Hi All Adding -U__MATH__ does not really fix the problem. However commenting math.h in gcc-4.3.2/libstdc++-v3/libmath/stubs.c does the trick. Anyone come across such an issue? Thanks and Regards Vardhan -----Original Message----- From: gcc-help-owner@xxxxxxxxxxx [mailto:gcc-help-owner@xxxxxxxxxxx] On Behalf Of Vardhan, Sundara (GE Infra, Energy) Sent: Wednesday, November 12, 2008 8:28 AM To: GCC-help Subject: GCC 4.3.2 in AIX 5.3 Hi All Found that when compiling GCC-4.3.2 on AIX 5.3 using either xlc or an existing gcc, it is required to set CFLAGS and CXXFLAGS to -U__MATH__. This is required for the various math functions defined in AIX clashes with those that are being defined in GCC. This is not just true for gcc, I had to include this flag in my application compilation too when using xlc to avoid math subroutine redefinition errros. Just wanted to share this. With Regards Vardhan