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 (modf)
8**
9** Purpose: Test to ensure that modf 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 double expected_intpart; /* expected result */
47 double variance_intpart; /* maximum delta between the expected and actual result */
48};
49
50/**
51 * validate
52 *
53 * test validation function
54 */
55void __cdecl validate(double value, double expected, double variance, double expected_intpart, double variance_intpart)
56{
57 double result_intpart;
58 double result = modf(value, &result_intpart);
59
60 /*
61 * The test is valid when the difference between result
62 * and expected is less than or equal to variance
63 */
64 double delta = fabs(result - expected);
65 double delta_intpart = fabs(result_intpart - expected_intpart);
66
67 if ((delta > variance) || (delta_intpart > variance_intpart))
68 {
69 Fail("modf(%g) returned %20.17g with an intpart of %20.17g when it should have returned %20.17g with an intpart of %20.17g",
70 value, result, result_intpart, expected, expected_intpart);
71 }
72}
73
74/**
75 * validate
76 *
77 * test validation function for values returning NaN
78 */
79void __cdecl validate_isnan(double value)
80{
81 double result_intpart;
82 double result = modf(value, &result_intpart);
83
84 if (!_isnan(result) || !_isnan(result_intpart))
85 {
86 Fail("modf(%g) returned %20.17g with an intpart of %20.17g when it should have returned %20.17g with an intpart of %20.17g",
87 value, result, result_intpart, PAL_NAN, PAL_NAN);
88 }
89}
90
91/**
92 * main
93 *
94 * executable entry point
95 */
96int __cdecl main(int argc, char **argv)
97{
98 struct test tests[] =
99 {
100 /* value expected variance expected_intpart variance_intpart */
101 { 0, 0, PAL_EPSILON, 0, PAL_EPSILON },
102 { 0.31830988618379067, 0.31830988618379067, PAL_EPSILON, 0, PAL_EPSILON }, // value: 1 / pi
103 { 0.43429448190325183, 0.43429448190325183, PAL_EPSILON, 0, PAL_EPSILON }, // value: log10(e)
104 { 0.63661977236758134, 0.63661977236758134, PAL_EPSILON, 0, PAL_EPSILON }, // value: 2 / pi
105 { 0.69314718055994531, 0.69314718055994531, PAL_EPSILON, 0, PAL_EPSILON }, // value: ln(2)
106 { 0.70710678118654752, 0.70710678118654752, PAL_EPSILON, 0, PAL_EPSILON }, // value: 1 / sqrt(2)
107 { 0.78539816339744831, 0.78539816339744831, PAL_EPSILON, 0, PAL_EPSILON }, // value: pi / 4
108 { 1, 0, PAL_EPSILON, 1, PAL_EPSILON * 10 },
109 { 1.1283791670955126, 0.1283791670955126, PAL_EPSILON, 1, PAL_EPSILON * 10 }, // value: 2 / sqrt(pi)
110 { 1.4142135623730950, 0.4142135623730950, PAL_EPSILON, 1, PAL_EPSILON * 10 }, // value: sqrt(2)
111 { 1.4426950408889634, 0.4426950408889634, PAL_EPSILON, 1, PAL_EPSILON * 10 }, // value: log2(e)
112 { 1.5707963267948966, 0.5707963267948966, PAL_EPSILON, 1, PAL_EPSILON * 10 }, // value: pi / 2
113 { 2.3025850929940457, 0.3025850929940457, PAL_EPSILON, 2, PAL_EPSILON * 10 }, // value: ln(10)
114 { 2.7182818284590452, 0.7182818284590452, PAL_EPSILON, 2, PAL_EPSILON * 10 }, // value: e
115 { 3.1415926535897932, 0.1415926535897932, PAL_EPSILON, 3, PAL_EPSILON * 10 }, // value: pi
116 { PAL_POSINF, 0, PAL_EPSILON, PAL_POSINF, 0 }
117
118 };
119
120 /* PAL initialization */
121 if (PAL_Initialize(argc, argv) != 0)
122 {
123 return FAIL;
124 }
125
126 for (int i = 0; i < (sizeof(tests) / sizeof(struct test)); i++)
127 {
128 validate( tests[i].value, tests[i].expected, tests[i].variance, tests[i].expected_intpart, tests[i].variance_intpart);
129 validate(-tests[i].value, -tests[i].expected, tests[i].variance, -tests[i].expected_intpart, tests[i].variance_intpart);
130 }
131
132 validate_isnan(PAL_NAN);
133
134 PAL_Terminate();
135 return PASS;
136}
137