FLA_Tevd_find_perfshift.c File Reference

(r)

Functions
FLA_Error	FLA_Tevd_find_perfshift_ops (int m_d, int m_l, float *buff_d, int inc_d, float *buff_e, int inc_e, float *buff_l, int inc_l, int *buff_ls, int inc_ls, float *buff_pu, int inc_pu, int *ij_shift)
FLA_Error	FLA_Tevd_find_perfshift_opd (int m_d, int m_l, double *buff_d, int inc_d, double *buff_e, int inc_e, double *buff_l, int inc_l, int *buff_ls, int inc_ls, double *buff_pu, int inc_pu, int *ij_shift)

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Function Documentation

FLA_Error FLA_Tevd_find_perfshift_opd	(	int	m_d,
		int	m_l,
		double *	buff_d,
		int	inc_d,
		double *	buff_e,
		int	inc_e,
		double *	buff_l,
		int	inc_l,
		int *	buff_ls,
		int	inc_ls,
		double *	buff_pu,
		int	inc_pu,
		int *	ij_shift
	)

References FLA_Wilkshift_tridiag_opd().

Referenced by FLA_Tevd_eigval_v_opd_var3().

{
    double* d1p;
    double* e1p;
    double* d2p;
    double  wilkshift;
    int     i;
    int     ij_cand;
    double  dist_cand;
    double  pshift_cand;
    
    d1p = buff_d + (m_d-2)*inc_d;
    e1p = buff_e + (m_d-2)*inc_e;
    d2p = buff_d + (m_d-1)*inc_d;

    if ( *buff_ls == -1 )
    {
        *ij_shift = -1;
        return FLA_FAILURE;
    }

    FLA_Wilkshift_tridiag_opd( *d1p,
                               *e1p,
                               *d2p,
                               &wilkshift );

/*
    // If we have shifted here previously, use a Wilkinson shfit.
    prev_shift = buff_pu[ (m_d-1)*inc_pu ];

    if ( prev_shift != 0.0 )
    {
        // *shift = prev_shift;
        *shift = wilkshift;
        return FLA_SUCCESS;
    }
*/
    ij_cand = -1;

    // Find an available (unused) shift.
    for ( i = 0; i < m_l; ++i )
    {
        int* status = buff_ls + (i  )*inc_ls;

        if ( *status == 0 )
        {
            double* lambda1 = buff_l + (i  )*inc_l;
            ij_cand     = i;
            pshift_cand = *lambda1;
            dist_cand   = fabs( wilkshift - pshift_cand );
        }
    }

    if ( ij_cand == -1 )
    {
        *ij_shift = -1;
        *buff_ls  = -1;
        return FLA_FAILURE;
    }

    // Now try to find a shift closer to wilkshift than the
    // first one we found.
    for ( i = 0; i < m_l; ++i )
    {
        double* lambda1 = buff_l  + (i  )*inc_l;
        int*    status  = buff_ls + (i  )*inc_ls;
        double  dist    = fabs( wilkshift - *lambda1 );

        if ( *status == 1 ) continue;

        if ( dist < dist_cand )
        {
            ij_cand = i;
            pshift_cand = *lambda1;
            dist_cand = dist;
        }
    }

    *ij_shift = ij_cand;

    return FLA_SUCCESS;
}

FLA_Error FLA_Tevd_find_perfshift_ops	(	int	m_d,
		int	m_l,
		float *	buff_d,
		int	inc_d,
		float *	buff_e,
		int	inc_e,
		float *	buff_l,
		int	inc_l,
		int *	buff_ls,
		int	inc_ls,
		float *	buff_pu,
		int	inc_pu,
		int *	ij_shift
	)

{
    FLA_Check_error_code( FLA_NOT_YET_IMPLEMENTED );

    return FLA_SUCCESS;
}