The calls fmod(x, 0) and fmod(inf, y) should both result in a domain error. For both of these calls, an invalid exception is correctly raised. However, errno is not set consistently. fmod(x, 0) does (correctly) set errno to EDOM. However, fmod(inf, y) does not set errno; it should do so. Background: On error, many glibc math functions both set errno and raise an exception (fetestexcept(3)). For example, the following function all do this: acos(), asin(), cosh(), sinh(), acosh(), asinh(), exp(), exp2(), ldexp(), log(), log10(), log2(). However, there is much inconsistency. Some functions raise an exception, but don't set errno. Some functions set errno for some errors, but not others. A few set errno, but don't raise an exception. This series of bug reports documents deviations from what I consider the ideal: all functions should BOTH set errno AND raise an exception for all errors. All of these reports relate to tests on glibc 2.8 (as provided by SUSE 11.0).
Created attachment 2849 [details] test program See also http://sourceware.org/bugzilla/show_bug.cgi?id=6783 sample runs showing problem. Note that EDOM is set in one case, but not the other. $ /tmp/mt_fmod -- inf 1 errno == 0 fetestexcept() says: FE_INVALID fmod(inf,1.00000000000000000e+00)=nan 0 FE_INVALID nan $ /tmp/mt_fmod -- 1 0 errno == EDOM fetestexcept() says: FE_INVALID fmod(1.00000000000000000e+00,0.00000000000000000e+00)=nan EDOM FE_INVALID nan
This bug was fixed in glibc 2.10. The man page is updated for man-pages-2.37.