https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63488
--- Comment #3 from joseph at codesourcery dot com <joseph at codesourcery dot com> --- Note that libquadmath has not been updated from glibc since November 2012. So, while in the Bessel function case large errors are already known for all floating-point types in glibc, in general libquadmath bugs are quite likely to have been fixed in glibc since the last update (and testing the glibc code directly on a platform with binary128 long double may be better - AArch64, Alpha, MIPS64, S/390, SPARC are all such platforms, and the GCC Compile Farm has some of them). (It is of course possible there are some bugs specific to libquadmath, arising from the adaptation of the glibc code.) (Eventually I think we should provide _Float128 functions directly in glibc's libm on x86/x86_64, with the TS 18661-3 names, in which case libquadmath could become a thin wrapper round the libm versions, on platforms using current glibc or any other library providing the TS 18661-3 functions.)
