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 acos return the correct values
10**
11** Dependencies: PAL_Initialize
12** PAL_Terminate
13** Fail
14** fabs
15**
16**===========================================================================*/
17
18#include <palsuite.h>
19
20// binary64 (double) has a machine epsilon of 2^-52 (approx. 2.22e-16). However, this
21// is slightly too accurate when writing tests meant to run against libm implementations
22// for various platforms. 2^-50 (approx. 8.88e-16) seems to be as accurate as we can get.
23//
24// The tests themselves will take PAL_EPSILON and adjust it according to the expected result
25// so that the delta used for comparison will compare the most significant digits and ignore
26// any digits that are outside the double precision range (15-17 digits).
27
28// For example, a test with an expect result in the format of 0.xxxxxxxxxxxxxxxxx will use
29// PAL_EPSILON for the variance, while an expected result in the format of 0.0xxxxxxxxxxxxxxxxx
30// will use PAL_EPSILON / 10 and and expected result in the format of x.xxxxxxxxxxxxxxxx will
31// use PAL_EPSILON * 10.
32#define PAL_EPSILON 8.8817841970012523e-16
33
34#define PAL_NAN sqrt(-1.0)
35#define PAL_POSINF -log(0.0)
36#define PAL_NEGINF log(0.0)
37
38/**
39 * Helper test structure
40 */
41struct test
42{
43 double value; /* value to test the function with */
44 double expected; /* expected result */
45 double variance; /* maximum delta between the expected and actual result */
46};
47
48/**
49 * validate
50 *
51 * test validation function
52 */
53void __cdecl validate(double value, double expected, double variance)
54{
55 double result = acos(value);
56
57 /*
58 * The test is valid when the difference between result
59 * and expected is less than or equal to variance
60 */
61 double delta = fabs(result - expected);
62
63 if (delta > variance)
64 {
65 Fail("acos(%g) returned %20.17g when it should have returned %20.17g",
66 value, result, expected);
67 }
68}
69
70/**
71 * validate
72 *
73 * test validation function for values returning NaN
74 */
75void __cdecl validate_isnan(double value)
76{
77 double result = acos(value);
78
79 if (!_isnan(result))
80 {
81 Fail("acos(%g) returned %20.17g when it should have returned %20.17g",
82 value, result, PAL_NAN);
83 }
84}
85
86/**
87 * main
88 *
89 * executable entry point
90 */
91int __cdecl main(int argc, char **argv)
92{
93 struct test tests[] =
94 {
95 /* value expected variance */
96 { -1, 3.1415926535897932, PAL_EPSILON * 10 }, // expected: pi
97 { -0.91173391478696510, 2.7182818284590452, PAL_EPSILON * 10 }, // expected: e
98 { -0.66820151019031295, 2.3025850929940457, PAL_EPSILON * 10 }, // expected: ln(10)
99 { 0, 1.5707963267948966, PAL_EPSILON * 10 }, // expected: pi / 2
100 { 0.12775121753523991, 1.4426950408889634, PAL_EPSILON * 10 }, // expected: log2(e)
101 { 0.15594369476537447, 1.4142135623730950, PAL_EPSILON * 10 }, // expected: sqrt(2)
102 { 0.42812514788535792, 1.1283791670955126, PAL_EPSILON * 10 }, // expected: 2 / sqrt(pi)
103 { 0.54030230586813972, 1, PAL_EPSILON * 10 },
104 { 0.70710678118654752, 0.78539816339744831, PAL_EPSILON }, // expected: pi / 4, value: 1 / sqrt(2)
105 { 0.76024459707563015, 0.70710678118654752, PAL_EPSILON }, // expected: 1 / sqrt(2)
106 { 0.76923890136397213, 0.69314718055994531, PAL_EPSILON }, // expected: ln(2)
107 { 0.80410982822879171, 0.63661977236758134, PAL_EPSILON }, // expected: 2 / pi
108 { 0.90716712923909839, 0.43429448190325183, PAL_EPSILON }, // expected: log10(e)
109 { 0.94976571538163866, 0.31830988618379067, PAL_EPSILON }, // expected: 1 / pi
110 { 1, 0, PAL_EPSILON },
111 };
112
113 /* PAL initialization */
114 if (PAL_Initialize(argc, argv) != 0)
115 {
116 return FAIL;
117 }
118
119 for (int i = 0; i < (sizeof(tests) / sizeof(struct test)); i++)
120 {
121 validate(tests[i].value, tests[i].expected, tests[i].variance);
122 }
123
124 validate_isnan(PAL_NEGINF);
125 validate_isnan(PAL_NAN);
126 validate_isnan(PAL_POSINF);
127
128 PAL_Terminate();
129 return PASS;
130}
131