/* nag_dgttrs (f07cec) 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, n, nrhs, pdb; /* Arrays */ double *b = 0, *d = 0, *dl = 0, *du = 0, *du2 = 0; Integer *ipiv = 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_dgttrs (f07cec) 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)) || !(du2 = NAG_ALLOC(n-2, double)) || !(ipiv = NAG_ALLOC(n, Integer))) { printf("Allocation failure\n"); exit_status = -1; goto END; } #ifdef NAG_COLUMN_MAJOR pdb = n; #else pdb = nrhs; #endif /* Read the tridiagonal matrix A 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]"); /* Read the right hand matrix B */ for (i = 1; i <= n; ++i) for (j = 1; j <= nrhs; ++j) scanf("%lf", &B(i, j)); scanf("%*[^\n]"); /* Factorize the tridiagonal matrix A using nag_dgttrf (f07cdc). */ nag_dgttrf(n, dl, d, du, du2, ipiv, &fail); if (fail.code != NE_NOERROR) { printf("Error from nag_dgttrf (f07cdc).\n%s\n", fail.message); exit_status = 1; goto END; } /* Solve the equations AX = B using nag_dgttrs (f07cec). */ nag_dgttrs(order, Nag_NoTrans, n, nrhs, dl, d, du, du2, ipiv, b, pdb, &fail); if (fail.code != NE_NOERROR) { printf("Error from nag_dgttrs (f07cec).\n%s\n", fail.message); exit_status = 1; goto END; } /* Print the solution usbing nag_gen_real_mat_print (x04cac). */ fflush(stdout); nag_gen_real_mat_print(order, Nag_GeneralMatrix, Nag_NonUnitDiag, n, nrhs, b, pdb, "Solution(s)", 0, &fail); if (fail.code != NE_NOERROR) { printf("Error from nag_gen_real_mat_print (x04cac).\n%s\n", fail.message); exit_status = 1; goto END; } END: if (b) NAG_FREE(b); if (d) NAG_FREE(d); if (dl) NAG_FREE(dl); if (du) NAG_FREE(du); if (du2) NAG_FREE(du2); if (ipiv) NAG_FREE(ipiv); return exit_status; } #undef B