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  1. #include <iostream>
  2. #include "mpi.h"
  3. using namespace std;
  4. //compute the trapzoidal area for the function x*x from 0 to 1 with 1024 trapzoid
  5. float f(float x)
  6. {
  7. 	return x * x;
  8. }
  9. float Trap(float a, float b, int n, float h)
  10. {
  11. 	float integral, x;
  12. 	int i;
  13. 	integral = (f(a) + f(b)) / 2.0;
  14. 	x = a;
  15. 	for (i = 1; i <= n - 1; i++)
  16. 	{
  17. 		x = x + h;
  18. 		integral = integral + f(x);
  19. 	}
  20. 	return integral * h;
  21. }
  22. int main(int argc, char** argv)
  23. {
  24. 	int my_rank, p;
  25. 	float a = 0.0;
  26. 	float b = 1.0;
  27. 	int n = 1024;
  28. 	float h, local_a, local_b;
  29. 	int local_n;
  30. 	float integral;
  31. 	float total = -1;
  32. 	int source;
  33. 	int dest = 0;
  34. 	int tage = 0;
  35. 	MPI_Status status;
  36. 	MPI_Init(&argc, &argv);
  37. 	MPI_Comm_rank(MPI_COMM_WORLD, &my_rank);
  38. 	MPI_Comm_size(MPI_COMM_WORLD, &p);
  39. 	h = (b - a) / n;
  40. 	local_n = n / p;
  41. 	local_a = a + my_rank * local_n * h;
  42. 	local_b = local_a + local_n * h;
  43. 	integral = Trap(local_a, local_b, local_n, h);
  44. 	if (my_rank == 0)
  45. 	{
  46. 		total = integral;
  47. 		for (source = 1; source < p; source++)
  48. 		{
  49. 			MPI_Recv(&integral, 1, MPI_FLOAT, source, tage, MPI_COMM_WORLD,
  50. 				&status);
  51. 			cout << "PE " << my_rank << " is " << source << " " << integral << "\n";
  52. 			total = total + integral;
  53. 		}
  54. 	}
  55. 	else
  56. 	{
  57. 		cout << "PE " << my_rank << " is " << dest << " " << integral << "\n";
  58. 		MPI_Send(&integral, 1, MPI_FLOAT, dest, tage, MPI_COMM_WORLD);
  59. 	}
  60. 	if (my_rank == 0)
  61. 	{
  62. 		cout << "with n == "<<n<<" trapezoids, \n Our estimate";
  63. 		cout << " of the integral from " << a << " to " << b << "= "<<total<<"\n";
  64. 	}
  65. 	MPI_Finalize();
  66. 	return 0;
  67. }
Success #stdin #stdout #stderr 0.27s 40600KB
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Standard output is empty
stderr
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Error: unexpected symbol in "using namespace"
Execution halted
https://ideone.com/unvk4A
language:
R (R 3.5.2)
created:
12 days ago
visibility:
public

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