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); 65
