Bug with square roots

Emil Vladov emil at emovla.com
Tue May 8 11:26:07 CEST 2012

Hi guys,

here's the information you have listed on the bug report page:

GMP version: 5.0.5

The program that follows takes sqrt of a long integer, then takes root(2). The resulting numbers are different (and both are wrong).  

#include <gmp.h>

const char* N2 = "999999999543345433645659999999999999123156456489789789789564564231999999999999999999999945665544577654999999999999999999999994654987987564564231999999999999999999999";

#define PR(v) gmp_printf (#v " = %Zd\n", v);

int main(int argc, const char * argv[])
   mpz_t N;
   mpz_t sq;
   mpz_t s1;
   mpz_init (N);
   mpz_set_str(N, N2, 10);
   mpz_sqrt (sq, N);
   mpz_root (s1, N, 2);

   return 0;

Output from gcc -v

Using built-in specs.
Target: i686-apple-darwin11
Configured with: /private/var/tmp/llvmgcc42/llvmgcc42-2336.9~22/src/configure --disable-checking --enable-werror --prefix=/Applications/Xcode.app/Contents/Developer/usr/llvm-gcc-4.2 --mandir=/share/man --enable-languages=c,objc,c++,obj-c++ --program-prefix=llvm- --program-transform-name=/^[cg][^.-]*$/s/$/-4.2/ --with-slibdir=/usr/lib --build=i686-apple-darwin11 --enable-llvm=/private/var/tmp/llvmgcc42/llvmgcc42-2336.9~22/dst-llvmCore/Developer/usr/local --program-prefix=i686-apple-darwin11- --host=x86_64-apple-darwin11 --target=i686-apple-darwin11 --with-gxx-include-dir=/usr/include/c++/4.2.1
Thread model: posix
gcc version 4.2.1 (Based on Apple Inc. build 5658) (LLVM build 2336.9.00)

(this is what comes with XCode 4.3.2)

uname - a:
Darwin embp 11.3.0 Darwin Kernel Version 11.3.0: Thu Jan 12 18:47:41 PST 2012; root:xnu-1699.24.23~1/RELEASE_X86_64 x86_64

$ ./configfsf.guess 

$ ./config.guess

'make check' tests pass.

Please feel free to ask me if you need more details.

Cheers, Emil

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