From 3f979187600897221c7e807373eb267af4db1ada Mon Sep 17 00:00:00 2001
From: Benoit Jacob <jacob.benoit.1@gmail.com>
Date: Sun, 14 Oct 2007 10:01:25 +0000
Subject: [PATCH] restrict identity() to square matrices; small change helping
 g++ optimize.

---
 src/Core/Identity.h | 15 ++++++++-------
 src/Core/Object.h   |  2 +-
 test/basicstuff.cpp |  2 +-
 3 files changed, 10 insertions(+), 9 deletions(-)

diff --git a/src/Core/Identity.h b/src/Core/Identity.h
index 78b380b04..4b437a844 100644
--- a/src/Core/Identity.h
+++ b/src/Core/Identity.h
@@ -36,30 +36,31 @@ template<typename MatrixType> class Identity
     static const int RowsAtCompileTime = MatrixType::RowsAtCompileTime,
                      ColsAtCompileTime = MatrixType::ColsAtCompileTime;
 
-    Identity(int rows, int cols) : m_rows(rows), m_cols(cols)
+    Identity(int rows) : m_rows(rows)
     {
-      assert(rows > 0 && cols > 0);
+      assert(rows > 0);
+      assert(RowsAtCompileTime == ColsAtCompileTime);
     }
     
   private:
     Identity& _ref() { return *this; }
     const Identity& _constRef() const { return *this; }
     int _rows() const { return m_rows; }
-    int _cols() const { return m_cols; }
+    int _cols() const { return m_rows; }
     
     Scalar _read(int row, int col) const
     {
-      return static_cast<Scalar>(row == col);
+      return row == col ? static_cast<Scalar>(1) : static_cast<Scalar>(0);
     }
     
   protected:
-    int m_rows, m_cols;
+    int m_rows;
 };
 
 template<typename Scalar, typename Derived>
-Identity<Derived> Object<Scalar, Derived>::identity(int rows, int cols)
+Identity<Derived> Object<Scalar, Derived>::identity(int rows)
 {
-  return Identity<Derived>(rows, cols);
+  return Identity<Derived>(rows);
 }
 
 #endif // EI_IDENTITY_H
diff --git a/src/Core/Object.h b/src/Core/Object.h
index 5b2e34f53..5792385e6 100644
--- a/src/Core/Object.h
+++ b/src/Core/Object.h
@@ -116,7 +116,7 @@ template<typename Scalar, typename Derived> class Object
     static Zero<Derived>
     zero(int rows = RowsAtCompileTime, int cols = ColsAtCompileTime);
     static Identity<Derived>
-    identity(int rows = RowsAtCompileTime, int cols = ColsAtCompileTime);
+    identity(int rows = RowsAtCompileTime);
     
     template<typename OtherDerived>
     bool isApprox(
diff --git a/test/basicstuff.cpp b/test/basicstuff.cpp
index c21a58979..3e734a498 100644
--- a/test/basicstuff.cpp
+++ b/test/basicstuff.cpp
@@ -37,7 +37,7 @@ template<typename MatrixType> void basicStuff(const MatrixType& m)
              m3,
              mzero = MatrixType::zero(rows, cols),
              identity = Matrix<Scalar, MatrixType::RowsAtCompileTime, MatrixType::RowsAtCompileTime>
-                              ::identity(rows, rows),
+                              ::identity(rows),
              square = Matrix<Scalar, MatrixType::RowsAtCompileTime, MatrixType::RowsAtCompileTime>
                               ::random(rows, rows);
   VectorType v1 = VectorType::random(rows),