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37 * Implements floating-point comparison routines from testasserts.h.
39 * \author Teemu Murtola <teemu.murtola@gmail.com>
40 * \ingroup module_testutils
42 #include "testutils/testasserts.h"
48 #include <gtest/gtest.h>
50 #include "gromacs/legacyheaders/types/simple.h"
52 #include "gromacs/utility/stringutil.h"
63 using ::testing::internal::FloatingPoint;
65 //! \internal \addtogroup module_testutils
68 /*! \name Helper functions for computing floating-point differences
70 * These routines are used to initialize FloatingPointDifference.
71 * They peek into some internal types from Google Test (gtest-internal.h),
72 * and duplicate some other functionality from there, but that is likely
73 * a better alternative than just copying all that code here.
78 * Computes biased integer representation for a floating-point value.
80 * This moves the integer representation from a sign-and-magnitude
81 * representation to a biased representation where the 0x8000... represents
82 * zero, and the order of the integer values matches the order of the
83 * floating-point values.
85 template <typename FloatType>
86 typename FloatingPoint<FloatType>::Bits
87 floatingPointToBiasedInteger(const FloatingPoint<FloatType> &value)
91 return ~value.bits() + 1;
95 return value.bits() | FloatingPoint<FloatType>::kSignBitMask;
100 * Computes difference in ULPs between two numbers, treating also values of
103 template <typename FloatType>
104 gmx_uint64_t calculateUlpDifference(const FloatingPoint<FloatType> &value1,
105 const FloatingPoint<FloatType> &value2)
107 typename FloatingPoint<FloatType>::Bits biased1
108 = floatingPointToBiasedInteger(value1);
109 typename FloatingPoint<FloatType>::Bits biased2
110 = floatingPointToBiasedInteger(value2);
111 return biased1 > biased2 ? biased1 - biased2 : biased2 - biased1;
115 * Helper to implement the constructors for FloatingPointDifference.
117 template <typename FloatType>
118 void initDifference(FloatType raw1, FloatType raw2, double *absoluteDifference,
119 gmx_uint64_t *ulpDifference, bool *bSignDifference)
121 FloatingPoint<FloatType> value1(raw1);
122 FloatingPoint<FloatType> value2(raw2);
124 if (value1.is_nan() || value2.is_nan())
126 *absoluteDifference = std::numeric_limits<double>::quiet_NaN();
127 *bSignDifference = false;
131 *absoluteDifference = std::fabs(raw1 - raw2);
132 *bSignDifference = (value1.sign_bit() != value2.sign_bit());
133 *ulpDifference = calculateUlpDifference(value1, value2);
141 /********************************************************************
142 * FloatingPointDifference
145 FloatingPointDifference::FloatingPointDifference(float value1, float value2)
147 initDifference(value1, value2,
148 &absoluteDifference_, &ulpDifference_, &bSignDifference_);
152 FloatingPointDifference::FloatingPointDifference(double value1, double value2)
154 initDifference(value1, value2,
155 &absoluteDifference_, &ulpDifference_, &bSignDifference_);
159 bool FloatingPointDifference::isNaN() const
161 return FloatingPoint<double>(absoluteDifference_).is_nan();
164 std::string FloatingPointDifference::toString() const
166 return formatString("%g (%" GMX_PRIu64 " %s-prec. ULPs)%s",
167 absoluteDifference_, ulpDifference_,
168 bDouble_ ? "double" : "single",
169 bSignDifference_ ? ", signs differ" : "");
172 /********************************************************************
173 * FloatingPointTolerance
176 bool FloatingPointTolerance::isWithin(
177 const FloatingPointDifference &difference) const
179 if (difference.isNaN())
184 if (bSignMustMatch_ && difference.signsDiffer())
189 if (difference.asAbsolute() < absoluteTolerance_)
194 if (ulpTolerance_ >= 0
195 && difference.asUlps() <= static_cast<gmx_uint64_t>(ulpTolerance_))
202 std::string FloatingPointTolerance::toString() const
205 if (absoluteTolerance_ > 0.0)
207 result.append(formatString("abs. %g", absoluteTolerance_));
209 if (ulpTolerance_ >= 0)
215 result.append(formatString("%d ULPs", ulpTolerance_));
223 result.append("sign must match");