Banana567777770111

#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>

#define N_MAX 100000000LL

typedef struct {
   long  thread_id; //Id du thread
   double  sum; //Somme commune
   int nbr_t; //Nombre de threads
} thread_data;


void* PartialSum(void* threadid);



int main (int argc, char* argv[]) {

    //Blindage sur les arguments en entrée
    if(argc != 2 ){
        printf("Invalid use of the program.\n use ./prgm <number of threads>\n");
    return -1;
    }

    //Conversion du nombres de threads de char* en integer
    int nbrThreads = atoi( argv[1] );

    //Allocation d'un tableau de thread
    pthread_t* threadArray = (pthread_t*) malloc(nbrThreads*sizeof( pthread_t ));

    double sum = 0.0;
    int rc; //Initialiser la valeur de retour du pthread create
    long t; //Initialiser la valeur de boucle
    thread_data* myData = (thread_data*)malloc(nbrThreads * sizeof(thread_data));

    //Creations des threads
    for( t = 0; t < nbrThreads; t++ ) {
        //printf("creating thread %ld\n", t);

        myData[t].thread_id = t;
        myData[t].sum = 0.0;
        myData[t].nbr_t = nbrThreads;

        rc = pthread_create( &threadArray[t], NULL, PartialSum, (void*)&myData[t]);
        if(rc) printf("Error creating thread...\n");

        (void) pthread_join(threadArray[t], NULL);

    }

    double megasum = 0.0;

    for( t = 0; t < nbrThreads; t++ ) megasum += myData[t].sum;

    free(myData);
    free(threadArray);
    //printf("megasum : %.12f\n",megasum);
    return 0 ;
}


void* PartialSum(void* th_data) {

    thread_data* data = (thread_data*) th_data;
        long myid = (long) data->thread_id;
    int start = (int)(myid*N_MAX) / data->nbr_t;
    int end = (int)( (myid+1) * N_MAX) / data->nbr_t;
       // printf("ID: %ld, Start: %d, End: %d\n", myid, start, end);
    long long  n;
    start = start == 0 ? 1 : start;
        for ( n = start; n < end ; n++) {
                if ( n % 2 == 0 ) {
                        data->sum -= 1.0 / ( double ) n ;
                } else {
                        data->sum += 1.0 / ( double ) n ;
                }
        }

    //printf("My partial sum (%ld) : %.12f\n", myid, data->sum);
    pthread_exit(NULL);
}