42 lines
1.3 KiB
JavaScript
42 lines
1.3 KiB
JavaScript
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// Copyright 2014 the V8 project authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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// Flags: --harmony-maths
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assertTrue(isNaN(Math.log1p(NaN)));
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assertTrue(isNaN(Math.log1p(function() {})));
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assertTrue(isNaN(Math.log1p({ toString: function() { return NaN; } })));
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assertTrue(isNaN(Math.log1p({ valueOf: function() { return "abc"; } })));
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assertEquals("Infinity", String(1/Math.log1p(0)));
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assertEquals("-Infinity", String(1/Math.log1p(-0)));
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assertEquals("Infinity", String(Math.log1p(Infinity)));
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assertEquals("-Infinity", String(Math.log1p(-1)));
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assertTrue(isNaN(Math.log1p(-2)));
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assertTrue(isNaN(Math.log1p(-Infinity)));
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for (var x = 1E300; x > 1E-1; x *= 0.8) {
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var expected = Math.log(x + 1);
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assertEqualsDelta(expected, Math.log1p(x), expected * 1E-14);
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}
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// Values close to 0:
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// Use Taylor expansion at 1 for log(x) as test expectation:
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// log1p(x) == log(x + 1) == 0 + x / 1 - x^2 / 2 + x^3 / 3 - ...
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function log1p(x) {
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var terms = [];
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var prod = x;
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for (var i = 1; i <= 20; i++) {
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terms.push(prod / i);
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prod *= -x;
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}
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var sum = 0;
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while (terms.length > 0) sum += terms.pop();
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return sum;
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}
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for (var x = 1E-1; x > 1E-300; x *= 0.8) {
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var expected = log1p(x);
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assertEqualsDelta(expected, Math.log1p(x), expected * 1E-14);
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}
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