/* nag_dtrrfs (f07thc) Example Program. * * Copyright 2001 Numerical Algorithms Group. * * Mark 7, 2001. */ #include #include #include #include #include int main(void) { /* Scalars */ Integer i, j, n, nrhs, berr_len, ferr_len; Integer pda, pdb, pdx; Integer exit_status = 0; Nag_UploType uplo; NagError fail; Nag_OrderType order; /* Arrays */ char nag_enum_arg[40]; double *a = 0, *b = 0, *berr = 0, *ferr = 0, *x = 0; #ifdef NAG_COLUMN_MAJOR #define A(I, J) a[(J-1)*pda + 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(I, J) a[(I-1)*pda + 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); printf("nag_dtrrfs (f07thc) Example Program Results\n\n"); /* Skip heading in data file */ scanf("%*[^\n] "); scanf("%ld%ld%*[^\n] ", &n, &nrhs); berr_len = nrhs; ferr_len = nrhs; #ifdef NAG_COLUMN_MAJOR pda = n; pdb = n; pdx = n; #else pda = n; pdb = nrhs; pdx = nrhs; #endif /* Allocate memory */ if (!(a = NAG_ALLOC(n * n, 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))) { printf("Allocation failure\n"); exit_status = -1; goto END; } /* Read A and B from data file, and copy B to X */ scanf(" %39s%*[^\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) scanf("%lf", &A(i, j)); } scanf("%*[^\n] "); } else { for (i = 1; i <= n; ++i) { for (j = 1; j <= i; ++j) scanf("%lf", &A(i, j)); } scanf("%*[^\n] "); } for (i = 1; i <= n; ++i) { for (j = 1; j <= nrhs; ++j) scanf("%lf", &B(i, j)); } scanf("%*[^\n] "); for (i = 1; i <= n; ++i) { for (j = 1; j <= nrhs; ++j) X(i, j) = B(i, j); } /* Compute solution in the array X */ /* nag_dtrtrs (f07tec). * Solution of real triangular system of linear equations, * multiple right-hand sides */ nag_dtrtrs(order, uplo, Nag_NoTrans, Nag_NonUnitDiag, n, nrhs, a, pda, x, pdx, &fail); if (fail.code != NE_NOERROR) { printf("Error from nag_dtrtrs (f07tec).\n%s\n", fail.message); exit_status = 1; goto END; } /* Compute backward errors and estimated bounds on the */ /* forward errors */ /* nag_dtrrfs (f07thc). * Error bounds for solution of real triangular system of * linear equations, multiple right-hand sides */ nag_dtrrfs(order, uplo, Nag_NoTrans, Nag_NonUnitDiag, n, nrhs, a, pda, b, pdb, x, pdx, ferr, berr, &fail); if (fail.code != NE_NOERROR) { printf("Error from nag_dtrrfs (f07thc).\n%s\n", fail.message); exit_status = 1; goto END; } /* Print solution */ printf("\n"); /* nag_gen_real_mat_print (x04cac). * Print real general matrix (easy-to-use) */ fflush(stdout); nag_gen_real_mat_print(order, Nag_GeneralMatrix, Nag_NonUnitDiag, n, nrhs, x, pdx, "Solution(s)", 0, &fail); if (fail.code != NE_NOERROR) { printf("Error from nag_gen_real_mat_print (x04cac).\n%s\n", fail.message); exit_status = 1; goto END; } printf("\nBackward errors (machine-dependent)\n"); for (j = 1; j <= nrhs; ++j) printf("%11.1e%s", berr[j-1], j%7 == 0?"\n":" "); printf("\nEstimated forward error bounds " "(machine-dependent)\n"); for (j = 1; j <= nrhs; ++j) printf("%11.1e%s", ferr[j-1], j%7 == 0?"\n":" "); printf("\n"); END: NAG_FREE(a); NAG_FREE(b); NAG_FREE(berr); NAG_FREE(ferr); NAG_FREE(x); return exit_status; }