<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta name="generator" content= "HTML Tidy for Linux/x86 (vers 1st March 2004), see www.w3.org" /> <meta http-equiv="Content-Type" content= "text/html; charset=us-ascii" /> <link rel="stylesheet" href="../../../../boost.css" type="text/css"/> <link rel="stylesheet" href="ublas.css" type="text/css" /> <script type="text/javascript" src="js/jquery-1.3.2.min.js" async="async" ></script> <script type="text/javascript" src="js/jquery.toc-gw.js" async="async" ></script> <title>Vector Expressions</title> </head> <body> <h1><img src="../../../../boost.png" align="middle" />Vector Expressions</h1> <div class="toc" id="toc"></div> <h2><a name="vector_expression"></a>Vector Expression</h2> <h4>Description</h4> <p>The templated class <code>vector_expression<E></code> is required to be a public base of all classes which model the Vector Expression concept.</p> <h4>Definition</h4> <p>Defined in the header expression_types.hpp.</p> <h4>Template parameters</h4> <table border="1" summary="parameters"> <tbody> <tr> <th>Parameter</th> <th>Description</th> <th>Default</th> </tr> <tr> <td><code>E</code></td> <td>The type of the vector expression.</td> <td> </td> </tr> </tbody> </table> <h4>Model of</h4> <p>None. <u>Not a Vector Expression</u>! </p> <h4>Type requirements</h4> <p>None.</p> <h4>Public base classes</h4> <p>None.</p> <h4>Members</h4> <table border="1" summary="members"> <tbody> <tr> <th>Member</th> <th>Description</th> </tr> <tr> <td><code>const expression_type &operator () () const</code></td> <td>Returns a <code>const</code> reference of the expression.</td> </tr> <tr> <td><code>expression_type &operator () ()</code></td> <td>Returns a reference of the expression.</td> </tr> </tbody> </table> <h4>Notes</h4> <p>The <code>range</code>, <code>slice</code> and <code>project</code> functions have been removed. Use the free functions defined in <a href="vector_proxy.htm">vector proxy</a> instead.</p> <h2><a name="vector_container"></a>Vector Container</h2> <h4>Description</h4> <p>The templated class <code>vector_container<C></code> is required to be a public base of all classes which model the Vector concept. This includes the class <code>vector</code> itself.</p> <h4>Definition</h4> <p>Defined in the header expression_types.hpp.</p> <h4>Template parameters</h4> <table border="1" summary="parameters"> <tbody> <tr> <th>Parameter</th> <th>Description</th> <th>Default</th> </tr> <tr> <td><code>C</code></td> <td>The type of the vector container.</td> <td> </td> </tr> </tbody> </table> <h4>Model of</h4> <p>None. <u>Not a Vector Expression OR Vector</u>! </p> <h4>Type requirements</h4> <p>None.</p> <h4>Public base classes</h4> <p><code>vector_expression<C></code></p> <h4>Members</h4> <table border="1" summary="members"> <tbody> <tr> <th>Member</th> <th>Description</th> </tr> <tr> <td><code>const container_type &operator () () const</code></td> <td>Returns a <code>const</code> reference of the container.</td> </tr> <tr> <td><code>container_type &operator () ()</code></td> <td>Returns a reference of the container.</td> </tr> </tbody> </table> <h2><a name="vector_references"></a>Vector References</h2> <h3>Reference</h3> <h4>Description</h4> <p>The templated class <code>vector_reference<E></code> contains a reference to a vector expression.</p> <h4>Definition</h4> <p>Defined in the header vector_expression.hpp.</p> <h4>Template parameters</h4> <table border="1" summary="parameters"> <tbody> <tr> <th>Parameter</th> <th>Description</th> <th>Default</th> </tr> <tr> <td><code>E</code></td> <td>The type of the vector expression.</td> <td> </td> </tr> </tbody> </table> <h4>Model of</h4> <p><a href="expression_concept.htm#vector_expression">Vector Expression</a> .</p> <h4>Type requirements</h4> <p>None, except for those imposed by the requirements of <a href= "expression_concept.htm#vector_expression">Vector Expression</a> .</p> <h4>Public base classes</h4> <p><code>vector_expression<vector_reference<E> ></code></p> <h4>Members</h4> <table border="1" summary="members"> <tbody> <tr> <th>Member</th> <th>Description</th> </tr> <tr> <td><code>vector_reference (expression_type &e)</code></td> <td>Constructs a reference of the expression.</td> </tr> <tr> <td><code>void resize (size_type size)</code></td> <td>Resizes the expression to hold at most <code>size</code> elements.</td> </tr> <tr> <td><code>size_type size () const</code></td> <td>Returns the size of the expression.</td> </tr> <tr> <td><code>const_reference operator () (size_type i) const</code></td> <td>Returns the value of the <code>i</code>-th element.</td> </tr> <tr> <td><code>reference operator () (size_type i)</code></td> <td>Returns a reference of the <code>i</code>-th element.</td> </tr> <tr> <td><code>const_iterator begin () const</code></td> <td>Returns a <code>const_iterator</code> pointing to the beginning of the expression.</td> </tr> <tr> <td><code>const_iterator end () const</code></td> <td>Returns a <code>const_iterator</code> pointing to the end of the expression.</td> </tr> <tr> <td><code>iterator begin ()</code></td> <td>Returns a <code>iterator</code> pointing to the beginning of the expression.</td> </tr> <tr> <td><code>iterator end ()</code></td> <td>Returns a <code>iterator</code> pointing to the end of the expression.</td> </tr> <tr> <td><code>const_reverse_iterator rbegin () const</code></td> <td>Returns a <code>const_reverse_iterator</code> pointing to the beginning of the reversed expression.</td> </tr> <tr> <td><code>const_reverse_iterator rend () const</code></td> <td>Returns a <code>const_reverse_iterator</code> pointing to the end of the reversed expression.</td> </tr> <tr> <td><code>reverse_iterator rbegin ()</code></td> <td>Returns a <code>reverse_iterator</code> pointing to the beginning of the reversed expression.</td> </tr> <tr> <td><code>reverse_iterator rend ()</code></td> <td>Returns a <code>reverse_iterator</code> pointing to the end of the reversed expression.</td> </tr> </tbody> </table> <h2><a name="vector_operations"></a>Vector Operations</h2> <h3>Unary Operation Description</h3> <h4>Description</h4> <p>The templated class <code>vector_unary<E, F></code> describes a unary vector operation.</p> <h4>Definition</h4> <p>Defined in the header vector_expression.hpp.</p> <h4>Template parameters</h4> <table border="1" summary="parameters"> <tbody> <tr> <th>Parameter</th> <th>Description</th> <th>Default</th> </tr> <tr> <td><code>E</code></td> <td>The type of the vector expression.</td> <td> </td> </tr> <tr> <td><code>F</code></td> <td>The type of the operation.</td> <td> </td> </tr> </tbody> </table> <h4>Model of</h4> <p><a href="expression_concept.htm#vector_expression">Vector Expression</a> .</p> <h4>Type requirements</h4> <p>None, except for those imposed by the requirements of <a href= "expression_concept.htm#vector_expression">Vector Expression</a> .</p> <h4>Public base classes</h4> <p><code>vector_expression<vector_unary<E, F> ></code></p> <h4>Members</h4> <table border="1" summary="members"> <tbody> <tr> <th>Member</th> <th>Description</th> </tr> <tr> <td><code>vector_unary (const expression_type &e)</code></td> <td>Constructs a description of the expression.</td> </tr> <tr> <td><code>size_type size () const</code></td> <td>Returns the size of the expression.</td> </tr> <tr> <td><code>const_reference operator () (size_type i) const</code></td> <td>Returns the value of the <code>i</code>-th element.</td> </tr> <tr> <td><code>const_iterator begin () const</code></td> <td>Returns a <code>const_iterator</code> pointing to the beginning of the expression.</td> </tr> <tr> <td><code>const_iterator end () const</code></td> <td>Returns a <code>const_iterator</code> pointing to the end of the expression.</td> </tr> <tr> <td><code>const_reverse_iterator rbegin () const</code></td> <td>Returns a <code>const_reverse_iterator</code> pointing to the beginning of the reversed expression.</td> </tr> <tr> <td><code>const_reverse_iterator rend () const</code></td> <td>Returns a <code>const_reverse_iterator</code> pointing to the end of the reversed expression.</td> </tr> </tbody> </table> <h3>Unary Operations</h3> <h4>Prototypes</h4> <pre> <code>template<class E, class F> struct vector_unary_traits { typedef vector_unary<typename E::const_closure_type, F> expression_type; typedef expression_type result_type; }; // (- v) [i] = - v [i] template<class E> typename vector_unary_traits<E, scalar_negate<typename E::value_type> >::result_type operator - (const vector_expression<E> &e); // (conj v) [i] = conj (v [i]) template<class E> typename vector_unary_traits<E, scalar_conj<typename E::value_type> >::result_type conj (const vector_expression<E> &e); // (real v) [i] = real (v [i]) template<class E> typename vector_unary_traits<E, scalar_real<typename E::value_type> >::result_type real (const vector_expression<E> &e); // (imag v) [i] = imag (v [i]) template<class E> typename vector_unary_traits<E, scalar_imag<typename E::value_type> >::result_type imag (const vector_expression<E> &e); // (trans v) [i] = v [i] template<class E> typename vector_unary_traits<E, scalar_identity<typename E::value_type> >::result_type trans (const vector_expression<E> &e); // (herm v) [i] = conj (v [i]) template<class E> typename vector_unary_traits<E, scalar_conj<typename E::value_type> >::result_type herm (const vector_expression<E> &e);</code> </pre> <h4>Description</h4> <p><code>operator -</code> computes the additive inverse of a vector expression. <code>conj</code> computes the complex conjugate of a vector expression. <code>real</code> and <code>imag</code> compute the real and imaginary parts of a vector expression. <code>trans</code> computes the transpose of a vector expression. <code>herm</code> computes the hermitian, i.e. the complex conjugate of the transpose of a vector expression.</p> <h4>Definition</h4> <p>Defined in the header vector_expression.hpp.</p> <h4>Type requirements</h4> <ul> <li><code>E</code> is a model of <a href= "expression_concept.htm#vector_expression">Vector Expression</a> .</li> </ul> <h4>Preconditions</h4> <p>None.</p> <h4>Complexity</h4> <p>Linear depending from the size of the vector expression.</p> <h4>Examples</h4> <pre> #include <boost/numeric/ublas/vector.hpp> #include <boost/numeric/ublas/io.hpp> int main () { using namespace boost::numeric::ublas; vector<std::complex<double> > v (3); for (unsigned i = 0; i < v.size (); ++ i) v (i) = std::complex<double> (i, i); std::cout << - v << std::endl; std::cout << conj (v) << std::endl; std::cout << real (v) << std::endl; std::cout << imag (v) << std::endl; std::cout << trans (v) << std::endl; std::cout << herm (v) << std::endl; } </pre> <h3>Binary Operation Description</h3> <h4>Description</h4> <p>The templated class <code>vector_binary<E1, E2, F></code> describes a binary vector operation.</p> <h4>Definition</h4> <p>Defined in the header vector_expression.hpp.</p> <h4>Template parameters</h4> <table border="1" summary="parameters"> <tbody> <tr> <th>Parameter</th> <th>Description</th> <th>Default</th> </tr> <tr> <td><code>E1</code></td> <td>The type of the first vector expression.</td> <td></td> </tr> <tr> <td><code>E2</code></td> <td>The type of the second vector expression.</td> <td></td> </tr> <tr> <td><code>F</code></td> <td>The type of the operation.</td> <td></td> </tr> </tbody> </table> <h4>Model of</h4> <p><a href="expression_concept.htm#vector_expression">Vector Expression</a> .</p> <h4>Type requirements</h4> <p>None, except for those imposed by the requirements of <a href= "expression_concept.htm#vector_expression">Vector Expression</a> .</p> <h4>Public base classes</h4> <p><code>vector_expression<vector_binary<E1, E2, F> ></code></p> <h4>Members</h4> <table border="1" summary="members"> <tbody> <tr> <th>Member</th> <th>Description</th> </tr> <tr> <td><code>vector_binary (const expression1_type &e1, const expression2_type &e2)</code></td> <td>Constructs a description of the expression.</td> </tr> <tr> <td><code>size_type size () const</code></td> <td>Returns the size of the expression.</td> </tr> <tr> <td><code>const_reference operator () (size_type i) const</code></td> <td>Returns the value of the <code>i</code>-th element.</td> </tr> <tr> <td><code>const_iterator begin () const</code></td> <td>Returns a <code>const_iterator</code> pointing to the beginning of the expression.</td> </tr> <tr> <td><code>const_iterator end () const</code></td> <td>Returns a <code>const_iterator</code> pointing to the end of the expression.</td> </tr> <tr> <td><code>const_reverse_iterator rbegin () const</code></td> <td>Returns a <code>const_reverse_iterator</code> pointing to the beginning of the reversed expression.</td> </tr> <tr> <td><code>const_reverse_iterator rend () const</code></td> <td>Returns a <code>const_reverse_iterator</code> pointing to the end of the reversed expression.</td> </tr> </tbody> </table> <h3>Binary Operations</h3> <h4>Prototypes</h4> <pre> <code>template<class E1, class E2, class F> struct vector_binary_traits { typedef vector_binary<typename E1::const_closure_type, typename E2::const_closure_type, F> expression_type; typedef expression_type result_type; }; // (v1 + v2) [i] = v1 [i] + v2 [i] template<class E1, class E2> typename vector_binary_traits<E1, E2, scalar_plus<typename E1::value_type, typename E2::value_type> >::result_type operator + (const vector_expression<E1> &e1, const vector_expression<E2> &e2); // (v1 - v2) [i] = v1 [i] - v2 [i] template<class E1, class E2> typename vector_binary_traits<E1, E2, scalar_minus<typename E1::value_type, typename E2::value_type> >::result_type operator - (const vector_expression<E1> &e1, const vector_expression<E2> &e2);</code> </pre> <h4>Description</h4> <p><code>operator +</code> computes the sum of two vector expressions. <code>operator -</code> computes the difference of two vector expressions.</p> <h4>Definition</h4> <p>Defined in the header vector_expression.hpp.</p> <h4>Type requirements</h4> <ul> <li><code>E1</code> is a model of <a href= "expression_concept.htm#vector_expression">Vector Expression</a> .</li> <li><code>E2</code> is a model of <a href= "expression_concept.htm#vector_expression">Vector Expression</a> .</li> </ul> <h4>Preconditions</h4> <ul> <li><code>e1 ().size () == e2 ().size ()</code></li> </ul> <h4>Complexity</h4> <p>Linear depending from the size of the vector expressions.</p> <h4>Examples</h4> <pre> #include <boost/numeric/ublas/vector.hpp> #include <boost/numeric/ublas/io.hpp> int main () { using namespace boost::numeric::ublas; vector<double> v1 (3), v2 (3); for (unsigned i = 0; i < std::min (v1.size (), v2.size ()); ++ i) v1 (i) = v2 (i) = i; std::cout << v1 + v2 << std::endl; std::cout << v1 - v2 << std::endl; } </pre> <h3>Binary Outer Operation Description</h3> <h4>Description</h4> <p>The templated class <code>vector_matrix_binary<E1, E2, F></code> describes a binary outer vector operation.</p> <h4>Definition</h4> <p>Defined in the header matrix_expression.hpp.</p> <h4>Template parameters</h4> <table border="1" summary="parameters"> <tbody> <tr> <th>Parameter</th> <th>Description</th> <th>Default</th> </tr> <tr> <td><code>E1</code></td> <td>The type of the first vector expression.</td> <td></td> </tr> <tr> <td><code>E2</code></td> <td>The type of the second vector expression.</td> <td></td> </tr> <tr> <td><code>F</code></td> <td>The type of the operation.</td> <td></td> </tr> </tbody> </table> <h4>Model of</h4> <p><a href="expression_concept.htm#matrix_expression">Matrix Expression</a> .</p> <h4>Type requirements</h4> <p>None, except for those imposed by the requirements of <a href= "expression_concept.htm#matrix_expression">Matrix Expression</a> .</p> <h4>Public base classes</h4> <p><code>matrix_expression<vector_matrix_binary<E1, E2, F> ></code></p> <h4>Members</h4> <table border="1" summary="members"> <tbody> <tr> <th>Member</th> <th>Description</th> </tr> <tr> <td><code>vector_matrix_binary (const expression1_type &e1, const expression2_type &e2)</code></td> <td>Constructs a description of the expression.</td> </tr> <tr> <td><code>size_type size1 () const</code></td> <td>Returns the number of rows.</td> </tr> <tr> <td><code>size_type size2 () const</code></td> <td>Returns the number of columns.</td> </tr> <tr> <td><code>const_reference operator () (size_type i, size_type j) const</code></td> <td>Returns the value of the <code>j</code>-th element in the <code>i</code>-th row.</td> </tr> <tr> <td><code>const_iterator1 begin1 () const</code></td> <td>Returns a <code>const_iterator1</code> pointing to the beginning of the expression.</td> </tr> <tr> <td><code>const_iterator1 end1 () const</code></td> <td>Returns a <code>const_iterator1</code> pointing to the end of the expression.</td> </tr> <tr> <td><code>const_iterator2 begin2 () const</code></td> <td>Returns a <code>const_iterator2</code> pointing to the beginning of the expression.</td> </tr> <tr> <td><code>const_iterator2 end2 () const</code></td> <td>Returns a <code>const_iterator2</code> pointing to the end of the expression.</td> </tr> <tr> <td><code>const_reverse_iterator1 rbegin1 () const</code></td> <td>Returns a <code>const_reverse_iterator1</code> pointing to the beginning of the reversed expression.</td> </tr> <tr> <td><code>const_reverse_iterator1 rend1 () const</code></td> <td>Returns a <code>const_reverse_iterator1</code> pointing to the end of the reversed expression.</td> </tr> <tr> <td><code>const_reverse_iterator2 rbegin2 () const</code></td> <td>Returns a <code>const_reverse_iterator2</code> pointing to the beginning of the reversed expression.</td> </tr> <tr> <td><code>const_reverse_iterator2 rend2 () const</code></td> <td>Returns a <code>const_reverse_iterator2</code> pointing to the end of the reversed expression.</td> </tr> </tbody> </table> <h3>Binary Outer Operations</h3> <h4>Prototypes</h4> <pre> <code>template<class E1, class E2, class F> struct vector_matrix_binary_traits { typedef vector_matrix_binary<typename E1::const_closure_type, typename E2::const_closure_type, F> expression_type; typedef expression_type result_type; }; // (outer_prod (v1, v2)) [i] [j] = v1 [i] * v2 [j] template<class E1, class E2> typename vector_matrix_binary_traits<E1, E2, scalar_multiplies<typename E1::value_type, typename E2::value_type> >::result_type outer_prod (const vector_expression<E1> &e1, const vector_expression<E2> &e2);</code> </pre> <h4>Description</h4> <p><code>outer_prod</code> computes the outer product of two vector expressions.</p> <h4>Definition</h4> <p>Defined in the header matrix_expression.hpp.</p> <h4>Type requirements</h4> <ul> <li><code>E1</code> is a model of <a href= "expression_concept.htm#vector_expression">Vector Expression</a> .</li> <li><code>E2</code> is a model of <a href= "expression_concept.htm#vector_expression">Vector Expression</a> .</li> </ul> <h4>Preconditions</h4> <p>None.</p> <h4>Complexity</h4> <p>Quadratic depending from the size of the vector expressions.</p> <h4>Examples</h4> <pre> #include <boost/numeric/ublas/matrix.hpp> #include <boost/numeric/ublas/io.hpp> int main () { using namespace boost::numeric::ublas; vector<double> v1 (3), v2 (3); for (unsigned i = 0; i < std::min (v1.size (), v2.size ()); ++ i) v1 (i) = v2 (i) = i; std::cout << outer_prod (v1, v2) << std::endl; } </pre> <h3>Scalar Vector Operation Description</h3> <h4>Description</h4> <p>The templated classes <code>vector_binary_scalar1<E1, E2, F></code> and <code>vector_binary_scalar2<E1, E2, F></code> describe binary operations between a scalar and a vector.</p> <h4>Definition</h4> <p>Defined in the header vector_expression.hpp.</p> <h4>Template parameters</h4> <table border="1" summary="parameters"> <tbody> <tr> <th>Parameter</th> <th>Description</th> <th>Default</th> </tr> <tr> <td><code>E1/E2</code></td> <td>The type of the scalar expression.</td> <td></td> </tr> <tr> <td><code>E2/E1</code></td> <td>The type of the vector expression.</td> <td></td> </tr> <tr> <td><code>F</code></td> <td>The type of the operation.</td> <td></td> </tr> </tbody> </table> <h4>Model of</h4> <p><a href="expression_concept.htm#vector_expression">Vector Expression</a> .</p> <h4>Type requirements</h4> <p>None, except for those imposed by the requirements of <a href= "expression_concept.htm#vector_expression">Vector Expression</a> .</p> <h4>Public base classes</h4> <p><code>vector_expression<vector_binary_scalar1<E1, E2, F> ></code> and <code>vector_expression<vector_binary_scalar2<E1, E2, F> ></code> resp.</p> <h4>Members</h4> <table border="1" summary="members"> <tbody> <tr> <th>Member</th> <th>Description</th> </tr> <tr> <td><code>vector_binary_scalar1 (const expression1_type &e1, const expression2_type &e2)</code></td> <td>Constructs a description of the expression.</td> </tr> <tr> <td><code>vector_binary_scalar2 (const expression1_type &e1, const expression2_type &e2)</code></td> <td>Constructs a description of the expression.</td> </tr> <tr> <td><code>size_type size () const</code></td> <td>Returns the size of the expression.</td> </tr> <tr> <td><code>const_reference operator () (size_type i) const</code></td> <td>Returns the value of the <code>i</code>-th element.</td> </tr> <tr> <td><code>const_iterator begin () const</code></td> <td>Returns a <code>const_iterator</code> pointing to the beginning of the expression.</td> </tr> <tr> <td><code>const_iterator end () const</code></td> <td>Returns a <code>const_iterator</code> pointing to the end of the expression.</td> </tr> <tr> <td><code>const_reverse_iterator rbegin () const</code></td> <td>Returns a <code>const_reverse_iterator</code> pointing to the beginning of the reversed expression.</td> </tr> <tr> <td><code>const_reverse_iterator rend () const</code></td> <td>Returns a <code>const_reverse_iterator</code> pointing to the end of the reversed expression.</td> </tr> </tbody> </table> <h3>Scalar Vector Operations</h3> <h4>Prototypes</h4> <pre> <code>template<class T1, class E2, class F> struct vector_binary_scalar1_traits { typedef vector_binary_scalar1<scalar_const_reference<T1>, typename E2::const_closure_type, F> expression_type; typedef expression_type result_type; }; // (t * v) [i] = t * v [i] template<class T1, class E2> typename vector_binary_scalar1_traits<T1, E2, scalar_multiplies<T1, typename E2::value_type> >::result_type operator * (const T1 &e1, const vector_expression<E2> &e2); template<class E1, class T2, class F> struct vector_binary_scalar2_traits { typedef vector_binary_scalar2<typename E1::const_closure_type, scalar_const_reference<T2>, F> expression_type; typedef expression_type result_type; }; // (v * t) [i] = v [i] * t template<class E1, class T2> typename vector_binary_scalar2_traits<E1, T2, scalar_multiplies<typename E1::value_type, T2> >::result_type operator * (const vector_expression<E1> &e1, const T2 &e2); // (v / t) [i] = v [i] / t template<class E1, class T2> typename vector_binary_scalar2_traits<E1, T2, scalar_divides<typename E1::value_type, T2> >::result_type operator / (const vector_expression<E1> &e1, const T2 &e2);</code> </pre> <h4>Description</h4> <p><code>operator *</code> computes the product of a scalar and a vector expression. <code>operator /</code> multiplies the vector with the reciprocal of the scalar.</p> <h4>Definition</h4> <p>Defined in the header vector_expression.hpp.</p> <h4>Type requirements</h4> <ul> <li><code>T1/T2</code> is a model of <a href= "expression_concept.htm#scalar_expression">Scalar Expression</a> .</li> <li><code>E2/E1</code> is a model of <a href= "expression_concept.htm#vector_expression">Vector Expression</a> .</li> </ul> <h4>Preconditions</h4> <p>None.</p> <h4>Complexity</h4> <p>Linear depending from the size of the vector expression.</p> <h4>Examples</h4> <pre> #include <boost/numeric/ublas/vector.hpp> #include <boost/numeric/ublas/io.hpp> int main () { using namespace boost::numeric::ublas; vector<double> v (3); for (unsigned i = 0; i < v.size (); ++ i) v (i) = i; std::cout << 2.0 * v << std::endl; std::cout << v * 2.0 << std::endl; } </pre> <h2><a name="vector_reductions"></a>Vector Reductions</h2> <h3>Unary Reductions</h3> <h4>Prototypes</h4> <pre> <code>template<class E, class F> struct vector_scalar_unary_traits { typedef typename F::result_type result_type; }; // sum v = sum (v [i]) template<class E> typename vector_scalar_unary_traits<E, vector_sum<typename E::value_type> >::result_type sum (const vector_expression<E> &e); // norm_1 v = sum (abs (v [i])) template<class E> typename vector_scalar_unary_traits<E, vector_norm_1<typename E::value_type> >::result_type norm_1 (const vector_expression<E> &e); // norm_2 v = sqrt (sum (v [i] * v [i])) template<class E> typename vector_scalar_unary_traits<E, vector_norm_2<typename E::value_type> >::result_type norm_2 (const vector_expression<E> &e); // norm_inf v = max (abs (v [i])) template<class E> typename vector_scalar_unary_traits<E, vector_norm_inf<typename E::value_type> >::result_type norm_inf (const vector_expression<E> &e); // index_norm_inf v = min (i: abs (v [i]) == max (abs (v [i]))) template<class E> typename vector_scalar_unary_traits<E, vector_index_norm_inf<typename E::value_type> >::result_type index_norm_inf (const vector_expression<E> &e);</code> </pre> <h4>Description</h4> <p><code>sum</code> computes the sum of the vector expression's elements. <code>norm_1</code>, <code>norm_2</code> and <code>norm_inf</code> compute the corresponding <em>||.||</em><sub><em>1</em></sub>, <em>||.||</em><sub><em>2</em></sub> and <em>||.||</em><sub><em>inf</em></sub> vector norms. <code>index_norm_1</code> computes the index of the vector expression's first element having maximal absolute value.</p> <h4>Definition</h4> <p>Defined in the header vector_expression.hpp.</p> <h4>Type requirements</h4> <ul> <li><code>E</code> is a model of <a href= "#vector_expression">Vector Expression</a> .</li> </ul> <h4>Preconditions</h4> <p>None.</p> <h4>Complexity</h4> <p>Linear depending from the size of the vector expression.</p> <h4>Examples</h4> <pre> #include <boost/numeric/ublas/vector.hpp> int main () { using namespace boost::numeric::ublas; vector<double> v (3); for (unsigned i = 0; i < v.size (); ++ i) v (i) = i; std::cout << sum (v) << std::endl; std::cout << norm_1 (v) << std::endl; std::cout << norm_2 (v) << std::endl; std::cout << norm_inf (v) << std::endl; std::cout << index_norm_inf (v) << std::endl; } </pre> <h3>Binary Reductions</h3> <h4>Prototypes</h4> <pre> <code>template<class E1, class E2, class F> struct vector_scalar_binary_traits { typedef typename F::result_type result_type; }; // inner_prod (v1, v2) = sum (v1 [i] * v2 [i]) template<class E1, class E2> typename vector_scalar_binary_traits<E1, E2, vector_inner_prod<typename E1::value_type, typename E2::value_type, typename promote_traits<typename E1::value_type, typename E2::value_type>::promote_type> >::result_type inner_prod (const vector_expression<E1> &e1, const vector_expression<E2> &e2); template<class E1, class E2> typename vector_scalar_binary_traits<E1, E2, vector_inner_prod<typename E1::value_type, typename E2::value_type, typename type_traits<typename promote_traits<typename E1::value_type, typename E2::value_type>::promote_type>::precision_type> >::result_type prec_inner_prod (const vector_expression<E1> &e1, const vector_expression<E2> &e2);</code> </pre> <h4>Description</h4> <p><code>inner_prod</code> computes the inner product of the vector expressions. <code>prec_inner_prod</code> computes the double precision inner product of the vector expressions<code>.</code></p> <h4>Definition</h4> <p>Defined in the header vector_expression.hpp.</p> <h4>Type requirements</h4> <ul> <li><code>E1</code> is a model of <a href= "#vector_expression">Vector Expression</a> .</li> <li><code>E2</code> is a model of <a href= "#vector_expression">Vector Expression</a> .</li> </ul> <h4>Preconditions</h4> <ul> <li><code>e1 ().size () == e2 ().size ()</code></li> </ul> <h4>Complexity</h4> <p>Linear depending from the size of the vector expressions.</p> <h4>Examples</h4> <pre> #include <boost/numeric/ublas/vector.hpp> int main () { using namespace boost::numeric::ublas; vector<double> v1 (3), v2 (3); for (unsigned i = 0; i < std::min (v1.size (), v2.size ()); ++ i) v1 (i) = v2 (i) = i; std::cout << inner_prod (v1, v2) << std::endl; } </pre> <hr /> <p>Copyright (©) 2000-2002 Joerg Walter, Mathias Koch<br /> Use, modification and distribution are subject to the Boost Software License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt"> http://www.boost.org/LICENSE_1_0.txt </a>). </p> <script type="text/javascript"> (function($) { $('#toc').toc(); })(jQuery); </script> </body> </html>