/* nag_dtprfs (f07uhc) Example Program. * * Copyright 2001 Numerical Algorithms Group. * * Mark 7, 2001. */ #include #include #include #include #include int main(void) { /* Scalars */ Integer ap_len, i, j, n, nrhs, berr_len, ferr_len; Integer pdb, pdx; Integer exit_status=0; Nag_UploType uplo_enum; NagError fail; Nag_OrderType order; /* Arrays */ char uplo[2]; double *ap=0, *b=0, *berr=0, *ferr=0, *x=0; #ifdef NAG_COLUMN_MAJOR #define A_UPPER(I,J) ap[J*(J-1)/2 + I - 1] #define A_LOWER(I,J) ap[(2*n-J)*(J-1)/2 + 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_LOWER(I,J) ap[I*(I-1)/2 + J - 1] #define A_UPPER(I,J) ap[(2*n-I)*(I-1)/2 + 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); Vprintf("nag_dtprfs (f07uhc) Example Program Results\n\n"); /* Skip heading in data file */ Vscanf("%*[^\n] "); Vscanf("%ld%ld%*[^\n] ", &n, &nrhs); berr_len = nrhs; ferr_len = nrhs; ap_len = n*(n+1)/2; #ifdef NAG_COLUMN_MAJOR pdb = n; pdx = n; #else pdb = nrhs; pdx = nrhs; #endif /* Allocate memory */ if ( !(ap = NAG_ALLOC(ap_len, double)) || !(b = NAG_ALLOC(n * nrhs, double)) || !(berr = NAG_ALLOC(berr_len, double)) || !(ferr = NAG_ALLOC(ferr_len, double)) || !(x = NAG_ALLOC(n * nrhs, double)) ) { Vprintf("Allocation failure\n"); exit_status = -1; goto END; } /* Read A and B from data file, and copy B to X */ Vscanf(" ' %1s '%*[^\n] ", uplo); if (*(unsigned char *)uplo == 'L') uplo_enum = Nag_Lower; else if (*(unsigned char *)uplo == 'U') uplo_enum = Nag_Upper; else { Vprintf("Unrecognised character for Nag_UploType type\n"); exit_status = -1; goto END; } if (uplo_enum == Nag_Upper) { for (i = 1; i <= n; ++i) { for (j = i; j <= n; ++j) Vscanf("%lf", &A_UPPER(i,j)); } Vscanf("%*[^\n] "); } else { for (i = 1; i <= n; ++i) { for (j = 1; j <= i; ++j) Vscanf("%lf", &A_LOWER(i,j)); } Vscanf("%*[^\n] "); } for (i = 1; i <= n; ++i) { for (j = 1; j <= nrhs; ++j) Vscanf("%lf", &B(i,j)); } Vscanf("%*[^\n] "); for (i = 1; i <= n; ++i) { for (j = 1; j <= nrhs; ++j) X(i,j) = B(i,j); } /* Compute solution in the array X */ /* nag_dtptrs (f07uec). * Solution of real triangular system of linear equations, * multiple right-hand sides, packed storage */ nag_dtptrs(order, uplo_enum, Nag_NoTrans, Nag_NonUnitDiag, n, nrhs, ap, x, pdx, &fail); if (fail.code != NE_NOERROR) { Vprintf("Error from nag_dtptrs (f07uec).\n%s\n", fail.message); exit_status = 1; goto END; } /* Compute backward errors and estimated bounds on the */ /* forward errors */ /* nag_dtprfs (f07uhc). * Error bounds for solution of real triangular system of * linear equations, multiple right-hand sides, packed * storage */ nag_dtprfs(order, uplo_enum, Nag_NoTrans, Nag_NonUnitDiag, n, nrhs, ap, b, pdb, x, pdx, ferr, berr, &fail); if (fail.code != NE_NOERROR) { Vprintf("Error from nag_dtprfs (f07uhc).\n%s\n", fail.message); exit_status = 1; goto END; } /* Print solution */ Vprintf("\n"); /* nag_gen_real_mat_print (x04cac). * Print real general matrix (easy-to-use) */ nag_gen_real_mat_print(order, Nag_GeneralMatrix, Nag_NonUnitDiag, n, nrhs, x, pdx, "Solution(s)", 0, &fail); if (fail.code != NE_NOERROR) { Vprintf("Error from nag_gen_real_mat_print (x04cac).\n%s\n", fail.message); exit_status = 1; goto END; } Vprintf("\nBackward errors (machine-dependent)\n"); for (j = 1; j <= nrhs; ++j) Vprintf("%11.1e%s", berr[j-1], j%7==0 ?"\n":" "); Vprintf("\nEstimated forward error bounds " "(machine-dependent)\n"); for (j = 1; j <= nrhs; ++j) Vprintf("%11.1e%s", ferr[j-1], (j%7==0||j==nrhs) ?"\n":" "); END: if (ap) NAG_FREE(ap); if (b) NAG_FREE(b); if (berr) NAG_FREE(berr); if (ferr) NAG_FREE(ferr); if (x) NAG_FREE(x); return exit_status; }