/* nag_dgehrd (f08nec) Example Program. * * Copyright 2001 Numerical Algorithms Group. * * Mark 7, 2001. */ #include #include #include #include #include int main(void) { /* Scalars */ Integer i, j, n, pda, tau_len; Integer exit_status=0; NagError fail; Nag_OrderType order; /* Arrays */ double *a=0, *tau=0; #ifdef NAG_COLUMN_MAJOR #define A(I,J) a[(J-1)*pda + I - 1] order = Nag_ColMajor; #else #define A(I,J) a[(I-1)*pda + J - 1] order = Nag_RowMajor; #endif INIT_FAIL(fail); Vprintf("f08nec Example Program Results\n\n"); /* Skip heading in data file */ Vscanf("%*[^\n] "); Vscanf("%ld%*[^\n] ", &n); #ifdef NAG_COLUMN_MAJOR pda = n; #else pda = n; #endif tau_len = n - 1; /* Allocate memory */ if ( !(a = NAG_ALLOC(n * n, double)) || !(tau = NAG_ALLOC(tau_len, double)) ) { Vprintf("Allocation failure\n"); exit_status = -1; goto END; } /* Read A from data file */ for (i = 1; i <= n; ++i) { for (j = 1; j <= n; ++j) Vscanf("%lf", &A(i,j)); } Vscanf("%*[^\n] "); /* Reduce A to upper Hessenberg form */ f08nec(order, n, 1, n, a, pda, tau, &fail); if (fail.code != NE_NOERROR) { Vprintf("Error from f08nec.\n%s\n", fail.message); exit_status = 1; goto END; } /* Set the elements below the first sub-diagonal to zero */ for (i = 1; i <= n - 2; ++i) { for (j = i + 2; j <= n; ++j) A(j, i) = 0.0; } /* Print upper Hessenberg form */ x04cac(order, Nag_GeneralMatrix, Nag_NonUnitDiag, n, n, a, pda, "Upper Hessenberg form", 0, &fail); if (fail.code != NE_NOERROR) { Vprintf("Error from x04cac.\n%s\n", fail.message); exit_status = 1; goto END; } END: if (a) NAG_FREE(a); if (tau) NAG_FREE(tau); return exit_status; }