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serenity/Userland/Tests/LibM/test-math.cpp
Mițca Dumitru 987cc904c2 LibM: Make the gamma family of functions more accurate and conformant
This patch makes tgamma use an approximation that is more accurate with
regards to floating point arithmetic, and fixes some issues when tgamma
was called with positive integer values.

It also makes lgamma set signgam to the correct value, and makes its
return value be more inline with what the C standard defines.
2021-03-15 22:02:38 +01:00

250 lines
13 KiB
C++

/*
* Copyright (c) 2018-2021, Andreas Kling <kling@serenityos.org>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include <AK/TestSuite.h>
#include <float.h>
#include <math.h>
TEST_CASE(trig)
{
EXPECT_APPROXIMATE(sin(1234), 0.601927);
EXPECT_APPROXIMATE(cos(1234), -0.798550);
EXPECT_APPROXIMATE(tan(1234), -0.753775);
EXPECT_APPROXIMATE(sqrt(1234), 35.128336);
EXPECT_APPROXIMATE(sin(-1), -0.8414709848078965);
EXPECT_APPROXIMATE(cos(-1), 0.5403023058681398);
EXPECT_APPROXIMATE(tan(-1), -1.5574077246549023);
EXPECT(isnan(sqrt(-1)));
EXPECT(isnan(asin(1.1)));
EXPECT(isnan(asin(-1.1)));
EXPECT_APPROXIMATE(asin(0), 0.0);
EXPECT_APPROXIMATE(asin(0.01), 0.01);
EXPECT_APPROXIMATE(asin(0.1), 0.100167);
EXPECT_APPROXIMATE(asin(0.3), 0.304693);
EXPECT_APPROXIMATE(asin(0.499), 0.522444);
EXPECT_APPROXIMATE(asin(0.5), 0.523599);
EXPECT_APPROXIMATE(asin(0.501), 0.524754);
EXPECT_APPROXIMATE(asin(0.9), 1.119770);
EXPECT_APPROXIMATE(asin(0.99), 1.429245);
EXPECT_APPROXIMATE(asin(1.0), 1.570750);
EXPECT_APPROXIMATE(atan(0), 0.0);
EXPECT_APPROXIMATE(atan(0.5), 0.463648);
EXPECT_APPROXIMATE(atan(-0.5), -0.463648);
EXPECT_APPROXIMATE(atan(5.5), 1.390943);
EXPECT_APPROXIMATE(atan(-5.5), -1.390943);
EXPECT_APPROXIMATE(atan(555.5), 1.568996);
}
TEST_CASE(other)
{
EXPECT_EQ(trunc(9999999999999.5), 9999999999999.0);
EXPECT_EQ(trunc(-9999999999999.5), -9999999999999.0);
}
TEST_CASE(exponents)
{
struct values {
double x;
double exp;
double sinh;
double cosh;
double tanh;
};
values values[8] {
{ 1.500000, 4.481626, 2.129246, 2.352379, 0.905148 },
{ 20.990000, 1304956710.432035, 652478355.216017, 652478355.216017, 1.000000 },
{ 20.010000, 490041186.687082, 245020593.343541, 245020593.343541, 1.000000 },
{ 0.000000, 1.000000, 0.000000, 1.000000, 0.000000 },
{ 0.010000, 1.010050, 0.010000, 1.000050, 0.010000 },
{ -0.010000, 0.990050, -0.010000, 1.000050, -0.010000 },
{ -1.000000, 0.367879, -1.175201, 1.543081, -0.761594 },
{ -17.000000, 0.000000, -12077476.376788, 12077476.376788, -1.000000 },
};
for (auto& v : values) {
EXPECT_APPROXIMATE(exp(v.x), v.exp);
EXPECT_APPROXIMATE(sinh(v.x), v.sinh);
EXPECT_APPROXIMATE(cosh(v.x), v.cosh);
EXPECT_APPROXIMATE(tanh(v.x), v.tanh);
}
EXPECT_EQ(exp(1000), __builtin_huge_val());
}
TEST_CASE(logarithms)
{
EXPECT(isnan(log(-1)));
EXPECT(log(0) < -1000000);
EXPECT_APPROXIMATE(log(0.5), -0.693233);
EXPECT_APPROXIMATE(log(1.1), 0.095310);
EXPECT_APPROXIMATE(log(5), 1.609480);
EXPECT_APPROXIMATE(log(5.5), 1.704842);
EXPECT_APPROXIMATE(log(500), 6.214104);
EXPECT_APPROXIMATE(log2(5), 2.321989);
EXPECT_APPROXIMATE(log10(5), 0.698988);
}
union Extractor {
explicit Extractor(double d)
: d(d)
{
}
Extractor(unsigned sign, unsigned exponent, unsigned long long mantissa)
: mantissa(mantissa)
, exponent(exponent)
, sign(sign)
{
}
struct {
unsigned long long mantissa : 52;
unsigned exponent : 11;
unsigned sign : 1;
};
double d;
bool operator==(const Extractor& other) const
{
return other.sign == sign && other.exponent == exponent && other.mantissa == mantissa;
}
};
namespace AK {
template<>
struct Formatter<Extractor> : StandardFormatter {
void format(FormatBuilder& builder, const Extractor& value)
{
builder.put_literal("{");
builder.put_u64(value.sign);
builder.put_literal(", ");
builder.put_u64(value.exponent, 16, true);
builder.put_literal(", ");
builder.put_u64(value.mantissa, 16, true);
builder.put_literal("}");
}
};
}
static Extractor nextafter_translator(Extractor x, Extractor target)
{
return Extractor(nextafter(x.d, target.d));
}
TEST_CASE(nextafter)
{
EXPECT_EQ(nextafter_translator(Extractor(0x0, 0x7fe, 0xfffffffffffff), Extractor(0x0, 0x7fe, 0xfffffffffffff)), Extractor(0x0, 0x7fe, 0xfffffffffffff));
EXPECT_EQ(nextafter_translator(Extractor(0x0, 0x1, 0x0), Extractor(0x0, 0x412, 0xe848000000000)), Extractor(0x0, 0x1, 0x1));
EXPECT_EQ(nextafter_translator(Extractor(0x0, 0x3ff, 0x0), Extractor(0x0, 0x412, 0xe848200000000)), Extractor(0x0, 0x3ff, 0x1));
EXPECT_EQ(nextafter_translator(Extractor(0x1, 0x0, 0x0), Extractor(0x0, 0x412, 0xe848000000000)), Extractor(0x0, 0x0, 0x1));
EXPECT_EQ(nextafter_translator(Extractor(0x0, 0x0, 0x0), Extractor(0x0, 0x412, 0xe848000000000)), Extractor(0x0, 0x0, 0x1));
EXPECT_EQ(nextafter_translator(Extractor(0x1, 0x3ff, 0x0), Extractor(0x0, 0x412, 0xe847e00000000)), Extractor(0x1, 0x3fe, 0xfffffffffffff));
EXPECT_EQ(nextafter_translator(Extractor(0x0, 0x0, 0x1), Extractor(0x0, 0x412, 0xe848000000000)), Extractor(0x0, 0x0, 0x2));
EXPECT_EQ(nextafter_translator(Extractor(0x0, 0x7fe, 0xfffffffffffff), Extractor(0x0, 0x7fe, 0xfffffffffffff)), Extractor(0x0, 0x7fe, 0xfffffffffffff));
EXPECT_EQ(nextafter_translator(Extractor(0x0, 0x412, 0xe848000000000), Extractor(0x0, 0x1, 0x0)), Extractor(0x0, 0x412, 0xe847fffffffff));
EXPECT_EQ(nextafter_translator(Extractor(0x0, 0x412, 0xe848200000000), Extractor(0x0, 0x3ff, 0x0)), Extractor(0x0, 0x412, 0xe8481ffffffff));
EXPECT_EQ(nextafter_translator(Extractor(0x0, 0x412, 0xe848000000000), Extractor(0x1, 0x0, 0x0)), Extractor(0x0, 0x412, 0xe847fffffffff));
EXPECT_EQ(nextafter_translator(Extractor(0x0, 0x412, 0xe848000000000), Extractor(0x0, 0x0, 0x0)), Extractor(0x0, 0x412, 0xe847fffffffff));
EXPECT_EQ(nextafter_translator(Extractor(0x0, 0x412, 0xe847e00000000), Extractor(0x1, 0x3ff, 0x0)), Extractor(0x0, 0x412, 0xe847dffffffff));
EXPECT_EQ(nextafter_translator(Extractor(0x0, 0x412, 0xe848000000000), Extractor(0x0, 0x0, 0x1)), Extractor(0x0, 0x412, 0xe847fffffffff));
EXPECT_EQ(nextafter_translator(Extractor(0x0, 0x7fe, 0xfffffffffffff), Extractor(0x0, 0x7fe, 0xfffffffffffff)), Extractor(0x0, 0x7fe, 0xfffffffffffff));
EXPECT_EQ(nextafter_translator(Extractor(0x0, 0x1, 0x0), Extractor(0x0, 0x1, 0x0)), Extractor(0x0, 0x1, 0x0));
EXPECT_EQ(nextafter_translator(Extractor(0x0, 0x3ff, 0x0), Extractor(0x0, 0x3ff, 0x0)), Extractor(0x0, 0x3ff, 0x0));
EXPECT_EQ(nextafter_translator(Extractor(0x1, 0x0, 0x0), Extractor(0x1, 0x0, 0x0)), Extractor(0x1, 0x0, 0x0));
EXPECT_EQ(nextafter_translator(Extractor(0x0, 0x0, 0x0), Extractor(0x0, 0x0, 0x0)), Extractor(0x0, 0x0, 0x0));
EXPECT_EQ(nextafter_translator(Extractor(0x1, 0x3ff, 0x0), Extractor(0x1, 0x3ff, 0x0)), Extractor(0x1, 0x3ff, 0x0));
EXPECT_EQ(nextafter_translator(Extractor(0x0, 0x0, 0x1), Extractor(0x0, 0x0, 0x1)), Extractor(0x0, 0x0, 0x1));
EXPECT_EQ(nextafter_translator(Extractor(0x1, 0x7fe, 0xfffffffffffff), Extractor(0x0, 0x7fe, 0xfffffffffffff)), Extractor(0x1, 0x7fe, 0xffffffffffffe));
EXPECT_EQ(nextafter_translator(Extractor(0x1, 0x1, 0x0), Extractor(0x0, 0x1, 0x0)), Extractor(0x1, 0x0, 0xfffffffffffff));
EXPECT_EQ(nextafter_translator(Extractor(0x1, 0x3ff, 0x0), Extractor(0x0, 0x3ff, 0x0)), Extractor(0x1, 0x3fe, 0xfffffffffffff));
EXPECT_EQ(nextafter_translator(Extractor(0x0, 0x0, 0x0), Extractor(0x1, 0x0, 0x0)), Extractor(0x1, 0x0, 0x0));
EXPECT_EQ(nextafter_translator(Extractor(0x1, 0x0, 0x0), Extractor(0x0, 0x0, 0x0)), Extractor(0x0, 0x0, 0x0));
EXPECT_EQ(nextafter_translator(Extractor(0x0, 0x3ff, 0x0), Extractor(0x1, 0x3ff, 0x0)), Extractor(0x0, 0x3fe, 0xfffffffffffff));
EXPECT_EQ(nextafter_translator(Extractor(0x1, 0x0, 0x1), Extractor(0x0, 0x0, 0x1)), Extractor(0x1, 0x0, 0x0));
EXPECT_EQ(nextafter_translator(Extractor(0x0, 0x7fe, 0xfffffffffffff), Extractor(0x1, 0x7fe, 0xfffffffffffff)), Extractor(0x0, 0x7fe, 0xffffffffffffe));
EXPECT_EQ(nextafter_translator(Extractor(0x0, 0x1, 0x0), Extractor(0x1, 0x1, 0x0)), Extractor(0x0, 0x0, 0xfffffffffffff));
EXPECT_EQ(nextafter_translator(Extractor(0x0, 0x3ff, 0x0), Extractor(0x1, 0x3ff, 0x0)), Extractor(0x0, 0x3fe, 0xfffffffffffff));
EXPECT_EQ(nextafter_translator(Extractor(0x1, 0x0, 0x0), Extractor(0x0, 0x0, 0x0)), Extractor(0x0, 0x0, 0x0));
EXPECT_EQ(nextafter_translator(Extractor(0x0, 0x0, 0x0), Extractor(0x1, 0x0, 0x0)), Extractor(0x1, 0x0, 0x0));
EXPECT_EQ(nextafter_translator(Extractor(0x1, 0x3ff, 0x0), Extractor(0x0, 0x3ff, 0x0)), Extractor(0x1, 0x3fe, 0xfffffffffffff));
EXPECT_EQ(nextafter_translator(Extractor(0x0, 0x0, 0x1), Extractor(0x1, 0x0, 0x1)), Extractor(0x0, 0x0, 0x0));
EXPECT_EQ(nextafter_translator(Extractor(0x0, 0x7fe, 0xfffffffffffff), Extractor(0x0, 0x7fe, 0xfffffffffffff)), Extractor(0x0, 0x7fe, 0xfffffffffffff));
EXPECT_EQ(nextafter_translator(Extractor(0x0, 0x1, 0x0), Extractor(0x1, 0x419, 0x7d78400000000)), Extractor(0x0, 0x0, 0xfffffffffffff));
EXPECT_EQ(nextafter_translator(Extractor(0x0, 0x3ff, 0x0), Extractor(0x1, 0x419, 0x7d783fc000000)), Extractor(0x0, 0x3fe, 0xfffffffffffff));
EXPECT_EQ(nextafter_translator(Extractor(0x1, 0x0, 0x0), Extractor(0x1, 0x419, 0x7d78400000000)), Extractor(0x1, 0x0, 0x1));
EXPECT_EQ(nextafter_translator(Extractor(0x0, 0x0, 0x0), Extractor(0x1, 0x419, 0x7d78400000000)), Extractor(0x1, 0x0, 0x1));
EXPECT_EQ(nextafter_translator(Extractor(0x1, 0x3ff, 0x0), Extractor(0x1, 0x419, 0x7d78404000000)), Extractor(0x1, 0x3ff, 0x1));
EXPECT_EQ(nextafter_translator(Extractor(0x0, 0x0, 0x1), Extractor(0x1, 0x419, 0x7d78400000000)), Extractor(0x0, 0x0, 0x0));
EXPECT_EQ(nextafter_translator(Extractor(0x0, 0x7fe, 0xfffffffffffff), Extractor(0x0, 0x7fe, 0xfffffffffffff)), Extractor(0x0, 0x7fe, 0xfffffffffffff));
EXPECT_EQ(nextafter_translator(Extractor(0x1, 0x419, 0x7d78400000000), Extractor(0x0, 0x1, 0x0)), Extractor(0x1, 0x419, 0x7d783ffffffff));
EXPECT_EQ(nextafter_translator(Extractor(0x1, 0x419, 0x7d783fc000000), Extractor(0x0, 0x3ff, 0x0)), Extractor(0x1, 0x419, 0x7d783fbffffff));
EXPECT_EQ(nextafter_translator(Extractor(0x1, 0x419, 0x7d78400000000), Extractor(0x1, 0x0, 0x0)), Extractor(0x1, 0x419, 0x7d783ffffffff));
EXPECT_EQ(nextafter_translator(Extractor(0x1, 0x419, 0x7d78400000000), Extractor(0x0, 0x0, 0x0)), Extractor(0x1, 0x419, 0x7d783ffffffff));
EXPECT_EQ(nextafter_translator(Extractor(0x1, 0x419, 0x7d78404000000), Extractor(0x1, 0x3ff, 0x0)), Extractor(0x1, 0x419, 0x7d78403ffffff));
EXPECT_EQ(nextafter_translator(Extractor(0x1, 0x419, 0x7d78400000000), Extractor(0x0, 0x0, 0x1)), Extractor(0x1, 0x419, 0x7d783ffffffff));
}
TEST_CASE(scalbn)
{
EXPECT(isnan(scalbn(NAN, 3)));
EXPECT(!isfinite(scalbn(INFINITY, 5)));
EXPECT_EQ(scalbn(0, 3), 0);
EXPECT_EQ(scalbn(15.3, 0), 15.3);
EXPECT_EQ(scalbn(0x0.0000000000008p-1022, 16), 0x0.0000000000008p-1006);
static constexpr auto biggest_subnormal = DBL_MIN - DBL_TRUE_MIN;
auto smallest_normal = scalbn(biggest_subnormal, 1);
Extractor ex(smallest_normal);
EXPECT(ex.exponent != 0);
EXPECT_EQ(scalbn(2.0, 4), 32.0);
}
TEST_CASE(gamma)
{
EXPECT(isinf(tgamma(+0.0)) && !signbit(tgamma(+0.0)));
EXPECT(isinf(tgamma(-0.0)) && signbit(tgamma(-0.0)));
EXPECT(isinf(tgamma(INFINITY)) && !signbit(tgamma(INFINITY)));
EXPECT(isnan(tgamma(NAN)));
EXPECT(isnan(tgamma(-INFINITY)));
EXPECT(isnan(tgamma(-5)));
EXPECT_APPROXIMATE(tgamma(0.5), sqrt(M_PI));
EXPECT_EQ(tgammal(21.0l), 2'432'902'008'176'640'000.0l);
EXPECT_EQ(tgamma(19.0), 6'402'373'705'728'000.0);
EXPECT_EQ(tgammaf(11.0f), 3628800.0f);
EXPECT_EQ(tgamma(4.0), 6);
EXPECT_EQ(lgamma(1.0), 0.0);
EXPECT_EQ(lgamma(2.0), 0.0);
EXPECT(isinf(lgamma(0.0)));
EXPECT(!signbit(lgamma(-0.0)));
EXPECT(isnan(lgamma(NAN)));
EXPECT(isinf(lgamma(INFINITY)));
EXPECT(isinf(lgamma(-INFINITY)));
EXPECT_EQ(signgam, 1);
lgamma(-2.5);
EXPECT_EQ(signgam, -1);
}
TEST_MAIN(Math)