Aim:

Design, develop and execute a parallel program in C to add, elementwise, two one dimensional arrays A and B of N integer elements and to store the result in another one dimensional array C of N integer elements.

Summary:

The Program add elements of two one dimensional array elementwise and stores it in another one dimensional array.

Algorithm:

1. Start.
2. Take input size of the arrays a[ ] and b[ ].
3. Input the elements to these arrays.
4. Set the number of threads.
5. Until size of reaches maxlength -1
   Perform addition in parallel by mentioning the function within parallel syntax.
6. Get thread numbers for the operations.
7. Print the resultant array.
8. stop.

Program: parallelprog.c

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

int main()
{
    int a[20],b[20],add[20],i,n;

    printf("Enter the array size\n");
    scanf("%d",&n); // input for size of the array //

    printf("Enter elements of array A\n");
    for(i=0;i<n;i++)
    scanf("%d",&a[i]); //taking elements of array A //

    printf("Enter elements of array B\n");
     for(i=0;i<n;i++)
      scanf("%d",&b[i]); //taking elements of array B //

    printf("Array elements are\n");

    printf("\tArray A\t\tArray B\n");

    for(i=0;i<n;i++)
       printf("\ta[%d]=%d\t\tb[%d]=%d\n",i,a[i],i,b[i]);
       printf("\nComputing Sum...\n");

    //parallel function to perform array addition //

    omp_set_num_threads(5);
    #pragma omp parallel for private(i)
    for(i=0;i<n;i++)
     {
        int tid=omp_get_thread_num();
        add[i]=a[i]+b[i]; // adding array A and B //
        printf("\nRES[%d]=%d, thread_id=%d",i,add[i],tid);
     }

    printf("\n\nResultant array is\n");

    for(i=0;i<n;i++)
         printf("%d\n",add[i]);//printing resultant array           //

    return 0;
}

Output:

Run the following commands in your terminal:

gcc parallelprog.c -fopenmp

./a.out

Enter the array size
5
Enter elements of array A 
1 2 3 4 5
Enter elements of array B 
2 3 4 5 6
Array elements are
Array A    Array B
  a[0]=1        b[0]=2
  a[1]=2        b[1]=3
  a[2]=3        b[2]=4
  a[3]=4        b[3]=5
  a[4]=5        b[4]=6

Computing Sum........
RES[4]=11,      thread id=4
RES[1]=5,       thread id=1
RES[2]=7,       thread id=2
RES[3]=9,       thread id=3
RES[0]=3,       thread id=0

The Resultant array is
3
5
7
9
11