* Add the possibility to customize the output of matrices, e.g.:

IoFormat OctaveFmt(4, AlignCols, ", ", ";\n", "", "", "[", "]");
   cout << mat.format(OctaveFmt);
  The first "4" is the precision.
  Documentation missing.
* Some compilation fixes

Eigen/Core

@@ -4,6 +4,7 @@
 #include "CoreDeclarations"
 #include <iostream>
 #include <cstring>
+#include <string>
 
 #ifdef EIGEN_VECTORIZE
 // it seems we cannot assume posix_memalign is defined in the stdlib header

Eigen/src/Array/PartialRedux.h

@@ -52,7 +52,7 @@ struct ei_traits<PartialReduxExpr<MatrixType, MemberOp, Direction> >
   typedef typename MemberOp::result_type Scalar;
   typedef typename MatrixType::Scalar InputScalar;
   typedef typename ei_nested<MatrixType>::type MatrixTypeNested;
-  typedef typename ei_unref<MatrixTypeNested>::type _MatrixTypeNested;
+  typedef typename ei_cleantype<MatrixTypeNested>::type _MatrixTypeNested;
   enum {
     RowsAtCompileTime = Direction==Vertical   ? 1 : MatrixType::RowsAtCompileTime,
     ColsAtCompileTime = Direction==Horizontal ? 1 : MatrixType::ColsAtCompileTime,
@@ -65,7 +65,7 @@ struct ei_traits<PartialReduxExpr<MatrixType, MemberOp, Direction> >
   };
   typedef typename MemberOp::template Cost<InputScalar,int(TraversalSize)> CostOpType;
   enum {
-    CoeffReadCost = TraversalSize * _MatrixTypeNested::CoeffReadCost + CostOpType::value
+    CoeffReadCost = TraversalSize * ei_traits<_MatrixTypeNested>::CoeffReadCost + int(CostOpType::value)
   };
 };
 

Eigen/src/Core/CacheFriendlyProduct.h

@@ -347,7 +347,7 @@ static void ei_cache_friendly_product(
  * TODO: since rhs gets evaluated only once, no need to evaluate it
  */
 template<typename Scalar, typename RhsType>
-EIGEN_DONT_INLINE static void ei_cache_friendly_product_colmajor_times_vector(
+static EIGEN_DONT_INLINE void ei_cache_friendly_product_colmajor_times_vector(
   int size,
   const Scalar* lhs, int lhsStride,
   const RhsType& rhs,
@@ -536,7 +536,7 @@ EIGEN_DONT_INLINE static void ei_cache_friendly_product_colmajor_times_vector(
 
 // TODO add peeling to mask unaligned load/stores
 template<typename Scalar, typename ResType>
-EIGEN_DONT_INLINE static void ei_cache_friendly_product_rowmajor_times_vector(
+static EIGEN_DONT_INLINE void ei_cache_friendly_product_rowmajor_times_vector(
   const Scalar* lhs, int lhsStride,
   const Scalar* rhs, int rhsSize,
   ResType& res)

Eigen/src/Core/IO.h

@@ -25,19 +25,96 @@
 #ifndef EIGEN_IO_H
 #define EIGEN_IO_H
 
-template<typename Derived>
-std::ostream & ei_print_matrix
-(std::ostream & s,
- const MatrixBase<Derived> & m)
+enum { Raw, AlignCols };
+
+struct IoFormat
 {
+  IoFormat(int _precision=4, int _flags=Raw,
+    const std::string& _coeffSeparator = " ",
+    const std::string& _rowSeparator = "\n", const std::string& _rowPrefix="", const std::string& _rowSuffix="",
+    const std::string& _matPrefix="", const std::string& _matSuffix="")
+  : matPrefix(_matPrefix), matSuffix(_matSuffix), rowPrefix(_rowPrefix), rowSuffix(_rowSuffix), rowSeparator(_rowSeparator),
+    coeffSeparator(_coeffSeparator), precision(_precision), flags(_flags)
+  {
+    rowSpacer = "";
+    int i=matSuffix.length()-1;
+    while (i>=0 && matSuffix[i]!='\n')
+    {
+      rowSpacer += ' ';
+      i--;
+    }
+  }
+  std::string matPrefix, matSuffix;
+  std::string rowPrefix, rowSuffix, rowSeparator, rowSpacer;
+  std::string coeffSeparator;
+  int precision;
+  int flags;
+};
+
+template<typename ExpressionType>
+class WithFormat
+{
+  public:
+
+    WithFormat(const ExpressionType& matrix, const IoFormat& format)
+      : m_matrix(matrix), m_format(format)
+    {}
+
+    friend std::ostream & operator << (std::ostream & s, const WithFormat& wf)
+    {
+      return ei_print_matrix(s, wf.m_matrix.eval(), wf.m_format);
+    }
+
+  protected:
+    const typename ExpressionType::Nested m_matrix;
+    IoFormat m_format;
+};
+
+template<typename Derived>
+inline const WithFormat<Derived>
+MatrixBase<Derived>::format(const IoFormat& fmt) const
+{
+  return WithFormat<Derived>(derived(), fmt);
+}
+
+template<typename Derived>
+std::ostream & ei_print_matrix(std::ostream & s, const MatrixBase<Derived> & _m,
+                               const IoFormat& fmt = IoFormat())
+{
+  const typename Derived::Nested m = _m;
+  int width = 0;
+  if (fmt.flags & AlignCols)
+  {
+    // compute the largest width
+    for(int j = 1; j < m.cols(); j++)
       for(int i = 0; i < m.rows(); i++)
       {
+        std::stringstream sstr;
+        sstr.precision(fmt.precision);
+        sstr << m.coeff(i,j);
+        width = std::max<int>(width, sstr.str().length());
+      }
+  }
+  s.precision(fmt.precision);
+  s << fmt.matPrefix;
+  for(int i = 0; i < m.rows(); i++)
+  {
+    if (i)
+      s << fmt.rowSpacer;
+    s << fmt.rowPrefix;
+    if(width) s.width(width);
     s << m.coeff(i, 0);
     for(int j = 1; j < m.cols(); j++)
-      s << " " << m.coeff(i, j);
-    if( i < m.rows() - 1)
-      s << "\n";
+    {
+      s << fmt.coeffSeparator;
+      if (width) s.width(width);
+      s << m.coeff(i, j);
     }
+    s << fmt.rowSuffix;
+    if( i < m.rows() - 1)
+      s << fmt.rowSeparator;
+  }
+  s << fmt.matSuffix;
   return s;
 }
 

Eigen/src/Core/MatrixBase.h

@@ -525,6 +525,8 @@ template<typename Derived> class MatrixBase
     const Cwise<Derived> cwise() const;
     Cwise<Derived> cwise();
 
+    inline const WithFormat<Derived> format(const IoFormat& fmt) const;
+
 /////////// Array module ///////////
 
     bool all(void) const;

Eigen/src/Core/Swap.h

@@ -130,7 +130,7 @@ template<typename Derived>
 template<typename OtherDerived>
 void MatrixBase<Derived>::swap(const MatrixBase<OtherDerived>& other)
 {
-  SwapWrapper<Derived>(derived()).lazyAssign(other);
+  (SwapWrapper<Derived>(derived())).lazyAssign(other);
 }
 
 #endif // EIGEN_SWAP_H

Eigen/src/Core/util/ForwardDeclarations.h

@@ -59,6 +59,7 @@ template<typename MatrixType, unsigned int Mode> class Extract;
 template<typename ExpressionType> class Cwise;
 template<typename ExpressionType, int Direction> class PartialRedux;
 template<typename MatrixType, typename BinaryOp, int Direction> class PartialReduxExpr;
+template<typename ExpressionType> class WithFormat;
 
 template<typename Lhs, typename Rhs> struct ei_product_mode;
 template<typename Lhs, typename Rhs, int ProductMode = ei_product_mode<Lhs,Rhs>::value> struct ProductReturnType;
@@ -89,6 +90,8 @@ template<typename Scalar> struct ei_scalar_max_op;
 template<typename Scalar> struct ei_scalar_random_op;
 template<typename Scalar> struct ei_scalar_add_op;
 
+struct IoFormat;
+
 template<typename Scalar>
 void ei_cache_friendly_product(
   int _rows, int _cols, int depth,

test/CMakeLists.txt

@@ -110,5 +110,6 @@ EI_ADD_TEST(eigensolver)
 EI_ADD_TEST(geometry)
 EI_ADD_TEST(regression)
 EI_ADD_TEST(svd)
+EI_ADD_TEST(ioformat)
 
 ENDIF(BUILD_TESTS)

test/ioformat.cpp

@@ -0,0 +1,44 @@
+// This file is part of Eigen, a lightweight C++ template library
+// for linear algebra. Eigen itself is part of the KDE project.
+//
+// Copyright (C) 2006-2008 Benoit Jacob <jacob@math.jussieu.fr>
+//
+// Eigen is free software; you can redistribute it and/or
+// modify it under the terms of the GNU Lesser General Public
+// License as published by the Free Software Foundation; either
+// version 3 of the License, or (at your option) any later version.
+//
+// Alternatively, 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 of
+// the License, 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 Lesser General Public License or the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public
+// License and a copy of the GNU General Public License along with
+// Eigen. If not, see <http://www.gnu.org/licenses/>.
+
+#include "main.h"
+
+void test_ioformat()
+{
+  std::string sep = "\n\n----------------------------------------\n\n";
+  Matrix4f m1;
+  m1 << 0, 1.111111, 2, 3.33333, 4, 5, 6, 7, 8.888888, 9, 10, 11, 12, 13, 14, 15;
+
+  IoFormat CommaInitFmt(4, Raw, ", ", ", ", "", "", " << ", ";");
+  IoFormat CleanFmt(4, AlignCols, ", ", "\n", "[", "]");
+  IoFormat OctaveFmt(4, AlignCols, ", ", ";\n", "", "", "[", "]");
+  IoFormat HeavyFmt(4, AlignCols, ", ", ";\n", "[", "]", "[", "]");
+  
+  
+  std::cout << m1 << sep;
+  std::cout << m1.format(CommaInitFmt) << sep;
+  std::cout << m1.format(CleanFmt) << sep;
+  std::cout << m1.format(OctaveFmt) << sep;
+  std::cout << m1.format(HeavyFmt) << sep;
+}