Ben Murdoch | b8a8cc1 | 2014-11-26 15:28:44 +0000 | [diff] [blame^] | 1 | // Copyright 2012 the V8 project authors. All rights reserved. |
| 2 | // Redistribution and use in source and binary forms, with or without |
| 3 | // modification, are permitted provided that the following conditions are |
| 4 | // met: |
| 5 | // |
| 6 | // * Redistributions of source code must retain the above copyright |
| 7 | // notice, this list of conditions and the following disclaimer. |
| 8 | // * Redistributions in binary form must reproduce the above |
| 9 | // copyright notice, this list of conditions and the following |
| 10 | // disclaimer in the documentation and/or other materials provided |
| 11 | // with the distribution. |
| 12 | // * Neither the name of Google Inc. nor the names of its |
| 13 | // contributors may be used to endorse or promote products derived |
| 14 | // from this software without specific prior written permission. |
| 15 | // |
| 16 | // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
| 17 | // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
| 18 | // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR |
| 19 | // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT |
| 20 | // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
| 21 | // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT |
| 22 | // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
| 23 | // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
| 24 | // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| 25 | // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |
| 26 | // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| 27 | |
| 28 | // Tests that the --fast-math implementation of Math.exp() has |
| 29 | // reasonable precision. |
| 30 | |
| 31 | function exp(x) { |
| 32 | return Math.exp(x); |
| 33 | } |
| 34 | |
| 35 | var first_call_result = exp(Math.PI); |
| 36 | var second_call_result = exp(Math.PI); |
| 37 | |
| 38 | function assertAlmostEquals(expected, actual, x) { |
| 39 | if (expected == 0 && actual == 0) return; // OK |
| 40 | if (expected == Number.POSITIVE_INFINITY && |
| 41 | actual == Number.POSITIVE_INFINITY) { |
| 42 | return; // OK |
| 43 | } |
| 44 | relative_diff = Math.abs(expected/actual - 1); |
| 45 | assertTrue(relative_diff < 1e-12, "relative difference of " + relative_diff + |
| 46 | " for input " + x); |
| 47 | } |
| 48 | |
| 49 | var increment = Math.PI / 35; // Roughly 0.1, but we want to try many |
| 50 | // different mantissae. |
| 51 | for (var x = -708; x < 710; x += increment) { |
| 52 | var ex = exp(x); |
| 53 | var reference = Math.pow(Math.E, x); |
| 54 | assertAlmostEquals(reference, ex, x); |
| 55 | if (ex > 0 && isFinite(ex)) { |
| 56 | var back = Math.log(ex); |
| 57 | assertAlmostEquals(x, back, x + " (backwards)"); |
| 58 | } |
| 59 | } |
| 60 | |
| 61 | // Make sure optimizing the function does not alter the result. |
| 62 | var last_call_result = exp(Math.PI); |
| 63 | assertEquals(first_call_result, second_call_result); |
| 64 | assertEquals(first_call_result, last_call_result); |