/* nag_dhseqr (f08pec) Example Program. * * Copyright 2001 Numerical Algorithms Group. * * Mark 7, 2001. */ #include #include #include #include #include int main(void) { /* Scalars */ Integer i, j, n, pdh, pdz, wi_len, wr_len; Integer exit_status=0; NagError fail; Nag_OrderType order; /* Arrays */ double *h=0, *wi=0, *wr=0, *z=0; #ifdef NAG_COLUMN_MAJOR #define H(I,J) h[(J-1)*pdh + I - 1] order = Nag_ColMajor; #else #define H(I,J) h[(I-1)*pdh + J - 1] order = Nag_RowMajor; #endif INIT_FAIL(fail); Vprintf("nag_dhseqr (f08pec) Example Program Results\n\n"); /* Skip heading in data file */ Vscanf("%*[^\n] "); Vscanf("%ld%*[^\n] ", &n); #ifdef NAG_COLUMN_MAJOR pdh = n; pdz = n; #else pdh = n; pdz = n; #endif wr_len = n; wi_len = n; /* Allocate memory */ if ( !(h = NAG_ALLOC(n * n, double)) || !(wi = NAG_ALLOC(wi_len, double)) || !(wr = NAG_ALLOC(wr_len, double)) || !(z = NAG_ALLOC(n * n, double)) ) { Vprintf("Allocation failure\n"); exit_status = -1; goto END; } /* Read H from data file */ for (i = 1; i <= n; ++i) { for (j = 1; j <= n; ++j) Vscanf("%lf", &H(i,j)); } Vscanf("%*[^\n] "); /* Calculate the eigenvalues and Schur factorization of H */ /* nag_dhseqr (f08pec). * Eigenvalues and Schur factorization of real upper * Hessenberg matrix reduced from real general matrix */ nag_dhseqr(order, Nag_Schur, Nag_InitZ, n, 1, n, h, pdh, wr, wi, z, pdz, &fail); if (fail.code != NE_NOERROR) { Vprintf("Error from nag_dhseqr (f08pec).\n%s\n", fail.message); exit_status = 1; goto END; } Vprintf(" Eigenvalues\n"); for (i = 1; i <= n; ++i) Vprintf(" (%8.4f,%8.4f)", wr[i-1], wi[i-1]); Vprintf("\n"); /* Print Schur form */ /* nag_gen_real_mat_print (x04cac). * Print real general matrix (easy-to-use) */ nag_gen_real_mat_print(order, Nag_GeneralMatrix, Nag_NonUnitDiag, n, n, h, pdh, "Schur form", 0, &fail); if (fail.code != NE_NOERROR) { Vprintf("Error from nag_gen_real_mat_print (x04cac).\n%s\n", fail.message); exit_status = 1; goto END; } /* Print Schur vectors */ Vprintf("\n"); /* nag_gen_real_mat_print (x04cac), see above. */ nag_gen_real_mat_print(order, Nag_GeneralMatrix, Nag_NonUnitDiag, n, n, z, pdz, "Schur vectors of H", 0, &fail); if (fail.code != NE_NOERROR) { Vprintf("Error from nag_gen_real_mat_print (x04cac).\n%s\n", fail.message); exit_status = 1; goto END; } END: if (h) NAG_FREE(h); if (wi) NAG_FREE(wi); if (wr) NAG_FREE(wr); if (z) NAG_FREE(z); return exit_status; }