/* nag_dposvx (f07fbc) Example Program. * * Copyright 2008 Numerical Algorithms Group. * * Mark 23, 2011. */ #include #include #include #include #include int main(void) { /* Scalars */ double rcond; Integer exit_status = 0, i, j, n, nrhs, pda, pdaf, pdb, pdx; /* Arrays */ double *a = 0, *af = 0, *b = 0, *berr = 0, *ferr = 0, *s = 0; double *x = 0; /* Nag Types */ NagError fail; Nag_OrderType order; Nag_EquilibrationType equed; #ifdef NAG_COLUMN_MAJOR #define A(I, J) a[(J-1)*pda + I - 1] #define B(I, J) b[(J-1)*pdb + 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] order = Nag_RowMajor; #endif INIT_FAIL(fail); printf("nag_dposvx (f07fbc) Example Program Results\n\n"); /* Skip heading in data file */ scanf("%*[^\n]"); scanf("%ld%ld%*[^\n]", &n, &nrhs); if (n < 0 || nrhs < 0) { printf("Invalid n or nrhs\n"); exit_status = 1; goto END; } pda = n; pdaf = n; #ifdef NAG_COLUMN_MAJOR pdb = n; pdx = n; #else pdb = nrhs; pdx = nrhs; #endif /* Allocate memory */ if (!(a = NAG_ALLOC(n * n, double)) || !(af = NAG_ALLOC(n * n, double)) || !(b = NAG_ALLOC(n * nrhs, double)) || !(berr = NAG_ALLOC(n, double)) || !(ferr = NAG_ALLOC(n, double)) || !(s = NAG_ALLOC(n, double)) || !(x = NAG_ALLOC(n * nrhs, double))) { printf("Allocation failure\n"); exit_status = -1; goto END; } /* Read the upper triangular part of A from data file */ for (i = 1; i <= n; ++i) for (j = i; j <= n; ++j) scanf("%lf", &A(i, j)); scanf("%*[^\n]"); /* Read B from data file */ for (i = 1; i <= n; ++i) for (j = 1; j <= nrhs; ++j) scanf("%lf", &B(i, j)); scanf("%*[^\n]"); /* Solve the equations AX = B for X using nag_dposvx (f07fbc). */ nag_dposvx(order, Nag_EquilibrateAndFactor, Nag_Upper, n, nrhs, a, pda, af, pdaf, &equed, s, b, pdb, x, pdx, &rcond, ferr, berr, &fail); if (fail.code != NE_NOERROR && fail.code != NE_SINGULAR) { printf("Error from nag_dposvx (f07fbc).\n%s\n", fail.message); exit_status = 1; goto END; } /* Print solution using nag_gen_real_mat_print (x04cac). */ 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; } /* Print error bounds, condition number and the form of equilibration */ printf("\nBackward errors (machine-dependent)\n"); for (j = 0; j < nrhs; ++j) printf("%11.1e%s", berr[j], j%7 == 6?"\n":" "); printf("\n\nEstimated forward error bounds (machine-dependent)\n"); for (j = 0; j < nrhs; ++j) printf("%11.1e%s", ferr[j], j%7 == 6?"\n":" "); printf("\n\nEstimate of reciprocal condition number\n%11.1e\n\n", rcond); if (equed == Nag_NoEquilibration) printf("A has not been equilibrated\n"); else if (equed == Nag_RowAndColumnEquilibration) printf("A has been row and column scaled as diag(S)*A*diag(S)\n"); if (fail.code == NE_SINGULAR) { printf("Error from nag_dposvx (f07fbc).\n%s\n", fail.message); exit_status = 1; } END: 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 (s) NAG_FREE(s); if (x) NAG_FREE(x); return exit_status; } #undef A #undef B