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https://github.com/triqs/dft_tools
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A first general restructuration of the doc according to the pattern [tour|tutorial|reference]. In the reference part, objects are documented per topic. In each topic, [definition|c++|python|hdf5] (not yet implemented)
105 lines
2.8 KiB
ReStructuredText
105 lines
2.8 KiB
ReStructuredText
.. highlight:: c
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.. _arr_call:
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Operator()
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==================================
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**Synopsis** ::
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value_type const & operator()(size_t ...) const (1a)
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value_type & operator()(size_t ...) (1b)
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view_type operator()() const (2a)
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view_type operator()( size_t | range | ellipsis ) const (2b)
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`clef expression` operator()( `at least a lazy argument` ) const (3)
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This is valid for both the container (e.g. array), and the view (e.g. array_view).
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.. _arr_element_access:
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(1) Element access
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---------------------------------
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Following the concept :ref:`ImmutableCuboidArray`, the form (1) is an access to the elements.
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It must be called with exactly `rank` size_t (or it is a compile time error).
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Example
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^^^^^^^^^
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.. triqs_example:: ./call_0.cpp
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Another ::
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A(1, range(0,2) ) // 1d slice
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A(1, range()) // 1d slice taking all the second dim
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A(range(0,10,2), range(0,10,2)) // a 2d slice viewing every each elements with even coordinates.
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array_view<T,1> SL = A(0,range(0,3)); // naming the view. No data copied here !
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array_view<T,1> SL ( A(0,range(0,3))); // same thing !
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.. _arr_making_view:
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(2) Building a view
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---------------------------------
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When the arguments contains at least one :ref:`range<arr_range>` or one :ref:`ellipsis<arr_ellipsis>`, and no placeholder (see 3)),
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the return type is a (partial) view of the container.
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The special case (2a) (no argument) returns a complete view of the object
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(equivalent to view_type(* this)).
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The return type of the () operator is:
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* Partial views of array or array_view return a array_view.
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* Partial views of vector or vector_view return a vector_view.
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* 2d partial views of matrix or matrix_view return a matrix_view.
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* BUT: (1d) partial view of matrix or matrix_view return a vector_view.
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Example
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^^^^^^^^^^^^
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.. triqs_example:: ./call_1.cpp
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.. toctree::
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:hidden:
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range_ell
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.. highlight:: c
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.. _arr_lazy:
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(3) Interaction with clef expressions
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-------------------------------------------------
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* The containers and their views can be used with the triqs::clef library:
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* Using the clef library offers a quick and efficient way to fill an array with multiple advantages:
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* It is simpler and more readeable than a series of for loops.
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* It is usually more optimal since the for loops are automatically written in the TraversalOrder of the
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array.
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* NB: the expression can be (and are) inlined by the compilers...
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* **Example**:
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.. triqs_example:: ./call_2.cpp
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.. note::
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The syntax uses a <<, not = since the array is not assigned to an expression
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but filled by the evaluation thereof.
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