src/testutils/testasserts.cpp

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  35 /*! \internal \file
  36  * \brief
  37  * Implements floating-point comparison routines from testasserts.h.
  38  *
  39  * \author Teemu Murtola <teemu.murtola@gmail.com>
  40  * \ingroup module_testutils
  41  */
  42 #include "gmxpre.h"
  43
  44 #include "testasserts.h"
  45
  46 #include <cmath>
  47
  48 #include <limits>
  49
  50 #include <gtest/gtest.h>
  51
  52 #include "gromacs/utility/basedefinitions.h"
  53 #include "gromacs/utility/stringutil.h"
  54
  55 namespace gmx
  56 {
  57
  58 namespace test
  59 {
  60
  61 namespace
  62 {
  63
  64 using ::testing::internal::FloatingPoint;
  65
  66 //! \internal \addtogroup module_testutils
  67 //! \{
  68
  69 /*! \name Helper functions for computing floating-point differences
  70  *
  71  * These routines are used to initialize FloatingPointDifference.
  72  * They peek into some internal types from Google Test (gtest-internal.h),
  73  * and duplicate some other functionality from there, but that is likely
  74  * a better alternative than just copying all that code here.
  75  */
  76 //! \{
  77
  78 /*! \brief
  79  * Computes biased integer representation for a floating-point value.
  80  *
  81  * This moves the integer representation from a sign-and-magnitude
  82  * representation to a biased representation where the 0x8000... represents
  83  * zero, and the order of the integer values matches the order of the
  84  * floating-point values.
  85  */
  86 template <typename FloatType>
  87 typename FloatingPoint<FloatType>::Bits
  88 floatingPointToBiasedInteger(const FloatingPoint<FloatType> &value)
  89 {
  90     if (value.sign_bit())
  91     {
  92         return ~value.bits() + 1;
  93     }
  94     else
  95     {
  96         return value.bits() | FloatingPoint<FloatType>::kSignBitMask;
  97     }
  98 }
  99
 100 /*! \brief
 101  * Computes the magnitude of the difference in ULPs between two numbers,
 102  * treating also values of different sign.
 103  */
 104 template <typename FloatType>
 105 gmx_uint64_t calculateUlpDifference(const FloatingPoint<FloatType> &value1,
 106                                     const FloatingPoint<FloatType> &value2)
 107 {
 108     typename FloatingPoint<FloatType>::Bits biased1
 109         = floatingPointToBiasedInteger(value1);
 110     typename FloatingPoint<FloatType>::Bits biased2
 111         = floatingPointToBiasedInteger(value2);
 112     return biased1 > biased2 ? biased1 - biased2 : biased2 - biased1;
 113 }
 114
 115 /*! \brief
 116  * Helper to implement the constructors for FloatingPointDifference.
 117  */
 118 template <typename FloatType>
 119 void initDifference(FloatType raw1, FloatType raw2, double *absoluteDifference,
 120                     gmx_uint64_t *ulpDifference, bool *bSignDifference)
 121 {
 122     FloatingPoint<FloatType> value1(raw1);
 123     FloatingPoint<FloatType> value2(raw2);
 124
 125     if (value1.is_nan() || value2.is_nan())
 126     {
 127         *absoluteDifference = std::numeric_limits<double>::quiet_NaN();
 128         *bSignDifference    = false;
 129         *ulpDifference      = 0;
 130         return;
 131     }
 132     *absoluteDifference = std::fabs(raw1 - raw2);
 133     *bSignDifference    = (value1.sign_bit() != value2.sign_bit());
 134     *ulpDifference      = calculateUlpDifference(value1, value2);
 135 }
 136
 137 /*! \brief
 138  * Converts a relative tolerance into an ULP difference.
 139  */
 140 template <typename FloatType>
 141 gmx_uint64_t relativeToleranceToUlp(FloatType tolerance)
 142 {
 143     FloatingPoint<FloatType> m(1.0);
 144     FloatingPoint<FloatType> t(1.0 + tolerance);
 145     return calculateUlpDifference<FloatType>(m, t);
 146 }
 147
 148 //! \}
 149 //! \}
 150
 151 }       // namespace
 152
 153 /********************************************************************
 154  * FloatingPointDifference
 155  */
 156
 157 FloatingPointDifference::FloatingPointDifference(float value1, float value2)
 158 {
 159     initDifference(value1, value2,
 160                    &absoluteDifference_, &ulpDifference_, &bSignDifference_);
 161     bDouble_ = false;
 162 }
 163
 164 FloatingPointDifference::FloatingPointDifference(double value1, double value2)
 165 {
 166     initDifference(value1, value2,
 167                    &absoluteDifference_, &ulpDifference_, &bSignDifference_);
 168     bDouble_ = true;
 169 }
 170
 171 bool FloatingPointDifference::isNaN() const
 172 {
 173     return FloatingPoint<double>(absoluteDifference_).is_nan();
 174 }
 175
 176 std::string FloatingPointDifference::toString() const
 177 {
 178     const double eps = isDouble() ? GMX_DOUBLE_EPS : GMX_FLOAT_EPS;
 179     return formatString("%g (%" GMX_PRIu64 " %s-prec. ULPs, rel. %.3g)%s",
 180                         absoluteDifference_, ulpDifference_,
 181                         isDouble() ? "double" : "single",
 182                         ulpDifference_ * eps,
 183                         bSignDifference_ ? ", signs differ" : "");
 184 }
 185
 186 /********************************************************************
 187  * FloatingPointTolerance
 188  */
 189
 190 bool FloatingPointTolerance::isWithin(
 191         const FloatingPointDifference &difference) const
 192 {
 193     if (difference.isNaN())
 194     {
 195         return false;
 196     }
 197
 198     if (bSignMustMatch_ && difference.signsDiffer())
 199     {
 200         return false;
 201     }
 202
 203     const double absoluteTolerance
 204         = difference.isDouble() ? doubleAbsoluteTolerance_ : singleAbsoluteTolerance_;
 205     if (difference.asAbsolute() < absoluteTolerance)
 206     {
 207         return true;
 208     }
 209
 210     const gmx_uint64_t ulpTolerance
 211         = difference.isDouble() ? doubleUlpTolerance_ : singleUlpTolerance_;
 212     if (ulpTolerance < GMX_UINT64_MAX && difference.asUlps() <= ulpTolerance)
 213     {
 214         return true;
 215     }
 216     return false;
 217 }
 218
 219 std::string FloatingPointTolerance::toString(const FloatingPointDifference &difference) const
 220 {
 221     std::string        result;
 222     const double       absoluteTolerance
 223         = difference.isDouble() ? doubleAbsoluteTolerance_ : singleAbsoluteTolerance_;
 224     const gmx_uint64_t ulpTolerance
 225         = difference.isDouble() ? doubleUlpTolerance_ : singleUlpTolerance_;
 226     const double       eps
 227         = difference.isDouble() ? GMX_DOUBLE_EPS : GMX_FLOAT_EPS;
 228
 229     if (absoluteTolerance > 0.0)
 230     {
 231         result.append(formatString("abs. %g", absoluteTolerance));
 232     }
 233     if (ulpTolerance < GMX_UINT64_MAX)
 234     {
 235         if (!result.empty())
 236         {
 237             result.append(", ");
 238         }
 239         result.append(formatString("%" GMX_PRIu64 " ULPs (rel. %.3g)", ulpTolerance, ulpTolerance * eps));
 240     }
 241     if (bSignMustMatch_)
 242     {
 243         if (!result.empty())
 244         {
 245             result.append(", ");
 246         }
 247         result.append("sign must match");
 248     }
 249     return result;
 250 }
 251
 252 // Doxygen does not recognize this as the same function as in the header...
 253 //! \cond
 254 FloatingPointTolerance
 255 relativeToleranceAsFloatingPoint(double magnitude, double tolerance)
 256 {
 257     const double absoluteTolerance = magnitude * tolerance;
 258     return FloatingPointTolerance(absoluteTolerance, absoluteTolerance,
 259                                   relativeToleranceToUlp<float>(tolerance),
 260                                   relativeToleranceToUlp<double>(tolerance),
 261                                   false);
 262 }
 263 //! \endcond
 264
 265 } // namespace test
 266 } // namespace gmx