P?(SY/HE)EV

    int izero=0;
    int ione=1;
    int myrank_mpi, nprocs_mpi;
    MPI_Init( &argc, &argv);
    MPI_Comm_rank(MPI_COMM_WORLD, &myrank_mpi);
    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 jobs='V'; // Block cyclic, Row major processor mapping
    double tau[8];
    char layout='R';
    double w[8];
    int iz;
    int jz;
    int descz;
    int lwork = 160;
    double work[160];
 
    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
    int mpZ    = numroc_( &n, &nb, &myrow, &izero, &nprow ); // My proc -> row of local Z
    int nqZ    = numroc_( &n, &nb, &mycol, &izero, &npcol ); // My proc -> col of local Z
 
    ofstream f1;
    string filename = to_string(myrank_mpi)+"A.dat";
    f1.open(filename);
    double *A;
    A = (double *)calloc(mpA*nqA,sizeof(double));
    double *Z;
    Z = (double *)calloc(mpZ*nqZ,sizeof(double));
    if (A==NULL){ printf("Error of memory allocation A on proc %dx%d\n",myrow,mycol); exit(0); }
    int k = 0;
    double globalA[n][n];
    for(int j = 0; j < n; j++) {
        for (int i = 0; i <= j; i++){
           if (i == j)    globalA[i][j]= 3 * n  +  (rand())%10;
           else {
               globalA[i][j] = n  +  (rand())%10;
              globalA[j][i] = n  +  (rand())%10;
            }
           if (myrank_mpi == 0)
           f1 <<i << " "<<j << " " << globalA[i][j]<<endl;    
       }
    }
    f1.close();
    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 <= j; 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);
            A[k] = globalA[I][J];
            // printf("%d %d -> %d %d -> %f\n", i, j, I, J, A[k]);
            k++;
        }
    }
 
    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);
    int descZ[9];
    descinit_( descZ,  &n, &n, &nb, &nb, &izero, &izero, &ictxt, &lddA, &info);
 
    if(info != 0) {
        printf("Error in descinit, info = %d\n", info);
    }
    double MPIt1 = MPI_Wtime();
    printf("[%dx%d] Starting \n", myrow, mycol);
    pdsyev_(&jobs, &uplo, &n, A,  &ione, &ione, descA, w, Z, &ione, &ione, descZ, work, &lwork, &info);
    if (info != 0) {
        printf("Error in calculate, info = %d\n", info);
    }
    double MPIt2 = MPI_Wtime();
 
    filename = to_string(myrank_mpi)+"Z.dat";
    f1.open(filename);
    k = 0;
    for (int j = 0; j < nqZ; 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 < mpZ; 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 << " " << Z[k]<<endl;
            k++;
        }
    }
    f1.close();
    for (int i = 0; i < n; i++) {
        printf("%lf ",w[i]);
    }
    printf("\n[%dx%d] Done, time %e s.\n", myrow, mycol, MPIt2 - MPIt1);
    free(A);
    blacs_gridexit_(&ictxt);
    MPI_Finalize();
    return 0;
/*
Origin A:
[[27.  0.  0.  0.  0.  0.  0.  0.]
 [14. 29.  0.  0.  0.  0.  0.  0.]
 [11. 14. 33.  0.  0.  0.  0.  0.]
 [ 9. 15. 17. 30.  0.  0.  0.  0.]
 [ 8. 10.  9. 15. 26.  0.  0.  0.]
 [ 8. 11. 13. 10. 16. 31.  0.  0.]
 [11.  9. 17.  9. 12. 16. 29.  0.]
 [ 8. 14.  8. 11.  8.  9. 13. 31.]]
Z:
[[-3.808840e-01  3.560630e-01  1.508930e-01  4.958660e-02 -2.479740e-01 5.474460e-01 -3.507160e-01 -4.676850e-01]
 [-1.215670e-01  9.875040e-02 -3.955830e-01 -3.017760e-02  3.132180e-01 1.838380e-01  7.044540e-01 -4.357930e-01]
 [ 5.219660e-01 -3.517350e-01 -4.716980e-01 -3.487300e-01 -2.010880e-01 2.340930e-01 -2.884750e-01 -2.850760e-01]
 [ 1.710940e-01 -4.669610e-01  7.019050e-01 -1.670770e-01  1.194220e-01 3.689920e-01  2.620540e-01 -1.140160e-01]
 [-3.644890e-01 -4.411160e-01  5.683900e-02  3.502880e-02 -3.815800e-01 -5.387890e-01  4.586880e-02 -4.796940e-01]
 [-8.826880e-04  3.503620e-02  1.090290e-01 -1.568230e-01  7.541030e-01 -2.801260e-01 -4.334450e-01 -3.567550e-01]
 [ 5.430560e-01  5.514490e-01  3.000940e-01 -1.117970e-01 -2.539910e-01 -3.196940e-01  1.823870e-01 -3.137810e-01]
 [ 3.326610e-01 -1.476200e-01 -1.999970e-02  8.993240e-01  8.318180e-02 6.770530e-02 -7.489810e-02 -2.030950e-01]]
W:
[-35.145752 -11.559735 -6.089042 -0.555364 16.500808 23.793150 25.601339 102.454598]
 */