65 lines
2.7 KiB
JavaScript
65 lines
2.7 KiB
JavaScript
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// Copyright 2012 the V8 project authors. All rights reserved.
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// Redistribution and use in source and binary forms, with or without
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// modification, are permitted provided that the following conditions are
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// met:
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//
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// * Redistributions of source code must retain the above copyright
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// notice, this list of conditions and the following disclaimer.
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// * Redistributions in binary form must reproduce the above
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// copyright notice, this list of conditions and the following
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// disclaimer in the documentation and/or other materials provided
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// with the distribution.
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// * Neither the name of Google Inc. nor the names of its
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// contributors may be used to endorse or promote products derived
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// from this software without specific prior written permission.
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//
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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// Tests that the --fast-math implementation of Math.exp() has
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// reasonable precision.
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function exp(x) {
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return Math.exp(x);
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}
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var first_call_result = exp(Math.PI);
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var second_call_result = exp(Math.PI);
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function assertAlmostEquals(expected, actual, x) {
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if (expected == 0 && actual == 0) return; // OK
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if (expected == Number.POSITIVE_INFINITY &&
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actual == Number.POSITIVE_INFINITY) {
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return; // OK
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}
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relative_diff = Math.abs(expected/actual - 1);
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assertTrue(relative_diff < 1e-12, "relative difference of " + relative_diff +
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" for input " + x);
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}
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var increment = Math.PI / 35; // Roughly 0.1, but we want to try many
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// different mantissae.
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for (var x = -708; x < 710; x += increment) {
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var ex = exp(x);
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var reference = Math.pow(Math.E, x);
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assertAlmostEquals(reference, ex, x);
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if (ex > 0 && isFinite(ex)) {
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var back = Math.log(ex);
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assertAlmostEquals(x, back, x + " (backwards)");
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}
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}
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// Make sure optimizing the function does not alter the result.
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var last_call_result = exp(Math.PI);
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assertEquals(first_call_result, second_call_result);
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assertEquals(first_call_result, last_call_result);
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