Exemplo n.º 1
0
Int KLU_rgrowth         /* return TRUE if successful, FALSE otherwise */
(
    Int *Ap,
    Int *Ai,
    double *Ax,
    KLU_symbolic *Symbolic,
    KLU_numeric *Numeric,
    KLU_common *Common
)
{
    double temp, max_ai, max_ui, min_block_rgrowth ;
    Entry aik ;
    Int *Q, *Ui, *Uip, *Ulen, *Pinv ;
    Unit *LU ;
    Entry *Aentry, *Ux, *Ukk ;
    double *Rs ;
    Int i, newrow, oldrow, k1, k2, nk, j, oldcol, k, pend, len ;

    /* ---------------------------------------------------------------------- */
    /* check inputs */
    /* ---------------------------------------------------------------------- */

    if (Common == NULL)
    {
        return (FALSE) ;
    }

    if (Symbolic == NULL || Ap == NULL || Ai == NULL || Ax == NULL)
    {
        Common->status = KLU_INVALID ;
        return (FALSE) ;
    }

    if (Numeric == NULL)
    {
        /* treat this as a singular matrix */
        Common->rgrowth = 0 ;
        Common->status = KLU_SINGULAR ;
        return (TRUE) ;
    }
    Common->status = KLU_OK ;

    /* ---------------------------------------------------------------------- */
    /* compute the reciprocal pivot growth */
    /* ---------------------------------------------------------------------- */

    Aentry = (Entry *) Ax ;
    Pinv = Numeric->Pinv ;
    Rs = Numeric->Rs ;
    Q = Symbolic->Q ;
    Common->rgrowth = 1 ;

    for (i = 0 ; i < Symbolic->nblocks ; i++)
    {
        k1 = Symbolic->R[i] ;
        k2 = Symbolic->R[i+1] ;
        nk = k2 - k1 ;
        if (nk == 1)
        {
            continue ;      /* skip singleton blocks */
        }
        LU = (Unit *) Numeric->LUbx[i] ;
        Uip = Numeric->Uip + k1 ;
        Ulen = Numeric->Ulen + k1 ;
        Ukk = ((Entry *) Numeric->Udiag) + k1 ;
        min_block_rgrowth = 1 ;
        for (j = 0 ; j < nk ; j++)
        {
            max_ai = 0 ;
            max_ui = 0 ;
            oldcol = Q[j + k1] ;
            pend = Ap [oldcol + 1] ;
            for (k = Ap [oldcol] ; k < pend ; k++)
            {
                oldrow = Ai [k] ;
                newrow = Pinv [oldrow] ;
                if (newrow < k1)
                {
                    continue ;  /* skip entry outside the block */
                }
                ASSERT (newrow < k2) ;
                if (Rs != NULL)
                {
                    /* aik = Aentry [k] / Rs [oldrow] */
                    SCALE_DIV_ASSIGN (aik, Aentry [k], Rs [newrow]) ;
                }
                else
                {
                    aik = Aentry [k] ;
                }
                /* temp = ABS (aik) */
                ABS (temp, aik) ;
                if (temp > max_ai)
                {
                    max_ai = temp ;
                }
            }

            /* Ui is set but not used.  This is OK, because otherwise the macro
               would have to be redesigned. */
            GET_POINTER (LU, Uip, Ulen, Ui, Ux, j, len) ;
            for (k = 0 ; k < len ; k++)
            {
                /* temp = ABS (Ux [k]) */
                ABS (temp, Ux [k]) ;
                if (temp > max_ui)
                {
                    max_ui = temp ;
                }
            }
            /* consider the diagonal element */
            ABS (temp, Ukk [j]) ;
            if (temp > max_ui)
            {
                max_ui = temp ;
            }

            /* if max_ui is 0, skip the column */
            if (SCALAR_IS_ZERO (max_ui))
            {
                continue ;
            }
            temp = max_ai / max_ui ;
            if (temp < min_block_rgrowth)
            {
                min_block_rgrowth = temp ;
            }
        }

        if (min_block_rgrowth < Common->rgrowth)
        {
            Common->rgrowth = min_block_rgrowth ;
        }
    }
    return (TRUE) ;
}
Exemplo n.º 2
0
Int KLU_solve
(
    /* inputs, not modified */
    KLU_symbolic *Symbolic,
    KLU_numeric *Numeric,
    Int d,		    /* leading dimension of B */
    Int nrhs,		    /* number of right-hand-sides */

    /* right-hand-side on input, overwritten with solution to Ax=b on output */
    double B [ ],	    /* size n*nrhs, in column-oriented form, with
			     * leading dimension d. */
    /* --------------- */
    KLU_common *Common
)
{
    Entry x [4], offik, s ;
    double rs, *Rs ;
    Entry *Offx, *X, *Bz, *Udiag ;
    Int *Q, *R, *Pnum, *Offp, *Offi, *Lip, *Uip, *Llen, *Ulen ;
    Unit **LUbx ;
    Int k1, k2, nk, k, block, pend, n, p, nblocks, chunk, nr, i ;

    /* ---------------------------------------------------------------------- */
    /* check inputs */
    /* ---------------------------------------------------------------------- */

    if (Common == NULL)
    {
	return (FALSE) ;
    }
    if (Numeric == NULL || Symbolic == NULL || d < Symbolic->n || nrhs < 0 ||
	B == NULL)
    {
	Common->status = KLU_INVALID ;
	return (FALSE) ;
    }
    Common->status = KLU_OK ;

    /* ---------------------------------------------------------------------- */
    /* get the contents of the Symbolic object */
    /* ---------------------------------------------------------------------- */

    Bz = (Entry *) B ;
    n = Symbolic->n ;
    nblocks = Symbolic->nblocks ;
    Q = Symbolic->Q ;
    R = Symbolic->R ;

    /* ---------------------------------------------------------------------- */
    /* get the contents of the Numeric object */
    /* ---------------------------------------------------------------------- */

    ASSERT (nblocks == Numeric->nblocks) ;
    Pnum = Numeric->Pnum ;
    Offp = Numeric->Offp ;
    Offi = Numeric->Offi ;
    Offx = (Entry *) Numeric->Offx ;

    Lip  = Numeric->Lip ;
    Llen = Numeric->Llen ;
    Uip  = Numeric->Uip ;
    Ulen = Numeric->Ulen ;
    LUbx = (Unit **) Numeric->LUbx ;
    Udiag = Numeric->Udiag ;

    Rs = Numeric->Rs ;
    X = (Entry *) Numeric->Xwork ;

    ASSERT (KLU_valid (n, Offp, Offi, Offx)) ;

    /* ---------------------------------------------------------------------- */
    /* solve in chunks of 4 columns at a time */
    /* ---------------------------------------------------------------------- */

    for (chunk = 0 ; chunk < nrhs ; chunk += 4)
    {

	/* ------------------------------------------------------------------ */
	/* get the size of the current chunk */
	/* ------------------------------------------------------------------ */

	nr = MIN (nrhs - chunk, 4) ;

	/* ------------------------------------------------------------------ */
	/* scale and permute the right hand side, X = P*(R\B) */
	/* ------------------------------------------------------------------ */

	if (Rs == NULL)
	{

	    /* no scaling */
	    switch (nr)
	    {

		case 1:

		    for (k = 0 ; k < n ; k++)
		    {
			X [k] = Bz [Pnum [k]] ;
		    }
		    break ;

		case 2:

		    for (k = 0 ; k < n ; k++)
		    {
			i = Pnum [k] ;
			X [2*k    ] = Bz [i      ] ;
			X [2*k + 1] = Bz  [i + d  ] ;
		    }
		    break ;

		case 3:

		    for (k = 0 ; k < n ; k++)
		    {
			i = Pnum [k] ;
			X [3*k    ] = Bz [i      ] ;
			X [3*k + 1] = Bz [i + d  ] ;
			X [3*k + 2] = Bz [i + d*2] ;
		    }
		    break ;

		case 4:

		    for (k = 0 ; k < n ; k++)
		    {
			i = Pnum [k] ;
			X [4*k    ] = Bz [i      ] ;
			X [4*k + 1] = Bz [i + d  ] ;
			X [4*k + 2] = Bz [i + d*2] ;
			X [4*k + 3] = Bz [i + d*3] ;
		    }
		    break ;
	    }

	}
	else
	{

	    switch (nr)
	    {

		case 1:

		    for (k = 0 ; k < n ; k++)
		    {
			SCALE_DIV_ASSIGN (X [k], Bz  [Pnum [k]], Rs [k]) ;
		    }
		    break ;

		case 2:

		    for (k = 0 ; k < n ; k++)
		    {
			i = Pnum [k] ;
			rs = Rs [k] ;
			SCALE_DIV_ASSIGN (X [2*k], Bz [i], rs) ;
			SCALE_DIV_ASSIGN (X [2*k + 1], Bz [i + d], rs) ;
		    }
		    break ;

		case 3:

		    for (k = 0 ; k < n ; k++)
		    {
			i = Pnum [k] ;
			rs = Rs [k] ;
			SCALE_DIV_ASSIGN (X [3*k], Bz [i], rs) ;
			SCALE_DIV_ASSIGN (X [3*k + 1], Bz [i + d], rs) ;
			SCALE_DIV_ASSIGN (X [3*k + 2], Bz [i + d*2], rs) ;
		    }
		    break ;

		case 4:

		    for (k = 0 ; k < n ; k++)
		    {
			i = Pnum [k] ;
			rs = Rs [k] ;
			SCALE_DIV_ASSIGN (X [4*k], Bz [i], rs) ;
			SCALE_DIV_ASSIGN (X [4*k + 1], Bz [i + d], rs) ;
			SCALE_DIV_ASSIGN (X [4*k + 2], Bz [i + d*2], rs) ;
			SCALE_DIV_ASSIGN (X [4*k + 3], Bz [i + d*3], rs) ;
		    }
		    break ;
	    }
	}

	/* ------------------------------------------------------------------ */
	/* solve X = (L*U + Off)\X */
	/* ------------------------------------------------------------------ */

	for (block = nblocks-1 ; block >= 0 ; block--)
	{

	    /* -------------------------------------------------------------- */
	    /* the block of size nk is from rows/columns k1 to k2-1 */
	    /* -------------------------------------------------------------- */

	    k1 = R [block] ;
	    k2 = R [block+1] ;
	    nk = k2 - k1 ;
	    PRINTF (("solve %d, k1 %d k2-1 %d nk %d\n", block, k1,k2-1,nk)) ;

	    /* solve the block system */
	    if (nk == 1)
	    {
		s = Udiag [k1] ;
		switch (nr)
		{

		    case 1:
			DIV (X [k1], X [k1], s) ;
			break ;

		    case 2:
			DIV (X [2*k1], X [2*k1], s) ;
			DIV (X [2*k1 + 1], X [2*k1 + 1], s) ;
			break ;

		    case 3:
			DIV (X [3*k1], X [3*k1], s) ;
			DIV (X [3*k1 + 1], X [3*k1 + 1], s) ;
			DIV (X [3*k1 + 2], X [3*k1 + 2], s) ;
			break ;

		    case 4:
			DIV (X [4*k1], X [4*k1], s) ;
			DIV (X [4*k1 + 1], X [4*k1 + 1], s) ;
			DIV (X [4*k1 + 2], X [4*k1 + 2], s) ;
			DIV (X [4*k1 + 3], X [4*k1 + 3], s) ;
			break ;

		}
	    }
	    else
	    {
		KLU_lsolve (nk, Lip + k1, Llen + k1, LUbx [block], nr,
			X + nr*k1) ;
		KLU_usolve (nk, Uip + k1, Ulen + k1, LUbx [block],
			Udiag + k1, nr, X + nr*k1) ;
	    }

	    /* -------------------------------------------------------------- */
	    /* block back-substitution for the off-diagonal-block entries */
	    /* -------------------------------------------------------------- */

	    if (block > 0)
	    {
		switch (nr)
		{

		    case 1:

			for (k = k1 ; k < k2 ; k++)
			{
			    pend = Offp [k+1] ;
			    x [0] = X [k] ;
			    for (p = Offp [k] ; p < pend ; p++)
			    {
				MULT_SUB (X [Offi [p]], Offx [p], x [0]) ;
			    }
			}
			break ;

		    case 2:

			for (k = k1 ; k < k2 ; k++)
			{
			    pend = Offp [k+1] ;
			    x [0] = X [2*k    ] ;
			    x [1] = X [2*k + 1] ;
			    for (p = Offp [k] ; p < pend ; p++)
			    {
				i = Offi [p] ;
				offik = Offx [p] ;
				MULT_SUB (X [2*i], offik, x [0]) ;
				MULT_SUB (X [2*i + 1], offik, x [1]) ;
			    }
			}
			break ;

		    case 3:

			for (k = k1 ; k < k2 ; k++)
			{
			    pend = Offp [k+1] ;
			    x [0] = X [3*k    ] ;
			    x [1] = X [3*k + 1] ;
			    x [2] = X [3*k + 2] ;
			    for (p = Offp [k] ; p < pend ; p++)
			    {
				i = Offi [p] ;
				offik = Offx [p] ;
				MULT_SUB (X [3*i], offik, x [0]) ;
				MULT_SUB (X [3*i + 1], offik, x [1]) ;
				MULT_SUB (X [3*i + 2], offik, x [2]) ;
			    }
			}
			break ;

		    case 4:

			for (k = k1 ; k < k2 ; k++)
			{
			    pend = Offp [k+1] ;
			    x [0] = X [4*k    ] ;
			    x [1] = X [4*k + 1] ;
			    x [2] = X [4*k + 2] ;
			    x [3] = X [4*k + 3] ;
			    for (p = Offp [k] ; p < pend ; p++)
			    {
				i = Offi [p] ;
				offik = Offx [p] ;
				MULT_SUB (X [4*i], offik, x [0]) ;
				MULT_SUB (X [4*i + 1], offik, x [1]) ;
				MULT_SUB (X [4*i + 2], offik, x [2]) ;
				MULT_SUB (X [4*i + 3], offik, x [3]) ;
			    }
			}
			break ;
		}
	    }
	}

	/* ------------------------------------------------------------------ */
	/* permute the result, Bz  = Q*X */
	/* ------------------------------------------------------------------ */

	switch (nr)
	{

	    case 1:

		for (k = 0 ; k < n ; k++)
		{
		    Bz  [Q [k]] = X [k] ;
		}
		break ;

	    case 2:

		for (k = 0 ; k < n ; k++)
		{
		    i = Q [k] ;
		    Bz  [i      ] = X [2*k    ] ;
		    Bz  [i + d  ] = X [2*k + 1] ;
		}
		break ;

	    case 3:

		for (k = 0 ; k < n ; k++)
		{
		    i = Q [k] ;
		    Bz  [i      ] = X [3*k    ] ;
		    Bz  [i + d  ] = X [3*k + 1] ;
		    Bz  [i + d*2] = X [3*k + 2] ;
		}
		break ;

	    case 4:

		for (k = 0 ; k < n ; k++)
		{
		    i = Q [k] ;
		    Bz  [i      ] = X [4*k    ] ;
		    Bz  [i + d  ] = X [4*k + 1] ;
		    Bz  [i + d*2] = X [4*k + 2] ;
		    Bz  [i + d*3] = X [4*k + 3] ;
		}
		break ;
	}

	/* ------------------------------------------------------------------ */
	/* go to the next chunk of B */
	/* ------------------------------------------------------------------ */

	Bz  += d*4 ;
    }
    return (TRUE) ;
}
Exemplo n.º 3
0
Int KLU_condest         /* return TRUE if successful, FALSE otherwise */
(
    Int Ap [ ],
    double Ax [ ],
    KLU_symbolic *Symbolic,
    KLU_numeric *Numeric,
    KLU_common *Common
)
{
    double xj, Xmax, csum, anorm, ainv_norm, est_old, est_new, abs_value ;
    Entry *Udiag, *Aentry, *X, *S ;
    Int i, j, jmax, jnew, pend, n ;
#ifndef COMPLEX
    Int unchanged ;
#endif

    /* ---------------------------------------------------------------------- */
    /* check inputs */
    /* ---------------------------------------------------------------------- */

    if (Common == NULL)
    {
        return (FALSE) ;
    }
    if (Symbolic == NULL || Ap == NULL || Ax == NULL)
    {
        Common->status = KLU_INVALID ;
        return (FALSE) ;
    }
    abs_value = 0 ;
    if (Numeric == NULL)
    {
        /* treat this as a singular matrix */
        Common->condest = 1 / abs_value ;
        Common->status = KLU_SINGULAR ;
        return (TRUE) ;
    }
    Common->status = KLU_OK ;

    /* ---------------------------------------------------------------------- */
    /* get inputs */
    /* ---------------------------------------------------------------------- */

    n = Symbolic->n ;
    Udiag = Numeric->Udiag ;

    /* ---------------------------------------------------------------------- */
    /* check if diagonal of U has a zero on it */
    /* ---------------------------------------------------------------------- */

    for (i = 0 ; i < n ; i++)
    {
        ABS (abs_value, Udiag [i]) ;
        if (SCALAR_IS_ZERO (abs_value))
        {
            Common->condest = 1 / abs_value ;
            Common->status = KLU_SINGULAR ;
            return (TRUE) ;
        }
    }

    /* ---------------------------------------------------------------------- */
    /* compute 1-norm (maximum column sum) of the matrix */
    /* ---------------------------------------------------------------------- */

    anorm =  0.0 ;
    Aentry = (Entry *) Ax ;
    for (i = 0 ; i < n ; i++)
    {
        pend = Ap [i + 1] ;
        csum = 0.0 ;
        for (j = Ap [i] ; j < pend ; j++)
        {
            ABS (abs_value, Aentry [j]) ;
            csum += abs_value ;
        }
        if (csum > anorm)
        {
            anorm = csum ;
        }
    }

    /* ---------------------------------------------------------------------- */
    /* compute estimate of 1-norm of inv (A) */
    /* ---------------------------------------------------------------------- */

    /* get workspace (size 2*n Entry's) */
    X = Numeric->Xwork ;            /* size n space used in KLU_solve, tsolve */
    X += n ;                        /* X is size n */
    S = X + n ;                     /* S is size n */

    for (i = 0 ; i < n ; i++)
    {
        CLEAR (S [i]) ;
        CLEAR (X [i]) ;
        REAL (X [i]) = 1.0 / ((double) n) ;
    }
    jmax = 0 ;

    ainv_norm = 0.0 ;
    for (i = 0 ; i < 5 ; i++)
    {
        if (i > 0)
        {
            /* X [jmax] is the largest entry in X */
            for (j = 0 ; j < n ; j++)
            {
                /* X [j] = 0 ;*/
                CLEAR (X [j]) ;
            }
            REAL (X [jmax]) = 1 ;
        }

        KLU_solve (Symbolic, Numeric, n, 1, (double *) X, Common) ;
        est_old = ainv_norm ;
        ainv_norm = 0.0 ;

        for (j = 0 ; j < n ; j++)
        {
            /* ainv_norm += ABS (X [j]) ;*/
            ABS (abs_value, X [j]) ;
            ainv_norm += abs_value ;
        }

#ifndef COMPLEX
        unchanged = TRUE ;

        for (j = 0 ; j < n ; j++)
        {
            double s = (X [j] >= 0) ? 1 : -1 ;
            if (s != (Int) REAL (S [j]))
            {
                S [j] = s ;
                unchanged = FALSE ;
            }
        }

        if (i > 0 && (ainv_norm <= est_old || unchanged))
        {
            break ;
        }
#else
        for (j = 0 ; j < n ; j++)
        {
            if (IS_NONZERO (X [j]))
            {
                ABS (abs_value, X [j]) ;
                SCALE_DIV_ASSIGN (S [j], X [j], abs_value) ;
            }
            else
            {
                CLEAR (S [j]) ;
                REAL (S [j]) = 1 ;
            }
        }

        if (i > 0 && ainv_norm <= est_old)
        {
            break ;
        }
#endif

        for (j = 0 ; j < n ; j++)
        {
            X [j] = S [j] ;
        }

#ifndef COMPLEX
        /* do a transpose solve */
        KLU_tsolve (Symbolic, Numeric, n, 1, X, Common) ;
#else
        /* do a conjugate transpose solve */
        KLU_tsolve (Symbolic, Numeric, n, 1, (double *) X, 1, Common) ;
#endif

        /* jnew = the position of the largest entry in X */
        jnew = 0 ;
        Xmax = 0 ;
        for (j = 0 ; j < n ; j++)
        {
            /* xj = ABS (X [j]) ;*/
            ABS (xj, X [j]) ;
            if (xj > Xmax)
            {
                Xmax = xj ;
                jnew = j ;
            }
        }
        if (i > 0 && jnew == jmax)
        {
            /* the position of the largest entry did not change
             * from the previous iteration */
            break ;
        }
        jmax = jnew ;
    }

    /* ---------------------------------------------------------------------- */
    /* compute another estimate of norm(inv(A),1), and take the largest one */
    /* ---------------------------------------------------------------------- */

    for (j = 0 ; j < n ; j++)
    {
        CLEAR (X [j]) ;
        if (j % 2)
        {
            REAL (X [j]) = 1 + ((double) j) / ((double) (n-1)) ;
        }
        else
        {
            REAL (X [j]) = -1 - ((double) j) / ((double) (n-1)) ;
        }
    }

    KLU_solve (Symbolic, Numeric, n, 1, (double *) X, Common) ;

    est_new = 0.0 ;
    for (j = 0 ; j < n ; j++)
    {
        /* est_new += ABS (X [j]) ;*/
        ABS (abs_value, X [j]) ;
        est_new += abs_value ;
    }
    est_new = 2 * est_new / (3 * n) ;
    ainv_norm = MAX (est_new, ainv_norm) ;

    /* ---------------------------------------------------------------------- */
    /* compute estimate of condition number */
    /* ---------------------------------------------------------------------- */

    Common->condest = ainv_norm * anorm ;
    return (TRUE) ;
}
Exemplo n.º 4
0
Int KLU_refactor        /* returns TRUE if successful, FALSE otherwise */
(
    /* inputs, not modified */
    Int Ap [ ],         /* size n+1, column pointers */
    Int Ai [ ],         /* size nz, row indices */
    double Ax [ ],
    KLU_symbolic<Entry, Int> *Symbolic,

    /* input/output */
    KLU_numeric<Entry, Int> *Numeric,
    KLU_common<Entry, Int>  *Common
)
{
    Entry ukk, ujk, s ;
    Entry *Offx, *Lx, *Ux, *X, *Az, *Udiag ;
    double *Rs ;
    Int *P, *Q, *R, *Pnum, *Offp, *Offi, *Ui, *Li, *Pinv, *Lip, *Uip, *Llen,
        *Ulen ;
    Unit **LUbx ;
    Unit *LU ;
    Int k1, k2, nk, k, block, oldcol, pend, oldrow, n, p, newrow, scale,
        nblocks, poff, i, j, up, ulen, llen, maxblock, nzoff ;

    /* ---------------------------------------------------------------------- */
    /* check inputs */
    /* ---------------------------------------------------------------------- */

    if (Common == NULL)
    {
        return (FALSE) ;
    }
    Common->status = KLU_OK ;

    if (Numeric == NULL)
    {
        /* invalid Numeric object */
        Common->status = KLU_INVALID ;
        return (FALSE) ;
    }

    Common->numerical_rank = EMPTY ;
    Common->singular_col = EMPTY ;

    Az = (Entry *) Ax ;

    /* ---------------------------------------------------------------------- */
    /* get the contents of the Symbolic object */
    /* ---------------------------------------------------------------------- */

    n = Symbolic->n ;
    P = Symbolic->P ;
    Q = Symbolic->Q ;
    R = Symbolic->R ;
    nblocks = Symbolic->nblocks ;
    maxblock = Symbolic->maxblock ;

    /* ---------------------------------------------------------------------- */
    /* get the contents of the Numeric object */
    /* ---------------------------------------------------------------------- */

    Pnum = Numeric->Pnum ;
    Offp = Numeric->Offp ;
    Offi = Numeric->Offi ;
    Offx = (Entry *) Numeric->Offx ;

    LUbx = (Unit **) Numeric->LUbx ;

    scale = Common->scale ;
    if (scale > 0)
    {
        /* factorization was not scaled, but refactorization is scaled */
        if (Numeric->Rs == NULL)
        {
            Numeric->Rs = (double *)KLU_malloc (n, sizeof (double), Common) ;
            if (Common->status < KLU_OK)
            {
                Common->status = KLU_OUT_OF_MEMORY ;
                return (FALSE) ;
            }
        }
    }
    else
    {
        /* no scaling for refactorization; ensure Numeric->Rs is freed.  This
         * does nothing if Numeric->Rs is already NULL. */
        Numeric->Rs = (double *) KLU_free (Numeric->Rs, n, sizeof (double), Common) ;
    }
    Rs = Numeric->Rs ;

    Pinv = Numeric->Pinv ;
    X = (Entry *) Numeric->Xwork ;
    Common->nrealloc = 0 ;
    Udiag = (Entry *) Numeric->Udiag ;
    nzoff = Symbolic->nzoff ;

    /* ---------------------------------------------------------------------- */
    /* check the input matrix compute the row scale factors, Rs */
    /* ---------------------------------------------------------------------- */

    /* do no scale, or check the input matrix, if scale < 0 */
    if (scale >= 0)
    {
        /* check for out-of-range indices, but do not check for duplicates */
        if (!KLU_scale (scale, n, Ap, Ai, Ax, Rs, NULL, Common))
        {
            return (FALSE) ;
        }
    }

    /* ---------------------------------------------------------------------- */
    /* clear workspace X */
    /* ---------------------------------------------------------------------- */

    for (k = 0 ; k < maxblock ; k++)
    {
        /* X [k] = 0 */
        CLEAR (X [k]) ;
    }

    poff = 0 ;

    /* ---------------------------------------------------------------------- */
    /* factor each block */
    /* ---------------------------------------------------------------------- */

    if (scale <= 0)
    {

        /* ------------------------------------------------------------------ */
        /* no scaling */
        /* ------------------------------------------------------------------ */

        for (block = 0 ; block < nblocks ; block++)
        {

            /* -------------------------------------------------------------- */
            /* the block is from rows/columns k1 to k2-1 */
            /* -------------------------------------------------------------- */

            k1 = R [block] ;
            k2 = R [block+1] ;
            nk = k2 - k1 ;

            if (nk == 1)
            {

                /* ---------------------------------------------------------- */
                /* singleton case */
                /* ---------------------------------------------------------- */

                oldcol = Q [k1] ;
                pend = Ap [oldcol+1] ;
                CLEAR (s) ;
                for (p = Ap [oldcol] ; p < pend ; p++)
                {
                    newrow = Pinv [Ai [p]] - k1 ;
                    if (newrow < 0 && poff < nzoff)
                    {
                        /* entry in off-diagonal block */
                        Offx [poff] = Az [p] ;
                        poff++ ;
                    }
                    else
                    {
                        /* singleton */
                        s = Az [p] ;
                    }
                }
                Udiag [k1] = s ;

            }
            else
            {

                /* ---------------------------------------------------------- */
                /* construct and factor the kth block */
                /* ---------------------------------------------------------- */

                Lip  = Numeric->Lip  + k1 ;
                Llen = Numeric->Llen + k1 ;
                Uip  = Numeric->Uip  + k1 ;
                Ulen = Numeric->Ulen + k1 ;
                LU = LUbx [block] ;

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

                    /* ------------------------------------------------------ */
                    /* scatter kth column of the block into workspace X */
                    /* ------------------------------------------------------ */

                    oldcol = Q [k+k1] ;
                    pend = Ap [oldcol+1] ;
                    for (p = Ap [oldcol] ; p < pend ; p++)
                    {
                        newrow = Pinv [Ai [p]] - k1 ;
                        if (newrow < 0 && poff < nzoff)
                        {
                            /* entry in off-diagonal block */
                            Offx [poff] = Az [p] ;
                            poff++ ;
                        }
                        else
                        {
                            /* (newrow,k) is an entry in the block */
                            X [newrow] = Az [p] ;
                        }
                    }

                    /* ------------------------------------------------------ */
                    /* compute kth column of U, and update kth column of A */
                    /* ------------------------------------------------------ */

                    GET_POINTER (LU, Uip, Ulen, Ui, Ux, k, ulen) ;
                    for (up = 0 ; up < ulen ; up++)
                    {
                        j = Ui [up] ;
                        ujk = X [j] ;
                        /* X [j] = 0 */
                        CLEAR (X [j]) ;
                        Ux [up] = ujk ;
                        GET_POINTER (LU, Lip, Llen, Li, Lx, j, llen) ;
                        for (p = 0 ; p < llen ; p++)
                        {
                            /* X [Li [p]] -= Lx [p] * ujk */
                            MULT_SUB (X [Li [p]], Lx [p], ujk) ;
                        }
                    }
                    /* get the diagonal entry of U */
                    ukk = X [k] ;
                    /* X [k] = 0 */
                    CLEAR (X [k]) ;
                    /* singular case */
                    if (IS_ZERO (ukk))
                    {
                        /* matrix is numerically singular */
                        Common->status = KLU_SINGULAR ;
                        if (Common->numerical_rank == EMPTY)
                        {
                            Common->numerical_rank = k+k1 ;
                            Common->singular_col = Q [k+k1] ;
                        }
                        if (Common->halt_if_singular)
                        {
                            /* do not continue the factorization */
                            return (FALSE) ;
                        }
                    }
                    Udiag [k+k1] = ukk ;
                    /* gather and divide by pivot to get kth column of L */
                    GET_POINTER (LU, Lip, Llen, Li, Lx, k, llen) ;
                    for (p = 0 ; p < llen ; p++)
                    {
                        i = Li [p] ;
                        DIV (Lx [p], X [i], ukk) ;
                        CLEAR (X [i]) ;
                    }

                }
            }
        }

    }
    else
    {

        /* ------------------------------------------------------------------ */
        /* scaling */
        /* ------------------------------------------------------------------ */

        for (block = 0 ; block < nblocks ; block++)
        {

            /* -------------------------------------------------------------- */
            /* the block is from rows/columns k1 to k2-1 */
            /* -------------------------------------------------------------- */

            k1 = R [block] ;
            k2 = R [block+1] ;
            nk = k2 - k1 ;

            if (nk == 1)
            {

                /* ---------------------------------------------------------- */
                /* singleton case */
                /* ---------------------------------------------------------- */

                oldcol = Q [k1] ;
                pend = Ap [oldcol+1] ;
                CLEAR (s) ;
                for (p = Ap [oldcol] ; p < pend ; p++)
                {
                    oldrow = Ai [p] ;
                    newrow = Pinv [oldrow] - k1 ;
                    if (newrow < 0 && poff < nzoff)
                    {
                        /* entry in off-diagonal block */
                        /* Offx [poff] = Az [p] / Rs [oldrow] */
                        SCALE_DIV_ASSIGN (Offx [poff], Az [p], Rs [oldrow]) ;
                        poff++ ;
                    }
                    else
                    {
                        /* singleton */
                        /* s = Az [p] / Rs [oldrow] */
                        SCALE_DIV_ASSIGN (s, Az [p], Rs [oldrow]) ;
                    }
                }
                Udiag [k1] = s ;

            }
            else
            {

                /* ---------------------------------------------------------- */
                /* construct and factor the kth block */
                /* ---------------------------------------------------------- */

                Lip  = Numeric->Lip  + k1 ;
                Llen = Numeric->Llen + k1 ;
                Uip  = Numeric->Uip  + k1 ;
                Ulen = Numeric->Ulen + k1 ;
                LU = LUbx [block] ;

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

                    /* ------------------------------------------------------ */
                    /* scatter kth column of the block into workspace X */
                    /* ------------------------------------------------------ */

                    oldcol = Q [k+k1] ;
                    pend = Ap [oldcol+1] ;
                    for (p = Ap [oldcol] ; p < pend ; p++)
                    {
                        oldrow = Ai [p] ;
                        newrow = Pinv [oldrow] - k1 ;
                        if (newrow < 0 && poff < nzoff)
                        {
                            /* entry in off-diagonal part */
                            /* Offx [poff] = Az [p] / Rs [oldrow] */
                            SCALE_DIV_ASSIGN (Offx [poff], Az [p], Rs [oldrow]);
                            poff++ ;
                        }
                        else
                        {
                            /* (newrow,k) is an entry in the block */
                            /* X [newrow] = Az [p] / Rs [oldrow] */
                            SCALE_DIV_ASSIGN (X [newrow], Az [p], Rs [oldrow]) ;
                        }
                    }

                    /* ------------------------------------------------------ */
                    /* compute kth column of U, and update kth column of A */
                    /* ------------------------------------------------------ */

                    GET_POINTER (LU, Uip, Ulen, Ui, Ux, k, ulen) ;
                    for (up = 0 ; up < ulen ; up++)
                    {
                        j = Ui [up] ;
                        ujk = X [j] ;
                        /* X [j] = 0 */
                        CLEAR (X [j]) ;
                        Ux [up] = ujk ;
                        GET_POINTER (LU, Lip, Llen, Li, Lx, j, llen) ;
                        for (p = 0 ; p < llen ; p++)
                        {
                            /* X [Li [p]] -= Lx [p] * ujk */
                            MULT_SUB (X [Li [p]], Lx [p], ujk) ;
                        }
                    }
                    /* get the diagonal entry of U */
                    ukk = X [k] ;
                    /* X [k] = 0 */
                    CLEAR (X [k]) ;
                    /* singular case */
                    if (IS_ZERO (ukk))
                    {
                        /* matrix is numerically singular */
                        Common->status = KLU_SINGULAR ;
                        if (Common->numerical_rank == EMPTY)
                        {
                            Common->numerical_rank = k+k1 ;
                            Common->singular_col = Q [k+k1] ;
                        }
                        if (Common->halt_if_singular)
                        {
                            /* do not continue the factorization */
                            return (FALSE) ;
                        }
                    }
                    Udiag [k+k1] = ukk ;
                    /* gather and divide by pivot to get kth column of L */
                    GET_POINTER (LU, Lip, Llen, Li, Lx, k, llen) ;
                    for (p = 0 ; p < llen ; p++)
                    {
                        i = Li [p] ;
                        DIV (Lx [p], X [i], ukk) ;
                        CLEAR (X [i]) ;
                    }
                }
            }
        }
    }

    /* ---------------------------------------------------------------------- */
    /* permute scale factors Rs according to pivotal row order */
    /* ---------------------------------------------------------------------- */

    if (scale > 0)
    {
        for (k = 0 ; k < n ; k++)
        {
            /* TODO : Check. REAL(X[k]) Can be just X[k] */
            /* REAL (X [k]) = Rs [Pnum [k]] ; */
            X [k] = Rs [Pnum [k]] ;
        }
        for (k = 0 ; k < n ; k++)
        {
            Rs [k] = REAL (X [k]) ;
        }
    }

#ifndef NDEBUGKLU2
    ASSERT (Offp [n] == poff) ;
    ASSERT (Symbolic->nzoff == poff) ;
    PRINTF (("\n------------------- Off diagonal entries, new:\n")) ;
    ASSERT (KLU_valid (n, Offp, Offi, Offx)) ;
    if (Common->status == KLU_OK)
    {
        PRINTF (("\n ########### KLU_BTF_REFACTOR done, nblocks %d\n",nblocks));
        for (block = 0 ; block < nblocks ; block++)
        {
            k1 = R [block] ;
            k2 = R [block+1] ;
            nk = k2 - k1 ;
            PRINTF ((
                "\n================KLU_refactor output: k1 %d k2 %d nk %d\n",
                k1, k2, nk)) ;
            if (nk == 1)
            {
                PRINTF (("singleton  ")) ;
                PRINT_ENTRY (Udiag [k1]) ;
            }
            else
            {
                Lip = Numeric->Lip + k1 ;
                Llen = Numeric->Llen + k1 ;
                LU = (Unit *) Numeric->LUbx [block] ;
                PRINTF (("\n---- L block %d\n", block)) ;
                ASSERT (KLU_valid_LU (nk, TRUE, Lip, Llen, LU)) ;
                Uip = Numeric->Uip + k1 ;
                Ulen = Numeric->Ulen + k1 ;
                PRINTF (("\n---- U block %d\n", block)) ;
                ASSERT (KLU_valid_LU (nk, FALSE, Uip, Ulen, LU)) ;
            }
        }
    }
#endif

    return (TRUE) ;
}