/* nag_dstedc (f08jhc) Example Program. * * Copyright 2011 Numerical Algorithms Group. * * Mark 23, 2011. */ #include #include #include #include #include int main(void) { /* Scalars */ Integer i, j, k, kd, n, pdab, pdq; Integer exit_status = 0; /* Arrays */ char nag_enum_arg[40]; double *ab = 0, *d = 0, *e = 0, *q = 0; /* Nag Types */ Nag_OrderType order; Nag_UploType uplo; NagError fail; #ifdef NAG_COLUMN_MAJOR #define AB_UPPER(I, J) ab[(J - 1) * pdab + k + I - J - 1] #define AB_LOWER(I, J) ab[(J - 1) * pdab + I - J] #define Q(I, J) q[(J - 1) * pdq + 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 + k + J - I - 1] #define Q(I, J) q[(I - 1) * pdq + J - 1] order = Nag_RowMajor; #endif INIT_FAIL(fail); printf("nag_dstedc (f08jhc) Example Program Results\n\n"); /* Skip heading in data file */ scanf("%*[^\n]"); scanf("%ld%ld%*[^\n]", &n, &kd); /* Read uplo */ 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); pdab = kd + 1; #ifdef NAG_COLUMN_MAJOR pdq = n; #else pdq = n; #endif /* Allocate memory */ if (!(ab = NAG_ALLOC(pdab*n, double)) || !(d = NAG_ALLOC(n, double)) || !(e = NAG_ALLOC(n-1, double)) || !(q = NAG_ALLOC(n*n, double))) { printf("Allocation failure\n"); exit_status = -1; goto END; } /* Read the upper or lower triangular part of the band matrix A * from data file. */ k = kd + 1; 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)); scanf("%*[^\n]"); } else if (uplo == Nag_Lower) { for (i = 1; i <= n; ++i) for (j = MAX(1, i - kd); j <= i; ++j) scanf("%lf", &AB_LOWER(i, j)); scanf("%*[^\n]"); } /* nag_dsbtrd (f08hec). * Reduce A to tridiagonal form T = (Q**T)*A*Q, and form Q. */ nag_dsbtrd(order, Nag_FormQ, uplo, n, kd, ab, pdab, d, e, q, pdq, &fail); if (fail.code != NE_NOERROR) { printf("Error from nag_dsbtrd (f08hec).\n%s\n", fail.message); exit_status = 1; goto END; } /* nag_dstedc (f08jhc) * Calculate all the eigenvalues and eigenvectors of A, * from T and Q. */ nag_dstedc(order, Nag_OrigEigVecs, n, d, e, q, pdq, &fail); if (fail.code != NE_NOERROR) { printf("Error from nag_dstedc (f08jhc).\n%s\n", fail.message); exit_status = 1; goto END; } /* Normalize the eigenvectors */ for(j=1; j<=n; j++) for(i=n; i>=1; i--) Q(i, j) = Q(i, j) / Q(1,j); /* Print eigenvalues and eigenvectors */ printf("%s\n", "Eigenvalues"); for (i = 0; i < n; ++i) printf("%8.4f%s", d[i], (i+1)%8 == 0?"\n":" "); printf("\n\n"); /* nag_gen_real_mat_print (x04cac). * Print eigenvectors. */ fflush(stdout); nag_gen_real_mat_print(order, Nag_GeneralMatrix, Nag_NonUnitDiag, n, n, q, pdq, "Eigenvectors", 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 (ab) NAG_FREE(ab); if (d) NAG_FREE(d); if (e) NAG_FREE(e); if (q) NAG_FREE(q); return exit_status; } #undef AB_UPPER #undef AB_LOWER #undef Q