while working on some kind of math simulation program I found many strange results; the function I found having strange behaving is cosh (hyperbolic cosine) Note that this results are consistent with the ones from any calctool compiled on the same machine (es Calcoo). This problem doesn't seems to affect gentoo systems NOT compiled for pentium4 Simply, the output of int main() { int i; double start_point=4.18524; for (i=0;i<10;i++) cout<<((double)i)*0.00001+start_point<<"\t"<<cosh(((double)i)*0.00001+start_point)<<endl; return(0); } isn't the right one // compile with c++ -o cosh_test Reproducible: Always Steps to Reproduce: 1.compile and run the program 2.compare the results with any gentoo not compiled with march=pentium4 Actual Results: output: 4.18524 65.7093 4.18525 65.7099 4.18526 inf 4.18527 inf 4.18528 65.7119 4.18529 65.7126 4.1853 inf 4.18531 inf 4.18532 65.7145 4.18533 65.7152 Expected Results: 4.18524 32.8622 4.18525 32.8626 4.18526 32.8629 4.18527 32.8632 4.18528 32.8636 4.18529 32.8639 4.1853 32.8642 4.18531 32.8645 4.18532 32.8649 4.18533 32.8652 Portage 2.0.47-r10 (default-x86-1.4, gcc-3.2.2, glibc-2.3.1-r4) ================================================================= System uname: 2.5.64 i686 Intel(R) Pentium(R) 4 CPU 2.00GHz GENTOO_MIRRORS=" ftp://ftp.tu-clausthal.de/pub/linux/gentoo/ ftp://ftp.snt.utwente.nl/pub/os/linux/gentoo http://212.219.56.162/sites/www.ibiblio.org/gentoo/" CONFIG_PROTECT="/etc /var/qmail/control /usr/kde/2/share/config /usr/kde/3/share/config /usr/X11R6/lib/X11/xkb /usr/kde/3.1/share/config /usr/share/config" CONFIG_PROTECT_MASK="/etc/gconf /etc/env.d" PORTDIR="/usr/portage" DISTDIR="/usr/portage/distfiles" PKGDIR="/usr/portage/packages" PORTAGE_TMPDIR="/var/tmp" PORTDIR_OVERLAY="" USE="x86 oss 3dnow apm arts avi crypt cups encode gif jpeg libg++ mikmod mpeg ncurses nls pdflib png quicktime spell truetype xml2 xmms xv zlib gdbm berkdb slang readline svga java guile sdl gpm tcpd pam libwww ssl perl python esd imlib oggvorbis qt motif opengl mozilla cdr X gtk gnome -alsa sse mmx -kde" COMPILER="gcc3" CHOST="i686-pc-linux-gnu" CFLAGS="-march=pentium4 -O3 -pipe" CXXFLAGS="-march=pentium4 -O3 -pipe" ACCEPT_KEYWORDS="x86" MAKEOPTS="-j1" AUTOCLEAN="no" SYNC="rsync://rsync.gentoo.org/gentoo-portage" FEATURES="sandbox ccache"
The warning in make.conf about not using -march=pentium4 is there for a reason :/
I knew I shouldn't have used -march=pentium4 but I needed, for a simulation, the fastest results I can, so I tried (thinking that the "illegal instructions" wouldn't have affected math functions in glibc...). Anyway, recompiling glibc with -march=pentium3 will solve the problem
old issue, newer toolchain solves these problems
