USING_pthread_for_dotproduct_dem

/*Author-XAgent Smith*/
/*Dot product using thread*/
/*Oct 16,2018*/
/*Creating 4 threads where each thread will compute 4 elements in consecutive order */
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <pthread.h>

#define NUM_THRED 4

typedef struct
{
  double *vectorA;
  double *vectorB;
  double sum;
  int length;
}vectorinfo;

typedef struct
{
   vectorinfo *info;
   int begining_index;
}Product;

pthread_mutex_t mutexsum;//Act as key


void dot_product(void *prod)
{
   printf("\n%d",pthread_self());
   Product *product =(Product*)prod;
  vectorinfo *vecinfo=product->info;
  int start=product->begining_index;
  int end=start+vecinfo->length;
  double total=0.0;

  for(int i=start;i<end;i++) total+=(vecinfo ->vectorA[i])*(vecinfo->vectorB[i]);

  pthread_mutex_lock(&mutexsum);

  vecinfo->sum=total;
  pthread_mutex_unlock(&mutexsum);
usleep(2000);

  pthread_exit((void*)0);
}

int main()
{
   vectorinfo vec;
   double VectorA[]={1.0,2.0,3.0,4.0,5.0,6.0,7.0,8.0,9.0,10.0,11.0,12.0,13.0,14.0,15.0,16.0};

    double VectorB[]={1.0,2.0,3.0,4.0,5.0,6.0,7.0,8.0,9.0,10.0,11.0,12.0,13.0,14.0,15.0,16.0};

    //double sum;

   vec.vectorA=VectorA;
   vec.vectorB=VectorB;

   vec.length=4;

  pthread_t threads[NUM_THRED];
  void *status;
  pthread_attr_t attr;
  pthread_mutex_init(&mutexsum,NULL);
  pthread_attr_init(&attr);

  pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_JOINABLE);

  int Return;
  int num;

  for(num=0;num<NUM_THRED;num++)
  {

  Product *product=(Product*)malloc(sizeof(Product));
   product->info=&vec;
   product->begining_index=num*4;

  Return=pthread_create(&threads[num], &attr,dot_product, (void*)product);

  if(Return) {printf("ERROR:Unable to creat thread:%d",Return); exit(-1);}
  }
pthread_attr_destroy(&attr);
for(int i=0;i<NUM_THRED;i++)
{
    pthread_join(&threads[i],(void**)&status);

}
  pthread_mutex_destroy(&mutexsum);
 usleep(2000);
 printf("\nDot product sum=%lf",vec.sum);

 pthread_exit(NULL);




return 0;
}