/* nag_dpteqr (f08jgc) Example Program. * * Copyright 2001 Numerical Algorithms Group. * * Mark 7, 2001. */ #include #include #include #include #include int main(void) { /* Scalars */ Integer i, n, pdz, d_len, e_len; Integer exit_status=0; NagError fail; Nag_OrderType order; /* Arrays */ double *z=0, *d=0, *e=0; #ifdef NAG_COLUMN_MAJOR order = Nag_ColMajor; #else order = Nag_RowMajor; #endif INIT_FAIL(fail); Vprintf("nag_dpteqr (f08jgc) Example Program Results\n\n"); /* Skip heading in data file */ Vscanf("%*[^\n] "); Vscanf("%ld%*[^\n] ", &n); pdz = n; d_len = n; e_len = n-1; /* Allocate memory */ if ( !(z = NAG_ALLOC(n * n, double)) || !(d = NAG_ALLOC(d_len, double)) || !(e = NAG_ALLOC(e_len, double)) ) { Vprintf("Allocation failure\n"); exit_status = -1; goto END; } /* Read T from data file */ for (i = 0; i < d_len; ++i) Vscanf("%lf", &d[i]); for (i = 0; i < e_len; ++i) Vscanf("%lf", &e[i]); /* Calculate all the eigenvalues and eigenvectors of T */ /* nag_dpteqr (f08jgc). * All eigenvalues and eigenvectors of real symmetric * positive-definite tridiagonal matrix, reduced from real * symmetric positive-definite matrix */ nag_dpteqr(order, Nag_InitZ, n, d, e, z, pdz, &fail); if (fail.code != NE_NOERROR) { Vprintf("Error from nag_dpteqr (f08jgc).\n%s\n", fail.message); exit_status = 1; goto END; } /* Print eigenvalues and eigenvectors */ Vprintf(" Eigenvalues\n"); for (i = 0; i < n; ++i) Vprintf(" %7.4lf",d[i]); Vprintf("\n\n"); /* 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, z, pdz, "Eigenvectors", 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 (d) NAG_FREE(d); if (e) NAG_FREE(e); if (z) NAG_FREE(z); return exit_status; }