/* nag_zgerfs (f07avc) Example Program. * * Copyright 2001 Numerical Algorithms Group. * * Mark 7, 2001. */ #include #include #include #include #include int main(void) { /* Scalars */ Integer berr_len, i, ferr_len, ipiv_len, j, n, nrhs; Integer pda, pdaf, pdb, pdx; Integer exit_status = 0; NagError fail; Nag_OrderType order; /* Arrays */ Complex *a = 0, *af = 0, *b = 0, *x = 0; double *berr = 0, *ferr = 0; Integer *ipiv = 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); printf("nag_zgerfs (f07avc) Example Program Results\n\n"); /* Skip heading in data file */ scanf("%*[^\n] "); scanf("%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 ipiv_len = n; ferr_len = n; berr_len = nrhs; /* Allocate memory */ if (!(a = NAG_ALLOC(n * n, Complex)) || !(af = NAG_ALLOC(n * n, Complex)) || !(b = NAG_ALLOC(n * nrhs, Complex)) || !(x = NAG_ALLOC(n * n, Complex)) || !(berr = NAG_ALLOC(berr_len, double)) || !(ferr = NAG_ALLOC(ferr_len, double)) || !(ipiv = NAG_ALLOC(ipiv_len, Integer))) { printf("Allocation failure\n"); exit_status = -1; goto END; } /* Read A and B from data file, and copy A to AF and B to X */ for (i = 1; i <= n; ++i) { for (j = 1; j <= n; ++j) scanf(" ( %lf , %lf )", &A(i, j).re, &A(i, j).im); } scanf("%*[^\n] "); for (i = 1; i <= n; ++i) { for (j = 1; j <= nrhs; ++j) scanf(" ( %lf , %lf )", &B(i, j).re, &B(i, j).im); } scanf("%*[^\n] "); for (i = 1; i <= n; ++i) { for (j = 1; j <= n; ++j) { AF(i, j).re = A(i, j).re; AF(i, j).im = A(i, j).im; } } for (i = 1; i <= n; ++i) { for (j = 1; j <= nrhs; ++j) { X(i, j).re = B(i, j).re; X(i, j).im = B(i, j).im; } } /* Factorize A in the array AF */ /* nag_zgetrf (f07arc). * LU factorization of complex m by n matrix */ nag_zgetrf(order, n, n, af, pdaf, ipiv, &fail); if (fail.code != NE_NOERROR) { printf("Error from nag_zgetrf (f07arc).\n%s\n", fail.message); exit_status = 1; goto END; } /* Compute solution in the array X */ /* nag_zgetrs (f07asc). * Solution of complex system of linear equations, multiple * right-hand sides, matrix already factorized by nag_zgetrf * (f07arc) */ nag_zgetrs(order, Nag_NoTrans, n, nrhs, af, pdaf, ipiv, x, pdx, &fail); if (fail.code != NE_NOERROR) { printf("Error from nag_zgetrs (f07asc).\n%s\n", fail.message); exit_status = 1; goto END; } /* Improve solution, and compute backward errors and */ /* estimated bounds on the forward errors */ /* nag_zgerfs (f07avc). * Refined solution with error bounds of complex system of * linear equations, multiple right-hand sides */ nag_zgerfs(order, Nag_NoTrans, n, nrhs, a, pda, af, pdaf, ipiv, b, pdb, x, pdx, ferr, berr, &fail); if (fail.code != NE_NOERROR) { printf("Error from nag_zgerfs (f07avc).\n%s\n", fail.message); exit_status = 1; goto END; } /* Print solution */ /* nag_gen_complx_mat_print_comp (x04dbc). * Print complex general matrix (comprehensive) */ fflush(stdout); nag_gen_complx_mat_print_comp(order, Nag_GeneralMatrix, Nag_NonUnitDiag, n, nrhs, x, pdx, Nag_BracketForm, "%7.4f", "Solution(s)", Nag_IntegerLabels, 0, Nag_IntegerLabels, 0, 80, 0, 0, &fail); if (fail.code != NE_NOERROR) { printf("Error from nag_gen_complx_mat_print_comp (x04dbc).\n%s\n", fail.message); exit_status = 1; goto END; } printf("\nBackward errors (machine-dependent)\n"); for (j = 1; j <= nrhs; ++j) printf("%11.1e%s", berr[j-1], j%4 == 0?"\n":" "); printf("\nEstimated forward error bounds (machine-dependent)\n"); for (j = 1; j <= nrhs; ++j) printf("%11.1e%s", ferr[j-1], j%4 == 0 || j == nrhs?"\n":" "); END: if (a) NAG_FREE(a); if (af) NAG_FREE(af); if (b) NAG_FREE(b); if (x) NAG_FREE(x); if (berr) NAG_FREE(berr); if (ferr) NAG_FREE(ferr); if (ipiv) NAG_FREE(ipiv); return exit_status; }