Hi, Nearly all tests fails for msvc12 because of the use of constexpr keyword. Could this be fixed? I prepared a pull request nearly a month ago: https://github.com/boostorg/ublas/pull/5 Btw, in those tests failing for all MSVC versions an assertion failure is reported by the STL: map/set iterators incompatible. Assertion failures should be visible in the regression results, shouldn't they? At least in the file test_inplace_solve.cpp (of course with -DUSE_MAPPED_VECTOR_OF_MAPPED_VECTOR) this assertion failure is caused by the matrix_sparse.hpp line 2002: return it_ == it.it_; Which is called by: triangular.hpp line 1328 matrix_expression.hpp line 1598 iterator.hpp line 185 ... test_inplace_solve.cpp line 72 I hope that helps. Do you plan to release the version of uBlas from develop in 1.56? Regards, Adam