Added EIGEN_DEFINE_STL_VECTOR_SPECIALIZATION macro including unit tests and documentation.

Eigen/StdVector

@@ -29,6 +29,45 @@
 #include "Core"
 #include <vector>
 
+// Define the explicit instantiation (e.g. necessary for the Intel compiler)
+#if defined(__INTEL_COMPILER) || defined(__GNUC__)
+  #define EIGEN_EXPLICIT_STL_VECTOR_INSTANTIATION(...) template class std::vector<__VA_ARGS__, Eigen::aligned_allocator<__VA_ARGS__> >;
+#else
+  #define EIGEN_EXPLICIT_STL_VECTOR_INSTANTIATION(...)
+#endif
+
+/**
+ * This section contains a convenience MACRO which allows an easy specialization of
+ * std::vector such that for data types with alignment issues the correct allocator
+ * is used automatically.
+ */
+#define EIGEN_DEFINE_STL_VECTOR_SPECIALIZATION(...) \
+EIGEN_EXPLICIT_STL_VECTOR_INSTANTIATION(__VA_ARGS__) \
+namespace std \
+{ \
+  template<typename _Ay> \
+  class vector<__VA_ARGS__, _Ay>  \
+    : public vector<__VA_ARGS__, Eigen::aligned_allocator<__VA_ARGS__> > \
+  { \
+    typedef vector<__VA_ARGS__, Eigen::aligned_allocator<__VA_ARGS__> > vector_base; \
+  public: \
+    typedef __VA_ARGS__ value_type; \
+    typedef typename vector_base::allocator_type allocator_type; \
+    typedef typename vector_base::size_type size_type;  \
+    typedef typename vector_base::iterator iterator;  \
+    explicit vector(const allocator_type& a = allocator_type()) : vector_base(a) {}  \
+    template<typename InputIterator> \
+    vector(InputIterator first, InputIterator last, const allocator_type& a = allocator_type()) : vector_base(first, last, a) {} \
+    vector(const vector& c) : vector_base(c) {}  \
+    explicit vector(size_type num, const value_type& val = value_type()) : vector_base(num, val) {} \
+    vector(iterator start, iterator end) : vector_base(start, end) {}  \
+    vector& operator=(const vector& x) {  \
+      vector_base::operator=(x);  \
+      return *this;  \
+    } \
+  }; \
+}
+
 namespace Eigen {
 
 // This one is needed to prevent reimplementing the whole std::vector.

doc/D01_StlContainers.dox

@@ -41,6 +41,21 @@ Here is an example:
 std::vector<Eigen::Vector4f,Eigen::aligned_allocator<Eigen::Vector4f> >
 \endcode
 
+\subsection vector_spec An alternative - specializing std::vector for Eigen types
+
+As an alternative to the recommended approach described above, you have the option to specialize std::vector for Eigen types requiring alignment. 
+The advantage is that you won't need to declare std::vector all over with Eigen::allocator. One drawback on the other hand side is that
+the specialization needs to be defined before all code pieces in which e.g. std::vector<Vector2d> is used. Otherwise, without knowing the specialization
+the compiler will compile that particular instance with the default std::allocator and you program is most likely to crash.
+
+Here is an example:
+\code
+#include<Eigen/StdVector>
+\/* ... *\/
+EIGEN_DEFINE_STL_VECTOR_SPECIALIZATION(Matrix2d)
+std::vector<Eigen::Vector2d>
+\endcode
+
 <span class="note">\b Explanation: The resize() method of std::vector takes a value_type argument (defaulting to value_type()). So with std::vector<Eigen::Vector4f>, some Eigen::Vector4f objects will be passed by value, which discards any alignment modifiers, so a Eigen::Vector4f can be created at an unaligned location. In order to avoid that, the only solution we saw was to specialize std::vector to make it work on a slight modification of, here, Eigen::Vector4f, that is able to deal properly with this situation.
 </span>
 

doc/snippets/DenseBase_LinSpaced.cpp

@@ -1,2 +1,2 @@
-cout << VectorXi::LinSpaced(7,10,4) << endl;
-cout << VectorXd::LinSpaced(0.0,1.0,5) << endl;
+cout << VectorXi::LinSpaced(7,10,4).transpose() << endl;
+cout << VectorXd::LinSpaced(0.0,1.0,5).transpose() << endl;

test/CMakeLists.txt

@@ -152,6 +152,7 @@ ei_add_test(geo_parametrizedline)
 ei_add_test(geo_alignedbox)
 ei_add_test(regression)
 ei_add_test(stdvector)
+ei_add_test(stdvector_overload)
 ei_add_test(resize)
 if(QT4_FOUND)
   ei_add_test(qtvector " " "${QT_QTCORE_LIBRARY}")