Fix precision loss in tabulated normal distribution

[gromacs.git] / src / gromacs / math / tests / functions.cpp

/*
 * This file is part of the GROMACS molecular simulation package.
 *
 * Copyright (c) 2015,2016, by the GROMACS development team, led by
 * Mark Abraham, David van der Spoel, Berk Hess, and Erik Lindahl,
 * and including many others, as listed in the AUTHORS file in the
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/*! \internal \file
 * \brief
 * Tests for simple math functions.
 *
 * \author Erik Lindahl <erik.lindahl@gmail.com>
 * \ingroup module_math
 */
#include "gmxpre.h"

#include "gromacs/math/functions.h"

#include <cmath>
#include <cstdint>

#include <gtest/gtest.h>

#include "testutils/refdata.h"
#include "testutils/testasserts.h"

namespace
{

TEST(FunctionTest, StaticLog2)
{
    gmx::test::TestReferenceData     data;
    gmx::test::TestReferenceChecker  checker(data.rootChecker());
    std::vector<int>                 result(11);

    // This needs to be expanded manually since it is evaluated at compile time,
    // and the compiler chokes if we put it as formal arguments to push_back
    result[0]  = gmx::StaticLog2<1>::value;
    result[1]  = gmx::StaticLog2<2>::value;
    result[2]  = gmx::StaticLog2<3>::value;
    result[3]  = gmx::StaticLog2<4>::value;
    result[4]  = gmx::StaticLog2<5>::value;
    result[5]  = gmx::StaticLog2<6>::value;
    result[6]  = gmx::StaticLog2<7>::value;
    result[7]  = gmx::StaticLog2<8>::value;
    result[8]  = gmx::StaticLog2<0xFFFFFFFF>::value;
    result[9]  = gmx::StaticLog2<9876543210>::value; // > 32 bits
    result[10] = gmx::StaticLog2<0xFFFFFFFFFFFFFFFFULL>::value;

    checker.checkSequence(result.begin(), result.end(), "StaticLog2");
}

TEST(FunctionTest, Log2I32Bit)
{
    gmx::test::TestReferenceData     data;
    gmx::test::TestReferenceChecker  checker(data.rootChecker());
    std::vector<int>                 result;

    for (std::uint32_t i = 1; i <= 0xF; i++)
    {
        result.push_back(gmx::log2I(i));
    }

    for (std::uint32_t i = 0; i <= 0xF; i++)
    {
        result.push_back(gmx::log2I(static_cast<std::uint32_t>(0xFFFFFFF0+i)));
    }
    checker.checkSequence(result.begin(), result.end(), "Log2I32Bit");
}

TEST(FunctionTest, Log2I64Bit)
{
    gmx::test::TestReferenceData     data;
    gmx::test::TestReferenceChecker  checker(data.rootChecker());
    std::vector<int>                 result;

    for (std::uint64_t i = 1; i <= 0xF; i++)
    {
        result.push_back(gmx::log2I(i));
    }

    for (std::uint64_t i = 0; i <= 0x1F; i++)
    {
        result.push_back(gmx::log2I(static_cast<std::uint64_t>(0xFFFFFFF0ULL+i)));
    }

    for (std::uint64_t i = 0; i <= 0xF; i++)
    {
        result.push_back(gmx::log2I(static_cast<std::uint64_t>(0xFFFFFFFFFFFFFFF0ULL+i)));
    }
    checker.checkSequence(result.begin(), result.end(), "Log2I64Bit");
}

TEST(FunctionTest, GreatestCommonDivisor)
{
    EXPECT_EQ(8, gmx::greatestCommonDivisor(24, 64));
    EXPECT_EQ(8, gmx::greatestCommonDivisor(64, 24));
    EXPECT_EQ(1, gmx::greatestCommonDivisor(169, 289));
}

TEST(FunctionTest, InvsqrtFloat)
{
    gmx::test::TestReferenceData     data;
    gmx::test::TestReferenceChecker  checker(data.rootChecker());
    std::vector<float>               result;

    for (float f = 1.0; f < 10.0; f += 1.0)
    {
        result.push_back(gmx::invsqrt(f));
    }
    checker.checkSequence(result.begin(), result.end(), "InvsqrtFloat");
}

TEST(FunctionTest, InvsqrtDouble)
{
    gmx::test::TestReferenceData     data;
    gmx::test::TestReferenceChecker  checker(data.rootChecker());
    std::vector<double>              result;

    for (double f = 1.0; f < 10.0; f += 1.0)
    {
        result.push_back(gmx::invsqrt(f));
    }
    checker.checkSequence(result.begin(), result.end(), "InvsqrtDouble");
}

TEST(FunctionTest, InvsqrtInteger)
{
    gmx::test::TestReferenceData     data;
    gmx::test::TestReferenceChecker  checker(data.rootChecker());
    std::vector<double>              result;

    for (int i = 1; i < 10; i++)
    {
        result.push_back(gmx::invsqrt(i));
    }
    checker.checkSequence(result.begin(), result.end(), "InvsqrtInteger");
}

TEST(FunctionTest, InvcbrtFloat)
{
    gmx::test::TestReferenceData     data;
    gmx::test::TestReferenceChecker  checker(data.rootChecker());
    std::vector<float>               result;

    for (float f : {-5, -4, -3, -2, -1, 1, 2, 3, 4})
    {
        result.push_back(gmx::invcbrt(f));
    }
    checker.checkSequence(result.begin(), result.end(), "InvcbrtFloat");
}

TEST(FunctionTest, InvcbrtDouble)
{
    gmx::test::TestReferenceData     data;
    gmx::test::TestReferenceChecker  checker(data.rootChecker());
    std::vector<double>              result;

    for (double d : {-5, -4, -3, -2, -1, 1, 2, 3, 4})
    {
        result.push_back(gmx::invcbrt(d));
    }
    checker.checkSequence(result.begin(), result.end(), "InvcbrtDouble");
}

TEST(FunctionTest, InvcbrtInteger)
{
    gmx::test::TestReferenceData     data;
    gmx::test::TestReferenceChecker  checker(data.rootChecker());
    std::vector<double>              result;

    for (int i : {-5, -4, -3, -2, -1, 1, 2, 3, 4})
    {
        result.push_back(gmx::invcbrt(i));
    }
    checker.checkSequence(result.begin(), result.end(), "InvcbrtInteger");
}


TEST(FunctionTest, SixthrootFloat)
{
    gmx::test::TestReferenceData     data;
    gmx::test::TestReferenceChecker  checker(data.rootChecker());
    std::vector<float>               result;

    for (float f = 0; f < 10.0; f += 1.0)
    {
        result.push_back(gmx::sixthroot(f));
    }
    checker.checkSequence(result.begin(), result.end(), "SixthrootFloat");
}

TEST(FunctionTest, SixthrootDouble)
{
    gmx::test::TestReferenceData     data;
    gmx::test::TestReferenceChecker  checker(data.rootChecker());
    std::vector<double>              result;

    for (double d = 0; d < 10.0; d += 1.0)
    {
        result.push_back(gmx::sixthroot(d));
    }
    checker.checkSequence(result.begin(), result.end(), "SixthrootDouble");
}

TEST(FunctionTest, SixthrootInteger)
{
    gmx::test::TestReferenceData     data;
    gmx::test::TestReferenceChecker  checker(data.rootChecker());
    std::vector<double>              result;

    for (int i = 0; i < 10; i++)
    {
        result.push_back(gmx::sixthroot(i));
    }
    checker.checkSequence(result.begin(), result.end(), "SixthrootInteger");
}

TEST(FunctionTest, InvsixthrootFloat)
{
    gmx::test::TestReferenceData     data;
    gmx::test::TestReferenceChecker  checker(data.rootChecker());
    std::vector<float>               result;

    for (float f = 1.0; f < 10.0; f += 1.0)
    {
        result.push_back(gmx::sixthroot(f));
    }
    checker.checkSequence(result.begin(), result.end(), "InvsixthrootFloat");
}

TEST(FunctionTest, InvsixthrootDouble)
{
    gmx::test::TestReferenceData     data;
    gmx::test::TestReferenceChecker  checker(data.rootChecker());
    std::vector<double>              result;

    for (double d = 1.0; d < 10.0; d += 1.0)
    {
        result.push_back(gmx::sixthroot(d));
    }
    checker.checkSequence(result.begin(), result.end(), "InvsixthrootDouble");
}

TEST(FunctionTest, InvsixthrootInteger)
{
    gmx::test::TestReferenceData     data;
    gmx::test::TestReferenceChecker  checker(data.rootChecker());
    std::vector<double>              result;

    for (int i = 1; i < 10; i++)
    {
        result.push_back(gmx::sixthroot(i));
    }
    checker.checkSequence(result.begin(), result.end(), "InvsixthrootInteger");
}

TEST(FunctionTest, Powers)
{
    // These should be remarkably difficult to screw up, but test each
    // of them once anyway with integer and fp arguments to catch typos.
    EXPECT_EQ(4,   gmx::square(2));
    EXPECT_EQ(8,   gmx::power3(2));
    EXPECT_EQ(16,  gmx::power4(2));
    EXPECT_EQ(32,  gmx::power5(2));
    EXPECT_EQ(64,  gmx::power6(2));
    EXPECT_EQ(4096, gmx::power12(2));

    EXPECT_EQ(6.25,               gmx::square(2.5));
    EXPECT_EQ(15.625,             gmx::power3(2.5));
    EXPECT_EQ(39.0625,            gmx::power4(2.5));
    EXPECT_EQ(97.65625,           gmx::power5(2.5));
    EXPECT_EQ(244.140625,         gmx::power6(2.5));
    EXPECT_EQ(59604.644775390625, gmx::power12(2.5));
}

TEST(FunctionTest, ErfInvFloat)
{
    gmx::test::TestReferenceData     data;
    gmx::test::TestReferenceChecker  checker(data.rootChecker());
    std::vector<float>               result;
    int                              npoints = 10;

    for (int i = 0; i < npoints; i++)
    {
        float r = -1.0 + 2.0 * (float(i) + 0.5) / npoints;

        result.push_back(gmx::erfinv(r));
    }
    checker.checkSequence(result.begin(), result.end(), "ErfInvFloat");
}

TEST(FunctionTest, ErfInvDouble)
{
    gmx::test::TestReferenceData     data;
    gmx::test::TestReferenceChecker  checker(data.rootChecker());
    std::vector<double>              result;
    int                              npoints = 10;

    for (int i = 0; i < npoints; i++)
    {
        double r = -1.0 + 2.0 * (double(i) + 0.5) / npoints;

        result.push_back(gmx::erfinv(r));
    }
    checker.checkSequence(result.begin(), result.end(), "ErfInvDouble");
}

TEST(FunctionTest, ErfAndErfInvAreInversesFloat)
{
    int npoints = 1000;

    for (int i = 0; i < npoints; i++)
    {
        float r = -1.0 + 2.0 * (float(i) + 0.5) / npoints;
        EXPECT_FLOAT_EQ_TOL(r, std::erf(gmx::erfinv(r)), gmx::test::ulpTolerance(10));
    }
}

TEST(FunctionTest, ErfAndErfInvAreInversesDouble)
{
    int npoints = 1000;

    for (int i = 0; i < npoints; i++)
    {
        double r = -1.0 + 2.0 * (double(i) + 0.5) / npoints;
        EXPECT_DOUBLE_EQ_TOL(r, std::erf(gmx::erfinv(r)), gmx::test::ulpTolerance(10));
    }
}

} // namespace