I am using MTL(Matrix Template Library) 4 (the version is mtl4-beta-1-r6916) for Matrix computing in Dev-C++ 4.9.8.0 and updated the gcc version from 3.2 to 4.4.1 by installing tdm-mingw-1.908.0-4.4.1-2 and the boost version is 1.34.1. The sample code is : #include int main(int argc, char* argv[]) { using namespace mtl; using namespace mtl::matrix; const unsigned xd= 2, yd= 5, n= xd * yd; dense2D<double> A(n, n); compressed2D<double> B(n, n); hessian_setup(A, 3.0); laplacian_setup(B, xd, yd); typedef std::complex<double> cdouble; dense_vector<cdouble> v(n), w(n); for (unsigned i= 0; i < size(v); i++) v[i]= cdouble(i+1, n-i), w[i]= cdouble(i+n); v+= A * w; w= B * v; std::cout << "v is " << v << "\n"; std::cout << "w is " << w << "\n"; return 0; } But the complier tolde me that : ……………………………… F:\CB2009\boost_1_34_1\boost_1_34_1/boost/mpl/apply_wrap.hpp:81:31: error: missing binary operator before token "(" F:\CB2009\boost_1_34_1\boost_1_34_1/boost/mpl/apply_wrap.hpp:173:31: error: missing binary operator before token "(" ……………………………… And the code in the corresponding lines of apply_wrap.hpp are: …………………………. #elif BOOST_PP_ITERATION_DEPTH() == 1 ……………………… #elif BOOST_PP_ITERATION_DEPTH() == 2 And I do not know how to solve it. Can any one with kindness help me?