/* nag_dsyrfs (f07mhc) Example Program. * * Copyright 2001 Numerical Algorithms Group. * * Mark 7, 2001. */ #include #include #include #include #include int main(void) { /* Scalars */ Integer berr_len, ferr_len, i, j, n, nrhs; Integer pda, pdaf, pdb, pdx; Integer exit_status=0; Nag_UploType uplo_enum; NagError fail; Nag_OrderType order; /* Arrays */ char uplo[2]; Integer *ipiv=0; double *a=0, *af=0, *b=0, *berr=0, *ferr=0, *x=0; #ifdef NAG_COLUMN_MAJOR #define A(I,J) a[(J-1)*pda + I - 1] #define AF(I,J) af[(J-1)*pdaf + 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 AF(I,J) af[(I-1)*pdaf + 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); Vprintf("nag_dsyrfs (f07mhc) Example Program Results\n\n"); /* Skip heading in data file */ Vscanf("%*[^\n] "); Vscanf("%ld%ld%*[^\n] ", &n, &nrhs); #ifdef NAG_COLUMN_MAJOR pda = n; pdaf = n; pdb = n; pdx = n; #else pda = n; pdaf = n; pdb = nrhs; pdx = nrhs; #endif ferr_len = nrhs; berr_len = nrhs; /* Allocate memory */ if ( !(ipiv = NAG_ALLOC(n, Integer)) || !(a = NAG_ALLOC(n * n, double)) || !(af = 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)) ) { Vprintf("Allocation failure\n"); exit_status = -1; goto END; } /* Read A and B from data file, and copy A to AF and B to X */ Vscanf(" ' %1s '%*[^\n] ", uplo); if (*(unsigned char *)uplo == 'L') uplo_enum = Nag_Lower; else if (*(unsigned char *)uplo == 'U') uplo_enum = Nag_Upper; else { Vprintf("Unrecognised character for Nag_UploType type\n"); exit_status = -1; goto END; } if (uplo_enum == Nag_Upper) { for (i = 1; i <= n; ++i) { for (j = i; j <= n; ++j) Vscanf("%lf", &A(i,j)); } Vscanf("%*[^\n] "); } else { for (i = 1; i <= n; ++i) { for (j = 1; j <= i; ++j) Vscanf("%lf", &A(i,j)); } Vscanf("%*[^\n] "); } for (i = 1; i <= n; ++i) { for (j = 1; j <= nrhs; ++j) Vscanf("%lf", &B(i,j)); } Vscanf("%*[^\n] "); /* Copy A to AF and B to X */ if (uplo_enum == Nag_Upper) { for (i = 1; i <= n; ++i) { for (j = i; j <= n; ++j) AF(i,j) = A(i,j); } } else { for (i = 1; i <= n; ++i) { for (j = 1; j <= i; ++j) AF(i,j) = A(i,j); } } for (i = 1; i <= n; ++i) { for (j = 1; j <= nrhs; ++j) X(i,j) = B(i,j); } /* Factorize A in the array AF */ /* nag_dsytrf (f07mdc). * Bunch-Kaufman factorization of real symmetric indefinite * matrix */ nag_dsytrf(order, uplo_enum, n, af, pdaf, ipiv, &fail); if (fail.code != NE_NOERROR) { Vprintf("Error from nag_dsytrf (f07mdc).\n%s\n", fail.message); exit_status = 1; goto END; } /* Compute solution in the array X */ /* nag_dsytrs (f07mec). * Solution of real symmetric indefinite system of linear * equations, multiple right-hand sides, matrix already * factorized by nag_dsytrf (f07mdc) */ nag_dsytrs(order, uplo_enum, n, nrhs, af, pdaf, ipiv, x, pdx, &fail); if (fail.code != NE_NOERROR) { Vprintf("Error from nag_dsytrs (f07mec).\n%s\n", fail.message); exit_status = 1; goto END; } /* Improve solution, and compute backward errors and */ /* estimated bounds on the forward errors */ /* nag_dsyrfs (f07mhc). * Refined solution with error bounds of real symmetric * indefinite system of linear equations, multiple * right-hand sides */ nag_dsyrfs(order, uplo_enum, n, nrhs, a, pda, af, pdaf, ipiv, b, pdb, x, pdx, ferr, berr, &fail); if (fail.code != NE_NOERROR) { Vprintf("Error from nag_dsyrfs (f07mhc).\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) */ nag_gen_real_mat_print(order, Nag_GeneralMatrix, Nag_NonUnitDiag, n, nrhs, x, pdx, "Solution(s)", 0, &fail); if (fail.code != NE_NOERROR) { Vprintf("Error from nag_gen_real_mat_print (x04cac).\n%s\n", fail.message); exit_status = 1; goto END; } Vprintf("\nBackward errors (machine-dependent)\n"); for (j = 1; j <= nrhs; ++j) Vprintf("%11.1e%s", berr[j-1], j%7==0 ?"\n":" "); Vprintf("\nEstimated forward error bounds" "(machine-dependent)\n"); for (j = 1; j <= nrhs; ++j) Vprintf("%11.1e%s", ferr[j-1], j%7==0 || j==nrhs ?"\n":" "); END: if (ipiv) NAG_FREE(ipiv); if (a) NAG_FREE(a); if (af) NAG_FREE(af); if (b) NAG_FREE(b); if (berr) NAG_FREE(berr); if (ferr) NAG_FREE(ferr); if (x) NAG_FREE(x); return exit_status; }