13 assertEquals("Infinity", String(Math.log1p(Infinity))); | |
14 assertEquals("-Infinity", String(Math.log1p(-1))); | |
15 assertTrue(isNaN(Math.log1p(-2))); | |
16 assertTrue(isNaN(Math.log1p(-Infinity))); | |
17 | |
18 for (var x = 1E300; x > 1E-1; x *= 0.8) { | |
19 var expected = Math.log(x + 1); | |
20 assertEqualsDelta(expected, Math.log1p(x), expected * 1E-14); | |
21 } | |
22 | |
23 // Values close to 0: | |
24 // Use Taylor expansion at 1 for log(x) as test expectation: | |
25 // log1p(x) == log(x + 1) == 0 + x / 1 - x^2 / 2 + x^3 / 3 - ... | |
26 function log1p(x) { | |
27 var terms = []; | |
28 var prod = x; | |
29 for (var i = 1; i <= 20; i++) { | |
30 terms.push(prod / i); | |
31 prod *= -x; | |
32 } | |
33 var sum = 0; | |
34 while (terms.length > 0) sum += terms.pop(); | |
35 return sum; | |
36 } | |
37 | |
38 for (var x = 1E-1; x > 1E-300; x *= 0.8) { | |
39 var expected = log1p(x); | |
40 assertEqualsDelta(expected, Math.log1p(x), expected * 1E-14); | |
41 } | |
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