I'm getting errors from fusion in cvs HEAD that I don't see if I use the 1.34 release, only with gcc-3.4 though, not with msvc: In file included from c:/data/boost/develop/boost/boost/fusion/sequence/adapted/struct.hpp:11, from c:/data/boost/develop/boost/boost/fusion/sequence/adapted/std_pair.hpp:12, from c:/data/boost/develop/boost/boost/tr1/tuple.hpp:51, from ../../../boost/math/tools/roots.hpp:13, from ../../../boost/math/special_functions/detail/igamma_inverse.hpp:11, from ../../../boost/math/special_functions/gamma.hpp:1785, from ../../../boost/math/special_functions/erf.hpp:11, from ../../../boost/math/distributions/normal.hpp:16, from test_dist_overloads.cpp:24: c:/data/boost/develop/boost/boost/fusion/sequence/adapted/struct/extension.hpp: In static member function `static typename boost::add_const<typename boost::fusion::extension::struct_assoc_member<Struct, Key>::type>::type& boost::fusion::extension::struct_assoc_member<const Struct, Key>::call(const Struct&)': c:/data/boost/develop/boost/boost/fusion/sequence/adapted/struct/extension.hpp:59: error: type/value mismatch at argument 2 in template parameter list for `template<class Struct, int N> struct boost::fusion::extension::struct_member' c:/data/boost/develop/boost/boost/fusion/sequence/adapted/struct/extension.hpp:59: error: expected a constant of type `int', got `Key' c:/data/boost/develop/boost/boost/fusion/sequence/adapted/struct/extension.hpp:59: error: `call' is not a member of `<declaration error>' Anyone any ideas? Thanks, John.