"Malte Clasen" wrote

Now it's tempting to use boost uBLAS with these quantities: A position in space can be expressed as a vector of length quantities etc. But there's one problem:

"// uBLAS assumes a common return type for all binary arithmetic operators" (traits.hpp, line 42, boost release 1.33)

The promote_traits class relies on this when computing the following:

(FWIW Boost.Typeof could be tried here instead of promote_traits)

static const std::size_t size = sizeof ( type_deduction_detail::test< typename base_type::x_type , typename base_type::y_type >(x + y) // Use x+y to stand of all the arithmetic actions );

I died some experiments on matrices with my quantities library pqs. http://www.servocomm.freeserve.co.uk/Cpp/physical_quantity/index.html I dont believe a simple use in UBLAS is possible because the members of a quantity<> matrix arent all the same type. Here for example are a couple of types representing homogeneous vectors and transformation matrices for 2D transforms. PQ == the physical-quantity parameter type ( eg length::m) K/PQ == the 'reciprocal' of the type ( eg reciprocal_length::div_m ( } N == numeric type ( eg double) rc_matrix<PQ>( // 2D transformation matrix laid out in row/column format //using a tuple of tuples N, N, K/PQ, N, N, K/PQ, PQ, PQ, N ); row_vector<PQ>( // 2D vertex in homogeneous coordinates implicit //conversion to/from x,y vertex<PQ>. N, N, K/PQ ); However I an pretty sure that UBLAS isnt laid out this way! regards Andy Little