mirror of
https://github.com/triqs/dft_tools
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147 lines
6.2 KiB
ReStructuredText
147 lines
6.2 KiB
ReStructuredText
.. highlight:: c
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array, matrix & vector
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===========================================
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**Synopsis**:
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.. code-block:: c
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template <typename ValueType, int Rank, ull_t OptionsFlags=0, ull_t TraversalOrder=0 > class array;
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template <typename ValueType, ull_t OptionsFlags=0, ull_t TraversalOrder=0 > class matrix;
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template <typename ValueType, ull_t OptionsFlags=0> class vector;
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where triqs::ull_t is the type defined by :
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.. code-block:: c
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typedef unsigned long long ull_t;
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* The library provides three basic containers :
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* array : general (rectangular) `N`-dimensionnal array; models :ref:`MutableCuboidArray` concept.
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* matrix : models the :ref:`MutableMatrix` concept.
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* vector : models the :ref:`MutableVector` concept.
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and the corresponding view classes : array_view, matrix_view, vector_view (Cf :ref:`partial_views`).
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* The matrix and vector are very similar to an array of dimension 2 and 1 respectivily,
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except for their algebra. Array form an array algebra, where operation are done element-wise, while matrix and vector
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form the usual algebra and vector space of linear algebra.
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* These classes are largely interoperable, as explained below : it is easy and quick to take a
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matrix_view of an array, or vice versa.
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Template parameters
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----------------------------
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============================ ============================== ========================== ====================================================================
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Template parameter Accepted type Access in the class Meaning
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============================ ============================== ========================== ====================================================================
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ValueType any regular type (typically a value_type The type of the element of the array
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scalar).
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Rank int rank The rank of the array
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OptionsFlags ull_t Compile time options, see below.
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TraversalOrder ull_t Compile time options, see below.
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============================ ============================== ========================== ====================================================================
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* Rank is only present for array, since matrix have rank 2 and vector rank 1.
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* OptionFlags is a series of flags determining various options at compile time.
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The possible flags are accessible via a constexpr ull_t in triqs::arrays or a macro :
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======================== =======================================
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Macro constexpr equivalent
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======================== =======================================
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BOUND_CHECK triqs::arrays::BoundCheck
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TRAVERSAL_ORDER_C triqs::arrays::TraversalOrderC
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TRAVERSAL_ORDER_FORTRAN triqs::arrays::TraversalOrderFortran
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DEFAULT_INIT triqs::arrays::DefaultInit
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======================== =======================================
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Defaults can be modified with the macros :
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* `TRIQS_ARRAYS_ENFORCE_BOUNDCHECK` : enforce BoundCheck by default (slows down codes ! Use only for debugging purposes).
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* TraversalOrder is a coding of the optimal ordering of indices, given by a permutation
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evaluated at **compile time**.
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The traversal of the arrays (iterators, foreach loop) will be written and optimised for this
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order.
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The default (0) is understood as regular C-style ordering (slowest index first).
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Note that an array can use any index ordering in memory, and that decision is take at run time
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(this is necessary for interfacing with python numpy arrays, see below).
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The code will be correct for any order, but optimised for the TraversalOrder.
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For a few very specials operations (e.g. regrouping of indices), the indices ordering in memory and TraversalOrder
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must coincide. This will be explicitely said below. By default, it is not necessary (but can be suboptimal).
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The permutation P encodes the position of the index : P[0] is the fastest index, P[rank - 1] the slowest index
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(see examples below).
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TraversalOrder is not present for vector since there is only one possibility in 1d.
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Member types
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-----------------
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=================== ======================================
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Member type Definitions
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=================== ======================================
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value_type ValueType
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view_type The corresponding view type
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=================== ======================================
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Member functions
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---------------------
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============================================= ==============================================
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Member function Meaning
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============================================= ==============================================
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:ref:`(constructor)<arr_reg_constr>`
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(destructor)
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:ref:`operator =<arr_reg_assign>` assigns values to the container
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:ref:`operator ()<arr_reg_call>` element of access/views/lazy expressions
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begin/cbegin returns iterator to the beginning
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end/cend returns iterator to the end
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:ref:`resize<arr_resize>` resize the container
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============================================= ==============================================
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.. toctree::
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:hidden:
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reg_constructors
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reg_assign
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call
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resize
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STL
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Non-member functions
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------------------------
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============================================= ==============================================
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Member function Meaning
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============================================= ==============================================
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:ref:`swap<arr_swap>`
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:ref:`deep_swap<arr_deep_swap>`
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============================================= ==============================================
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.. toctree::
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:hidden:
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swap
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