src/gromacs/random/tests/tabulatednormaldistribution.cpp

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  35 /*! \internal \file
  36  * \brief Tests for GROMACS tabulated normal distribution
  37  *
  38  * \author Erik Lindahl <erik.lindahl@gmail.com>
  39  * \ingroup module_random
  40  */
  41 #include "gmxpre.h"
  42
  43 #include "gromacs/random/tabulatednormaldistribution.h"
  44
  45 #include <gtest/gtest.h>
  46
  47 #include "gromacs/random/threefry.h"
  48
  49 #include "testutils/refdata.h"
  50 #include "testutils/testasserts.h"
  51
  52 namespace gmx
  53 {
  54
  55 namespace
  56 {
  57
  58 TEST(TabulatedNormalDistributionTest, Output14)
  59 {
  60     gmx::test::TestReferenceData         data;
  61     gmx::test::TestReferenceChecker      checker(data.rootChecker());
  62
  63     gmx::ThreeFry2x64<2>                 rng(123456, gmx::RandomDomain::Other);
  64     gmx::TabulatedNormalDistribution<>   dist(2.0, 5.0); // Use default 14-bit resolution
  65     std::vector<float>                   result;
  66
  67     for (int i = 0; i < 10; i++)
  68     {
  69         result.push_back(dist(rng));
  70     }
  71     checker.checkSequence(result.begin(), result.end(), "TabulatedNormalDistribution14");
  72 }
  73
  74 TEST(TabulatedNormalDistributionTest, Output16)
  75 {
  76     gmx::test::TestReferenceData                  data;
  77     gmx::test::TestReferenceChecker               checker(data.rootChecker());
  78
  79     gmx::ThreeFry2x64<2>                          rng(123456, gmx::RandomDomain::Other);
  80     gmx::TabulatedNormalDistribution<float, 16>   dist(2.0, 5.0); // Use larger 16-bit table
  81     std::vector<float>                            result;
  82
  83     for (int i = 0; i < 10; i++)
  84     {
  85         result.push_back(dist(rng));
  86     }
  87     checker.checkSequence(result.begin(), result.end(), "TabulatedNormalDistribution16");
  88 }
  89
  90 TEST(TabulatedNormalDistributionTest, OutputDouble14)
  91 {
  92     gmx::test::TestReferenceData                  data;
  93     gmx::test::TestReferenceChecker               checker(data.rootChecker());
  94
  95     gmx::ThreeFry2x64<2>                          rng(123456, gmx::RandomDomain::Other);
  96     gmx::TabulatedNormalDistribution<double>      dist(2.0, 5.0);
  97     std::vector<double>                           result;
  98
  99     for (int i = 0; i < 10; i++)
 100     {
 101         result.push_back(dist(rng));
 102     }
 103     checker.checkSequence(result.begin(), result.end(), "TabulatedNormalDistributionDouble14");
 104 }
 105
 106 TEST(TabulatedNormalDistributionTest, Logical)
 107 {
 108     gmx::ThreeFry2x64<2>                 rng(123456, gmx::RandomDomain::Other);
 109     gmx::TabulatedNormalDistribution<>   distA(2.0, 5.0);
 110     gmx::TabulatedNormalDistribution<>   distB(2.0, 5.0);
 111     gmx::TabulatedNormalDistribution<>   distC(3.0, 5.0);
 112     gmx::TabulatedNormalDistribution<>   distD(2.0, 4.0);
 113
 114     EXPECT_EQ(distA, distB);
 115     EXPECT_NE(distA, distC);
 116     EXPECT_NE(distA, distD);
 117 }
 118
 119
 120 TEST(TabulatedNormalDistributionTest, Reset)
 121 {
 122     gmx::ThreeFry2x64<2>                                      rng(123456, gmx::RandomDomain::Other);
 123     gmx::TabulatedNormalDistribution<>                        distA(2.0, 5.0);
 124     gmx::TabulatedNormalDistribution<>                        distB(2.0, 5.0);
 125     gmx::TabulatedNormalDistribution<>::result_type           valA, valB;
 126
 127     valA = distA(rng);
 128
 129     distB(rng);
 130     rng.restart();
 131     distB.reset();
 132
 133     valB = distB(rng);
 134
 135     EXPECT_REAL_EQ_TOL(valA, valB, gmx::test::ulpTolerance(0));
 136 }
 137
 138 TEST(TabulatedNormalDistributionTest, AltParam)
 139 {
 140     gmx::ThreeFry2x64<2>                            rngA(123456, gmx::RandomDomain::Other);
 141     gmx::ThreeFry2x64<2>                            rngB(123456, gmx::RandomDomain::Other);
 142     gmx::TabulatedNormalDistribution<>              distA(2.0, 5.0);
 143     gmx::TabulatedNormalDistribution<>              distB;
 144     gmx::TabulatedNormalDistribution<>::param_type  paramA(2.0, 5.0);
 145
 146     EXPECT_NE(distA(rngA), distB(rngB));
 147     rngA.restart();
 148     rngB.restart();
 149     distA.reset();
 150     distB.reset();
 151     EXPECT_REAL_EQ_TOL(distA(rngA), distB(rngB, paramA), gmx::test::ulpTolerance(0));
 152 }
 153
 154 TEST(TabulatedNormalDistributionTableTest, HasValidProperties)
 155 {
 156     std::vector<real> table = TabulatedNormalDistribution<real>::makeTable();
 157
 158     EXPECT_EQ(table.size() % 2, 0) << "Table must have even number of entries";
 159
 160     size_t halfSize     = table.size() / 2;
 161     double sumOfSquares = 0.0;
 162     // accept errors of a few ULP since the exact value of the summation
 163     // below will depend on whether the compiler issues FMA instructions
 164     auto   tolerance    = gmx::test::ulpTolerance(10);
 165     for (size_t i = 0, iFromEnd = table.size()-1; i < halfSize; ++i, --iFromEnd)
 166     {
 167         EXPECT_REAL_EQ_TOL(table.at(i), -table.at(iFromEnd), tolerance)
 168         << "Table is not an odd-valued function for entries " << i << " and " << iFromEnd;
 169         // Add up the squares of the table values in order of ascending
 170         // magnitude (to minimize accumulation of round-off error).
 171         sumOfSquares += table.at(i) * table.at(i) + table.at(iFromEnd) * table.at(iFromEnd);
 172     }
 173
 174     double variance = sumOfSquares / table.size();
 175     EXPECT_REAL_EQ_TOL(1.0, variance, tolerance) << "Table should have unit variance";
 176 }
 177
 178 }      // namespace anonymous
 179
 180 }      // namespace gmx