add zero() and identity() static methods, update unit-tests

src/Core.h

@@ -27,6 +27,8 @@ namespace Eigen {
 #include "Core/Trace.h"
 #include "Core/Dot.h"
 #include "Core/Random.h"
+#include "Core/Zero.h"
+#include "Core/Identity.h"
 #include "Core/Fuzzy.h"
 
 } // namespace Eigen

src/Core/Fuzzy.h

@@ -33,6 +33,7 @@ bool Object<Scalar, Derived>::isApprox(
   const typename NumTraits<Scalar>::Real& prec
 ) const
 {
+  assert(rows() == other.rows() && cols() == other.cols());
   if(IsVector)
   {
     return((*this - other).norm2() <= std::min(norm2(), other.norm2()) * prec * prec);
@@ -73,6 +74,7 @@ bool Object<Scalar, Derived>::isMuchSmallerThan(
   const typename NumTraits<Scalar>::Real& prec
 ) const
 {
+  assert(rows() == other.rows() && cols() == other.cols());
   if(IsVector)
   {
     return(norm2() <= other.norm2() * prec * prec);

src/Core/Identity.h

@@ -0,0 +1,65 @@
+// 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.
+
+#ifndef EI_IDENTITY_H
+#define EI_IDENTITY_H
+
+template<typename MatrixType> class Identity
+  : public Object<typename MatrixType::Scalar, Identity<MatrixType> >
+{
+  public:
+    typedef typename MatrixType::Scalar Scalar;
+    friend class Object<Scalar, Identity<MatrixType> >;
+    
+    static const int RowsAtCompileTime = MatrixType::RowsAtCompileTime,
+                     ColsAtCompileTime = MatrixType::ColsAtCompileTime;
+
+    Identity(int rows, int cols) : m_rows(rows), m_cols(cols)
+    {
+      assert(rows > 0 && cols > 0);
+    }
+    
+  private:
+    Identity& _ref() { return *this; }
+    const Identity& _constRef() const { return *this; }
+    int _rows() const { return m_rows; }
+    int _cols() const { return m_cols; }
+    
+    Scalar _read(int row, int col) const
+    {
+      return static_cast<Scalar>(row == col);
+    }
+    
+  protected:
+    int m_rows, m_cols;
+};
+
+template<typename Scalar, typename Derived>
+Identity<Derived> Object<Scalar, Derived>::identity(int rows, int cols)
+{
+  return Identity<Derived>(rows, cols);
+}
+
+#endif // EI_IDENTITY_H

src/Core/Object.h

@@ -113,6 +113,10 @@ template<typename Scalar, typename Derived> class Object
     
     static Eval<Random<Derived> >
     random(int rows = RowsAtCompileTime, int cols = ColsAtCompileTime);
+    static Zero<Derived>
+    zero(int rows = RowsAtCompileTime, int cols = ColsAtCompileTime);
+    static Identity<Derived>
+    identity(int rows = RowsAtCompileTime, int cols = ColsAtCompileTime);
     
     template<typename OtherDerived>
     bool isApprox(

src/Core/Util.h

@@ -56,6 +56,8 @@ template<typename Lhs, typename Rhs> class Difference;
 template<typename Lhs, typename Rhs> class Product;
 template<typename MatrixType> class ScalarMultiple;
 template<typename MatrixType> class Random;
+template<typename MatrixType> class Zero;
+template<typename MatrixType> class Identity;
 template<typename ExpressionType> class Eval;
 
 template<typename T> struct ForwardDecl

src/Core/Zero.h

@@ -0,0 +1,67 @@
+// 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.
+
+#ifndef EI_ZERO_H
+#define EI_ZERO_H
+
+template<typename MatrixType> class Zero
+  : public Object<typename MatrixType::Scalar, Zero<MatrixType> >
+{
+  public:
+    typedef typename MatrixType::Scalar Scalar;
+    friend class Object<Scalar, Zero<MatrixType> >;
+    
+    static const int RowsAtCompileTime = MatrixType::RowsAtCompileTime,
+                     ColsAtCompileTime = MatrixType::ColsAtCompileTime;
+
+    Zero(int rows, int cols) : m_rows(rows), m_cols(cols)
+    {
+      assert(rows > 0 && cols > 0);
+    }
+    
+  private:
+    Zero& _ref() { return *this; }
+    const Zero& _constRef() const { return *this; }
+    int _rows() const { return m_rows; }
+    int _cols() const { return m_cols; }
+    
+    Scalar _read(int row, int col) const
+    {
+      EI_UNUSED(row);
+      EI_UNUSED(col);
+      return static_cast<Scalar>(0);
+    }
+    
+  protected:
+    int m_rows, m_cols;
+};
+
+template<typename Scalar, typename Derived>
+Zero<Derived> Object<Scalar, Derived>::zero(int rows, int cols)
+{
+  return Zero<Derived>(rows, cols);
+}
+
+#endif // EI_ZERO_H