>Does ANSI C99 say that it provides the long double maths functions? I'm not sure. I'll endeavour to find out. >If yes, and if glibc is trying to give a full C99 implementation, then it's >a glibc failing (or "bug"), isn't it? Yes. I don't know what the effect would be of turning on glibc's long double support in absence of real functionality in the compiler, but it wouldn't be difficult to try it out. p.