/* nag_dgesv (f07aac) Example Program. * * Copyright 2008 Numerical Algorithms Group. * * Mark 23, 2011. */ #include #include #include #include #include int main(void) { /* Scalars */ Integer exit_status = 0, i, j, n, nrhs, pda, pdb; /* Arrays */ double *a = 0, *b = 0; Integer *ipiv = 0; /* Nag Types */ NagError fail; Nag_OrderType order; #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_dgesv (f07aac) 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; #ifdef NAG_COLUMN_MAJOR pdb = n; #else pdb = nrhs; #endif /* Allocate memory */ if (!(a = NAG_ALLOC(n*n, double)) || !(b = NAG_ALLOC(n*nrhs, 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_dgesv (f07aac) */ nag_dgesv(order, n, nrhs, a, pda, ipiv, b, pdb, &fail); if (fail.code != NE_NOERROR) { printf("Error from nag_dgesv (f07aac).\n%s\n", fail.message); exit_status = 1; goto END; } /* Print solution */ printf("Solution\n"); for (i = 1; i <= n; ++i) for (j = 1; j <= nrhs; ++j) printf("%11.4f%s", B(i, j), j%7 == 0 || j == nrhs?"\n":" "); /* Print details of factorization using * nag_gen_real_mat_print (x04cac) */ printf("\n"); fflush(stdout); nag_gen_real_mat_print(order, Nag_GeneralMatrix, Nag_NonUnitDiag, n, n, a, pda, "Details of factorization", 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 pivot indices */ printf("\nPivot indices\n"); for (i = 1; i <= n; ++i) printf("%11ld%s", ipiv[i-1], i%7 == 0 || i == n?"\n":" "); END: NAG_FREE(a); NAG_FREE(b); NAG_FREE(ipiv); return exit_status; } #undef A #undef B