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// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.
/*=============================================================================
**
** Source: test1.c
**
** Purpose: Test to ensure that atan return the correct values
**
** Dependencies: PAL_Initialize
** PAL_Terminate
** Fail
** fabs
**
**===========================================================================*/
#include <palsuite.h>
// binary64 (double) has a machine epsilon of 2^-52 (approx. 2.22e-16). However, this
// is slightly too accurate when writing tests meant to run against libm implementations
// for various platforms. 2^-50 (approx. 8.88e-16) seems to be as accurate as we can get.
//
// The tests themselves will take PAL_EPSILON and adjust it according to the expected result
// so that the delta used for comparison will compare the most significant digits and ignore
// any digits that are outside the double precision range (15-17 digits).
// For example, a test with an expect result in the format of 0.xxxxxxxxxxxxxxxxx will use
// PAL_EPSILON for the variance, while an expected result in the format of 0.0xxxxxxxxxxxxxxxxx
// will use PAL_EPSILON / 10 and and expected result in the format of x.xxxxxxxxxxxxxxxx will
// use PAL_EPSILON * 10.
#define PAL_EPSILON 8.8817841970012523e-16
#define PAL_NAN sqrt(-1.0)
#define PAL_POSINF -log(0.0)
#define PAL_NEGINF log(0.0)
/**
* Helper test structure
*/
struct test
{
double value; /* value to test the function with */
double expected; /* expected result */
double variance; /* maximum delta between the expected and actual result */
};
/**
* validate
*
* test validation function
*/
void __cdecl validate(double value, double expected, double variance)
{
double result = atan(value);
/*
* The test is valid when the difference between result
* and expected is less than or equal to variance
*/
double delta = fabs(result - expected);
if (delta > variance)
{
Fail("atan(%g) returned %20.17g when it should have returned %20.17g",
value, result, expected);
}
}
/**
* validate
*
* test validation function for values returning NaN
*/
void __cdecl validate_isnan(double value)
{
double result = atan(value);
if (!_isnan(result))
{
Fail("atan(%g) returned %20.17g when it should have returned %20.17g",
value, result, PAL_NAN);
}
}
/**
* main
*
* executable entry point
*/
int __cdecl main(int argc, char **argv)
{
struct test tests[] =
{
/* value expected variance */
{ 0, 0, PAL_EPSILON },
{ 0.32951473309607836, 0.31830988618379067, PAL_EPSILON }, // expected: 1 / pi
{ 0.45054953406980750, 0.42331082513074800, PAL_EPSILON }, // expected: pi - e
{ 0.46382906716062964, 0.43429448190325183, PAL_EPSILON }, // expected: log10(e)
{ 0.73930295048660405, 0.63661977236758134, PAL_EPSILON }, // expected: 2 / pi
{ 0.83064087786078395, 0.69314718055994531, PAL_EPSILON }, // expected: ln(2)
{ 0.85451043200960189, 0.70710678118654752, PAL_EPSILON }, // expected: 1 / sqrt(2)
{ 1, 0.78539816339744831, PAL_EPSILON }, // expected: pi / 4
{ 1.1134071468135374, 0.83900756059574755, PAL_EPSILON }, // expected: pi - ln(10)
{ 1.5574077246549022, 1, PAL_EPSILON * 10 },
{ 2.1108768356626451, 1.1283791670955126, PAL_EPSILON * 10 }, // expected: 2 / sqrt(pi)
{ 6.3341191670421916, 1.4142135623730950, PAL_EPSILON * 10 }, // expected: sqrt(2)
{ 7.7635756709721848, 1.4426950408889634, PAL_EPSILON * 10 }, // expected: log2(e)
{ PAL_POSINF, 1.5707963267948966, PAL_EPSILON * 10 }, // expected: pi / 2
};
/* PAL initialization */
if (PAL_Initialize(argc, argv) != 0)
{
return FAIL;
}
for (int i = 0; i < (sizeof(tests) / sizeof(struct test)); i++)
{
validate( tests[i].value, tests[i].expected, tests[i].variance);
validate(-tests[i].value, -tests[i].expected, tests[i].variance);
}
validate_isnan(PAL_NAN);
PAL_Terminate();
return PASS;
}
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