/* nag_dsprfs (f07phc) Example Program. * * Copyright 2001 Numerical Algorithms Group. * * Mark 7, 2001. */ #include #include #include #include #include int main(void) { /* 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_enum; Nag_OrderType order; /* Arrays */ Integer *ipiv=0; char uplo[2]; 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); Vprintf("nag_dsprfs (f07phc) Example Program Results\n\n"); /* Skip heading in data file */ Vscanf("%*[^\n] "); Vscanf("%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)) ) { Vprintf("Allocation failure\n"); exit_status = -1; goto END; } /* Read A and B from data file, and copy A to AFP 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_UPPER(i,j)); } Vscanf("%*[^\n] "); } else { for (i = 1; i <= n; ++i) { for (j = 1; j <= i; ++j) Vscanf("%lf", &A_LOWER(i,j)); } Vscanf("%*[^\n] "); } for (i = 1; i <= n; ++i) { for (j = 1; j <= nrhs; ++j) Vscanf("%lf", &B(i,j)); } Vscanf("%*[^\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_enum, n, afp, ipiv, &fail); if (fail.code != NE_NOERROR) { Vprintf("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_enum, n, nrhs, afp, ipiv, x, pdx, &fail); if (fail.code != NE_NOERROR) { Vprintf("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_enum, n, nrhs, ap, afp, ipiv, b, pdb, x, pdx, ferr, berr, &fail); if (fail.code != NE_NOERROR) { Vprintf("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) */ 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 ?"\n":" "); Vprintf("\n"); END: 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; }