dae6dfe08b
Adapted from Raymond Toy's (rtoy@chromium.org) port, extracted from fdlibm's pow implementation. R=rtoy@chromium.org BUG=v8:3579 LOG=N Review URL: https://codereview.chromium.org/786823003 Cr-Commit-Position: refs/heads/master@{#25768}
100 lines
3.7 KiB
JavaScript
100 lines
3.7 KiB
JavaScript
// Copyright 2013 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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// Flags: --allow-natives-syntax
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[Math.log10, Math.log2].forEach( function(fun) {
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assertTrue(isNaN(fun(NaN)));
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assertTrue(isNaN(fun(fun)));
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assertTrue(isNaN(fun({ toString: function() { return NaN; } })));
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assertTrue(isNaN(fun({ valueOf: function() { return -1; } })));
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assertTrue(isNaN(fun({ valueOf: function() { return "abc"; } })));
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assertTrue(isNaN(fun(-0.1)));
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assertTrue(isNaN(fun(-1)));
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assertEquals("-Infinity", String(fun(0)));
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assertEquals("-Infinity", String(fun(-0)));
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assertEquals(0, fun(1));
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assertEquals("Infinity", String(fun(Infinity)));
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});
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for (var i = -310; i <= 308; i += 0.5) {
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assertEquals(i, Math.log10(Math.pow(10, i)));
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// Square roots are tested below.
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if (i != -0.5 && i != 0.5) assertEquals(i, Math.log2(Math.pow(2, i)));
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}
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// Test denormals.
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assertEquals(-307.77759430519706, Math.log10(1.5 * Math.pow(2, -1023)));
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// Test Math.log2(2^k) for -1074 <= k <= 1023.
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var n = -1074;
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// This loop covers n from -1074 to -1043
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for (var lowbits = 1; lowbits <= 0x80000000; lowbits *= 2) {
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var x = %_ConstructDouble(0, lowbits);
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assertEquals(n, Math.log2(x));
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n++;
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}
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// This loop covers n from -1042 to -1023
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for (var hibits = 1; hibits <= 0x80000; hibits *= 2) {
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var x = %_ConstructDouble(hibits, 0);
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assertEquals(n, Math.log2(x));
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n++;
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}
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// The rest of the normal values of 2^n
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var x = 1;
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for (var n = -1022; n <= 1023; ++n) {
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var x = Math.pow(2, n);
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assertEquals(n, Math.log2(x));
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}
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// Test special values.
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// Expectation isn't exactly 1/2 because Math.SQRT2 isn't exactly sqrt(2).
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assertEquals(0.5000000000000001, Math.log2(Math.SQRT2));
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// Expectation isn't exactly -1/2 because Math.SQRT1_2 isn't exactly sqrt(1/2).
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assertEquals(-0.4999999999999999, Math.log2(Math.SQRT1_2));
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assertEquals(3.321928094887362, Math.log2(10));
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assertEquals(6.643856189774724, Math.log2(100));
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// Test relationships
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x = 1;
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for (var k = 0; k < 1000; ++k) {
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var y = Math.abs(Math.log2(x) + Math.log2(1/x));
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assertEqualsDelta(0, y, 1.5e-14);
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x *= 1.1;
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}
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x = Math.pow(2, -100);
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for (var k = 0; k < 1000; ++k) {
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var y = Math.log2(x);
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var expected = Math.log(x) / Math.LN2;
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var err = Math.abs(y - expected) / expected;
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assertEqualsDelta(0, err, 1e-15);
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x *= 1.1;
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}
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