GMP mpf functions causing a segmentation fault - c++

Question

I can not figure out that is causing this error. I just installed GMP on ubuntu. This is a 64 bit OS on an AMD cpu (not sure if it matters). I keep getting a segmentation fault.
#include <stdio.h>
#include <stdlib.h>
#include <gmp.h>
#include <time.h>
int main(int argc, char** argv)
{
mpz_t sum, fac;
mpf_t fsum, ffac;
int i;
time_t t;
mpz_init_set_ui(sum, 1);
mpz_init_set_ui(fac, 1);
t = time(NULL);
for(i = 10000; i >= 1; --i)
{
mpz_mul_ui(fac, fac, i);
mpz_add(sum, sum, fac);
if(i % 10000 == 0)
{
printf("%d\n", i);
}
}
printf("Time %d\n", (time(0) - t));
mpf_init(fsum);
mpf_init(ffac);
mpf_set_z(fsum, sum);
mpf_set_z(ffac, fac);
mpz_clear(sum);
mpz_clear(fac);
mpf_div(fac, sum, fac);
mpf_out_str(stdout, 10, 50, fac);
mpf_clear(fsum);
mpf_clear(ffac);
return(EXIT_SUCCESS);
}
This code outputs the following...
10000
Time 0
Segmentation fault (core dumped)
I then tried to run this program with valgrind and this is the output.
==25427== Memcheck, a memory error detector
==25427== Copyright (C) 2002-2013, and GNU GPL'd, by Julian Seward et al.
==25427== Using Valgrind-3.10.0.SVN and LibVEX; rerun with -h for copyright info
==25427== Command: /home/chase/NetBeansProjects/GmpECalc/dist/Debug/GNU-Linux-x86/gmpecalc
==25427==
10000
Time 1
==25427== Invalid read of size 8
==25427== at 0x4E8E590: __gmpn_copyi (in /usr/lib/x86_64-linux-gnu/libgmp.so.10.1.3)
==25427== by 0x400B27: main (main.c:40)
==25427== Address 0x73b0000073c is not stack'd, malloc'd or (recently) free'd
==25427==
==25427==
==25427== Process terminating with default action of signal 11 (SIGSEGV)
==25427== Access not within mapped region at address 0x73B0000073C
==25427== at 0x4E8E590: __gmpn_copyi (in /usr/lib/x86_64-linux-gnu/libgmp.so.10.1.3)
==25427== by 0x400B27: main (main.c:40)
==25427== If you believe this happened as a result of a stack
==25427== overflow in your program's main thread (unlikely but
==25427== possible), you can try to increase the size of the
==25427== main thread stack using the --main-stacksize= flag.
==25427== The main thread stack size used in this run was 8388608.
==25427==
==25427== HEAP SUMMARY:
==25427== in use at exit: 48 bytes in 2 blocks
==25427== total heap usage: 3,706 allocs, 3,704 frees, 27,454,096 bytes allocated
==25427==
==25427== LEAK SUMMARY:
==25427== definitely lost: 0 bytes in 0 blocks
==25427== indirectly lost: 0 bytes in 0 blocks
==25427== possibly lost: 0 bytes in 0 blocks
==25427== still reachable: 48 bytes in 2 blocks
==25427== suppressed: 0 bytes in 0 blocks
==25427== Rerun with --leak-check=full to see details of leaked memory
==25427==
==25427== For counts of detected and suppressed errors, rerun with: -v
==25427== ERROR SUMMARY: 1 errors from 1 contexts (suppressed: 0 from 0)
Segmentation fault (core dumped)
The error seems to be occurring at the mpf_div function. However, if I remove this function the error will occur at mpf_out_str. I also tried initializing ffac and fsum to doubles (instead of setting them to the fac and sum) and I get the same error.

Answer 1

Problem is in this lines:
mpz_clear(sum); // You clear the variables, GMP deallocates their memory
mpz_clear(fac);
mpf_div(fac, sum, fac); // You use cleared variables, segfault
Maybe you meant:
mpf_div(ffac, fsum, ffac);