/* nag_dsbevd (f08hcc) Example Program. * * Copyright 2001 Numerical Algorithms Group. * * Mark 7, 2001. */ #include #include #include #include #include int main(void) { /* Scalars */ Integer i, j, k, kd, n, pdab, pdz, w_len; Integer exit_status = 0; NagError fail; Nag_JobType job; Nag_UploType uplo; Nag_OrderType order; /* Arrays */ char nag_enum_arg[40]; double *ab = 0, *w = 0, *z = 0; #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 Z(I, J) z[(J - 1) * pdz + 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 Z(I, J) z[(I - 1) * pdz + J - 1] order = Nag_RowMajor; #endif INIT_FAIL(fail); printf("nag_dsbevd (f08hcc) Example Program Results\n\n"); /* Skip heading in data file */ scanf("%*[^\n] "); scanf("%ld%ld%*[^\n] ", &n, &kd); pdab = kd + 1; pdz = n; w_len = n; /* Allocate memory */ if (!(ab = NAG_ALLOC(pdab * n, double)) || !(w = NAG_ALLOC(w_len, double)) || !(z = NAG_ALLOC(n * n, double))) { printf("Allocation failure\n"); exit_status = -1; goto END; } /* Read whether Upper or Lower part of A is stored */ 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); /* Read A from data file */ k = kd + 1; if (uplo == Nag_Upper) { for (i = 1; i <= n; ++i) { for (j = i; j <= MIN(i + kd, n); ++j) scanf("%lf", &AB_UPPER(i, j)); } scanf("%*[^\n] "); } else { for (i = 1; i <= n; ++i) { for (j = MAX(1, i - kd); j <= i; ++j) scanf("%lf", &AB_LOWER(i, j)); } scanf("%*[^\n] "); } /* Read type of job to be performed */ scanf("%s%*[^\n] ", nag_enum_arg); job = (Nag_JobType) nag_enum_name_to_value(nag_enum_arg); /* Calculate all the eigenvalues and eigenvectors of A */ /* nag_dsbevd (f08hcc). * All eigenvalues and optionally all eigenvectors of real * symmetric band matrix (divide-and-conquer) */ nag_dsbevd(order, job, uplo, n, kd, ab, pdab, w, z, pdz, &fail); if (fail.code != NE_NOERROR) { printf("Error from nag_dsbevd (f08hcc).\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--) { Z(i, j) = Z(i, j) / Z(1,j); } } /* Print eigenvalues and eigenvectors */ printf(" Eigenvalues\n"); for (i = 0; i < n; ++i) printf(" %8.4lf", w[i]); printf("\n\n"); /* nag_gen_real_mat_print (x04cac). * Print real general matrix (easy-to-use) */ fflush(stdout); nag_gen_real_mat_print(order, Nag_GeneralMatrix, Nag_NonUnitDiag, n, n, z, pdz, "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 (w) NAG_FREE(w); if (z) NAG_FREE(z); return exit_status; }