Greetings,
mpf_get_d_2exp() always returns a non-negative value, even for negative
input. I think this is a bug.
The attached program exhibits the problem, tested with the GMP version
packaged by Debian Stretch:
$ apt-cache policy libgmp10
libgmp10:
Installed: 2:6.1.2+dfsg-1
Candidate: 2:6.1.2+dfsg-1
Version table:
*** 2:6.1.2+dfsg-1 500
500 http://ftp.uk.debian.org/debian stretch/main amd64 Packages
100 /var/lib/dpkg/status
I browsed the development repository and the latest generic source seems
to miss taking the sign into account.
$ gcc -v
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/6/lto-wrapper
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Debian 6.3.0-6'
--with-bugurl=file:///usr/share/doc/gcc-6/README.Bugs
--enable-languages=c,ada,c++,java,go,d,fortran,objc,obj-c++
--prefix=/usr --program-suffix=-6 --program-prefix=x86_64-linux-gnu-
--enable-shared --enable-linker-build-id --libexecdir=/usr/lib
--without-included-gettext --enable-threads=posix --libdir=/usr/lib
--enable-nls --with-sysroot=/ --enable-clocale=gnu
--enable-libstdcxx-debug --enable-libstdcxx-time=yes
--with-default-libstdcxx-abi=new --enable-gnu-unique-object
--disable-vtable-verify --enable-libmpx --enable-plugin
--enable-default-pie --with-system-zlib --disable-browser-plugin
--enable-java-awt=gtk --enable-gtk-cairo
--with-java-home=/usr/lib/jvm/java-1.5.0-gcj-6-amd64/jre
--enable-java-home
--with-jvm-root-dir=/usr/lib/jvm/java-1.5.0-gcj-6-amd64
--with-jvm-jar-dir=/usr/lib/jvm-exports/java-1.5.0-gcj-6-amd64
--with-arch-directory=amd64
--with-ecj-jar=/usr/share/java/eclipse-ecj.jar --with-target-system-zlib
--enable-objc-gc=auto --enable-multiarch --with-arch-32=i686
--with-abi=m64 --with-multilib-list=m32,m64,mx32 --enable-multilib
--with-tune=generic --enable-checking=release --build=x86_64-linux-gnu
--host=x86_64-linux-gnu --target=x86_64-linux-gnu
Thread model: posix
gcc version 6.3.0 20170205 (Debian 6.3.0-6)
$ uname -a
Linux frappuccino 4.7.0-1-amd64 #1 SMP Debian 4.7.8-1 (2016-10-19)
x86_64 GNU/Linux
$ cat /proc/cpuinfo | grep model\ name | uniq -c
4 model name : AMD Athlon(tm) II X4 640 Processor
I hope it can be fixed. Thanks,
Claude
--
https://mathr.co.uk
// gcc mpf_get_d_2exp_bug.c -lgmp && ./a.out
#include <stdio.h>
#include <gmp.h>
int main()
{
double input = -1;
mpf_t f;
mpf_init2(f, 100);
mpf_set_d(f, input);
signed long int e;
double output = mpf_get_d_2exp(&e, f);
int status = (input > 0) == (output > 0);
printf("expected: 1\n");
printf("got: %d\n", status);
mpf_clear(f);
return !(status == 1);
}
_______________________________________________
gmp-bugs mailing list
gmp-bugs@gmplib.org
https://gmplib.org/mailman/listinfo/gmp-bugs
