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: Test to ensure that log10 returns correct values.
10**
11** Dependencies: PAL_Initialize
12** PAL_Terminate
13** Fail
14** fabs
15** _isnan
16**
17**===========================================================================*/
18
19#include <palsuite.h>
20
21// binary64 (double) has a machine epsilon of 2^-52 (approx. 2.22e-16). However, this
22// is slightly too accurate when writing tests meant to run against libm implementations
23// for various platforms. 2^-50 (approx. 8.88e-16) seems to be as accurate as we can get.
24//
25// The tests themselves will take PAL_EPSILON and adjust it according to the expected result
26// so that the delta used for comparison will compare the most significant digits and ignore
27// any digits that are outside the double precision range (15-17 digits).
28
29// For example, a test with an expect result in the format of 0.xxxxxxxxxxxxxxxxx will use
30// PAL_EPSILON for the variance, while an expected result in the format of 0.0xxxxxxxxxxxxxxxxx
31// will use PAL_EPSILON / 10 and and expected result in the format of x.xxxxxxxxxxxxxxxx will
32// use PAL_EPSILON * 10.
33#define PAL_EPSILON 8.8817841970012523e-16
34
35#define PAL_NAN sqrt(-1.0)
36#define PAL_POSINF -log(0.0)
37#define PAL_NEGINF log(0.0)
38
39/**
40 * Helper test structure
41 */
42struct test
43{
44 double value; /* value to test the function with */
45 double expected; /* expected result */
46 double variance; /* maximum delta between the expected and actual result */
47};
48
49/**
50 * validate
51 *
52 * test validation function
53 */
54void __cdecl validate(double value, double expected, double variance)
55{
56 double result = log10(value);
57
58 /*
59 * The test is valid when the difference between result
60 * and expected is less than or equal to variance
61 */
62 double delta = fabs(result - expected);
63
64 if (delta > variance)
65 {
66 Fail("log10(%g) returned %20.17g when it should have returned %20.17g",
67 value, result, expected);
68 }
69}
70
71/**
72 * validate
73 *
74 * test validation function for values returning NaN
75 */
76void __cdecl validate_isnan(double value)
77{
78 double result = log10(value);
79
80 if (!_isnan(result))
81 {
82 Fail("log10(%g) returned %20.17g when it should have returned %20.17g",
83 value, result, PAL_NAN);
84 }
85}
86
87/**
88 * main
89 *
90 * executable entry point
91 */
92int __cdecl main(int argc, char **argv)
93{
94 struct test tests[] =
95 {
96 /* value expected variance */
97 { 0, PAL_NEGINF, 0 },
98 { 0.00072178415907472774, -3.1415926535897932, PAL_EPSILON * 10 }, // expected: -(pi)
99 { 0.0019130141022243176, -2.7182818284590452, PAL_EPSILON * 10 }, // expected: -(e)
100 { 0.0049821282964407206, -2.3025850929940457, PAL_EPSILON * 10 }, // expected: -(ln(10))
101 { 0.026866041001136132, -1.5707963267948966, PAL_EPSILON * 10 }, // expected: -(pi / 2)
102 { 0.036083192820787210, -1.4426950408889634, PAL_EPSILON * 10 }, // expected: -(log2(e))
103 { 0.038528884700322026, -1.4142135623730950, PAL_EPSILON * 10 }, // expected: -(sqrt(2))
104 { 0.074408205860642723, -1.1283791670955126, PAL_EPSILON * 10 }, // expected: -(2 / sqrt(pi))
105 { 0.1, -1, PAL_EPSILON * 10 }, // expected: -(1)
106 { 0.16390863613957665, -0.78539816339744831, PAL_EPSILON }, // expected: -(pi / 4)
107 { 0.19628775993505562, -0.70710678118654752, PAL_EPSILON }, // expected: -(1 / sqrt(2))
108 { 0.20269956628651730, -0.69314718055994531, PAL_EPSILON }, // expected: -(ln(2))
109 { 0.23087676451600055, -0.63661977236758134, PAL_EPSILON }, // expected: -(2 / pi)
110 { 0.36787944117144232, -0.43429448190325183, PAL_EPSILON }, // expected: -(log10(e))
111 { 0.48049637305186868, -0.31830988618379067, PAL_EPSILON }, // expected: -(1 / pi)
112 { 1, 0, PAL_EPSILON },
113 { 2.0811811619898573, 0.31830988618379067, PAL_EPSILON }, // expected: 1 / pi
114 { 2.7182818284590452, 0.43429448190325183, PAL_EPSILON }, // expected: log10(e) value: e
115 { 4.3313150290214525, 0.63661977236758134, PAL_EPSILON }, // expected: 2 / pi
116 { 4.9334096679145963, 0.69314718055994531, PAL_EPSILON }, // expected: ln(2)
117 { 5.0945611704512962, 0.70710678118654752, PAL_EPSILON }, // expected: 1 / sqrt(2)
118 { 6.1009598002416937, 0.78539816339744831, PAL_EPSILON }, // expected: pi / 4
119 { 10, 1, PAL_EPSILON * 10 },
120 { 13.439377934644400, 1.1283791670955126, PAL_EPSILON * 10 }, // expected: 2 / sqrt(pi)
121 { 25.954553519470081, 1.4142135623730950, PAL_EPSILON * 10 }, // expected: sqrt(2)
122 { 27.713733786437790, 1.4426950408889634, PAL_EPSILON * 10 }, // expected: log2(e)
123 { 37.221710484165167, 1.5707963267948966, PAL_EPSILON * 10 }, // expected: pi / 2
124 { 200.71743249053009, 2.3025850929940457, PAL_EPSILON * 10 }, // expected: ln(10)
125 { 522.73529967043665, 2.7182818284590452, PAL_EPSILON * 10 }, // expected: e
126 { 1385.4557313670111, 3.1415926535897932, PAL_EPSILON * 10 }, // expected: pi
127 { PAL_POSINF, PAL_POSINF, 0 },
128 };
129
130
131 if (PAL_Initialize(argc, argv) != 0)
132 {
133 return FAIL;
134 }
135
136 for (int i = 0; i < (sizeof(tests) / sizeof(struct test)); i++)
137 {
138 validate(tests[i].value, tests[i].expected, tests[i].variance);
139 }
140
141 validate_isnan(PAL_NEGINF);
142 validate_isnan(PAL_NAN);
143
144 PAL_Terminate();
145 return PASS;
146}
147