I am trying to run a project that uses a boost library class called matrix in another custom class. In the custom class there is a Rotate method that takes a reference to matrix object as a constant argument. When I try to run the project I get an error meassage "error C4430: missing type specifier - int assumed. Note: C++ does not support default-int" "error C2143: syntax error : missing ',' before '&' " " error C2146: syntax error : missing ';' before identifier 'v' " " error C3861: 'v': identifier not found " Can any one help me what the problem could be. Below is the line that generates the error. I am trying to run the project in Microsoft Visual C++ 2008. The boost version is 1_32_0. Do I need to configure Boost first? class Space { public: . . . void Rotate( const Matrix& matx ) { Matrix v(3,1); v.Row(1) << x(); v.Row(2) << y(); v.Row(3) << z(); v = matx*v; setX( v(1,1) ); setY( v(2,1) ); setZ( v(3,1) ); }