/* nag_dpbsv (f07hac) Example Program. * * Copyright 2004 Numerical Algorithms Group. * * Mark 23, 2011. */ #include #include #include #include #include int main(void) { /* Scalars */ Integer exit_status = 0, i, j, kd, n, nrhs, pdb, pdab; /* Arrays */ double *ab = 0, *b = 0; char nag_enum_arg[40]; /* Nag Types */ NagError fail; Nag_OrderType order; Nag_UploType uplo; #ifdef NAG_COLUMN_MAJOR #define AB_UPPER(I, J) ab[(J-1)*pdab + kd + I - J] #define AB_LOWER(I, J) ab[(J-1)*pdab + I - J] #define B(I, J) b[(J-1)*pdb + 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 + kd + J - I] #define B(I, J) b[(I-1)*pdb + J - 1] order = Nag_RowMajor; #endif INIT_FAIL(fail); printf("nag_dpbsv (f07hac) Example Program Results\n\n"); /* Skip heading in data file */ scanf("%*[^\n]"); scanf("%ld%ld%ld%*[^\n]", &n, &kd, &nrhs); if (n < 0 || nrhs < 0 || kd < 0) { printf("Invalid n, kd or nrhs\n"); exit_status = 1; goto END; } scanf("%s%*[^\n]", nag_enum_arg); /* nag_enum_name_to_value(x04nac). * Converts NAG enum member name to value */ uplo = (Nag_UploType) nag_enum_name_to_value(nag_enum_arg); /* Allocate memory */ if (!(ab = NAG_ALLOC((kd+1) * n, double)) || !(b = NAG_ALLOC(n*nrhs, double))) { printf("Allocation failure\n"); exit_status = -1; goto END; } pdab = kd + 1; #ifdef NAG_COLUMN_MAJOR pdb = n; #else pdb = nrhs; #endif /* Read the upper or lower triangular part of the band matrix A from * data file. */ if (uplo == Nag_Upper) for (i = 1; i <= n; ++i) for (j = i; j <= MIN(n, i + kd); ++j) scanf("%lf", &AB_UPPER(i, j)); else for (i = 1; i <= n; ++i) for (j = MAX(1, i - kd); j <= i; ++j) scanf("%lf", &AB_LOWER(i, j)); scanf("%*[^\n]"); /* Read b from data file */ 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_dpbsv (f07hac). */ nag_dpbsv(order, uplo, n, kd, nrhs, ab, pdab, b, pdb, &fail); if (fail.code != NE_NOERROR) { printf("Error from nag_dpbsv (f07hac).\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?"\n":" "); printf("\n"); } /* Print details of factorization */ printf("\n"); fflush(stdout); if (uplo == Nag_Upper) nag_band_real_mat_print(order, n, n, 0, kd, ab, pdab, "Cholesky factor U", 0, &fail); else nag_band_real_mat_print(order, n, n, kd, 0, ab, pdab, "Cholesky factor L", 0, &fail); if (fail.code != NE_NOERROR) { printf("Error from nag_band_real_mat_print (x04cec).\n%s\n", fail.message); exit_status = 1; } END: if (ab) NAG_FREE(ab); if (b) NAG_FREE(b); return exit_status; } #undef AB_LOWER #undef AB_UPPER #undef B