diff options
Diffstat (limited to 'doc/examples/class_Block.cpp')
-rw-r--r-- | doc/examples/class_Block.cpp | 15 |
1 files changed, 9 insertions, 6 deletions
diff --git a/doc/examples/class_Block.cpp b/doc/examples/class_Block.cpp index 17dc4bce1..efd90ddbb 100644 --- a/doc/examples/class_Block.cpp +++ b/doc/examples/class_Block.cpp @@ -7,17 +7,20 @@ Eigen::Block<Derived, 2, 2> topLeft2x2Corner(MatrixBase<Scalar, Derived>& m) { return Eigen::Block<Derived, 2, 2>(m.ref(), 0, 0); - // note: tempting as it is, writing "m.block<2,2>(0,0)" here - // causes a compile error with g++ 4.2, apparently due to - // g++ getting confused by the many template types and - // template arguments involved. +} + +template<typename Scalar, typename Derived> +const Eigen::Block<Derived, 2, 2> +topLeft2x2Corner(const MatrixBase<Scalar, Derived>& m) +{ + return Eigen::Block<Derived, 2, 2>(m.ref(), 0, 0); } int main(int, char**) { Matrix3d m = Matrix3d::identity(); - cout << topLeft2x2Corner(m) << endl; - topLeft2x2Corner(m) *= 2; + cout << topLeft2x2Corner(4*m) << endl; // calls the const version + topLeft2x2Corner(m) *= 2; // calls the non-const version cout << "Now the matrix m is:" << endl << m << endl; return 0; } |