FLA_Tevd_eigval_n_opt_var1.c File Reference

(r)

Functions
FLA_Error	FLA_Tevd_eigval_n_opt_var1 (FLA_Obj G, FLA_Obj d, FLA_Obj e, FLA_Obj k)
FLA_Error	FLA_Tevd_eigval_n_ops_var1 (int m_A, int n_G, float *buff_d, int inc_d, float *buff_e, int inc_e, int *n_iter)
FLA_Error	FLA_Tevd_eigval_n_opd_var1 (int m_A, int n_G, double *buff_d, int inc_d, double *buff_e, int inc_e, int *n_iter)

---

Function Documentation

FLA_Error FLA_Tevd_eigval_n_opd_var1	(	int	m_A,
		int	n_G,
		double *	buff_d,
		int	inc_d,
		double *	buff_e,
		int	inc_e,
		int *	n_iter
	)

References FLA_Mach_params_opd(), FLA_Tevd_francis_n_opd_var1(), and FLA_Wilkshift_tridiag_opd().

Referenced by FLA_Tevd_eigval_n_opt_var1(), and FLA_Tevd_iteracc_n_opd_var1().

{
    FLA_Error r_val;
    double    eps2;
    double    safmin;
    double*   e_last;
    double*   d_last;
    double*   d_last_m1;
    double    shift;
    int       k;
    int       n_iter_allowed = n_G;

    // Query epsilon and safmin, which are used in the test for convergence.
    eps2   = FLA_Mach_params_opd( FLA_MACH_EPS2 );
    safmin = FLA_Mach_params_opd( FLA_MACH_SFMIN );

    // Initialize a pointer to the last sub-diagonal element and two
    // more to the last and second last
    e_last    = &buff_e[ (m_A-2)*inc_e ];
    d_last_m1 = &buff_d[ (m_A-2)*inc_d ];
    d_last    = &buff_d[ (m_A-1)*inc_d ];

    for ( k = 0; k < n_iter_allowed; ++k )
    {

        /*------------------------------------------------------------*/

        // If we've converged, record k and return index of eigenvalue found.
        // The reason we check before the Francis step (rather than after)
        // is so we correctly handle situations where the last diagonal
        // element has already converged from previous eigenvalue searches
        // and thus no iteration is necessary. If we checked after the
        // Francis step, we would have unnecessarily executed an additional
        // Francis step's worth of rotations with a sub-optimal shift (since
        // it would be using a 2x2 that was not "centered" properly).
        if ( MAC_Tevd_eigval_converged2_opd( eps2, safmin, *d_last_m1, *e_last, *d_last ) )
        {
            *e_last = 0.0;
            *n_iter = k;
            return m_A - 1;
        }

//if ( (n_iter_allowed - k) % 2 == 0 )
        // Compute a Wilkinson shift with the last 2x2 matrix.
        FLA_Wilkshift_tridiag_opd( *d_last_m1,
                                   *e_last,
                                   *d_last,
                                   &shift );
//else
//  shift = *d_last;

        // Perform a Francis step.
        r_val = FLA_Tevd_francis_n_opd_var1( m_A,
                                             &shift,
                                             buff_d, inc_d,
                                             buff_e, inc_e );

        // Check for internal deflation.
        if ( r_val != FLA_SUCCESS )
        {
#ifdef PRINTF
            printf( "FLA_Tevd_eigval_n_opt_var1: Internal deflation in col %d, eig %d\n", r_val, m_A - 1 );
            printf( "FLA_Tevd_eigval_n_opt_var1: alpha11         = %23.19e\n", buff_d[r_val*inc_d] );
            printf( "FLA_Tevd_eigval_n_opt_var1: alpha21 alpha22 = %23.19e %23.19e\n", buff_e[r_val*inc_e], buff_d[(r_val+1)*inc_d] );
#endif

            // Set the off-diagonal element to zero.
            buff_e[ r_val*inc_e ] = 0.0;

            *n_iter = k + 1;
            return r_val;
        }

        /*------------------------------------------------------------*/
    }

    *n_iter = n_iter_allowed;
    return FLA_FAILURE;
}

FLA_Error FLA_Tevd_eigval_n_ops_var1	(	int	m_A,
		int	n_G,
		float *	buff_d,
		int	inc_d,
		float *	buff_e,
		int	inc_e,
		int *	n_iter
	)

Referenced by FLA_Tevd_eigval_n_opt_var1().

{
    return FLA_SUCCESS;
}

FLA_Error FLA_Tevd_eigval_n_opt_var1	(	FLA_Obj	G,
		FLA_Obj	d,
		FLA_Obj	e,
		FLA_Obj	k
	)

References FLA_Obj_datatype(), FLA_Obj_vector_dim(), FLA_Obj_vector_inc(), FLA_Obj_width(), FLA_Tevd_eigval_n_opd_var1(), and FLA_Tevd_eigval_n_ops_var1().

{
    FLA_Datatype datatype;
    int          m_A, n_G;
    int          inc_d;
    int          inc_e;

    datatype = FLA_Obj_datatype( d );

    m_A      = FLA_Obj_vector_dim( d );
    n_G      = FLA_Obj_width( G );

    inc_d    = FLA_Obj_vector_inc( d );
    inc_e    = FLA_Obj_vector_inc( e );
    

    switch ( datatype )
    {
        case FLA_FLOAT:
        {
            float*    buff_d = FLA_FLOAT_PTR( d );
            float*    buff_e = FLA_FLOAT_PTR( e );
            int*      buff_k = FLA_INT_PTR( k );

            FLA_Tevd_eigval_n_ops_var1( m_A,
                                        n_G,
                                        buff_d, inc_d,
                                        buff_e, inc_e,
                                        buff_k );

            break;
        }

        case FLA_DOUBLE:
        {
            double*   buff_d = FLA_DOUBLE_PTR( d );
            double*   buff_e = FLA_DOUBLE_PTR( e );
            int*      buff_k = FLA_INT_PTR( k );

            FLA_Tevd_eigval_n_opd_var1( m_A,
                                        n_G,
                                        buff_d, inc_d,
                                        buff_e, inc_e,
                                        buff_k );

            break;
        }
    }

    return FLA_SUCCESS;
}