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