TensorExpressions Namespace Reference

Classes
struct	AddSub
struct	AddSub< T1, T2, ArgsList1< Args1... >, ArgsList2< Args2... >, Sign >
struct	LhsTensorSymmAndIndices
	Determines and stores a LHS tensor's symmetry and index list from a RHS tensor expression and desired LHS index order. More...
struct	LhsTensorSymmAndIndices< RhsTensorIndexList, tmpl::list< LhsTensorIndices... >, RhsSymmetry, RhsTensorIndexTypeList, NumIndices, std::index_sequence< Ints... > >
struct	NumberAsExpression
	Defines an expression representing a double More...
struct	OuterProduct
	Defines the tensor expression representing the outer product of two tensor expressions. More...
struct	OuterProduct< T1, T2, IndexList1< Indices1... >, IndexList2< Indices2... >, ArgsList1< Args1... >, ArgsList2< Args2... > >
struct	SquareRoot
	Defines the tensor expression representing the square root of a tensor expression that evaluates to a rank 0 tensor. More...
struct	TensorAsExpression
	Defines an expression representing a Tensor. More...
struct	TensorAsExpression< Tensor< X, Symm, IndexList< Indices... > >, ArgsList< Args... > >
struct	TensorContract

Functions
template<auto &... LhsTensorIndices, typename X , typename LhsSymmetry , typename LhsIndexList , typename Derived , typename RhsSymmetry , typename RhsIndexList , typename... RhsTensorIndices>
void	evaluate (const gsl::not_null< Tensor< X, LhsSymmetry, LhsIndexList > * > lhs_tensor, const TensorExpression< Derived, X, RhsSymmetry, RhsIndexList, tmpl::list< RhsTensorIndices... > > &rhs_tensorexpression)
	Evaluate a RHS tensor expression to a tensor with the LHS index order set in the template parameters. More...
template<auto &... LhsTensorIndices, typename RhsTE , Requires< std::is_base_of_v< Expression, RhsTE > > = nullptr>
auto	evaluate (const RhsTE &rhs_tensorexpression)
	Evaluate a RHS tensor expression to a tensor with the LHS index order set in the template parameters. More...
template<size_t NumIndices>
constexpr std::array< size_t, NumIndices >	compute_tensorindex_transformation (const std::array< size_t, NumIndices > &tensorindices1, const std::array< size_t, NumIndices > &tensorindices2) noexcept
	Computes a transformation from one generic tensor index order to another. More...
template<size_t NumIndices>
constexpr std::array< size_t, NumIndices >	transform_multi_index (const std::array< size_t, NumIndices > &input_multi_index, const std::array< size_t, NumIndices > &tensorindex_transformation) noexcept
	Computes the tensor multi-index that is equivalent to a given tensor multi-index, according to the differences in their generic index orders. More...

Detailed Description

Holds all possible TensorExpressions currently implemented

Function Documentation

compute_tensorindex_transformation()

template<size_t NumIndices>

constexpr std::array< size_t, NumIndices > TensorExpressions::compute_tensorindex_transformation ( const std::array< size_t, NumIndices > &  tensorindices1, const std::array< size_t, NumIndices > &  tensorindices2  )

constexprnoexcept

Computes a transformation from one generic tensor index order to another.

Details

The elements of the transformation are the positions of the second list of generic indices in the first list of generic indices. Put another way, for some i, tensorindices2[i] == tensorindices1[index_transformation[i]].

Here is an example of what the algorithm does:

Transformation between (1) \(R_{cab}\) and (2) \(S_{abc}\) tensorindices1:

{2, 0, 1} // TensorIndex values for {c, a, b}

tensorindices2:

{0, 1, 2} // TensorIndex values for {a, b, c}

returned tensorindex_transformation:

{1, 2, 0} // positions of S' indices {a, b, c} in R's indices {c, a, b}

Template Parameters

NumIndices

the number of indices

Parameters

tensorindices1	the TensorIndex values of the first generic index order
tensorindices2	the TensorIndex values of the second generic index order

Returns: a transformation from the first generic index order to the second

transform_multi_index()

template<size_t NumIndices>

constexpr std::array< size_t, NumIndices > TensorExpressions::transform_multi_index ( const std::array< size_t, NumIndices > &  input_multi_index, const std::array< size_t, NumIndices > &  tensorindex_transformation  )

constexprnoexcept

Computes the tensor multi-index that is equivalent to a given tensor multi-index, according to the differences in their generic index orders.

Details

Here is an example of what the algorithm does:

Transform (input) multi-index of \(R_{cab}\) to the equivalent (output) multi-index of \(S_{abc}\) tensorindex_transformation:

{1, 2, 0} // positions of S' indices {a, b, c} in R's indices {c, a, b}

input_multi_index:

{3, 4, 5} // i.e. c = 3, a = 4, b = 5

returned equivalent output_multi_index:

{4, 5, 3} // i.e. a = 4, b = 5, c = 3

Template Parameters

NumIndices

the number of indices

Parameters

input_multi_index	the input tensor multi-index to transform
tensorindex_transformation	the positions of the output's generic indices in the input's generic indices (see example in details)

Returns: the output tensor multi-index that is equivalent to input_multi_index, according to generic index order differences