1// Licensed to the .NET Foundation under one or more agreements.
2// The .NET Foundation licenses this file to you under the MIT license.
3// See the LICENSE file in the project root for more information.
4
5/*=====================================================================
6**
7** Source: test1.c
8**
9** Purpose: Tests exp with a normal set of values.
10**
11**===================================================================*/
12
13#include <palsuite.h>
14
15// binary64 (double) has a machine epsilon of 2^-52 (approx. 2.22e-16). However, this
16// is slightly too accurate when writing tests meant to run against libm implementations
17// for various platforms. 2^-50 (approx. 8.88e-16) seems to be as accurate as we can get.
18//
19// The tests themselves will take PAL_EPSILON and adjust it according to the expected result
20// so that the delta used for comparison will compare the most significant digits and ignore
21// any digits that are outside the double precision range (15-17 digits).
22
23// For example, a test with an expect result in the format of 0.xxxxxxxxxxxxxxxxx will use
24// PAL_EPSILON for the variance, while an expected result in the format of 0.0xxxxxxxxxxxxxxxxx
25// will use PAL_EPSILON / 10 and and expected result in the format of x.xxxxxxxxxxxxxxxx will
26// use PAL_EPSILON * 10.
27#define PAL_EPSILON 8.8817841970012523e-16
28
29#define PAL_NAN sqrt(-1.0)
30#define PAL_POSINF -log(0.0)
31#define PAL_NEGINF log(0.0)
32
33/**
34 * Helper test structure
35 */
36struct test
37{
38 double value; /* value to test the function with */
39 double expected; /* expected result */
40 double variance; /* maximum delta between the expected and actual result */
41};
42
43/**
44 * validate
45 *
46 * test validation function
47 */
48void __cdecl validate(double value, double expected, double variance)
49{
50 double result = exp(value);
51
52 /*
53 * The test is valid when the difference between result
54 * and expected is less than or equal to variance
55 */
56 double delta = fabs(result - expected);
57
58 if (delta > variance)
59 {
60 Fail("exp(%g) returned %20.17g when it should have returned %20.17g",
61 value, result, expected);
62 }
63}
64
65/**
66 * validate
67 *
68 * test validation function for values returning NaN
69 */
70void __cdecl validate_isnan(double value)
71{
72 double result = exp(value);
73
74 if (!_isnan(result))
75 {
76 Fail("exp(%g) returned %20.17g when it should have returned %20.17g",
77 value, result, PAL_NAN);
78 }
79}
80
81/**
82 * main
83 *
84 * executable entry point
85 */
86int __cdecl main(int argc, char **argv)
87{
88 struct test tests[] =
89 {
90 /* value expected variance */
91 { PAL_NEGINF, 0, PAL_EPSILON },
92 { -3.1415926535897932, 0.043213918263772250, PAL_EPSILON / 10 }, // value: -(pi)
93 { -2.7182818284590452, 0.065988035845312537, PAL_EPSILON / 10 }, // value: -(e)
94 { -2.3025850929940457, 0.1, PAL_EPSILON }, // value: -(ln(10))
95 { -1.5707963267948966, 0.20787957635076191, PAL_EPSILON }, // value: -(pi / 2)
96 { -1.4426950408889634, 0.23629008834452270, PAL_EPSILON }, // value: -(log2(e))
97 { -1.4142135623730950, 0.24311673443421421, PAL_EPSILON }, // value: -(sqrt(2))
98 { -1.1283791670955126, 0.32355726390307110, PAL_EPSILON }, // value: -(2 / sqrt(pi))
99 { -1, 0.36787944117144232, PAL_EPSILON }, // value: -(1)
100 { -0.78539816339744831, 0.45593812776599624, PAL_EPSILON }, // value: -(pi / 4)
101 { -0.70710678118654752, 0.49306869139523979, PAL_EPSILON }, // value: -(1 / sqrt(2))
102 { -0.69314718055994531, 0.5, PAL_EPSILON }, // value: -(ln(2))
103 { -0.63661977236758134, 0.52907780826773535, PAL_EPSILON }, // value: -(2 / pi)
104 { -0.43429448190325183, 0.64772148514180065, PAL_EPSILON }, // value: -(log10(e))
105 { -0.31830988618379067, 0.72737734929521647, PAL_EPSILON }, // value: -(1 / pi)
106 { 0, 1, PAL_EPSILON * 10 },
107 { 0.31830988618379067, 1.3748022274393586, PAL_EPSILON * 10 }, // value: 1 / pi
108 { 0.43429448190325183, 1.5438734439711811, PAL_EPSILON * 10 }, // value: log10(e)
109 { 0.63661977236758134, 1.8900811645722220, PAL_EPSILON * 10 }, // value: 2 / pi
110 { 0.69314718055994531, 2, PAL_EPSILON * 10 }, // value: ln(2)
111 { 0.70710678118654752, 2.0281149816474725, PAL_EPSILON * 10 }, // value: 1 / sqrt(2)
112 { 0.78539816339744831, 2.1932800507380155, PAL_EPSILON * 10 }, // value: pi / 4
113 { 1, 2.7182818284590452, PAL_EPSILON * 10 }, // expected: e
114 { 1.1283791670955126, 3.0906430223107976, PAL_EPSILON * 10 }, // value: 2 / sqrt(pi)
115 { 1.4142135623730950, 4.1132503787829275, PAL_EPSILON * 10 }, // value: sqrt(2)
116 { 1.4426950408889634, 4.2320861065570819, PAL_EPSILON * 10 }, // value: log2(e)
117 { 1.5707963267948966, 4.8104773809653517, PAL_EPSILON * 10 }, // value: pi / 2
118 { 2.3025850929940457, 10, PAL_EPSILON * 100 }, // value: ln(10)
119 { 2.7182818284590452, 15.154262241479264, PAL_EPSILON * 100 }, // value: e
120 { 3.1415926535897932, 23.140692632779269, PAL_EPSILON * 100 }, // value: pi
121 { PAL_POSINF, PAL_POSINF, 0 },
122 };
123
124 if (PAL_Initialize(argc, argv) != 0)
125 {
126 return FAIL;
127 }
128
129 for (int i = 0; i < (sizeof(tests) / sizeof(struct test)); i++)
130 {
131 validate(tests[i].value, tests[i].expected, tests[i].variance);
132 }
133
134 validate_isnan(PAL_NAN);
135
136 PAL_Terminate();
137 return PASS;
138}
139