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<html>
<head>
<title>Blitz++ User's Guide </title>
</head>
<body fgcolor="#27408B" bgcolor="#FFFAF0" >
<hr>
<ul>
<li> <a href="blitz08.html">Next chapter</a>
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<hr>
<a name="l108"></a>
<h1>Chapter 7: TinyVector</h1>
<a name="tinyvector"></a>
<!-- BZINDEX TinyVector --><a name="index00424">
<p>The <code>TinyVector</code> class provides a small, lightweight vector
object whose size is known at compile time. It is included
via the header <code><blitz/tinyvec.h></code>.
<p>Note that <code>TinyVector</code> lives in the <code>blitz</code> namespace,
so you will need to refer to it as <code>blitz::TinyVector</code>,
or use the directive <code>using namespace blitz;</code>.
<p>The Blitz++ <code>Array</code> object uses <code>TinyVector</code> internally, so
if you include <code><blitz/array.h></code>, the TinyVector
header is automatically included.
<p><br><br><br><table width="100%" border="0" cellpadding=10 align=center><tr><td align="left" bgcolor="#0b6698"><font color="#ffffff" face="Helvetica" size=+5>7.1: Template parameters and types</font></td></tr></table><br><a name="l109"></a>
<p>The <code>TinyVector<T,N></code> class has two template parameters:
<p><dl>
<p><p></p><dt><strong><code>T</code></strong><dd> is the numeric type of the vector (float, double, int,
<code>complex<float></code>, etc.;
<p><p></p><dt><strong><code>N</code></strong><dd> is the number of elements in the vector.
<p></dl>
<p>Inside the <code>TinyVector</code> class, these types are declared:
<p><dl>
<p><p></p><dt><strong><code>T_numtype</code></strong><dd> is the numeric type stored in the vector (the
template parameter <code>T</code>)
<p><p></p><dt><strong><code>T_vector</code></strong><dd> is the vector type <code>TinyVector<T,N></code>.
<p><p></p><dt><strong><code>iterator</code></strong><dd> is an STL-style iterator.
<p><p></p><dt><strong><code>constIterator</code></strong><dd> is an STL-style const iterator.
<p></dl>
<p><br><br><br><table width="100%" border="0" cellpadding=10 align=center><tr><td align="left" bgcolor="#0b6698"><font color="#ffffff" face="Helvetica" size=+5>7.2: Constructors</font></td></tr></table><br><a name="l110"></a>
<p><strong><pre>TinyVector();
</pre></strong>
The elements of the vector are left uninitialized.
<p><strong><pre>TinyVector(const TinyVector<T,N>& x);
</pre></strong>
The elements of vector <code>x</code> are copied.
<p><strong><pre>TinyVector(T value);
</pre></strong>
All elements are initialized to <code>value</code>.
<p><strong><pre>TinyVector(T value1, T value2, ...)
</pre></strong>
The vector is initialized with the list of values given.
These constructors are provided for up to N=11.
<p><br><br><br><table width="100%" border="0" cellpadding=10 align=center><tr><td align="left" bgcolor="#0b6698"><font color="#ffffff" face="Helvetica" size=+5>7.3: Member functions</font></td></tr></table><br><a name="l111"></a>
<p><strong><pre>TinyVector<T,N>::iterator begin();
TinyVector<T,N>::const_iterator begin() const;
</pre></strong>
Returns an STL-style iterator for the vector, positioned
at the beginning of the data.
<p><strong><pre>TinyVector<T,N>::iterator end();
TinyVector<T,N>::const_iterator end() const;
</pre></strong>
Returns an STL-style iterator for the vector, positioned
at the end of the data.
<p><strong><pre>T_numtype* [restrict] data();
const T_numtype* [restrict] data() const;
</pre></strong>
Returns a pointer to the first element in the vector.
<p><strong><pre>int length() const;
</pre></strong>
Returns the length of the vector (the template parameter <code>N</code>).
<p><strong><pre>T_numtype operator()(int i) const;
T_numtype& operator()(int i);
T_numtype operator[](int i) const;
T_numtype& operator[](int i);
</pre></strong>
Returns the <code>i</code>th element of the vector. If the
code is compiled with debugging enabled (<code>-DBZ_DEBUG</code>),
bounds checking is performed.
<p><br><br><br><table width="100%" border="0" cellpadding=10 align=center><tr><td align="left" bgcolor="#0b6698"><font color="#ffffff" face="Helvetica" size=+5>7.4: Assignment operators</font></td></tr></table><br><a name="l112"></a>
<p>The assignment operators =, +=, -=, *=, /=, %=, ^=, &=, |=, >>= and <<=
are all provided. The right hand side of an assignment may be a
scalar of type <code>T_numtype</code>, a <code>TinyVector</code> of any type but the
same size, or a vector expression.
<p><br><br><br><table width="100%" border="0" cellpadding=10 align=center><tr><td align="left" bgcolor="#0b6698"><font color="#ffffff" face="Helvetica" size=+5>7.5: Expressions</font></td></tr></table><br><a name="l113"></a>
<p>Expressions involving tiny vectors may contain any combination
of the operators
<p><code>+ - * / % ^ & | >> <<</code>
<p>with operands of type TinyVector, scalar, or vector expressions.
The usual math functions (see the Array documentation) are supported
on TinyVector.
<p><br><br><br><table width="100%" border="0" cellpadding=10 align=center><tr><td align="left" bgcolor="#0b6698"><font color="#ffffff" face="Helvetica" size=+5>7.6: Global functions</font></td></tr></table><br><a name="l114"></a>
<p><strong><pre>dot(TinyVector, TinyVector);
dot(vector-expr, TinyVector);
dot(TinyVector, vector-expr);
dot(vector-expr, vector-expr);
</pre></strong>
These functions calculate a dot product between TinyVectors
(or vector expressions). The result is a scalar; the type
of the scalar follows the usual type promotion rules.
<p><strong><pre>product(TinyVector);
</pre></strong>
Returns the product of all the elements in the vector.
<p><strong><pre>sum(TinyVector);
</pre></strong>
Returns the sum of the elements in the vector.
<p><strong><pre>TinyVector<T,3> cross(TinyVector<T,3> x, TinyVector<T,3> y);
</pre></strong>
Returns the cross product of <code>x</code> and <code>y</code>.
<p><br><br><br><table width="100%" border="0" cellpadding=10 align=center><tr><td align="left" bgcolor="#0b6698"><font color="#ffffff" face="Helvetica" size=+5>7.7: Arrays of TinyVector</font></td></tr></table><br><a name="l115"></a>
<p><br><br><br><table width="100%" border="0" cellpadding=10 align=center><tr><td align="left" bgcolor="#0b6698"><font color="#ffffff" face="Helvetica" size=+5>7.8: Input/output</font></td></tr></table><br><a name="l116"></a>
<p><strong><pre>ostream& operator<<(ostream&, const TinyVector<T,N>& x)
</pre></strong>
This function outputs a TinyVector onto a stream. Here's
an illustration of the format for a length 3 vector:
<p><strong><pre>[ 0.5 0.2 0.9 ]
</pre></strong>
<p>
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