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Diffstat (limited to 'unsupported/Eigen/CXX11/src/TensorSymmetry/Symmetry.h')
| -rw-r--r-- | unsupported/Eigen/CXX11/src/TensorSymmetry/Symmetry.h | 338 |
1 files changed, 338 insertions, 0 deletions
diff --git a/unsupported/Eigen/CXX11/src/TensorSymmetry/Symmetry.h b/unsupported/Eigen/CXX11/src/TensorSymmetry/Symmetry.h new file mode 100644 index 000000000..879d6cd77 --- /dev/null +++ b/unsupported/Eigen/CXX11/src/TensorSymmetry/Symmetry.h @@ -0,0 +1,338 @@ +// This file is part of Eigen, a lightweight C++ template library +// for linear algebra. +// +// Copyright (C) 2013 Christian Seiler <christian@iwakd.de> +// +// This Source Code Form is subject to the terms of the Mozilla +// Public License v. 2.0. If a copy of the MPL was not distributed +// with this file, You can obtain one at http://mozilla.org/MPL/2.0/. + +#ifndef EIGEN_CXX11_TENSORSYMMETRY_SYMMETRY_H +#define EIGEN_CXX11_TENSORSYMMETRY_SYMMETRY_H + +namespace Eigen { + +enum { + NegationFlag = 0x01, + ConjugationFlag = 0x02 +}; + +enum { + GlobalRealFlag = 0x01, + GlobalImagFlag = 0x02, + GlobalZeroFlag = 0x03 +}; + +namespace internal { + +template<std::size_t NumIndices, typename... Sym> struct tensor_symmetry_pre_analysis; +template<std::size_t NumIndices, typename... Sym> struct tensor_static_symgroup; +template<bool instantiate, std::size_t NumIndices, typename... Sym> struct tensor_static_symgroup_if; +template<typename Tensor_> struct tensor_symmetry_calculate_flags; +template<typename Tensor_> struct tensor_symmetry_assign_value; +template<typename... Sym> struct tensor_symmetry_num_indices; + +} // end namespace internal + +template<int One_, int Two_> +struct Symmetry +{ + static_assert(One_ != Two_, "Symmetries must cover distinct indices."); + constexpr static int One = One_; + constexpr static int Two = Two_; + constexpr static int Flags = 0; +}; + +template<int One_, int Two_> +struct AntiSymmetry +{ + static_assert(One_ != Two_, "Symmetries must cover distinct indices."); + constexpr static int One = One_; + constexpr static int Two = Two_; + constexpr static int Flags = NegationFlag; +}; + +template<int One_, int Two_> +struct Hermiticity +{ + static_assert(One_ != Two_, "Symmetries must cover distinct indices."); + constexpr static int One = One_; + constexpr static int Two = Two_; + constexpr static int Flags = ConjugationFlag; +}; + +template<int One_, int Two_> +struct AntiHermiticity +{ + static_assert(One_ != Two_, "Symmetries must cover distinct indices."); + constexpr static int One = One_; + constexpr static int Two = Two_; + constexpr static int Flags = ConjugationFlag | NegationFlag; +}; + +/** \class DynamicSGroup + * \ingroup TensorSymmetry_Module + * + * \brief Dynamic symmetry group + * + * The %DynamicSGroup class represents a symmetry group that need not be known at + * compile time. It is useful if one wants to support arbitrary run-time defineable + * symmetries for tensors, but it is also instantiated if a symmetry group is defined + * at compile time that would be either too large for the compiler to reasonably + * generate (using templates to calculate this at compile time is very inefficient) + * or that the compiler could generate the group but that it wouldn't make sense to + * unroll the loop for setting coefficients anymore. + */ +class DynamicSGroup; + +/** \internal + * + * \class DynamicSGroupFromTemplateArgs + * \ingroup TensorSymmetry_Module + * + * \brief Dynamic symmetry group, initialized from template arguments + * + * This class is a child class of DynamicSGroup. It uses the template arguments + * specified to initialize itself. + */ +template<typename... Gen> +class DynamicSGroupFromTemplateArgs; + +/** \class StaticSGroup + * \ingroup TensorSymmetry_Module + * + * \brief Static symmetry group + * + * This class represents a symmetry group that is known and resolved completely + * at compile time. Ideally, no run-time penalty is incurred compared to the + * manual unrolling of the symmetry. + * + * <b><i>CAUTION:</i></b> + * + * Do not use this class directly for large symmetry groups. The compiler + * may run into a limit, or segfault or in the very least will take a very, + * very, very long time to compile the code. Use the SGroup class instead + * if you want a static group. That class contains logic that will + * automatically select the DynamicSGroup class instead if the symmetry + * group becomes too large. (In that case, unrolling may not even be + * beneficial.) + */ +template<typename... Gen> +class StaticSGroup; + +/** \class SGroup + * \ingroup TensorSymmetry_Module + * + * \brief Symmetry group, initialized from template arguments + * + * This class represents a symmetry group whose generators are already + * known at compile time. It may or may not be resolved at compile time, + * depending on the estimated size of the group. + * + * \sa StaticSGroup + * \sa DynamicSGroup + */ +template<typename... Gen> +class SGroup : public internal::tensor_symmetry_pre_analysis<internal::tensor_symmetry_num_indices<Gen...>::value, Gen...>::root_type +{ + public: + constexpr static std::size_t NumIndices = internal::tensor_symmetry_num_indices<Gen...>::value; + typedef typename internal::tensor_symmetry_pre_analysis<NumIndices, Gen...>::root_type Base; + + // make standard constructors + assignment operators public + inline SGroup() : Base() { } + inline SGroup(const SGroup<Gen...>& other) : Base(other) { } + inline SGroup(SGroup<Gen...>&& other) : Base(other) { } + inline SGroup<Gen...>& operator=(const SGroup<Gen...>& other) { Base::operator=(other); return *this; } + inline SGroup<Gen...>& operator=(SGroup<Gen...>&& other) { Base::operator=(other); return *this; } + + // all else is defined in the base class +}; + +namespace internal { + +template<typename... Sym> struct tensor_symmetry_num_indices +{ + constexpr static std::size_t value = 1; +}; + +template<int One_, int Two_, typename... Sym> struct tensor_symmetry_num_indices<Symmetry<One_, Two_>, Sym...> +{ +private: + constexpr static std::size_t One = static_cast<std::size_t>(One_); + constexpr static std::size_t Two = static_cast<std::size_t>(Two_); + constexpr static std::size_t Three = tensor_symmetry_num_indices<Sym...>::value; + + // don't use std::max, since it's not constexpr until C++14... + constexpr static std::size_t maxOneTwoPlusOne = ((One > Two) ? One : Two) + 1; +public: + constexpr static std::size_t value = (maxOneTwoPlusOne > Three) ? maxOneTwoPlusOne : Three; +}; + +template<int One_, int Two_, typename... Sym> struct tensor_symmetry_num_indices<AntiSymmetry<One_, Two_>, Sym...> + : public tensor_symmetry_num_indices<Symmetry<One_, Two_>, Sym...> {}; +template<int One_, int Two_, typename... Sym> struct tensor_symmetry_num_indices<Hermiticity<One_, Two_>, Sym...> + : public tensor_symmetry_num_indices<Symmetry<One_, Two_>, Sym...> {}; +template<int One_, int Two_, typename... Sym> struct tensor_symmetry_num_indices<AntiHermiticity<One_, Two_>, Sym...> + : public tensor_symmetry_num_indices<Symmetry<One_, Two_>, Sym...> {}; + +/** \internal + * + * \class tensor_symmetry_pre_analysis + * \ingroup TensorSymmetry_Module + * + * \brief Pre-select whether to use a static or dynamic symmetry group + * + * When a symmetry group could in principle be determined at compile time, + * this template implements the logic whether to actually do that or whether + * to rather defer that to runtime. + * + * The logic is as follows: + * <dl> + * <dt><b>No generators (trivial symmetry):</b></dt> + * <dd>Use a trivial static group. Ideally, this has no performance impact + * compared to not using symmetry at all. In practice, this might not + * be the case.</dd> + * <dt><b>More than 4 generators:</b></dt> + * <dd>Calculate the group at run time, it is likely far too large for the + * compiler to be able to properly generate it in a realistic time.</dd> + * <dt><b>Up to and including 4 generators:</b></dt> + * <dd>Actually enumerate all group elements, but then check how many there + * are. If there are more than 16, it is unlikely that unrolling the + * loop (as is done in the static compile-time case) is sensible, so + * use a dynamic group instead. If there are at most 16 elements, actually + * use that static group. Note that the largest group with 4 generators + * still compiles with reasonable resources.</dd> + * </dl> + * + * Note: Example compile time performance with g++-4.6 on an Intenl Core i5-3470 + * with 16 GiB RAM (all generators non-redundant and the subgroups don't + * factorize): + * + * # Generators -O0 -ggdb -O2 + * ------------------------------------------------------------------- + * 1 0.5 s / 250 MiB 0.45s / 230 MiB + * 2 0.5 s / 260 MiB 0.5 s / 250 MiB + * 3 0.65s / 310 MiB 0.62s / 310 MiB + * 4 2.2 s / 860 MiB 1.7 s / 770 MiB + * 5 130 s / 13000 MiB 120 s / 11000 MiB + * + * It is clear that everything is still very efficient up to 4 generators, then + * the memory and CPU requirements become unreasonable. Thus we only instantiate + * the template group theory logic if the number of generators supplied is 4 or + * lower, otherwise this will be forced to be done during runtime, where the + * algorithm is reasonably fast. + */ +template<std::size_t NumIndices> +struct tensor_symmetry_pre_analysis<NumIndices> +{ + typedef StaticSGroup<> root_type; +}; + +template<std::size_t NumIndices, typename Gen_, typename... Gens_> +struct tensor_symmetry_pre_analysis<NumIndices, Gen_, Gens_...> +{ + constexpr static std::size_t max_static_generators = 4; + constexpr static std::size_t max_static_elements = 16; + typedef tensor_static_symgroup_if<(sizeof...(Gens_) + 1 <= max_static_generators), NumIndices, Gen_, Gens_...> helper; + constexpr static std::size_t possible_size = helper::size; + + typedef typename conditional< + possible_size == 0 || possible_size >= max_static_elements, + DynamicSGroupFromTemplateArgs<Gen_, Gens_...>, + typename helper::type + >::type root_type; +}; + +template<bool instantiate, std::size_t NumIndices, typename... Gens> +struct tensor_static_symgroup_if +{ + constexpr static std::size_t size = 0; + typedef void type; +}; + +template<std::size_t NumIndices, typename... Gens> +struct tensor_static_symgroup_if<true, NumIndices, Gens...> : tensor_static_symgroup<NumIndices, Gens...> {}; + +template<typename Tensor_> +struct tensor_symmetry_assign_value +{ + typedef typename Tensor_::Index Index; + typedef typename Tensor_::Scalar Scalar; + constexpr static std::size_t NumIndices = Tensor_::NumIndices; + + static inline int run(const std::array<Index, NumIndices>& transformed_indices, int transformation_flags, int dummy, Tensor_& tensor, const Scalar& value_) + { + Scalar value(value_); + if (transformation_flags & ConjugationFlag) + value = numext::conj(value); + if (transformation_flags & NegationFlag) + value = -value; + tensor.coeffRef(transformed_indices) = value; + return dummy; + } +}; + +template<typename Tensor_> +struct tensor_symmetry_calculate_flags +{ + typedef typename Tensor_::Index Index; + constexpr static std::size_t NumIndices = Tensor_::NumIndices; + + static inline int run(const std::array<Index, NumIndices>& transformed_indices, int transform_flags, int current_flags, const std::array<Index, NumIndices>& orig_indices) + { + if (transformed_indices == orig_indices) { + if (transform_flags & (ConjugationFlag | NegationFlag)) + return current_flags | GlobalImagFlag; // anti-hermitian diagonal + else if (transform_flags & ConjugationFlag) + return current_flags | GlobalRealFlag; // hermitian diagonal + else if (transform_flags & NegationFlag) + return current_flags | GlobalZeroFlag; // anti-symmetric diagonal + } + return current_flags; + } +}; + +template<typename Tensor_, typename Symmetry_, int Flags = 0> +class tensor_symmetry_value_setter +{ + public: + typedef typename Tensor_::Index Index; + typedef typename Tensor_::Scalar Scalar; + constexpr static std::size_t NumIndices = Tensor_::NumIndices; + + inline tensor_symmetry_value_setter(Tensor_& tensor, Symmetry_ const& symmetry, std::array<Index, NumIndices> const& indices) + : m_tensor(tensor), m_symmetry(symmetry), m_indices(indices) { } + + inline tensor_symmetry_value_setter<Tensor_, Symmetry_, Flags>& operator=(Scalar const& value) + { + doAssign(value); + return *this; + } + private: + Tensor_& m_tensor; + Symmetry_ m_symmetry; + std::array<Index, NumIndices> m_indices; + + inline void doAssign(Scalar const& value) + { + #ifdef EIGEN_TENSOR_SYMMETRY_CHECK_VALUES + int value_flags = m_symmetry.template apply<internal::tensor_symmetry_calculate_flags<Tensor_>, int>(m_indices, m_symmetry.globalFlags(), m_indices); + if (value_flags & GlobalRealFlag) + eigen_assert(numext::imag(value) == 0); + if (value_flags & GlobalImagFlag) + eigen_assert(numext::real(value) == 0); + #endif + m_symmetry.template apply<internal::tensor_symmetry_assign_value<Tensor_>, int>(m_indices, 0, m_tensor, value); + } +}; + +} // end namespace internal + +} // end namespace Eigen + +#endif // EIGEN_CXX11_TENSORSYMMETRY_SYMMETRY_H + +/* + * kate: space-indent on; indent-width 2; mixedindent off; indent-mode cstyle; + */ |