/* nag_dgetrs (f07aec) Example Program. * * Copyright 2001 Numerical Algorithms Group. * * Mark 7, 2001. */ #include #include #include #include #include int main(int argc, char *argv[]) { FILE *fpin, *fpout; char *outfile = 0; /* Scalars */ Integer i, j, n, nrhs, pda, pdb; Integer exit_status = 0; NagError fail; Nag_OrderType order; /* Arrays */ double *a = 0, *b = 0; Integer *ipiv = 0; #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); /* Check for command-line IO options */ fpin = nag_example_file_io(argc, argv, "-data", NULL); fpout = nag_example_file_io(argc, argv, "-results", NULL); (void) nag_example_file_io(argc, argv, "-nag_write", &outfile); fprintf(fpout, "nag_dgetrs (f07aec) Example Program Results\n\n"); /* Skip heading in data file */ fscanf(fpin, "%*[^\n] "); fscanf(fpin, "%ld%ld%*[^\n] ", &n, &nrhs); /* Allocate memory */ if (!(a = NAG_ALLOC(n * n, double)) || !(b = NAG_ALLOC(n * nrhs, double)) || !(ipiv = NAG_ALLOC(n, Integer))) { fprintf(fpout, "Allocation failure\n"); exit_status = -1; goto END; } #ifdef NAG_COLUMN_MAJOR pda = n; pdb = n; #else pda = n; pdb = nrhs; #endif /* Read A and B from data file */ for (i = 1; i <= n; ++i) { for (j = 1; j <= n; ++j) fscanf(fpin, "%lf", &A(i, j)); } fscanf(fpin, "%*[^\n] "); for (i = 1; i <= n; ++i) { for (j = 1; j <= nrhs; ++j) fscanf(fpin, "%lf", &B(i, j)); } fscanf(fpin, "%*[^\n] "); /* Factorize A */ /* nag_dgetrf (f07adc). * LU factorization of real m by n matrix */ nag_dgetrf(order, n, n, a, pda, ipiv, &fail); if (fail.code != NE_NOERROR) { fprintf(fpout, "Error from nag_dgetrf (f07adc).\n%s\n", fail.message); exit_status = 1; goto END; } /* Compute solution */ /* nag_dgetrs (f07aec). * Solution of real system of linear equations, multiple * right-hand sides, matrix already factorized by nag_dgetrf * (f07adc) */ nag_dgetrs(order, Nag_NoTrans, n, nrhs, a, pda, ipiv, b, pdb, &fail); if (fail.code != NE_NOERROR) { fprintf(fpout, "Error from nag_dgetrs (f07aec).\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) */ if (outfile) fclose(fpout); nag_gen_real_mat_print(order, Nag_GeneralMatrix, Nag_NonUnitDiag, n, nrhs, b, pdb, "Solution(s)", outfile, &fail); if (outfile && !(fpout = fopen(outfile, "a"))) { exit_status = 2; goto END; } if (fail.code != NE_NOERROR) { fprintf(fpout, "Error from nag_gen_real_mat_print (x04cac).\n%s\n", fail.message); exit_status = 1; goto END; } END: if (fpin != stdin) fclose(fpin); if (fpout != stdout) fclose(fpout); if (a) NAG_FREE(a); if (b) NAG_FREE(b); if (ipiv) NAG_FREE(ipiv); return exit_status; }