c - Pi calculator with mutex Synchronization -

finishing assignment here. got code work , calculate pie except random values receive following errors:

1. ./piesync 10 3 pi computed 10 terms in 3 threads 3.14183961892940200045 * error in `./piesync': free(): invalid next size (fast): 0x0000000001ca3010 *

2. ./piesync 100 5 * error in `./piesync': double free or corruption (out): 0x0000000000ee5040 *

i know might array or mutex cant figure out what.

code:

//pini vaknine #include <stdio.h> #include <stdlib.h> #include <pthread.h>  //global variables int n, t; double gpie = 3.0; pthread_mutex_t mutex;  //pie function void* pie_runner(void* arg) {     long j = (long)arg;         long lower = (n/t)*(j-1)+1;     long upper = ((n/t)*(j));     double mypartialsum = 0;     //printf("lower=%lu upper=%lu\n",lower , upper);      for(long = lower; <= upper; i++)     {                 if(i % 2 == 0){             mypartialsum -= 4.0/((2*i)*(2*i+1)*(2*i+2));              //printf("vsum %lu = %f\n", j, vsum[j]);                   }         else{             mypartialsum += 4.0/((2*i)*(2*i+1)*(2*i+2));             //printf("vsum %lu = %f\n", j, vsum[j]);                   }       }     pthread_mutex_lock (&mutex);     gpie = gpie + mypartialsum;     pthread_mutex_unlock (&mutex);          pthread_exit(0);     //return null; }  int main(int argc, char **argv) {      if(argc != 3) {         printf("error: must send 2 parameters, sent %d\n", argc-1);         exit(1);     }     n = atoi(argv[1]);     t = atoi(argv[2]);        if(n <= t) {         printf("error: number of terms must greater number of threads.\n");         exit(1);         }        //launch threads     pthread_attr_t attr;     pthread_t *tids = (pthread_t *) calloc(t, sizeof(pthread_t));     if(tids == null) {         fprintf(stderr, "memory allocation problem\n");         exit(1);     }           pthread_mutex_init(&mutex, null);         pthread_attr_init(&attr);         pthread_attr_setdetachstate(&attr, pthread_create_joinable);      for(long = 1; i<=t; i++)     {          int r = pthread_create(&tids[i], &attr, pie_runner, (void*)i);         if(r<0) {             printf("error: pthread_create() returned %d\n", r);             exit(2);         }     }      //wait threads...     for(int k = 1; k<=t; k++)     {         pthread_join(tids[k], null);     }       printf("pi computed %d terms in %d threads %.20f\n", n, t, gpie);      pthread_mutex_destroy(&mutex);         pthread_attr_destroy(&attr);      free(tids);      return 0; } 

you indexing out of range of array. have allocated array t elements here

pthread_t *tids = (pthread_t *) calloc(t, sizeof(pthread_t)); 

but index incorrectly, here

for(int k = 1; k<=t; k++)     {         pthread_join(tids[k], null);     } 

and other instances too. in c index array 0 loop should be

for(int k=0; k<t; k++)