PGETRI

    int izero=0;
    int ione=1;
    int myid, nprocs_mpi;
    MPI_Init( &argc, &argv);
    MPI_Comm_rank(MPI_COMM_WORLD, &myid);
    MPI_Comm_size(MPI_COMM_WORLD, &nprocs_mpi);
    int n = 8;       // (Global) Matrix size
    int nprow = 2;   // Number of row procs
    int npcol = 2;   // Number of column procs
    int nb = 4;      // (Global) Block size
    char uplo='L';   // Matrix is lower triangular
    char layout='R'; // Block cyclic, Row major processor mapping
    if(argc > 1) {
        n = atoi(argv[1]);
    }
    if(argc > 2) {
        nb = atoi(argv[2]);
    }
    if(argc > 3) {
        nprow = atoi(argv[3]);
    }
    if(argc > 4) {
        npcol = atoi(argv[4]);
    }
    assert(nprow * npcol == nprocs_mpi);
    // Initialize BLACS
    int iam, nprocs;
    int zero = 0;
    int ictxt, myrow, mycol;
    blacs_pinfo_(&iam, &nprocs) ; // BLACS rank and world size
    blacs_get_(&zero, &zero, &ictxt ); // -> Create context
    blacs_gridinit_(&ictxt, &layout, &nprow, &npcol ); // Context -> Initialize the grid
    blacs_gridinfo_(&ictxt, &nprow, &npcol, &myrow, &mycol ); // Context -> Context grid info (# procs row/col, current procs row/col)
    // Compute the size of the local matrices
    int mpA    = numroc_( &n, &nb, &myrow, &izero, &nprow ); // My proc -> row of local A
    int nqA    = numroc_( &n, &nb, &mycol, &izero, &npcol ); // My proc -> col of local A
    ofstream f1;
    string filename;
    double *A;
    A = (double *)calloc(mpA*nqA,sizeof(double)) ;
    if (A==NULL){ printf("Error of memory allocation A on proc %dx%d\n",myrow,mycol); exit(0); }
    int k = 0;
    for (int j = 0; j < nqA; j++) { // local col
        int l_j = j / nb; // which block
        int x_j = j % nb; // where within that block
        int J   = (l_j * npcol + mycol) * nb + x_j; // global col
        for (int i = 0; i < mpA; i++) { // local row
            int l_i = i / nb; // which block
            int x_i = i % nb; // where within that block
            int I   = (l_i * nprow + myrow) * nb + x_i; // global row
            assert(I < n);
            assert(J < n);
            if(I == J) {
                A[k] = i + j + 1.5  +  (rand())%10;
            } else {
                A[k] = n + rand()% 10;
            }
            //printf("%d %d -> %d %d -> %f\n", i, j, I, J, A[k]);
            k++;
        }
    }
    if (myid == 0) 
        printf("*****************begin test**********************\n");
    //creat descriptor
    int descA[9];
    int info=0;
    int ipiv[10] = {0};
    int lddA = mpA > 1 ? mpA : 1;
    descinit_( descA,  &n, &n, &nb, &nb, &izero, &izero, &ictxt, &lddA, &info);
    if(info != 0) {
        printf("Error in descinit, info = %d\n", info);
    } else {
        if (myid == 0)
            printf("Finish descinit !\n");
    }
    
    pdgetrf_(&n, &n, A, &ione, &ione, descA, ipiv, &info);
    int lwork = 20, liwork = 20; //
    double * work;
    int* iwork;
    work = (double *)calloc(lwork, sizeof(double));
    iwork = (int *)calloc(liwork, sizeof(int));
    if (myid == 0) 
        printf("Finish preparing\n");
    filename = to_string(myid)+"begin.dat";
    f1.open(filename);
    k = 0;
    for (int j = 0; j < nqA; j++) { // local col
        int l_j = j / nb; // which block
        int x_j = j % nb; // where within that block
        int J   = (l_j * npcol + mycol) * nb + x_j; // global col
        for (int i = 0; i < mpA; i++) { // local row
            int l_i = i / nb; // which block
            int x_i = i % nb; // where within that block
            int I   = (l_i * nprow + myrow) * nb + x_i; // global row
            assert(I < n);
            assert(J < n);
            f1 <<I << " "<<J << " " << A[k]<<endl;
            k++;
        }
    }
    f1.close();
    double MPIt1 = MPI_Wtime();
    printf("[%dx%d] Starting pdgetri \n", myrow, mycol);
    pdgetri_(&n, A, &ione, &ione, descA, ipiv, work, &lwork, iwork, &liwork, &info);
    if (info != 0) {
        printf("Error in calculate, info = %d\n", info);
    }
    double MPIt2 = MPI_Wtime();
    printf("[%dx%d] Done, time %e s.\n", myrow, mycol, MPIt2 - MPIt1);
    filename = to_string(myid)+"end.dat";
    f1.open(filename);
    k = 0;
    for (int j = 0; j < nqA; j++) { // local col
        int l_j = j / nb; // which block
        int x_j = j % nb; // where within that block
        int J   = (l_j * npcol + mycol) * nb + x_j; // global col
        for (int i = 0; i < mpA; i++) { // local row
            int l_i = i / nb; // which block
            int x_i = i % nb; // where within that block
            int I   = (l_i * nprow + myrow) * nb + x_i; // global row
            assert(I < n);
            assert(J < n);
            f1 <<I << " "<<J << " " << A[k]<<endl;
            k++;
        }
    }
    f1.close();
    free(A);
    //exit and finanlize
    blacs_gridexit_(&ictxt);
    MPI_Finalize();
    return 0;

/*输入矩阵A
[[ 1.500000e+01  1.400000e+01  7.500000e+00  1.100000e+01  1.500000e+01
   1.400000e+01  1.000000e+01  1.100000e+01]
 [ 3.000000e-01  6.800000e+00  1.475000e+01  4.700000e+00  6.500000e+00
   6.800000e+00  1.400000e+01  4.700000e+00]
 [ 8.666670e-01 -3.137250e-01  1.312750e+01  5.441180e+00  2.039220e+00
  -1.223420e-16  1.072550e+01  5.941180e+00]
 [ 9.333330e-01 -9.803920e-03  1.633680e-01  5.890500e+00 -2.694170e-01
  -4.500000e+00 -1.948280e+00  5.808810e+00]
 [ 7.333330e-01  1.078430e-01  7.548540e-01 -7.946400e-01 -8.954380e+00
  -3.575880e+00 -1.487500e+00 -4.423370e-01]
 [ 9.333330e-01 -6.715690e-01  9.069270e-01  8.411780e-01 -3.062640e-01
   7.190140e+00  5.246760e-01 -5.202240e-01]
 [ 1.000000e+00  0.000000e+00  1.904410e-01 -1.759140e-01  4.866260e-02
  -8.589560e-02 -4.767850e+00 -1.327490e-01]
 [ 8.666670e-01 -3.137250e-01  1.000000e+00  8.488250e-02 -2.553930e-03
   5.185420e-02 -2.818240e-02 -9.709620e-01]]
*/
/*输出矩阵A
[[-0.130400 -0.056865  0.030892  0.076706  0.023446 -0.056865  0.030892
   0.076706]
 [ 0.043322 -0.078041  0.013146 -0.076609  0.043322  0.144181  0.013146
  -0.076609]
 [ 0.004289 -0.019433 -0.208930  0.028675  0.004289 -0.019433  0.191070
   0.028675]
 [ 0.014375  0.050912 -0.029025 -1.029910  0.014375  0.050912 -0.029025
   0.970093]
 [ 0.023446 -0.056865  0.030892  0.076706 -0.130400 -0.056865  0.030892
   0.076706]
 [ 0.043322  0.144181  0.013146 -0.076609  0.043322 -0.078041  0.013146
  -0.076609]
 [ 0.004289 -0.019433  0.191070  0.028675  0.004289 -0.019433 -0.208930
   0.028675]
 [ 0.014375  0.050912 -0.029025  0.970093  0.014375  0.050912 -0.029025
  -1.029910]]
*/