Hi all, I got error while installing GTL-1.2.4 in ubuntu 11.04. My gcc version is 4.5.2 The ./configure runs good. But after that when I run make, I get the following error: In file included from ../include/GTL/node.h:13:0,                  from ../include/GTL/node_data.h:13,                  from edge.cpp:9: ../include/GTL/edge.h:135:23: error: 'ostream' does not name a type In file included from ../include/GTL/node_data.h:13:0,                  from edge.cpp:9: ../include/GTL/node.h:234:23: error: 'ostream' does not name a type edge.cpp: In function 'std::ostream& GTL::operator<<(std::ostream&, const GTL::edge&)': edge.cpp:38:24: error: no match for 'operator<<' in 'os << ((const GTL::edge*)e)->GTL::edge::source()' Here is the download link from where I downloaded GTL: http://www.fim.uni-passau.de/f... I hope somebody could help. Thanks.