/* nag_dgttrf (f07cdc) Example Program. * * Copyright 2004 Numerical Algorithms Group. * * Mark 23, 2011 */ #include #include #include #include int main(void) { /* Scalars */ Integer exit_status = 0, i, n; /* Arrays */ double *d = 0, *dl = 0, *du = 0, *du2 = 0; Integer *ipiv = 0; /* Nag Types */ NagError fail; INIT_FAIL(fail); printf("nag_dgttrf (f07cdc) Example Program Results\n\n"); /* Skip heading in data file */ scanf("%*[^\n]"); scanf("%ld%*[^\n]", &n); if (n < 0) { printf("Invalid n\n"); exit_status = 1; goto END; } /* Allocate memory */ if (!(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; } /* 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]"); /* 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; } /* Print details of the factorization */ printf("Details of factorization\n\n"); printf(" Second super-diagonal of U\n"); for (i = 0; i < n - 2; ++i) printf("%9.4f%s", du2[i], i%8 == 7?"\n":" "); printf("\n\n First super-diagonal of U\n"); for (i = 0; i < n - 1; ++i) printf("%9.4f%s", du[i], i%8 == 7?"\n":" "); printf("\n\n Main diagonal of U\n"); for (i = 0; i < n; ++i) printf("%9.4f%s", d[i], i%8 == 7?"\n":" "); printf("\n\n Multipliers\n"); for (i = 0; i < n - 1; ++i) printf("%9.4f%s", dl[i], i%8 == 7?"\n":" "); printf("\n\n Vector of interchanges\n"); for (i = 0; i < n; ++i) printf("%9ld%s", ipiv[i], i%5 == 4?"\n":" "); printf("\n"); END: NAG_FREE(d); NAG_FREE(dl); NAG_FREE(du); NAG_FREE(du2); NAG_FREE(ipiv); return exit_status; }