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<HEAD>
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<TITLE>slice_array</TITLE>
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<LINK REL=StyleSheet HREF="../rw.css" TYPE="text/css" TITLE="Apache stdcxx Stylesheet"></HEAD>
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<BODY BGCOLOR=#FFFFFF>
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<A HREF="slice.html"><IMG SRC="images/bprev.gif" WIDTH=20 HEIGHT=21 ALT="Previous file" BORDER=O></A><A HREF="noframes.html"><IMG SRC="images/btop.gif" WIDTH=56 HEIGHT=21 ALT="Top of Document" BORDER=O></A><A HREF="booktoc.html"><IMG SRC="images/btoc.gif" WIDTH=56 HEIGHT=21 ALT="Contents" BORDER=O></A><A HREF="tindex.html"><IMG SRC="images/bindex.gif" WIDTH=56 HEIGHT=21 ALT="Index page" BORDER=O></A><A HREF="sort.html"><IMG SRC="images/bnext.gif" WIDTH=25 HEIGHT=21 ALT="Next file" BORDER=O></A><DIV CLASS="DOCUMENTNAME"><B>Apache C++ Standard Library Reference Guide</B></DIV>
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<H2>slice_array</H2>
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<P><B>Library:</B> <A HREF="2-10.html">Numerics</A></P>
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<PRE><HR><B><I>Does not inherit</I></B><HR></PRE>
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<UL>
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<LI><A HREF="#sec1">Local Index</A></LI>
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<LI><A HREF="#sec2">Summary</A></LI>
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<LI><A HREF="#sec3">Synopsis</A></LI>
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<LI><A HREF="#sec4">Description</A></LI>
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<LI><A HREF="#sec5">Interface</A></LI>
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<LI><A HREF="#sec6">Constructors</A></LI>
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<LI><A HREF="#sec7">Assignment Operators</A></LI>
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<LI><A HREF="#sec8">Computed Assignment Operators</A></LI>
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<LI><A HREF="#sec9">Example</A></LI>
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<LI><A HREF="#sec10">See Also</A></LI>
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<LI><A HREF="#sec11">Standards Conformance</A></LI>
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</UL>
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<A NAME="sec1"><H3>Local Index</H3></A>
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<H4>Members</H4>
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<UL><TABLE CELLPADDING=3>
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<TR><TD VALIGN=top>
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<A HREF="#idx1180">operator%=()</A><BR>
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<A HREF="#idx1180">operator&=()</A><BR>
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<A HREF="#idx1180">operator>>=()</A><BR>
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</TD>
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<TD VALIGN=top><A HREF="#idx1180">operator<<=()</A><BR>
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<A HREF="#idx1180">operator*=()</A><BR>
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<A HREF="#idx1180">operator+=()</A><BR>
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</TD>
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<TD VALIGN=top><A HREF="#idx1180">operator-=()</A><BR>
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<A HREF="#idx1180">operator/=()</A><BR>
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<A HREF="#idx1177">operator=()</A><BR>
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</TD>
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<TD VALIGN=top><A HREF="#idx1180">operator^=()</A><BR>
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<A HREF="#idx1180">operator|=()</A><BR>
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<A HREF="#idx1176">slice_array()</A><BR>
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</TD></TR>
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</TABLE></UL>
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<A NAME="sec2"><H3>Summary</H3></A>
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<P>A numeric array class for representing a BLAS-like slice from a <B><I><A HREF="valarray.html">valarray</A></I></B></P>
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<A NAME="sec3"><H3>Synopsis</H3></A>
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<PRE>#include <valarray>
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namespace std {
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template <class T>
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class slice_array;
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}
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</PRE>
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<A NAME="sec4"><H3>Description</H3></A>
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<P>The <B><I><A HREF="valarray.html">valarray</A></I></B> helper class <B><I>slice_array</I></B> gives a slice view into a <B><I>valarray</I></B>. A <B><I>slice_array</I></B> is only produced by applying the slice subscript operator to a <B><I>valarray</I></B>. The elements in a <B><I>slice_array</I></B> are references to selected elements in the <B><I>valarray</I></B> (so changing an element in the <B><I>slice_array</I></B> really changes the corresponding element in the <B><I>valarray</I></B>). A <B><I>slice_array</I></B> does not itself hold any distinct elements. The template cannot be instantiated directly since all its constructors are private. However, you can easily copy a <B><I>slice_array</I></B> to a <B><I>valarray</I></B> using either the <B><I>valarray</I></B> copy constructor or the assignment operator. Reference semantics are lost at that point. </P>
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<A NAME="sec5"><H3>Interface</H3></A>
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<UL><PRE>namespace std {
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template <class T> class slice_array {
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public:
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// types
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typedef T value_type;
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// destructor
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~slice_array();
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// public assignment
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void operator=(const valarray<T>& array) const;
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// computed assignment
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void operator*=(const valarray<T>& array) const;
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void operator/=(const valarray<T>& array) const;
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void operator%=(const valarray<T>& array) const;
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void operator+=(const valarray<T>& array) const;
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void operator-=(const valarray<T>& array) const;
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void operator^=(const valarray<T>& array) const;
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void operator&=(const valarray<T>& array) const;
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void operator|=(const valarray<T>& array) const;
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void operator<<=(const valarray<T>& array) const;
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void operator>>=(const valarray<T>& array) const;
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// other
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void operator=(const T&);
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private:
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// constructors
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slice_array();
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slice_array(const slice_array<T>&);
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// operator=
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slice_array<T>& operator=(const slice_array<T>& array);
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};
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}
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</PRE></UL>
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<A NAME="sec6"><H3>Constructors</H3></A>
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<A NAME="idx1176"></A><PRE><B>slice_array</B>();
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<B>slice_array</B>(const slice_array&);</PRE>
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<UL>
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<P>All <B><I>slice_array</I></B> constructors are private and cannot be called directly. This prevents copy construction of <B><I>slice_array</I></B>s.</P>
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</UL>
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<A NAME="sec7"><H3>Assignment Operators</H3></A>
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<A NAME="idx1177"></A><PRE>void <B>operator=</B>(const valarray<T>& x) const;</PRE>
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<UL>
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<P>Assigns values from <SAMP>x </SAMP>to the selected elements of the <B><I><A HREF="valarray.html">valarray</A></I></B> that self refers to. Remember that a <B><I>slice_array</I></B> never holds any elements itself, it simply refers to selected elements in the <B><I>valarray</I></B> used to generate it.</P>
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</UL>
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<A NAME="idx1178"></A><PRE>slice_array<T>&
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<B>operator=</B>(const slice-_array<T>& x);</PRE>
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<UL>
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<P>Private assignment operator. Cannot be called directly, thus preventing assignment between <B><I>slice_array</I></B>s.</P>
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</UL>
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<A NAME="idx1179"></A><PRE>void <B>operator=</B>(const T& x);</PRE>
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<UL>
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<P>Assigns <SAMP>x</SAMP> to the selected elements of the <B><I><A HREF="valarray.html">valarray</A></I></B> that self refers to. </P>
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</UL>
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<A NAME="sec8"><H3>Computed Assignment Operators</H3></A>
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<A NAME="idx1180"></A><PRE>void <B>operator*=</B>(const valarray<T>& val) const;
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void <B>operator/=</B>(const valarray<T>& val) const;
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void <B>operator%=</B>(const valarray<T>& val) const;
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void <B>operator+=</B>(const valarray<T>& val) const;
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void <B>operator-=</B>(const valarray<T>& val) const;
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void <B>operator^=</B>(const valarray<T>& val) const;
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void <B>operator&=</B>(const valarray<T>& val) const;
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void <B>operator|=</B>(const valarray<T>& val) const;
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void <B>operator<<=</B>(const valarray<T>& val) const;
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void <B>operator>>=</B>(const valarray<T>& val) const;</PRE>
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<UL>
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<P>Applies the indicated operation using elements from <SAMP>val</SAMP> to the selected elements of the <B><I><A HREF="valarray.html">valarray</A></I></B> that self refers to. Remember that a <B><I>slice_array</I></B> never holds any elements itself; it simply refers to selected elements in the <B><I>valarray</I></B> used to generate it.</P>
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</UL>
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<A NAME="sec9"><H3>Example</H3></A>
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<UL><PRE>//
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// slice_array.cpp
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//
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#include <valarray.h> // Includes valarray and provides stream inserter.
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typedef std::valarray<int> valarray_t;
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int main(void) {
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valarray_t::value_type ibuf[9] = {0,1,2,3,4,5,6,7,8};
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// Create a valarray initialized to the sequence of
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// integers above.
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valarray_t vi (ibuf,9);
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std::cout << "original valarray vi\n\n" << vi << "\n\n";
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// Display a slice of the valarray.
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std::cout << "vi[slice(0,3,3)]\n\n"
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<< vi[std::slice(0,3,3)] << "\n\n";
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// Unfortunately, slice_arrays were not designed to be
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// easily combined. An explicit conversion to valarray
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// is required, leaving us with this awkward casting
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// syntax.
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vi[std::slice (0,3,3)] =
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static_cast<valarray_t>(vi[std::slice (1,3,3)]) +
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static_cast<valarray_t>(vi[std::slice (2,3,3)]);
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// The operation above uses slices ([0-2],3,3) to treat
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// our valarray as a 3-dimensional array:
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//
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// 0 1 2 3 = 1 + 2
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// 3 4 5 9 = 4 + 5
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// 6 7 8 15 = 7 + 8
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// | | | | | |
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// | | +-slice(2,3,3) | | +- slice_array for
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// | | | | arithmetic operand.
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// | +---slice(1,3,3) | +----- slice_array for
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// | | arithmetic operand.
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// +-----slice(0,3,3) +---slice_array assignment
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// refers to valarray.
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std::cout << "vi[slice(0,3,3)] = vi[slice(1,3,3)] + "
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<< "vi[slice(2,3,3)]\n\n"
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<< vi << std::endl;
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return 0;
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}
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Program Output:
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</PRE></UL>
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<UL><PRE>original valarray vi
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[0,1,2,3,4,5,6,7,8]
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vi[slice(0,3,3)]
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[0,3,6]
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vi[slice(0,3,3)] = vi[slice(1,3,3)] + vi[slice(2,3,3)]
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[3,1,2,9,4,5,15,7,8]
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</PRE></UL>
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<A NAME="sec10"><H3>See Also</H3></A>
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<P><B><I><A HREF="slice.html">slice</A></I></B>, <B><I><A HREF="valarray.html">valarray</A></I></B>, <B><I><A HREF="gslice.html">gslice</A></I></B>, <B><I><A HREF="gslice-array.html">gslice_array</A></I></B>, <B><I><A HREF="mask-array.html">mask_array</A></I></B>, <B><I><A HREF="indirect-array.html">indirect_array</A></I></B></P>
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<A NAME="sec11"><H3>Standards Conformance</H3></A>
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<P><I>ISO/IEC 14882:1998 -- International Standard for Information Systems -- Programming Language C++, Section 26.3.5</I></P>
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<BR>
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