/* nag_dsprfs (f07phc) Example Program. * * Copyright 2001 Numerical Algorithms Group. * * Mark 7, 2001. */ #include #include #include #include #include int main(int argc, char *argv[]) { FILE *fpin, *fpout; char *outfile = 0; /* Scalars */ Integer i, j, n, nrhs, ap_len, afp_len, pdb, pdx, ferr_len, berr_len; Integer exit_status = 0; NagError fail; Nag_UploType uplo; Nag_OrderType order; /* Arrays */ Integer *ipiv = 0; char nag_enum_arg[40]; double *afp = 0, *ap = 0, *b = 0, *berr = 0, *ferr = 0, *x = 0; #ifdef NAG_COLUMN_MAJOR #define A_LOWER(I, J) ap[(2*n-J)*(J-1)/2 + I - 1] #define A_UPPER(I, J) ap[J*(J-1)/2 + I - 1] #define B(I, J) b[(J-1)*pdb + I - 1] #define X(I, J) x[(J-1)*pdx + I - 1] order = Nag_ColMajor; #else #define A_LOWER(I, J) ap[I*(I-1)/2 + J - 1] #define A_UPPER(I, J) ap[(2*n-I)*(I-1)/2 + J - 1] #define B(I, J) b[(I-1)*pdb + J - 1] #define X(I, J) x[(I-1)*pdx + J - 1] order = Nag_RowMajor; #endif INIT_FAIL(fail); /* Check for command-line IO options */ fpin = nag_example_file_io(argc, argv, "-data", NULL); fpout = nag_example_file_io(argc, argv, "-results", NULL); (void) nag_example_file_io(argc, argv, "-nag_write", &outfile); fprintf(fpout, "nag_dsprfs (f07phc) Example Program Results\n\n"); /* Skip heading in data file */ fscanf(fpin, "%*[^\n] "); fscanf(fpin, "%ld%ld%*[^\n] ", &n, &nrhs); ap_len = n * (n + 1)/2; afp_len = n * (n + 1)/2; #ifdef NAG_COLUMN_MAJOR pdb = n; pdx = n; #else pdb = nrhs; pdx = nrhs; #endif ferr_len = nrhs; berr_len = nrhs; /* Allocate memory */ if (!(ipiv = NAG_ALLOC(n, Integer)) || !(afp = NAG_ALLOC(ap_len, double)) || !(ap = NAG_ALLOC(afp_len, double)) || !(b = NAG_ALLOC(n * nrhs, double)) || !(berr = NAG_ALLOC(berr_len, double)) || !(ferr = NAG_ALLOC(ferr_len, double)) || !(x = NAG_ALLOC(n * nrhs, double))) { fprintf(fpout, "Allocation failure\n"); exit_status = -1; goto END; } /* Read A and B from data file, and copy A to AFP and B to X */ fscanf(fpin, " %s%*[^\n] ", nag_enum_arg); /* nag_enum_name_to_value(x04nac). * Converts NAG enum member name to value */ uplo = (Nag_UploType) nag_enum_name_to_value(nag_enum_arg); if (uplo == Nag_Upper) { for (i = 1; i <= n; ++i) { for (j = i; j <= n; ++j) fscanf(fpin, "%lf", &A_UPPER(i, j)); } fscanf(fpin, "%*[^\n] "); } else { for (i = 1; i <= n; ++i) { for (j = 1; j <= i; ++j) fscanf(fpin, "%lf", &A_LOWER(i, j)); } fscanf(fpin, "%*[^\n] "); } for (i = 1; i <= n; ++i) { for (j = 1; j <= nrhs; ++j) fscanf(fpin, "%lf", &B(i, j)); } fscanf(fpin, "%*[^\n] "); for (i = 1; i <= n * (n + 1) / 2; ++i) afp[i - 1] = ap[i - 1]; for (i = 1; i <= n; ++i) { for (j = 1; j <= nrhs; ++j) X(i, j) = B(i, j); } /* Factorize A in the array AFP */ /* nag_dsptrf (f07pdc). * Bunch-Kaufman factorization of real symmetric indefinite * matrix, packed storage */ nag_dsptrf(order, uplo, n, afp, ipiv, &fail); if (fail.code != NE_NOERROR) { fprintf(fpout, "Error from nag_dsptrf (f07pdc).\n%s\n", fail.message); exit_status = 1; goto END; } /* Compute solution in the array X */ /* nag_dsptrs (f07pec). * Solution of real symmetric indefinite system of linear * equations, multiple right-hand sides, matrix already * factorized by nag_dsptrf (f07pdc), packed storage */ nag_dsptrs(order, uplo, n, nrhs, afp, ipiv, x, pdx, &fail); if (fail.code != NE_NOERROR) { fprintf(fpout, "Error from nag_dsptrs (f07pec).\n%s\n", fail.message); exit_status = 1; goto END; } /* Improve solution, and compute backward errors and */ /* estimated bounds on the forward errors */ /* nag_dsprfs (f07phc). * Refined solution with error bounds of real symmetric * indefinite system of linear equations, multiple * right-hand sides, packed storage */ nag_dsprfs(order, uplo, n, nrhs, ap, afp, ipiv, b, pdb, x, pdx, ferr, berr, &fail); if (fail.code != NE_NOERROR) { fprintf(fpout, "Error from nag_dsprfs (f07phc).\n%s\n", fail.message); exit_status = 1; goto END; } /* Print solution */ /* nag_gen_real_mat_print (x04cac). * Print real general matrix (easy-to-use) */ if (outfile) fclose(fpout); nag_gen_real_mat_print(order, Nag_GeneralMatrix, Nag_NonUnitDiag, n, nrhs, x, pdx, "Solution(s)", outfile, &fail); if (outfile && !(fpout = fopen(outfile, "a"))) { exit_status = 2; goto END; } if (fail.code != NE_NOERROR) { fprintf(fpout, "Error from nag_gen_real_mat_print (x04cac).\n%s\n", fail.message); exit_status = 1; goto END; } fprintf(fpout, "\nBackward errors (machine-dependent)\n"); for (j = 1; j <= nrhs; ++j) fprintf(fpout, "%11.1e%s", berr[j-1], j%7 == 0?"\n":" "); fprintf(fpout, "\nEstimated forward error bounds (machine-dependent)\n"); for (j = 1; j <= nrhs; ++j) fprintf(fpout, "%11.1e%s", ferr[j-1], j%7 == 0?"\n":" "); fprintf(fpout, "\n"); END: if (fpin != stdin) fclose(fpin); if (fpout != stdout) fclose(fpout); if (ipiv) NAG_FREE(ipiv); if (afp) NAG_FREE(afp); if (ap) NAG_FREE(ap); if (b) NAG_FREE(b); if (berr) NAG_FREE(berr); if (ferr) NAG_FREE(ferr); if (x) NAG_FREE(x); return exit_status; }