<sect2 id="multi_array_ref">

<title><literal>multi_array_ref</literal></title>

<para>

<literal>multi_array_ref</literal> is a multi-dimensional container

adaptor. It provides the MultiArray interface over any contiguous

block of elements. <literal>multi_array_ref</literal> exports the

same interface as <literal>multi_array</literal>, with the exception

of the constructors.

</para>

<formalpara>

<title>Model Of.</title>

<para>

<literal>multi_array_ref</literal> models

<link linkend="MultiArray">MultiArray</link>,

<ulink url="../../../libs/utility/CopyConstructible.html">CopyConstructible</ulink>

and depending on the element type, it may also model

<ulink url="https://www.boost.org/sgi/stl/EqualityComparable.html">EqualityComparable</ulink> and <ulink url="https://www.boost.org/sgi/stl/LessThanComparable.html">LessThanComparable</ulink>.

Detailed descriptions are provided here only for operations that are

not described in the <literal>multi_array</literal> reference.

</para>

</formalpara>

<formalpara>

<title>Synopsis</title>

<programlisting>

</programlisting>

</formalpara>

<formalpara>

<title>Constructors</title>

<variablelist>

<varlistentry>

<term><programlisting>template &lt;typename ExtentList&gt;

explicit multi_array_ref(element* data,

const ExtentList&amp; sizes,

const storage_order&amp; store = c_storage_order(),

const Allocator&amp; alloc = Allocator());

</programlisting></term>

<listitem>

<para>

This constructs a <literal>multi_array_ref</literal> using the specified

parameters. <literal>sizes</literal> specifies the shape of the

constructed <literal>multi_array_ref</literal>. <literal>store</literal>

specifies the storage order or layout in memory of the array

dimensions. <literal>alloc</literal> is used to

allocate the contained elements.

</para>

<formalpara><title><literal>ExtentList</literal> Requirements</title>

<para>

<literal>ExtentList</literal> must model <ulink url="../../utility/Collection.html">Collection</ulink>.

</para>

</formalpara>

<formalpara><title>Preconditions</title>

<para><literal>sizes.size() == NumDims;</literal></para>

</formalpara>

</listitem>

</varlistentry>

<varlistentry>

<term>

<programlisting><![CDATA[explicit multi_array_ref(element* data,

</programlisting></term>

<listitem>

<para>

This constructs a <literal>multi_array_ref</literal> using the specified

parameters. <literal>ranges</literal> specifies the shape and

index bases of the constructed multi_array_ref. It is the result of

<literal>NumDims</literal> chained calls to

<literal>extent_gen::operator[]</literal>. <literal>store</literal>

specifies the storage order or layout in memory of the array

dimensions.

</para>

</listitem>

</varlistentry>

<varlistentry>

<term><programlisting>

</programlisting></term>

<listitem>

<para>This constructs a shallow copy of <literal>x</literal>.

</para>

<formalpara>

<title>Complexity</title>

<para> Constant time (for contrast, compare this to

the <literal>multi_array</literal> class copy constructor).

</para></formalpara>

</listitem>

</varlistentry>

</variablelist>

</formalpara>

<formalpara>

<title>Modifiers</title>

<variablelist>

<varlistentry>

<term><programlisting>

</programlisting>

</term>

<listitem>

<para>This performs an element-wise copy of <literal>x</literal>

into the current <literal>multi_array_ref</literal>.</para>

<formalpara>

<title><literal>Array</literal> Requirements</title>

<para><literal>Array</literal> must model MultiArray.

</para></formalpara>

<formalpara>

<title>Preconditions</title>

<para>

<programlisting>std::equal(this->shape(),this->shape()+this->num_dimensions(),

x.shape());</programlisting></para>

</formalpara>

<formalpara>

<title>Postconditions</title>

<para>

<programlisting>(*.this) == x;</programlisting>

</para>

</formalpara>

<formalpara>

<title>Complexity</title>

<para>The assignment operators perform

O(<literal>x.num_elements()</literal>) calls to <literal>element</literal>'s

copy constructor.</para></formalpara>

</listitem>

</varlistentry>

</variablelist>

</formalpara>

</sect2>