/* nag_dgtsv (f07cac) Example Program. * * Copyright 2004 Numerical Algorithms Group. * * Mark 23, 2011 */ #include #include #include #include int main(void) { /* Scalars */ Integer exit_status = 0, i, j, n, nrhs, pdb; /* Arrays */ double *b = 0, *d = 0, *dl = 0, *du = 0; /* Nag Types */ NagError fail; Nag_OrderType order; #ifdef NAG_COLUMN_MAJOR #define B(I, J) b[(J-1)*pdb + I - 1] order = Nag_ColMajor; #else #define B(I, J) b[(I-1)*pdb + J - 1] order = Nag_RowMajor; #endif INIT_FAIL(fail); printf("nag_dgtsv (f07cac) Example Program Results\n\n"); /* Skip heading in data file */ scanf("%*[^\n]"); scanf("%ld%ld%*[^\n]", &n, &nrhs); if (n < 0 || nrhs < 0) { printf("Invalid n or nrhs\n"); exit_status = 1; goto END; } /* Allocate memory */ if (!(b = NAG_ALLOC(n*nrhs, double)) || !(d = NAG_ALLOC(n, double)) || !(dl = NAG_ALLOC(n-1, double)) || !(du = NAG_ALLOC(n-1, double))) { printf("Allocation failure\n"); exit_status = -1; goto END; } #ifdef NAG_COLUMN_MAJOR pdb = n; #else pdb = nrhs; #endif /* Read the tridiagonal matrix A and the right hand side B from data file */ for (i = 0; i < n - 1; ++i) scanf("%lf", &du[i]); scanf("%*[^\n]"); for (i = 0; i < n; ++i) scanf("%lf", &d[i]); scanf("%*[^\n]"); for (i = 0; i < n - 1; ++i) scanf("%lf", &dl[i]); scanf("%*[^\n]"); 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_dgtsv (f07cac). */ nag_dgtsv(order, n, nrhs, dl, d, du, b, pdb, &fail); if (fail.code != NE_NOERROR) { printf("Error from nag_dgtsv (f07cac).\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"); } END: NAG_FREE(b); NAG_FREE(d); NAG_FREE(dl); NAG_FREE(du); return exit_status; }