[builtins] Make sure the Math functions and constants agree.

test/unittests/base/ieee754-unittest.cc

 // Copyright 2016 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include <limits>
 
 #include "src/base/ieee754.h"
 #include "src/base/macros.h"
 #include "testing/gmock-support.h"
 #include "testing/gtest-support.h"
@@ skipping 112 matching lines @@
   EXPECT_EQ(0.0, exp(-1000));
   EXPECT_EQ(0.0, exp(-745.1332191019412));
   EXPECT_EQ(2.2250738585072626e-308, exp(-708.39641853226408));
   EXPECT_EQ(3.307553003638408e-308, exp(-708.0));
   EXPECT_EQ(4.9406564584124654e-324, exp(-7.45133219101941108420e+02));
   EXPECT_EQ(0.36787944117144233, exp(-1.0));
   EXPECT_EQ(1.0, exp(-0.0));
   EXPECT_EQ(1.0, exp(0.0));
   EXPECT_EQ(1.0, exp(2.2250738585072014e-308));
   EXPECT_GE(exp(1.0), exp(0.9999999999999999));
   EXPECT_LE(exp(1.0), exp(1.0000000000000002));

[Raymond Toy, 2016/06/21 16:20:12]

I remember now what the tests in 132 and 133 are doing.  0.999999... is the
largest FP number < 1.  1.000...2 is the smallest FP number > 1.  These two
tests verify that exp(x) is monotonic at 1.

[Benedikt Meurer, 2016/06/22 03:55:59]

Acknowledged.

-  EXPECT_EQ(2.7182818284590455, exp(1.0));

[Raymond Toy, 2016/06/21 16:20:12]

Is it possible to use the constant E here, like you did in the implementation of
exp(x)?

[Benedikt Meurer, 2016/06/22 03:55:59]

Done.

+  EXPECT_EQ(2.718281828459045, exp(1.0));
   EXPECT_EQ(7.38905609893065e0, exp(2.0));
   EXPECT_EQ(1.7976931348622732e308, exp(7.09782712893383973096e+02));
   EXPECT_EQ(2.6881171418161356e+43, exp(100.0));
   EXPECT_EQ(8.218407461554972e+307, exp(709.0));
   EXPECT_EQ(1.7968190737295725e308, exp(709.7822265625e0));
   EXPECT_EQ(std::numeric_limits<double>::infinity(), exp(709.7827128933841e0));
   EXPECT_EQ(std::numeric_limits<double>::infinity(), exp(710.0));
   EXPECT_EQ(std::numeric_limits<double>::infinity(), exp(1000.0));
   EXPECT_EQ(std::numeric_limits<double>::infinity(),
             exp(std::numeric_limits<double>::infinity()));
@@ skipping 160 matching lines @@
   EXPECT_EQ(2.910566692924059e11, tan(1048575.0 / 2.0 * kPI));
 
   // Test Hayne-Panek reduction.
   EXPECT_EQ(-0.40806638884180424e0, tan(kTwo120));
   EXPECT_EQ(0.40806638884180424e0, tan(-kTwo120));
 }
 
 }  // namespace ieee754
 }  // namespace base
 }  // namespace v8