sparse module: makes -= and += operator working Question 1: why are *=scalar and /=scalar working right away ? Same weirdness in DynamicSparseMatrix where operators += and -= work wihout having to redefine them ???

diff --git a/Eigen/src/Sparse/DynamicSparseMatrix.h b/Eigen/src/Sparse/DynamicSparseMatrix.h
index 1cd302f..d59b814 100644
--- a/Eigen/src/Sparse/DynamicSparseMatrix.h
+++ b/Eigen/src/Sparse/DynamicSparseMatrix.h

@@ -63,6 +63,9 @@
 {
   public:
     EIGEN_SPARSE_GENERIC_PUBLIC_INTERFACE(DynamicSparseMatrix)
+    // FIXME: why are these operator already alvailable ???
+    // EIGEN_SPARSE_INHERIT_ASSIGNMENT_OPERATOR(DynamicSparseMatrix, +=)
+    // EIGEN_SPARSE_INHERIT_ASSIGNMENT_OPERATOR(DynamicSparseMatrix, -=)
     typedef MappedSparseMatrix<Scalar,Flags> Map;
 
   protected:

diff --git a/Eigen/src/Sparse/SparseCwiseBinaryOp.h b/Eigen/src/Sparse/SparseCwiseBinaryOp.h
index 9007c6b..87fd429 100644
--- a/Eigen/src/Sparse/SparseCwiseBinaryOp.h
+++ b/Eigen/src/Sparse/SparseCwiseBinaryOp.h

@@ -344,7 +344,7 @@
 EIGEN_STRONG_INLINE Derived &
 SparseMatrixBase<Derived>::operator-=(const SparseMatrixBase<OtherDerived> &other)
 {
-  return *this = *this - other;
+  return *this = derived() - other.derived();
 }
 
 template<typename Derived>
@@ -360,7 +360,7 @@
 EIGEN_STRONG_INLINE Derived &
 SparseMatrixBase<Derived>::operator+=(const SparseMatrixBase<OtherDerived>& other)
 {
-  return *this = *this + other;
+  return *this = derived() + other.derived();
 }
 
 template<typename ExpressionType>
@@ -399,7 +399,7 @@
 template<typename OtherDerived>
 inline ExpressionType& SparseCwise<ExpressionType>::operator*=(const SparseMatrixBase<OtherDerived> &other)
 {
-  return m_matrix.const_cast_derived() = *this * other;
+  return m_matrix.const_cast_derived() = _expression() * other.derived();
 }
 
 // template<typename ExpressionType>

diff --git a/Eigen/src/Sparse/SparseMatrix.h b/Eigen/src/Sparse/SparseMatrix.h
index 5e8ca84..b2665cf 100644
--- a/Eigen/src/Sparse/SparseMatrix.h
+++ b/Eigen/src/Sparse/SparseMatrix.h

@@ -57,6 +57,12 @@
 {
   public:
     EIGEN_SPARSE_GENERIC_PUBLIC_INTERFACE(SparseMatrix)
+    EIGEN_SPARSE_INHERIT_ASSIGNMENT_OPERATOR(SparseMatrix, +=)
+    EIGEN_SPARSE_INHERIT_ASSIGNMENT_OPERATOR(SparseMatrix, -=)
+    // FIXME: why are these operator already alvailable ???
+    // EIGEN_SPARSE_INHERIT_SCALAR_ASSIGNMENT_OPERATOR(SparseMatrix, *=)
+    // EIGEN_SPARSE_INHERIT_SCALAR_ASSIGNMENT_OPERATOR(SparseMatrix, /=)
+    
     typedef MappedSparseMatrix<Scalar,Flags> Map;
 
   protected:

diff --git a/Eigen/src/Sparse/SparseVector.h b/Eigen/src/Sparse/SparseVector.h
index 9af5653..457984c 100644
--- a/Eigen/src/Sparse/SparseVector.h
+++ b/Eigen/src/Sparse/SparseVector.h

@@ -57,6 +57,8 @@
 {
   public:
     EIGEN_SPARSE_GENERIC_PUBLIC_INTERFACE(SparseVector)
+    EIGEN_SPARSE_INHERIT_ASSIGNMENT_OPERATOR(SparseVector, +=)
+    EIGEN_SPARSE_INHERIT_ASSIGNMENT_OPERATOR(SparseVector, -=)
 
   protected:
   public:
@@ -117,14 +119,32 @@
     /**
       */
     inline void reserve(int reserveSize) { m_data.reserve(reserveSize); }
+    
+    inline void startFill(int reserve)
+    {
+      setZero();
+      m_data.reserve(reserve);
+    }
 
     /**
       */
+    inline Scalar& fill(int r, int c)
+    {
+      ei_assert(r==0 || c==0);
+      return fill(IsColVector ? r : c);
+    }
+    
     inline Scalar& fill(int i)
     {
       m_data.append(0, i);
       return m_data.value(m_data.size()-1);
     }
+    
+    inline Scalar& fillrand(int r, int c)
+    {
+      ei_assert(r==0 || c==0);
+      return fillrand(IsColVector ? r : c);
+    }
 
     /** Like fill() but with random coordinates.
       */
@@ -145,10 +165,18 @@
       return m_data.value(id+1);
     }
     
+    inline void endFill() {}
+    
     void prune(Scalar reference, RealScalar epsilon = precision<RealScalar>())
     {
       m_data.prune(reference,epsilon);
     }
+    
+    void resize(int rows, int cols)
+    {
+      ei_assert(rows==1 || cols==1);
+      resize(IsColVector ? rows : cols);
+    }
 
     void resize(int newSize)
     {
@@ -161,6 +189,8 @@
     inline SparseVector() : m_size(0) { resize(0); }
 
     inline SparseVector(int size) : m_size(0) { resize(size); }
+    
+    inline SparseVector(int rows, int cols) : m_size(0) { resize(rows,cols); }
 
     template<typename OtherDerived>
     inline SparseVector(const MatrixBase<OtherDerived>& other)

diff --git a/test/sparse_basic.cpp b/test/sparse_basic.cpp
index 93065bb..4394581 100644
--- a/test/sparse_basic.cpp
+++ b/test/sparse_basic.cpp

@@ -235,7 +235,10 @@
 
     VERIFY_IS_APPROX(m1*=s1, refM1*=s1);
     VERIFY_IS_APPROX(m1/=s1, refM1/=s1);
-
+    
+    VERIFY_IS_APPROX(m1+=m2, refM1+=refM2);
+    VERIFY_IS_APPROX(m1-=m2, refM1-=refM2);
+    
     refM4.setRandom();
     // sparse cwise* dense
     VERIFY_IS_APPROX(m3.cwise()*refM4, refM3.cwise()*refM4);

diff --git a/test/sparse_vector.cpp b/test/sparse_vector.cpp
index 64f52cb..8207e52 100644
--- a/test/sparse_vector.cpp
+++ b/test/sparse_vector.cpp

@@ -79,6 +79,9 @@
 
   VERIFY_IS_APPROX(v1*=s1, refV1*=s1);
   VERIFY_IS_APPROX(v1/=s1, refV1/=s1);
+  
+  VERIFY_IS_APPROX(v1+=v2, refV1+=refV2);
+  VERIFY_IS_APPROX(v1-=v2, refV1-=refV2);
 
   VERIFY_IS_APPROX(v1.dot(v2), refV1.dot(refV2));