[linalg.conj.conjugated]

# 29 Numerics library [[numerics]](./#numerics)

## 29.9 Basic linear algebra algorithms [[linalg]](linalg#conj.conjugated)

### 29.9.9 Conjugated in-place transformation [[linalg.conj]](linalg.conj#conjugated)

#### 29.9.9.3 Function template conjugated [linalg.conj.conjugated]

[🔗](#itemdecl:1)

`  template<class ElementType, class Extents, class Layout, class Accessor>
    constexpr auto [conjugated](#lib:conjugated "29.9.9.3 Function template conjugated [linalg.conj.conjugated]")(mdspan<ElementType, Extents, Layout, Accessor> a);
`

[1](#1)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/numerics.tex#L12875)

Let A be

- [(1.1)](#1.1)

remove_cvref_t<decltype(a.accessor().nested_accessor())> if Accessor is a specialization of conjugated_accessor;

- [(1.2)](#1.2)

otherwise,Accessor if remove_cvref_t<ElementType> is an arithmetic type;

- [(1.3)](#1.3)

otherwise,conjugated_accessor<Accessor> if the expression conj(E) is valid for any subexpression E whose type is remove_cvref_t<ElementType> with overload resolution performed in a context that includes the declarationtemplate<class U> U conj(const U&) = delete;;

- [(1.4)](#1.4)

otherwise,Accessor[.](#1.sentence-1)

[2](#2)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/numerics.tex#L12896)

*Returns*: Let MD be mdspan<typename A​::​element_type, Extents, Layout, A>[.](#2.sentence-1)

- [(2.1)](#2.1)

MD(a.data_handle(), a.mapping(), a.accessor().nested_accessor()) if Accessor is a  
specialization of conjugated_accessor;

- [(2.2)](#2.2)

otherwise,a, if is_same_v<A, Accessor> is true;

- [(2.3)](#2.3)

otherwise,MD(a.data_handle(), a.mapping(), conjugated_accessor(a.accessor())).

[3](#3)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/numerics.tex#L12912)

[*Example [1](#example-1)*: void test_conjugated_complex(mdspan<complex<double>, extents<int, 10>> a) {auto a_conj = conjugated(a); for (int i = 0; i < a.extent(0); ++i) { assert(a_conj[i] == conj(a[i]); }auto a_conj_conj = conjugated(a_conj); for (int i = 0; i < a.extent(0); ++i) { assert(a_conj_conj[i] == a[i]); }}void test_conjugated_real(mdspan<double, extents<int, 10>> a) {auto a_conj = conjugated(a); for (int i = 0; i < a.extent(0); ++i) { assert(a_conj[i] == a[i]); }auto a_conj_conj = conjugated(a_conj); for (int i = 0; i < a.extent(0); ++i) { assert(a_conj_conj[i] == a[i]); }} — *end example*]