259 lines
8.9 KiB
Markdown
259 lines
8.9 KiB
Markdown
[simd.ctor]
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# 29 Numerics library [[numerics]](./#numerics)
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## 29.10 Data-parallel types [[simd]](simd#ctor)
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### 29.10.7 Class template basic_vec [[simd.class]](simd.class#simd.ctor)
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#### 29.10.7.2 basic_vec constructors [simd.ctor]
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[ð](#lib:basic_vec,constructor)
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`template<class U> constexpr explicit(see below) basic_vec(U&& value) noexcept;
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`
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[1](#1)
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[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/numerics.tex#L17699)
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Let From denote the type remove_cvref_t<U>[.](#1.sentence-1)
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[2](#2)
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[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/numerics.tex#L17702)
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*Constraints*: value_type satisfies [constructible_from](concept.constructible#concept:constructible_from "18.4.11 Concept constructible_from [concept.constructible]")<U>[.](#2.sentence-1)
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[3](#3)
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[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/numerics.tex#L17706)
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*Effects*: Initializes each element to the value of the argument after conversion tovalue_type[.](#3.sentence-1)
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[4](#4)
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[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/numerics.tex#L17711)
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*Remarks*: The expression inside explicit evaluates to false if and only ifU satisfies [convertible_to](concept.convertible#concept:convertible_to "18.4.4 Concept convertible_to [concept.convertible]")<value_type>, and either
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- [(4.1)](#4.1)
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From is not an arithmetic type and does not satisfy [*constexpr-wrapper-like*](simd.expos#concept:constexpr-wrapper-like "29.10.2 Exposition-only types, variables, and concepts [simd.expos]"),
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- [(4.2)](#4.2)
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From is an arithmetic type and the conversion from From to value_type is value-preserving ([[simd.general]](simd.general "29.10.1 General")), or
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- [(4.3)](#4.3)
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From satisfies [*constexpr-wrapper-like*](simd.expos#concept:constexpr-wrapper-like "29.10.2 Exposition-only types, variables, and concepts [simd.expos]"), remove_const_t<decltype(From::value)> is an arithmetic type, and From::value is representable by value_type[.](#4.sentence-1)
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[ð](#lib:basic_vec,constructor_)
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`template<class U, class UAbi>
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constexpr explicit(see below) basic_vec(const basic_vec<U, UAbi>& x) noexcept;
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`
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[5](#5)
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[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/numerics.tex#L17736)
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*Constraints*: *simd-size-v*<U, UAbi> == size() is true[.](#5.sentence-1)
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[6](#6)
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[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/numerics.tex#L17740)
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*Effects*: Initializes the ith element with static_cast<T>(x[i]) for
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all i in the range of [0, size())[.](#6.sentence-1)
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[7](#7)
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[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/numerics.tex#L17745)
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*Remarks*: The expression inside explicit evaluates to true if either
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- [(7.1)](#7.1)
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the conversion from U to value_type is not value-preserving,
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or
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- [(7.2)](#7.2)
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both U and value_type are integral types and the integer
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conversion rank ([[conv.rank]](conv.rank "6.9.6 Conversion ranks")) of U is greater than the integer
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conversion rank of value_type, or
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- [(7.3)](#7.3)
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both U and value_type are floating-point types and the
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floating-point conversion rank ([[conv.rank]](conv.rank "6.9.6 Conversion ranks")) of U is greater than
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the floating-point conversion rank of value_type[.](#7.sentence-1)
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[ð](#lib:basic_vec,constructor__)
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`template<class G> constexpr explicit basic_vec(G&& gen);
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`
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[8](#8)
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[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/numerics.tex#L17769)
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Let Fromi denote the typedecltype(gen(integral_constant<*simd-size-type*, i>()))[.](#8.sentence-1)
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[9](#9)
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[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/numerics.tex#L17773)
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*Constraints*: Fromi satisfies [convertible_to](concept.convertible#concept:convertible_to "18.4.4 Concept convertible_to [concept.convertible]")<value_type> for all i in
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the range of [0, size())[.](#9.sentence-1)
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In addition, for all i in the range of [0, size()), if Fromi is an arithmetic type, conversion from Fromi to value_type is value-preserving[.](#9.sentence-2)
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[10](#10)
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[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/numerics.tex#L17781)
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*Effects*: Initializes the ith element withstatic_cast<value_type>(gen(integral_constant<*simd-size-type*,
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i>())) for all i in the range of [0, size())[.](#10.sentence-1)
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[11](#11)
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[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/numerics.tex#L17787)
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*Remarks*: gen is invoked exactly once for each i, in increasing order of i[.](#11.sentence-1)
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[ð](#lib:basic_vec,constructor___)
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`template<class R, class... Flags>
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constexpr basic_vec(R&& r, flags<Flags...> = {});
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template<class R, class... Flags>
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constexpr basic_vec(R&& r, const mask_type& mask, flags<Flags...> = {});
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`
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[12](#12)
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[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/numerics.tex#L17801)
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Let mask be mask_type(true) for the overload with nomask parameter[.](#12.sentence-1)
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[13](#13)
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[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/numerics.tex#L17805)
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*Constraints*:
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- [(13.1)](#13.1)
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R models ranges::[contiguous_range](range.refinements#concept:contiguous_range "25.4.6 Other range refinements [range.refinements]") and ranges::[sized_range](range.sized#concept:sized_range "25.4.4 Sized ranges [range.sized]"),
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- [(13.2)](#13.2)
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ranges::size(r) is a constant expression, and
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- [(13.3)](#13.3)
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ranges::size(r) is equal to size()[.](#13.sentence-1)
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[14](#14)
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[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/numerics.tex#L17814)
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*Mandates*:
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- [(14.1)](#14.1)
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ranges::range_value_t<R> is a vectorizable type, and
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- [(14.2)](#14.2)
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if the template parameter pack Flags does not contain *convert-flag*, then the conversion from ranges::range_value_t<R> to value_type is value-preserving[.](#14.sentence-1)
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[15](#15)
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[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/numerics.tex#L17825)
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*Preconditions*:
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- [(15.1)](#15.1)
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If the template parameter pack Flags contains *aligned-flag*, ranges::data(r) points to
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storage aligned by alignment_v<basic_vec,
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ranges::range_value_t<R>>[.](#15.1.sentence-1)
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- [(15.2)](#15.2)
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If the template parameter pack Flags contains *overaligned-flag*<N>, ranges::data(r) points to
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storage aligned by N[.](#15.2.sentence-1)
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[16](#16)
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[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/numerics.tex#L17839)
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*Effects*: Initializes the ith element with mask[i] ?static_cast<T>(ranges::data(r)[i]) : T() for all i in the
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range of [0, size())[.](#16.sentence-1)
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[ð](#itemdecl:5)
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`template<class R, class... Ts>
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basic_vec(R&& r, Ts...) -> see below;
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`
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[17](#17)
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[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/numerics.tex#L17852)
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*Constraints*:
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- [(17.1)](#17.1)
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R models ranges::[contiguous_range](range.refinements#concept:contiguous_range "25.4.6 Other range refinements [range.refinements]") and ranges::[sized_range](range.sized#concept:sized_range "25.4.4 Sized ranges [range.sized]"), and
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- [(17.2)](#17.2)
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ranges::size(r) is a constant expression[.](#17.sentence-1)
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[18](#18)
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[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/numerics.tex#L17860)
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*Remarks*: The deduced type is equivalent to vec<ranges::range_value_t<R>,
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ranges::size(r)>[.](#18.sentence-1)
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[ð](#lib:basic_vec,constructor____)
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`template<[simd-floating-point](simd.expos#concept:simd-floating-point "29.10.2 Exposition-only types, variables, and concepts [simd.expos]") V>
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constexpr explicit(see below)
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basic_vec(const V& reals, const V& imags = {}) noexcept;
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`
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[19](#19)
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[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/numerics.tex#L17874)
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*Constraints*:
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- [(19.1)](#19.1)
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[*simd-complex*](simd.expos#concept:simd-complex "29.10.2 Exposition-only types, variables, and concepts [simd.expos]")<basic_vec> is modeled, and
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- [(19.2)](#19.2)
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V::size() == size() is true[.](#19.sentence-1)
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[20](#20)
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[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/numerics.tex#L17883)
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*Effects*: Initializes the ith element with value_type(reals[i],
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imags[i]) for all i in the range [0, size())[.](#20.sentence-1)
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[21](#21)
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[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/numerics.tex#L17888)
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*Remarks*: The expression inside explicit evaluates to false if and only
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if the floating-point conversion rank of T::value_type is greater than
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or equal to the floating-point conversion rank of V::value_type[.](#21.sentence-1)
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