On 09/03/2011 09:59, sguazt wrote:

namespace ublas = ::boost::numeric::ublas;

template<typename MatrixT> inline ublas::matrix_range<MatrixT> topleft(MatrixT& M) { return ublas::subrange(M, 0, 3, 0, 3); }

and use this function just like the case here below:

...

matrix<double> A(9,9); topleft(A) = zero_matrix<double>(3,3);

You might want to provide a const overload as well.

On 09/03/2011 17:11, Ryan wrote:

On Wed, Mar 9, 2011 at 4:09 AM, Mathias Gaunard mailto:mathias.gaunard@ens-lyon.org> wrote:

On 09/03/2011 09:59, sguazt wrote:

namespace ublas = ::boost::numeric::ublas;

template<typename MatrixT> inline ublas::matrix_range<MatrixT> topleft(MatrixT& M) { return ublas::subrange(M, 0, 3, 0, 3); }

You might want to provide a const overload as well.

Why would I want a const overload? I want to be able to change the values in the matrix passed to the function.

To allow rvalues and propagate constness, so as to make it behave more like a typedef or macro. In the snippet you gave, of course, it needs to be non-const. But it's good practice to provide both when you write such adaptors.

On Wed, Mar 9, 2011 at 3:59 AM, sguazt wrote:

template <typename MatrixT> inline ublas::matrix_range<MatrixT> topleft(MatrixT& M) { return ublas::subrange(M, 0, 3, 0, 3); }

This is perfect. Thank you. Ryan