-------- Original Message -------- Subject: [Bug math/6869] sin() and cos() return grossly wrong results when rounding is set to upward Date: 24 Sep 2008 10:43:58 -0000 From: anders dot lennartsson at foi dot se sourceware-bugzilla@sourceware.org Reply-To: sourceware-bugzilla@sourceware.org To: bagnara@cs.unipr.it References: 20080905193441.6869.bagnara@cs.unipr.it
------- Additional Comments From anders dot lennartsson at foi dot se 2008-09-24 10:43 ------- The problem may occur on 64-bits only. I compiled and ran the test program on three computers, all Intel machines running Debian. Two of these use Debian 4.0 Etch, one 32 and one 64-bits, and the problem was present only on 64 bits. It is still there on a 64-bits machine with Debian unstable.
Etch 32-bits:
theta = 5.27906 sin(theta) = -0.843695 cos(theta) = 0.536822 Repeating after setting the rounding direction to UPWARD: theta = 5.27906 sin(theta) = -0.843695 cos(theta) = 0.536822
user@computer1:~/gcc$ g++ --v Using built-in specs. Target: i486-linux-gnu Configured with: ../src/configure -v --enable-languages=c,c++,fortran,objc,obj-c++,treelang --prefix=/usr --enable-shared --with-system-zlib --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --enable-nls --program-suffix=-4.1 --enable-__cxa_atexit --enable-clocale=gnu --enable-libstdcxx-debug --enable-mpfr --with-tune=i686 --enable-checking=release i486-linux-gnu Thread model: posix gcc version 4.1.2 20061115 (prerelease) (Debian 4.1.1-21)
Etch 64-bits:
theta = 5.27906 sin(theta) = -0.843695 cos(theta) = 0.536822 Repeating after setting the rounding direction to UPWARD: theta = 5.27906 sin(theta) = -0.212522 cos(theta) = 8.2185
user@computer2:~/gcc$ g++ --v Using built-in specs. Target: x86_64-linux-gnu Configured with: ../src/configure -v --enable-languages=c,c++,fortran,objc,obj-c++,treelang --prefix=/usr --enable-shared --with-system-zlib --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --enable-nls --program-suffix=-4.1 --enable-__cxa_atexit --enable-clocale=gnu --enable-libstdcxx-debug --enable-mpfr --enable-checking=release x86_64-linux-gnu Thread model: posix gcc version 4.1.2 20061115 (prerelease) (Debian 4.1.1-21)
Sid 64-bits:
theta = 5.27906 sin(theta) = -0.843695 cos(theta) = 0.536822 Repeating after setting the rounding direction to UPWARD: theta = 5.27906 sin(theta) = -0.247529 cos(theta) = 7.26962 user@computer3:/home_2/abel/gcc$ g++ --v Using built-in specs. Target: x86_64-linux-gnu Configured with: ../src/configure -v --with-pkgversion='Debian 4.3.2-1' --with-bugurl=file:///usr/share/doc/gcc-4.3/README.Bugs --enable-languages=c,c++,fortran,objc,obj-c++ --prefix=/usr --enable-shared --with-system-zlib --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --enable-nls --with-gxx-include-dir=/usr/include/c++/4.3 --program-suffix=-4.3 --enable-clocale=gnu --enable-libstdcxx-debug --enable-objc-gc --enable-mpfr --enable-cld --enable-checking=release --build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=x86_64-linux-gnu Thread model: posix gcc version 4.3.2 (Debian 4.3.2-1)