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<A HREF="22-6.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="VII.html"><IMG SRC="images/bnext.gif" WIDTH=25 HEIGHT=21 ALT="Next file" BORDER=O></A><DIV CLASS="DOCUMENTNAME"><B>Apache C++ Standard Library User's Guide</B></DIV>
<H2>22.7 Non-Member Functions</H2>
<A NAME="2271"><H3>22.7.1 Binary Operators</H3></A>
<A NAME="idx472"><!></A>
<P>Class <B><I><A HREF="../stdlibref/valarray.html">valarray</A></I></B> provides a large block of binary operators that allow a program to apply these operators to two <B><I>valarray</I></B>s or to a <B><I>valarray</I></B> and a <SAMP>T</SAMP> value, where the <SAMP>T</SAMP> can occur on the left- or right-hand side of the expression. As you'd expect, these operators do not modify either of their arguments, but instead return a new <B><I>valarray</I></B> containing the result of the operation. Each version that takes two <B><I>valarray</I></B> arguments returns the result of applying the operation to the corresponding elements of the arrays. The versions with a <SAMP>T&amp;</SAMP> argument return a <B><I>valarray</I></B> whose elements result from applying the operation to each element in the <B><I>valarray</I></B> argument along with the <SAMP>T&amp;</SAMP> argument. See the <B><I>valarray</I></B> entry in the <A HREF="../stdlibref/noframes.html"><I>C++ Standard Library Module Reference Guide</I></A> for a complete list of binary operators.</P>
<P>Arithmetic and bitwise operators return a <B><I><A HREF="../stdlibref/valarray.html">valarray</A></I></B> of <SAMP>T</SAMP>. Logical operators return a <B><I>valarray&lt;bool&gt;</I></B>, where each element represents the comparison of corresponding elements in two <B><I>valarray</I></B>s or the comparison of each element in an array with a particular value. For example:</P>

<UL><PRE>
int a[3] = {1,2,3};
int b[3] = {0,1,4};
std::valarray&lt;int&gt; v1(a,3);
std::valarray&lt;int&gt; v2(b,3); 
std::valarray&lt;int&gt; v3(0,3);
std::valarray&lt;bool&gt; v4(false,3);
v3 = v1 + v2;                      // v3 = {1,3,7}
v4 = v1 == v2;                     // v4 = {false,false,false}
v4 = v1 &lt; v2;                      // v4 = {false,false,true}
</PRE></UL>
<A NAME="2272"><H3>22.7.2 Transcendental Functions</H3></A>
<A NAME="idx473"><!></A>
<P>Class <B><I><A HREF="../stdlibref/valarray.html">valarray</A></I></B> also provides 20 transcendental functions, four of which are overloads. Each function returns a new <B><I>valarray</I></B> that contains elements resulting from the application of the transcendental function to each element in the <B><I>valarray</I></B> passed as an argument. See the <B><I>valarray</I></B> entry in the <A HREF="../stdlibref/noframes.html"><I>C++ Standard Library Module Reference Guide</I></A> for a complete list of transcendental functions. </P>
<P>The following example squares each of the elements of an array:</P>

<UL><PRE>
using std::pow;

float a[3] = {2.0, 4.0, 16.0};
std::valarray&lt;float&gt; v(a,3);            // v = {2.0, 4.0, 16.0}
std::valarray&lt;float&gt; v2(0.0,3);         // v2 = {0.0, 0.0, 0.0}
v2 = std::pow(v,2.0);                   // v2 = {4.0, 16.0, 256.0 }
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