I have a personal work to complete in C programming language

MPI-02/Question-03/Standard-Deviation.c

/////////////////////////////////////////////////////////////////////////////////////// // // This is an MPI program that computes the standard deviation for an array of elements. // // Note: The array is generated according to its size (the number of elements), which // is specified by users from the command line. In the program, we assume its // maximum number is 10. // // Compile: mpicc Standard-Deviation.c -o Stddev -lm // // Run: mpiexec -n <p> ./Stddev <N> // // -p: the number of processes // -N: the number of elements // /////////////////////////////////////////////////////////////////////////////////////// #include <stdio.h> #include <stdlib.h> #include <time.h> #include <math.h> #include <mpi.h> int *Random_Num_Generator(int Num_Elements); int Compute_Sum(int *array, int num_elements); int main(int argc, char** argv) { int comm_sz, my_rank; int i, Product; double local_start, local_finish, local_elapsed, elapsed; //Seed the random number generator to get different results each time srand(time(NULL)); MPI_Init(&argc, &argv); MPI_Comm_rank(MPI_COMM_WORLD, &my_rank); MPI_Comm_size(MPI_COMM_WORLD, &comm_sz); //The error checking here should be performed to ensure that the number of arguments is 2. Otherwise, the usage is printed. if (argc != 2) { if (my_rank == 0) fprintf(stderr, "USAGE: mpiexec -n <num_of_processes> Stddev <num_elements>\n"); MPI_Finalize(); return 0; } int Num_Elements = atoi(argv[1]); //The error checking here is performed to ensure that the size of vector is an integer in the range between 1 and 10. if (Num_Elements < 1 || Num_Elements > 10) { if (my_rank == 0) fprintf(stderr, "Error: The size of the vector should be an integer in the range between 1 and 10!\n"); MPI_Finalize(); return 0; } // The error checking here is performed to ensure that the number of elements are evenly divisible by the number of the processes if (Num_Elements % comm_sz != 0) { if (my_rank == 0) fprintf(stderr, "Error: The size of the vector should be evenly divisible by the number of Processes!\n"); MPI_Finalize(); return 0; } // Generate a random array of elements on process 0 int *Random_Nums = NULL; if (my_rank == 0) { Random_Nums = Random_Num_Generator(Num_Elements); printf("\nThe random numbers generated: \n"); for (i = 0; i < Num_Elements; i++) printf("%d ", Random_Nums[i]); printf("\n"); } // Compute number of random intergers on each process int Num_Per_Proc = Num_Elements / comm_sz; // Generate a buffer for holding a subset of the entire array int *Sub_Random_Nums = (int *)malloc(sizeof(int) * Num_Per_Proc); // Scatter the random integer numbers from process 0 to all processes MPI_Scatter(Random_Nums, Num_Per_Proc, MPI_INT, Sub_Random_Nums, Num_Per_Proc, MPI_INT, 0, MPI_COMM_WORLD); /////////////////////////////////////////////////////////////////////////////////////////////////////////////// // // Start point for code to be timed // /////////////////////////////////////////////////////////////////////////////////////////////////////////////// MPI_Barrier(MPI_COMM_WORLD); local_start = MPI_Wtime(); // Compute the sum of the subset array on each process int Sub_Sum = Compute_Sum(Sub_Random_Nums, Num_Per_Proc); // Compute the sum of the entire array and distribute it to each process int Total_Sum; MPI_Allreduce(&Sub_Sum, &Total_Sum, 1, MPI_INT, MPI_SUM, MPI_COMM_WORLD); // Compute the average of the entire array on each process float Average = (float) Total_Sum / Num_Elements; // Compute the partial sum of the squared differences from the average on each process float Sub_Square_diff = 0; for (i = 0; i < Num_Per_Proc; i++) Sub_Square_diff += (Sub_Random_Nums[i] - Average) * (Sub_Random_Nums[i] - Average); // Reduce the total sum of the squared differences to the process 0 (root process) float Total_Square_diff; MPI_Reduce(&Sub_Square_diff, &Total_Square_diff, 1, MPI_FLOAT, MPI_SUM, 0, MPI_COMM_WORLD); // Compute the standard deviation if (my_rank == 0) { // The standard deviation is the square root of the averaged total sum of squared differences float Standard_Deviation = sqrt(Total_Square_diff / Num_Elements); printf("Standard deviation = %f\n", Standard_Deviation); } local_finish = MPI_Wtime(); local_elapsed = local_finish - local_start; MPI_Reduce(&local_elapsed, &elapsed, 1, MPI_DOUBLE, MPI_MAX, 0, MPI_COMM_WORLD); if (my_rank == 0) printf("Elapsed time = %e seconds\n", elapsed); /////////////////////////////////////////////////////////////////////////////////////////////////////////////// // // End point for Code to be timed // /////////////////////////////////////////////////////////////////////////////////////////////////////////////// // Clean up if (my_rank == 0) free(Random_Nums); free(Sub_Random_Nums); MPI_Barrier(MPI_COMM_WORLD); MPI_Finalize(); return 0; } // Create an array of random integer numbers ranging from 1 to 10 int *Random_Num_Generator(int Num_Elements) { int *Rand_Nums = (int *)malloc(sizeof(int) * Num_Elements); int i; for (i = 0; i < Num_Elements; i++) Rand_Nums[i] = (rand() % 10) + 1; return Rand_Nums; } // Computes the sum of an array of numbers int Compute_Sum(int *array, int num_elements) { int sum = 0; int i; for (i = 0; i < num_elements; i++) sum += array[i]; return sum; }