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Possible GMP bug

From: Shawn Dyer
Subject: Possible GMP bug
Date: Sun, 28 Jul 2002 02:04:44 -0500

I do not know if I have found a bug or not. It may be some built in limitation in gmp that I did not notice the documentation for. I was attempting to do a computation of pi using a quartically convergent algorithm using GMP floating point numbers. Here is the information you requested in the bug report:

* GMP version 4.1 compiled locally
* A small test program is attached. (I linked it statically) It works fine for 9 iterations which returns a value of pi accurate to 715,319 digits, requiring a precision of about 2,376,240 bits. It fails on 10 iterations, which should return a value accurate to over 2,800,000 digits, and requires about 9,505,060 bits of precision. The error begins to appear between 8 and 8.5 million bits of precision. * Also attached is the output from running the program under gdb. I am not sure whether it will be useful or not. If you can reproduce the problem, I am sure you will have more informative output, but I can attempt to provide you with anything else you need.
* I used no configuration options when building gmp.
* I built it using gcc:
gcc -v
Reading specs from /usr/lib/gcc-lib/i386-slackware-linux/2.95.3/specs
gcc version 2.95.3 20010315 (release)
(I had originally observed the problem using Intel's 32 bit compiler:
icc -V
Intel(R) C++ Compiler for 32-bit applications, Version 6.0   Build 020312Z
The gdb output was very similar as for compiled under gcc)
* Linux nonus 2.4.5 #10 Fri Jun 22 02:20:21 PDT 2001 i686 unknown
(I also observed the same problem on a Linux 2.4.18 kernel as well)
* The output of config.guess and configfsf.guess is:
pentium3-pc-linux-gnu    and     i686-pc-linux-gnu

If there is anything other information you need, Please let me know.

Attachment: gdb_output
Description: Text document

Attachment: pi-icc-quartic.c
Description: Text document

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