/* nag_dtbrfs (f07vhc) Example Program. * * Copyright 2001 Numerical Algorithms Group. * * Mark 7, 2001. */ #include #include #include #include #include int main(void) { /* Scalars */ Integer i, j, k, kd, n, nrhs, pdab, pdb, pdx; Integer ferr_len, berr_len; Integer exit_status=0; Nag_UploType uplo_enum; NagError fail; Nag_OrderType order; /* Arrays */ char uplo[2]; double *ab=0, *b=0, *berr=0, *ferr=0, *x=0; #ifdef NAG_COLUMN_MAJOR #define AB_UPPER(I,J) ab[(J-1)*pdab + k + I - J - 1] #define AB_LOWER(I,J) ab[(J-1)*pdab + I - J] #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 AB_UPPER(I,J) ab[(I-1)*pdab + J - I] #define AB_LOWER(I,J) ab[(I-1)*pdab + k + J - I - 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("f07vhc Example Program Results\n\n"); /* Skip heading in data file */ Vscanf("%*[^\n] "); Vscanf("%ld%ld%ld%*[^\n] ", &n, &kd, &nrhs); pdab = kd + 1; #ifdef NAG_COLUMN_MAJOR pdb = n; pdx = n; #else pdb = nrhs; pdx = nrhs; #endif ferr_len = nrhs; berr_len = nrhs; /* Allocate memory */ if ( !(berr = NAG_ALLOC(berr_len, double)) || !(ferr = NAG_ALLOC(ferr_len, double)) || !(ab = NAG_ALLOC((kd+1) * n, double)) || !(b = NAG_ALLOC(n * nrhs, 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; } k = kd + 1; if (uplo_enum == Nag_Upper) { for (i = 1; i <= n; ++i) { for (j = i; j <= MIN(i+kd,n); ++j) Vscanf("%lf", &AB_UPPER(i,j)); } Vscanf("%*[^\n] "); } else { for (i = 1; i <= n; ++i) { for (j = MAX(1,i-kd); j <= i; ++j) Vscanf("%lf", &AB_LOWER(i,j)); } Vscanf("%*[^\n] "); } for (i = 1; i <= n; ++i) { for (j = 1; j <= nrhs; ++j) Vscanf("%lf", &B(i,j)); } Vscanf("%*[^\n] "); /* Copy B to X */ for (i = 1; i <= n; ++i) { for (j = 1; j <= nrhs; ++j) X(i,j) = B(i,j); } /* Compute solution in the array X */ f07vec(order, uplo_enum, Nag_NoTrans, Nag_NonUnitDiag, n, kd, nrhs, ab, pdab, x, pdx, &fail); if (fail.code != NE_NOERROR) { Vprintf("Error from f07vec.\n%s\n", fail.message); exit_status = 1; goto END; } /* Improve solution, and compute backward errors and */ /* estimated bounds on the forward errors */ f07vhc(order, uplo_enum, Nag_NoTrans, Nag_NonUnitDiag, n, kd, nrhs, ab, pdab, b, pdb, x, pdx, ferr, berr, &fail); if (fail.code != NE_NOERROR) { Vprintf("Error from f07vhc.\n%s\n", fail.message); exit_status = 1; goto END; } /* Print details of solution */ x04cac(order, Nag_GeneralMatrix, Nag_NonUnitDiag, n, nrhs, x, pdx, "Solution(s)", 0, &fail); if (fail.code != NE_NOERROR) { Vprintf("Error from 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 ?"\n":" "); Vprintf("\n"); END: if (berr) NAG_FREE(berr); if (ferr) NAG_FREE(ferr); if (ab) NAG_FREE(ab); if (b) NAG_FREE(b); if (x) NAG_FREE(x); return exit_status; }