Some more results: Intel on Linux/Itanium: maddock@td178.testdrive.hp.com> icc -I ~ -O3 -fast -fp-model fast=2 *.cpp ../*. cpp 2>&1 | less IPO: performing multi-file optimizations IPO: generating object file /tmp/ipo_iccEKNWIV.o maddock@td178.testdrive.hp.com> ./a.out Testing float Testing double Testing long double a.out: test.cpp:133: void test_basic() [with T = long double]: Assertion `(isnor mal)(x)' failed. Aborted HP aCC on HP-UX on itanium: maddock@td176> aCC -AA -O3 -I ~ *.cpp ../*.cpp test.cpp: "test.cpp", line 32: error #2735: using-declaration of function "boost::math::isinf(float)" conflicts with function "isinf(float)" (declared at line 1380 of "/opt/aCC/include_std/cmath") using boost::math::isinf; ^ "test.cpp", line 33: error #2735: using-declaration of function "boost::math::isnan(float)" conflicts with function "isnan(float)" (declared at line 1379 of "/opt/aCC/include_std/cmath") using boost::math::isnan; ^ 2 errors detected in the compilation of "test.cpp". ../long_double_mask.cpp: Intel/Linux/Xeon: maddock@td185.testdrive.hp.com> icc -I ~ -O3 -fp-model fast=2 *.cpp ../*.cpp -s tatic maddock@td185.testdrive.hp.com> ./a.out Testing float Testing double Testing long double a.out: test.cpp:133: void test_basic() [with T = long double]: Assertion `(isnor mal)(x)' failed. Aborted John.