Limits.h

// -*- tab-width: 2; indent-tabs-mode: nil; coding: utf-8-with-signature -*-
//-----------------------------------------------------------------------------
// Copyright 2000-2026 CEA (www.cea.fr) IFPEN (www.ifpenergiesnouvelles.com)
// See the top-level COPYRIGHT file for details.
// SPDX-License-Identifier: Apache-2.0
//-----------------------------------------------------------------------------
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/* Limits.h                                                    (C) 2000-2024 */
/*                                                                           */
/* Files encapsulating <limits> and associated types.                        */
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#ifndef ARCANE_UTILS_LIMITS_H
#define ARCANE_UTILS_LIMITS_H
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#include "arcane/utils/StdHeader.h"
 
// Since <limits> defines min, max, abs, ... and some software
// makes them macros, we remove them
#ifdef min
#undef min
#endif
#ifdef max
#undef max
#endif
#ifdef abs
#undef abs
#endif
#include <limits>
 
#include <float.h>
 
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namespace Arcane
{
 
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/*!
 * \brief Information about the floating-point type.
 * \note Mandatory specialization for floating-point types.
 */
template <typename T>
class FloatInfo
{
 public:
 
  //! Indicates if the instantiation is for a floating-point type.
  typedef FalseType _IsFloatType;
};
 
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/*!
 * \brief Specialization of the FloatInfo class for the \c float type.
 */
template <>
class FloatInfo<float>
{
 public:
 
  //! Indicates that the instantiation is for a floating-point type.
  typedef TrueType _IsFloatType;
 
 public:
 
  ARCCORE_HOST_DEVICE static constexpr unsigned int precision() { return 1; }
  ARCCORE_HOST_DEVICE static constexpr unsigned int maxDigit() { return FLT_DIG; }
  ARCCORE_HOST_DEVICE static constexpr float epsilon() { return FLT_EPSILON; }
  ARCCORE_HOST_DEVICE static constexpr float nearlyEpsilon() { return FLT_EPSILON * 10.0f; }
  ARCCORE_HOST_DEVICE static constexpr float maxValue() { return FLT_MAX; }
  ARCCORE_HOST_DEVICE static constexpr float zero() { return 0.0f; }
};
 
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/*!
 * \brief Specialization of the FloatInfo class for the <tt>double</tt> type.
 */
template <>
class FloatInfo<double>
{
 public:
 
  //! Indicates that the instantiation is for a floating-point type.
  typedef TrueType _IsFloatType;
 
 public:
 
  ARCCORE_HOST_DEVICE static constexpr unsigned int precision() { return 2; }
  ARCCORE_HOST_DEVICE static constexpr unsigned int maxDigit() { return DBL_DIG; }
  ARCCORE_HOST_DEVICE static constexpr double epsilon() { return DBL_EPSILON; }
  ARCCORE_HOST_DEVICE static constexpr double nearlyEpsilon() { return DBL_EPSILON * 10.0; }
  ARCCORE_HOST_DEVICE static constexpr double maxValue() { return DBL_MAX; }
  ARCCORE_HOST_DEVICE static constexpr double zero() { return 0.0; }
};
 
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/*!
 * \brief Specialization of the FloatInfo class for the type
 * <tt>long double</tt>.
 *
 * \todo Verify that this class is valid for all architectures.
 */
template <>
class FloatInfo<long double>
{
 public:
 
  //! Indicates that the instantiation is for a floating-point type.
  typedef TrueType _IsFloatType;
 
 public:
 
  ARCCORE_HOST_DEVICE static constexpr unsigned int precision() { return 3; }
  ARCCORE_HOST_DEVICE static constexpr unsigned int maxDigit() { return LDBL_DIG; }
  ARCCORE_HOST_DEVICE static constexpr long double epsilon() { return LDBL_EPSILON; }
  ARCCORE_HOST_DEVICE static constexpr long double nearlyEpsilon() { return LDBL_EPSILON * 10.0; }
  ARCCORE_HOST_DEVICE static constexpr long double maxValue() { return LDBL_MAX; }
  ARCCORE_HOST_DEVICE static constexpr long double zero() { return 0.0l; }
};
 
#ifdef ARCANE_REAL_USE_APFLOAT
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/*!
 * \brief Specialization of the FloatInfo class for the type
 * <tt>long double</tt>.
 *
 * \todo Verify that this class is valid for all architectures.
 */
template <>
class FloatInfo<apfloat>
{
 public:
 
  //! Indicates that the instantiation is for a floating-point type.
  typedef TrueType _IsFloatType;
 
 public:
 
  ARCCORE_HOST_DEVICE static constexpr unsigned int precision() { return 3; }
  ARCCORE_HOST_DEVICE static constexpr unsigned int maxDigit() { return 35; }
  ARCCORE_HOST_DEVICE static constexpr apfloat epsilon() { return 1e-30; }
  ARCCORE_HOST_DEVICE static constexpr apfloat nearlyEpsilon() { return 1e-28; }
  ARCCORE_HOST_DEVICE static constexpr apfloat maxValue() { return apfloat("1e1000"); }
  ARCCORE_HOST_DEVICE static constexpr apfloat zero() { return apfloat("0.0"); }
};
#endif
 
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} // End namespace Arcane
 
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#endif