MPI 並行解上三角矩陣表示的方程組

MPI最基本的回代法實現

1. #include "mpi.h"
2. #include <stdio.h>
3. #include <stdlib.h>
5. #define ROOT 0
6. #define TAG 0
7. int main(int argc,char *argv[]) {
8. float matrix[][4]={{2,3,4,5},//the upper trangular matrix representing a equation set
9. {0,2,3,4},
10. {0,0,2,3}};
11. int xcnt=3;//cout of x
12. int self,size,tag=0;
13. MPI_Init(&argc,&argv);
14. MPI_Comm_rank(MPI_COMM_WORLD,&self);
15. MPI_Comm_size(MPI_COMM_WORLD,&size);
17. MPI_Request r;
18. MPI_Status s;
20. MPI_Datatype MPI_VEC;
21. MPI_Type_vector(xcnt+1,1,1,MPI_FLOAT,&MPI_VEC);
22. MPI_Type_commit(&MPI_VEC);
23. float* equation=(float*)malloc((xcnt+1)*sizeof(float));
24. float xs,xr;
25. if(0==self) {//send each process the correspond equation
26. //parellel send and copy
27. MPI_Issend(matrix[1],1,MPI_VEC,1,TAG,MPI_COMM_WORLD,&r);
28. for(int i=0;i<=xcnt;++i) {
29. equation[i]=matrix[0][i];
30. }
31. MPI_Wait(&r,&s);
32. for(int i=2;i<size;++i) {
33. MPI_Ssend(matrix[i],1,MPI_VEC,i,TAG,MPI_COMM_WORLD);
34. }
35. } else {
36. MPI_Recv(equation,1,MPI_VEC,ROOT,TAG,MPI_COMM_WORLD,&s);
37. }
39. for(int i=xcnt-1;i>=0;--i) {
40. if(i==self) {
41. xs=equation[xcnt]/equation[i];
42. printf("x%d = %f \n",self,xs);
43. MPI_Bcast(&xs,1,MPI_FLOAT,i,MPI_COMM_WORLD);
44. } else {
45. MPI_Bcast(&xs,1,MPI_FLOAT,i,MPI_COMM_WORLD);
46. if(i>self) {
47. equation[xcnt]-=equation[i]*xs;
48. }
49. }
50. }
51. free(equation);
52. MPI_Finalize();
53. return 0;
54. }