/* nag_dgesvx (f07abc) Example Program. * * Copyright 2008 Numerical Algorithms Group. * * Mark 23, 2011. */ #include #include #include #include #include int main(void) { /* Scalars */ double growth_factor, rcond; Integer exit_status = 0, i, j, n, nrhs, pda, pdaf, pdb, pdx; /* Arrays */ double *a = 0, *af = 0, *b = 0, *berr = 0, *c = 0, *ferr = 0; double *r = 0, *x = 0; Integer *ipiv = 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_dgesvx (f07abc) 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; return exit_status; } 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 * n, double)) || !(berr = NAG_ALLOC(n, double)) || !(c = NAG_ALLOC(n, double)) || !(ferr = NAG_ALLOC(n, double)) || !(r = NAG_ALLOC(n, double)) || !(x = NAG_ALLOC(n*n, double)) || !(ipiv = NAG_ALLOC(n, Integer))) { printf("Allocation failure\n"); exit_status = -1; goto END; } /* Read A and B from data file */ for (i = 1; i <= n; ++i) for (j = 1; j <= n; ++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] "); /* Solve the equations AX = B for X using * nag_dgesvx (f07abc) */ nag_dgesvx(order, Nag_EquilibrateAndFactor, Nag_NoTrans, n, nrhs, a, pda, af, pdaf, ipiv, &equed, r, c, b, pdb, x, pdx, &rcond, ferr, berr, &growth_factor, &fail); if (fail.code != NE_NOERROR && fail.code != NE_SINGULAR) { printf("Error from nag_dgesvx (f07abc).\n%s\n", fail.message); goto END; exit_status = 1; } /* 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, the form of equilibration * and the pivot growth factor */ printf("\nBackward errors (machine-dependent)\n"); for (j = 1; j <= nrhs; ++j) printf("%11.1e%s", berr[j - 1], j%7 == 0 || j == nrhs?"\n":" "); printf("\n\nEstimated forward error bounds (machine-dependent)\n"); for (j = 1; j <= nrhs; ++j) printf("%11.1e%s", ferr[j - 1], j%7 == 0 || j == nrhs?"\n":" "); printf("\n"); if (equed == Nag_NoEquilibration) printf("A has not been equilibrated\n"); else if (equed == Nag_RowEquilibration) printf("A has been row scaled as diag(R)*A\n"); else if (equed == Nag_ColumnEquilibration) printf("A has been column scaled as A*diag(C)\n"); else if (equed == Nag_RowAndColumnEquilibration) printf("A has been row and column scaled as diag(R)*A*diag(C)\n"); printf("\nReciprocal condition number estimate of scaled matrix\n"); printf("%11.1e\n\n", rcond); printf("Estimate of reciprocal pivot growth factor\n"); printf("%11.1e\n", growth_factor); if (fail.code == NE_SINGULAR) { printf("Error from nag_dgesvx (f07abc).\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 (c) NAG_FREE(c); if (ferr) NAG_FREE(ferr); if (r) NAG_FREE(r); if (x) NAG_FREE(x); if (ipiv) NAG_FREE(ipiv); return exit_status; } #undef B #undef A