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  1. PO
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    <p>The following is a corrected version of your code. The debugging tool I used was valgrind. Install it, compile bspsieve with <code>-g</code>, and use <code>valgrind 8 30 ./bspsieve</code> and you will be told info about any memory errors.</p> <pre><code>#include &lt;stdio.h&gt; #include &lt;stdlib.h&gt; #include &lt;math.h&gt; #include &lt;mcbsp.h&gt; /* Compile using gcc -Wall -g -o bspsieve bspsieve.c lib/libmcbsp1.1.0.a -pthread -lrt -lm -Iinclude */ int procs; float upperbound; int *primes; //////////////// //////////////// BSPSIEVE //SPMD function void bspSieve () { bsp_begin (procs); float p = bsp_nprocs (); // p = number of procs obtained int s = bsp_pid (); // s = proc number float blocksize; // block size to be used, note last proc has a different size! if (s != p-1) { blocksize = ceil (upperbound / p); } else { blocksize = upperbound - (p - 1) * ceil (upperbound / p); } // Initialize start time and end time, set start time to now. double start_time, end_time; start_time = bsp_time (); // Create vector that has block of candidates int *blockvector; blockvector = (int *) malloc (blocksize * sizeof (int)); int q; for (q = 0; q &lt; blocksize; q++) { //List contains the integers from s*blocksize till blocksize + s*blocksize blockvector[q] = q + s * blocksize; } //We neglect the first 2 'primes' in processor 0. if (s == 0) { blockvector[0] = 0; blockvector[1] = 0; } // We are using the block distribution. We assume that n is large enough to // assure that n/p is larger than sqrt(n). This means that we will always find the // sieving prime in the first block, and so have to broadcast from the first // processor to the others. long sieving_prime; int i; bsp_push_reg (&amp;sieving_prime, sizeof (long)); bsp_sync (); for (i = 2; i * i &lt; upperbound; i++) { //Part 1: if first processor, get the newest sieving prime, broadcast. Search for newest prime starting from i. if (s == 0) { int findPrimeNb; for (findPrimeNb = i; findPrimeNb &lt;= blocksize; findPrimeNb++) { if (blockvector[findPrimeNb] != 0) { sieving_prime = blockvector[findPrimeNb]; //broadcast int procNb; for (procNb = 0; procNb &lt; p; ++procNb) { bsp_put (procNb, &amp;sieving_prime, &amp;sieving_prime, 0, sizeof (long)); } break; } } } bsp_sync (); //Part 2: Sieve using the sieving prime int sievingNb; for (sievingNb = 0; sievingNb &lt; blocksize; sievingNb++) { //check if element is multiple of sieving prime, if so, pcross out (put to zero) if (blockvector[sievingNb] != sieving_prime) if (blockvector[sievingNb] % sieving_prime == 0) { blockvector[sievingNb] = 0; } } } //part 3: get local primes to central area int transferNb; long transferPrime; for (transferNb = 0; transferNb &lt; blocksize; transferNb++) { transferPrime = blockvector[transferNb]; primes[transferPrime] = transferPrime; } // take the end time. end_time = bsp_time (); //Print amount of taken time, only processor 0 has to do this. if (s == 0) { printf ("It took : %.6lf seconds for proc %d out of %d. \n", end_time - start_time, bsp_pid (), bsp_nprocs ()); fflush (stdout); } bsp_end (); } //////////////// //////////////// //////////////// //////////////// MAIN int main (int argc, char **argv) { if (argc != 3) { printf("Usage: %s &lt;processor count&gt; &lt;upper bound&gt;\n", argv[0]); exit(1); } printf ("processors to use: %s \n", argv[1]); printf ("upper bound: %s \n", argv[2]); //retrieve parameters procs = atoi (argv[1]); upperbound = atoi (argv[2]); primes = (int *) malloc (upperbound * sizeof (int)); // init and call parallel part bsp_init (bspSieve, argc, argv); bspSieve (); //Print all non zeros of candidates, these are the primes. // DO Primes only go to p*p &lt;= n? The rest of the numbers seem to be prime int i; for (i = 0; i &lt; upperbound; i++) { if (primes[i] &gt; 0) { printf ("%d, ", primes[i]); } } printf("\n"); return 0; } </code></pre>
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    1. POBSP Sieve Of Erastothenes C implementation gives Segmentation fault (core dumped)
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    1. USGavin Haynes
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    1. VO
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      1. VTUpMod
    1. COThank you, this is exactly what I needed! When I try your program however, I run into a problem (both when compiling it 'my' way and 'your' way), it prints this: See original post.
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      1. USSven
 

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