add constructors and accessors/mutators specific to small vectors.

Add corresponding unit-test.

src/Core/Matrix.h

@@ -90,11 +90,61 @@ class Matrix : public MatrixBase<_Scalar, Matrix<_Scalar, _Rows, _Cols> >,
           || (ColsAtCompileTime == 1
               && (RowsAtCompileTime == Dynamic || RowsAtCompileTime == dim)));
     }
-    explicit Matrix(int rows, int cols) : Storage(rows, cols)
+    
+    // this constructor is very tricky.
+    // When Matrix is a fixed-size vector type of size 2,
+    // Matrix(x,y) should mean "construct vector with coefficients x,y".
+    // Otherwise, Matrix(x,y) should mean "construct matrix with x rows and y cols".
+    // Note that in the case of fixed-size, Storage::Storage(int,int) does nothing,
+    // so it is harmless to call it and afterwards we just fill the m_data array
+    // with the two coefficients. In the case of dynamic size, Storage::Storage(int,int)
+    // does what we want to, so it only remains to add some asserts.
+    Matrix(int x, int y) : Storage(x, y)
     {
-      assert(rows > 0 && (RowsAtCompileTime == Dynamic || RowsAtCompileTime == rows)
-          && cols > 0 && (ColsAtCompileTime == Dynamic || ColsAtCompileTime == cols));
+      if((RowsAtCompileTime == 1 && ColsAtCompileTime == 2)
+      || (RowsAtCompileTime == 2 && ColsAtCompileTime == 1))
+      {
+        (Storage::m_data)[0] = x;
+        (Storage::m_data)[1] = y;
+      }
+      else
+      {
+        assert(x > 0 && (RowsAtCompileTime == Dynamic || RowsAtCompileTime == x)
+            && y > 0 && (ColsAtCompileTime == Dynamic || ColsAtCompileTime == y));
+      }
     }
+    Matrix(const float& x, const float& y)
+    {
+      assert((RowsAtCompileTime == 1 && ColsAtCompileTime == 2)
+          || (RowsAtCompileTime == 2 && ColsAtCompileTime == 1));
+      (Storage::m_data)[0] = x;
+      (Storage::m_data)[1] = y;
+    }
+    Matrix(const double& x, const double& y)
+    {
+      assert((RowsAtCompileTime == 1 && ColsAtCompileTime == 2)
+          || (RowsAtCompileTime == 2 && ColsAtCompileTime == 1));
+      (Storage::m_data)[0] = x;
+      (Storage::m_data)[1] = y;
+    }
+    Matrix(const Scalar& x, const Scalar& y, const Scalar& z)
+    {
+      assert((RowsAtCompileTime == 1 && ColsAtCompileTime == 3)
+          || (RowsAtCompileTime == 3 && ColsAtCompileTime == 1));
+      (Storage::m_data)[0] = x;
+      (Storage::m_data)[1] = y;
+      (Storage::m_data)[2] = z;
+    }
+    Matrix(const Scalar& x, const Scalar& y, const Scalar& z, const Scalar& w)
+    {
+      assert((RowsAtCompileTime == 1 && ColsAtCompileTime == 4)
+          || (RowsAtCompileTime == 4 && ColsAtCompileTime == 1));
+      (Storage::m_data)[0] = x;
+      (Storage::m_data)[1] = y;
+      (Storage::m_data)[2] = z;
+      (Storage::m_data)[3] = w;
+    }
+    
     template<typename OtherDerived>
     Matrix(const MatrixBase<Scalar, OtherDerived>& other)
              : Storage(other.rows(), other.cols())

src/Core/MatrixBase.h

@@ -186,6 +186,16 @@ template<typename Scalar, typename Derived> class MatrixBase
     }
     Scalar& operator[](int index) { return coeffRef(index, UserDebugging); }
     
+    Scalar x() const { return coeff(0, UserDebugging); }
+    Scalar y() const { return coeff(1, UserDebugging); }
+    Scalar z() const { return coeff(2, UserDebugging); }
+    Scalar w() const { return coeff(3, UserDebugging); }
+    Scalar& x() { return coeffRef(0, UserDebugging); }
+    Scalar& y() { return coeffRef(1, UserDebugging); }
+    Scalar& z() { return coeffRef(2, UserDebugging); }
+    Scalar& w() { return coeffRef(3, UserDebugging); }
+
+    
     Eval<Derived> eval() const EIGEN_ALWAYS_INLINE;
 };
 

src/Core/MatrixStorage.h

@@ -49,11 +49,8 @@ class MatrixStorage
 
   public:
     MatrixStorage() {}
-    
     MatrixStorage(int) {}
-    
     MatrixStorage(int, int) {}
-    
     ~MatrixStorage() {};
 };
 

test/CMakeLists.txt

@@ -10,6 +10,7 @@ SET(test_SRCS
   adjoint.cpp
   submatrices.cpp
   miscmatrices.cpp
+  smallvectors.cpp
 )
 QT4_AUTOMOC(${test_SRCS})
 

test/main.h

@@ -117,6 +117,7 @@ class EigenTest : public QObject
     void testAdjoint();
     void testSubmatrices();
     void testMiscMatrices();
+    void testSmallVectors();
   protected:
     int m_repeat;
 };

test/smallvectors.cpp

@@ -0,0 +1,62 @@
+// This file is part of Eigen, a lightweight C++ template library
+// for linear algebra. Eigen itself is part of the KDE project.
+//
+// Copyright (C) 2006-2007 Benoit Jacob <jacob@math.jussieu.fr>
+//
+// Eigen is free software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the Free Software
+// Foundation; either version 2 or (at your option) any later version.
+//
+// Eigen is distributed in the hope that it will be useful, but WITHOUT ANY
+// WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+// FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
+// details.
+//
+// You should have received a copy of the GNU General Public License along
+// with Eigen; if not, write to the Free Software Foundation, Inc., 51
+// Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+//
+// As a special exception, if other files instantiate templates or use macros
+// or functions from this file, or you compile this file and link it
+// with other works to produce a work based on this file, this file does not
+// by itself cause the resulting work to be covered by the GNU General Public
+// License. This exception does not invalidate any other reasons why a work
+// based on this file might be covered by the GNU General Public License.
+
+#include "main.h"
+
+namespace Eigen {
+
+template<typename Scalar> void smallVectors()
+{
+  typedef Matrix<Scalar, 1, 2> V2;
+  typedef Matrix<Scalar, 3, 1> V3;
+  typedef Matrix<Scalar, 1, 4> V4;
+  Scalar x1 = random<Scalar>(),
+         x2 = random<Scalar>(),
+         x3 = random<Scalar>(),
+         x4 = random<Scalar>();
+  V2 v2(x1, x2);
+  V3 v3(x1, x2, x3);
+  V4 v4(x1, x2, x3, x4);
+  VERIFY_IS_APPROX(x1, v2.x());
+  VERIFY_IS_APPROX(x1, v3.x());
+  VERIFY_IS_APPROX(x1, v4.x());
+  VERIFY_IS_APPROX(x2, v2.y());
+  VERIFY_IS_APPROX(x2, v3.y());
+  VERIFY_IS_APPROX(x2, v4.y());
+  VERIFY_IS_APPROX(x3, v3.z());
+  VERIFY_IS_APPROX(x3, v4.z());
+  VERIFY_IS_APPROX(x4, v4.w());
+}
+
+void EigenTest::testSmallVectors()
+{
+  for(int i = 0; i < m_repeat; i++) {
+    smallVectors<int>();
+    smallVectors<float>();
+    smallVectors<double>();
+  }
+}
+
+} // namespace Eigen