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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/utility/basedefinitions.h"
51 #include "gromacs/utility/stringutil.h"
62 using ::testing::internal::FloatingPoint;
64 //! \internal \addtogroup module_testutils
67 /*! \name Helper functions for computing floating-point differences
69 * These routines are used to initialize FloatingPointDifference.
70 * They peek into some internal types from Google Test (gtest-internal.h),
71 * and duplicate some other functionality from there, but that is likely
72 * a better alternative than just copying all that code here.
77 * Computes biased integer representation for a floating-point value.
79 * This moves the integer representation from a sign-and-magnitude
80 * representation to a biased representation where the 0x8000... represents
81 * zero, and the order of the integer values matches the order of the
82 * floating-point values.
84 template <typename FloatType>
85 typename FloatingPoint<FloatType>::Bits
86 floatingPointToBiasedInteger(const FloatingPoint<FloatType> &value)
90 return ~value.bits() + 1;
94 return value.bits() | FloatingPoint<FloatType>::kSignBitMask;
99 * Computes difference in ULPs between two numbers, treating also values of
102 template <typename FloatType>
103 gmx_uint64_t calculateUlpDifference(const FloatingPoint<FloatType> &value1,
104 const FloatingPoint<FloatType> &value2)
106 typename FloatingPoint<FloatType>::Bits biased1
107 = floatingPointToBiasedInteger(value1);
108 typename FloatingPoint<FloatType>::Bits biased2
109 = floatingPointToBiasedInteger(value2);
110 return biased1 > biased2 ? biased1 - biased2 : biased2 - biased1;
114 * Helper to implement the constructors for FloatingPointDifference.
116 template <typename FloatType>
117 void initDifference(FloatType raw1, FloatType raw2, double *absoluteDifference,
118 gmx_uint64_t *ulpDifference, bool *bSignDifference)
120 FloatingPoint<FloatType> value1(raw1);
121 FloatingPoint<FloatType> value2(raw2);
123 if (value1.is_nan() || value2.is_nan())
125 *absoluteDifference = std::numeric_limits<double>::quiet_NaN();
126 *bSignDifference = false;
130 *absoluteDifference = std::fabs(raw1 - raw2);
131 *bSignDifference = (value1.sign_bit() != value2.sign_bit());
132 *ulpDifference = calculateUlpDifference(value1, value2);
140 /********************************************************************
141 * FloatingPointDifference
144 FloatingPointDifference::FloatingPointDifference(float value1, float value2)
146 initDifference(value1, value2,
147 &absoluteDifference_, &ulpDifference_, &bSignDifference_);
151 FloatingPointDifference::FloatingPointDifference(double value1, double value2)
153 initDifference(value1, value2,
154 &absoluteDifference_, &ulpDifference_, &bSignDifference_);
158 bool FloatingPointDifference::isNaN() const
160 return FloatingPoint<double>(absoluteDifference_).is_nan();
163 std::string FloatingPointDifference::toString() const
165 return formatString("%g (%" GMX_PRIu64 " %s-prec. ULPs)%s",
166 absoluteDifference_, ulpDifference_,
167 bDouble_ ? "double" : "single",
168 bSignDifference_ ? ", signs differ" : "");
171 /********************************************************************
172 * FloatingPointTolerance
175 bool FloatingPointTolerance::isWithin(
176 const FloatingPointDifference &difference) const
178 if (difference.isNaN())
183 if (bSignMustMatch_ && difference.signsDiffer())
188 if (difference.asAbsolute() < absoluteTolerance_)
193 if (ulpTolerance_ >= 0
194 && difference.asUlps() <= static_cast<gmx_uint64_t>(ulpTolerance_))
201 std::string FloatingPointTolerance::toString() const
204 if (absoluteTolerance_ > 0.0)
206 result.append(formatString("abs. %g", absoluteTolerance_));
208 if (ulpTolerance_ >= 0)
214 result.append(formatString("%d ULPs", ulpTolerance_));
222 result.append("sign must match");