/* nag_dtbsv (f16pkc) Example Program. * * Copyright 2005 Numerical Algorithms Group. * * Mark 8, 2005. */ #include #include #include #include #include int main(void) { /* Scalars */ double alpha; Integer exit_status, i, incx, j, kd, n, pdab, xlen; /* Arrays */ double *ab=0, *x=0; char nag_enum_arg[40]; /* Nag Types */ NagError fail; Nag_OrderType order; Nag_TransType trans; Nag_UploType uplo; Nag_DiagType diag; #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 exit_status = 0; INIT_FAIL(fail); Vprintf( "nag_dtbsv (f16pkc) Example Program Results\n\n"); /* Skip heading in data file */ Vscanf("%*[^\n] "); /* Read the problem dimensions */ Vscanf("%ld%ld%*[^\n] ", &n, &kd); /* Read the uplo storage parameter */ Vscanf("%s%*[^\n] ", nag_enum_arg); /* nag_enum_name_to_value(x04nac). * Converts NAG enum member name to value */ uplo = nag_enum_name_to_value(nag_enum_arg); /* Read the transpose parameter */ Vscanf("%s%*[^\n] ", nag_enum_arg); /* nag_enum_name_to_value(x04nac), see above. */ trans = nag_enum_name_to_value(nag_enum_arg); /* Read the unit-diagonal parameter */ Vscanf("%s%*[^\n] ", nag_enum_arg); /* nag_enum_name_to_value(x04nac), see above. */ diag = nag_enum_name_to_value(nag_enum_arg); /* Read scalar parameters */ Vscanf("%lf%*[^\n] ", &alpha); /* Read increment parameter */ Vscanf("%ld%*[^\n] ", &incx); pdab = kd + 1; xlen = MAX(1, 1 + (n - 1)*ABS(incx)); if (n > 0) { /* Allocate memory */ if ( !(ab = NAG_ALLOC(pdab*n, double)) || !(x = NAG_ALLOC(xlen, double))) { Vprintf("Allocation failure\n"); exit_status = -1; goto END; } } else { Vprintf("Invalid n\n"); exit_status = 1; return exit_status; } /* Input matrix AB and vector x*/ if (uplo == Nag_Upper) { for (i = 1; i <= n; ++i) { if (diag == Nag_NonUnitDiag) Vscanf("%lf", &AB_UPPER(i,i)); for (j = i+1; 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)); if (diag == Nag_NonUnitDiag) Vscanf("%lf", &AB_LOWER(i,i)); } Vscanf("%*[^\n] "); } for (i = 0; i < xlen; ++i) Vscanf("%lf%*[^\n] ", &x[i]); /* nag_dtbsv(f16pkc). * Solution of real triangular band system of linear equations. * */ nag_dtbsv(order, uplo, trans, diag, n, kd, alpha, ab, pdab, x, incx, &fail); if (fail.code != NE_NOERROR) { Vprintf("Error from nag_dtbsv.\n%s\n", fail.message); exit_status = 1; goto END; } /* Print output vector x */ Vprintf("%s\n", " Solution x:"); for (i = 0; i < xlen; i = ++i) { Vprintf("%11f\n", x[i]); } END: if (ab) NAG_FREE(ab); if (x) NAG_FREE(x); return exit_status; }