/* nag_sparse_nsym_precon_ilu_solve (f11dbc) Example Program. * * Copyright 2011, Numerical Algorithms Group. * * Mark 23, 2011. */ #include #include #include int main(void) { /* Scalars */ Integer exit_status = 0; double dtol; Integer i, la, lfill, n, nnz, nnzc, npivm; /* Arrays */ double *a = 0, *x = 0, *y = 0; Integer *icol = 0, *idiag = 0, *ipivp = 0, *ipivq = 0, *irow = 0, *istr = 0; /* NAG types */ Nag_SparseNsym_Piv pstrat; Nag_SparseNsym_Fact milu; Nag_SparseNsym_CheckData check; Nag_TransType trans; NagError fail; INIT_FAIL(fail); printf("nag_sparse_nsym_precon_ilu_solve (f11dbc) Example Program Results"); printf("\n\n"); /* Skip heading in data file*/ scanf("%*[^\n]"); scanf("%ld%*[^\n]", &n); scanf("%ld%*[^\n]", &nnz); la = 2 * nnz; if ( !(a = NAG_ALLOC((la), double)) || !(x = NAG_ALLOC((n), double)) || !(y = NAG_ALLOC((n), double)) || !(icol = NAG_ALLOC((la), Integer)) || !(idiag = NAG_ALLOC((n), Integer)) || !(ipivp = NAG_ALLOC((n), Integer)) || !(ipivq = NAG_ALLOC((n), Integer)) || !(irow = NAG_ALLOC((la), Integer)) || !(istr = NAG_ALLOC((n + 1), Integer)) ) { printf("Allocation failure\n"); exit_status = -1; goto END; } /* Read the non-zero elements of the matrix a*/ for (i = 0; i < nnz; i++) scanf("%lf%ld%ld%*[^\n] ", &a[i], &irow[i], &icol[i]); /* Read the vector y*/ for (i = 0; i < n; i++) scanf("%lf", &y[i]); /* Calculate LU factorization*/ lfill = -1; dtol = 0.0; pstrat = Nag_SparseNsym_CompletePiv; milu = Nag_SparseNsym_UnModFact; /* nag_sparse_nsym_fac (f11dac). * Incomplete LU factorization (nonsymmetric) */ nag_sparse_nsym_fac(n, nnz, &a, &la, &irow, &icol, lfill, dtol, pstrat, milu, ipivp, ipivq, istr, idiag, &nnzc, &npivm, &fail); if (fail.code != NE_NOERROR) { printf("Error from nag_sparse_nsym_fac (f11dac)\n%s\n", fail.message); exit_status = 1; goto END; } /* Check value of npivm*/ if (npivm > 0) { printf("Factorization is not complete \n"); goto END; } /* Solve P L D U x = y*/ check = Nag_SparseNsym_Check; trans = Nag_NoTrans; /* nag_sparse_nsym_precon_ilu_solve (f11dbc) * Solution of linear system involving incomplete LU preconditioning matrix */ nag_sparse_nsym_precon_ilu_solve(trans, n, a, la, irow, icol, ipivp, ipivq, istr, idiag, check, y, x, &fail); if (fail.code != NE_NOERROR) { printf("Error from nag_sparse_nsym_precon_ilu_solve (f11dbc)\n%s\n", fail.message); exit_status = 2; goto END; } /* Output results*/ printf(" Solution of linear system \n"); for (i = 0; i < n; i++) printf("%16.4e\n", x[i]); END: if (a) NAG_FREE(a); if (x) NAG_FREE(x); if (y) NAG_FREE(y); if (icol) NAG_FREE(icol); if (idiag) NAG_FREE(idiag); if (ipivp) NAG_FREE(ipivp); if (ipivq) NAG_FREE(ipivq); if (irow) NAG_FREE(irow); if (istr) NAG_FREE(istr); return exit_status; }