static void construct_column
(
    /* inputs, not modified on output */
    Int k,	    /* the column of A (or the column of the block) to get */
    Int Ap [ ],
    Int Ai [ ],
    Entry Ax [ ],
    Int Q [ ],	    /* column pre-ordering */

    /* zero on input, modified on output */
    Entry X [ ],

    /* ---- the following are only used in the TRILINOS_BTF case --- */

    /* inputs, not modified on output */
    Int k1,	    /* the block of A is from k1 to k2-1 */
    Int PSinv [ ],  /* inverse of P from symbolic factorization */
    double Rs [ ],  /* scale factors for A */
    Int scale,	    /* 0: no scaling, nonzero: scale the rows with Rs */

    /* inputs, modified on output */
    Int Offp [ ],   /* off-diagonal matrix (modified by this routine) */
    Int Offi [ ],
    Entry Offx [ ]
)
{
    Entry aik ;
    Int i, p, pend, oldcol, kglobal, poff, oldrow ;

    /* ---------------------------------------------------------------------- */
    /* Scale and scatter the column into X. */
    /* ---------------------------------------------------------------------- */

    kglobal = k + k1 ;		/* column k of the block is col kglobal of A */
    poff = Offp [kglobal] ;	/* start of off-diagonal column */
    oldcol = Q [kglobal] ;
    pend = Ap [oldcol+1] ;

    if (scale <= 0)
    {
	/* no scaling */
	for (p = Ap [oldcol] ; p < pend ; p++)
	{
	    oldrow = Ai [p] ;
	    i = PSinv [oldrow] - k1 ;
	    aik = Ax [p] ;
	    if (i < 0)
	    {
		/* this is an entry in the off-diagonal part */
		Offi [poff] = oldrow ;
		Offx [poff] = aik ;
		poff++ ;
	    }
	    else
	    {
		/* (i,k) is an entry in the block.  scatter into X */
		X [i] = aik ;
	    }
	}
    }
    else
    {
	/* row scaling */
	for (p = Ap [oldcol] ; p < pend ; p++)
	{
	    oldrow = Ai [p] ;
	    i = PSinv [oldrow] - k1 ;
	    aik = Ax [p] ;
	    SCALE_DIV (aik, Rs [oldrow]) ;
	    if (i < 0)
	    {
		/* this is an entry in the off-diagonal part */
		Offi [poff] = oldrow ;
		Offx [poff] = aik ;
		poff++ ;
	    }
	    else
	    {
		/* (i,k) is an entry in the block.  scatter into X */
		X [i] = aik ;
	    }
	}
    }

    Offp [kglobal+1] = poff ;   /* start of the next col of off-diag part */
}
GLOBAL Int UMFPACK_get_determinant
(
    double *Mx,
#ifdef COMPLEX
    double *Mz,
#endif
    double *Ex,
    void *NumericHandle,
    double User_Info [UMFPACK_INFO]
)
{
    /* ---------------------------------------------------------------------- */
    /* local variables */
    /* ---------------------------------------------------------------------- */

    Entry d_mantissa, d_tmp ;
    double d_exponent, Info2 [UMFPACK_INFO], one [2] = {1.0, 0.0}, d_sign ;
    Entry *D ;
    double *Info, *Rs ;
    NumericType *Numeric ;
    Int i, n, itmp, npiv, *Wi, *Rperm, *Cperm, do_scale ;

#ifndef NRECIPROCAL
    Int do_recip ;
#endif

    /* ---------------------------------------------------------------------- */
    /* check input parameters */
    /* ---------------------------------------------------------------------- */

    if (User_Info != (double *) NULL)
    {
	/* return Info in user's array */
	Info = User_Info ;
    }
    else
    {
	/* no Info array passed - use local one instead */
	Info = Info2 ;
	for (i = 0 ; i < UMFPACK_INFO ; i++)
	{
	    Info [i] = EMPTY ;
	}
    }

    Info [UMFPACK_STATUS] = UMFPACK_OK ;

    Numeric = (NumericType *) NumericHandle ;
    if (!UMF_valid_numeric (Numeric))
    {
	Info [UMFPACK_STATUS] = UMFPACK_ERROR_invalid_Numeric_object ;
	return (UMFPACK_ERROR_invalid_Numeric_object) ;
    }

    if (Numeric->n_row != Numeric->n_col)
    {
	/* only square systems can be handled */
	Info [UMFPACK_STATUS] = UMFPACK_ERROR_invalid_system ;
	return (UMFPACK_ERROR_invalid_system) ;
    }

    if (Mx == (double *) NULL)
    {
	Info [UMFPACK_STATUS] = UMFPACK_ERROR_argument_missing ;
	return (UMFPACK_ERROR_argument_missing) ;
    }

    n = Numeric->n_row ;

    /* ---------------------------------------------------------------------- */
    /* allocate workspace */
    /* ---------------------------------------------------------------------- */

    Wi = (Int *) UMF_malloc (n, sizeof (Int)) ;

    if (!Wi)
    {
	DEBUGm4 (("out of memory: get determinant\n")) ;
	Info [UMFPACK_STATUS] = UMFPACK_ERROR_out_of_memory ;
	return (UMFPACK_ERROR_out_of_memory) ;
    }

    /* ---------------------------------------------------------------------- */
    /* compute the determinant */
    /* ---------------------------------------------------------------------- */

    Rs = Numeric->Rs ;		/* row scale factors */
    do_scale = (Rs != (double *) NULL) ;

#ifndef NRECIPROCAL
    do_recip = Numeric->do_recip ;
#endif

    d_mantissa = ((Entry *) one) [0] ;
    d_exponent = 0.0 ;
    D = Numeric->D ;

    /* compute product of diagonal entries of U */
    for (i = 0 ; i < n ; i++)
    {
	MULT (d_tmp, d_mantissa, D [i]) ;
	d_mantissa = d_tmp ;

	if (!rescale_determinant (&d_mantissa, &d_exponent))
	{
	    /* the determinant is zero or NaN */
	    Info [UMFPACK_STATUS] = UMFPACK_WARNING_singular_matrix ;
	    /* no need to compute the determinant of R */
	    do_scale = FALSE ;
	    break ;
	}
    }

    /* compute product of diagonal entries of R (or its inverse) */
    if (do_scale)
    {
	for (i = 0 ; i < n ; i++)
	{
#ifndef NRECIPROCAL
	    if (do_recip)
	    {
		/* compute determinant of R inverse */
		SCALE_DIV (d_mantissa, Rs [i]) ;
	    }
	    else
#endif
	    {
		/* compute determinant of R */
		SCALE (d_mantissa, Rs [i]) ;
	    }
	    if (!rescale_determinant (&d_mantissa, &d_exponent))
	    {
		/* the determinant is zero or NaN.  This is very unlikey to
		 * occur here, since the scale factors for a tiny or zero row
		 * are set to 1. */
		Info [UMFPACK_STATUS] = UMFPACK_WARNING_singular_matrix ;
		break ;
	    }
	}
    }

    /* ---------------------------------------------------------------------- */
    /* determine if P and Q are odd or even permutations */
    /* ---------------------------------------------------------------------- */

    npiv = 0 ;
    Rperm = Numeric->Rperm ;

    for (i = 0 ; i < n ; i++)
    {
	Wi [i] = Rperm [i] ;
    }

    for (i = 0 ; i < n ; i++)
    {
	while (Wi [i] != i)
	{
	    itmp = Wi [Wi [i]] ;
	    Wi [Wi [i]] = Wi [i] ;
	    Wi [i] = itmp ;
	    npiv++ ;
	}
    }

    Cperm = Numeric->Cperm ;

    for (i = 0 ; i < n ; i++)
    {
	Wi [i] = Cperm [i] ;
    }

    for (i = 0 ; i < n ; i++)
    {
	while (Wi [i] != i)
	{
	    itmp = Wi [Wi [i]] ;
	    Wi [Wi [i]] = Wi [i] ;
	    Wi [i] = itmp ;
	    npiv++ ;
	}
    }

    /* if npiv is odd, the sign is -1.  if it is even, the sign is +1 */
    d_sign = (npiv % 2) ? -1. : 1. ;

    /* ---------------------------------------------------------------------- */
    /* free workspace */
    /* ---------------------------------------------------------------------- */

    (void) UMF_free ((void *) Wi) ;

    /* ---------------------------------------------------------------------- */
    /* compute the magnitude and exponent of the determinant */
    /* ---------------------------------------------------------------------- */

    if (Ex == (double *) NULL)
    {
	/* Ex is not provided, so return the entire determinant in d_mantissa */
	SCALE (d_mantissa, pow (10.0, d_exponent)) ;
    }
    else
    {
	Ex [0] = d_exponent ;
    }

    Mx [0] = d_sign * REAL_COMPONENT (d_mantissa) ;

#ifdef COMPLEX
    if (SPLIT (Mz))
    {
	Mz [0] = d_sign * IMAG_COMPONENT (d_mantissa) ;
    }
    else
    {
	Mx [1] = d_sign * IMAG_COMPONENT (d_mantissa) ;
    }
#endif

    /* determine if the determinant has (or will) overflow or underflow */
    if (d_exponent + 1.0 > log10 (DBL_MAX))
    {
	Info [UMFPACK_STATUS] = UMFPACK_WARNING_determinant_overflow ;
    }
    else if (d_exponent - 1.0 < log10 (DBL_MIN))
    {
	Info [UMFPACK_STATUS] = UMFPACK_WARNING_determinant_underflow ;
    }

    return (UMFPACK_OK) ;
}
示例#3
0
GLOBAL Int UMF_solve
(
    Int sys,
    const Int Ap [ ],
    const Int Ai [ ],
    const double Ax [ ],
    double Xx [ ],
    const double Bx [ ],
#ifdef COMPLEX
    const double Az [ ],
    double Xz [ ],
    const double Bz [ ],
#endif
    NumericType *Numeric,
    Int irstep,
    double Info [UMFPACK_INFO],
    Int Pattern [ ],		/* size n */
    double SolveWork [ ]	/* if irstep>0 real:  size 5*n.  complex:10*n */
				/* otherwise   real:  size   n.  complex: 4*n */
)
{
    /* ---------------------------------------------------------------------- */
    /* local variables */
    /* ---------------------------------------------------------------------- */

    Entry axx, wi, xj, zi, xi, aij, bi ;
    double omega [3], d, z2i, yi, flops ;
    Entry *W, *Z, *S, *X ;
    double *Z2, *Y, *B2, *Rs ;
    Int *Rperm, *Cperm, i, n, p, step, j, nz, status, p2, do_scale ;
#ifdef COMPLEX
    Int AXsplit ;
    Int Bsplit ;
#endif
#ifndef NRECIPROCAL
    Int do_recip = Numeric->do_recip ;
#endif

    /* ---------------------------------------------------------------------- */
    /* initializations */
    /* ---------------------------------------------------------------------- */

#ifndef NDEBUG
    UMF_dump_lu (Numeric) ;
    ASSERT (Numeric && Xx && Bx && Pattern && SolveWork && Info) ;
#endif

    nz = 0 ;
    omega [0] = 0. ;
    omega [1] = 0. ;
    omega [2] = 0. ;
    Rperm = Numeric->Rperm ;
    Cperm = Numeric->Cperm ;
    Rs = Numeric->Rs ;		/* row scale factors */
    do_scale = (Rs != (double *) NULL) ;
    flops = 0 ;
    Info [UMFPACK_SOLVE_FLOPS] = 0 ;
    Info [UMFPACK_IR_TAKEN] = 0 ;
    Info [UMFPACK_IR_ATTEMPTED] = 0 ;

    /* UMFPACK_solve does not call this routine if A is rectangular */
    ASSERT (Numeric->n_row == Numeric->n_col) ;
    n = Numeric->n_row ;
    if (Numeric->nnzpiv < n
	|| SCALAR_IS_ZERO (Numeric->rcond) || SCALAR_IS_NAN (Numeric->rcond))
    {
	/* Note that systems involving just L return UMFPACK_OK, even if */
	/* A is singular (L is always has a unit diagonal). */
	DEBUGm4 (("Note, matrix is singular in umf_solve\n")) ;
	status = UMFPACK_WARNING_singular_matrix ;
	irstep = 0 ;
    }
    else
    {
	status = UMFPACK_OK ;
    }
    irstep = MAX (0, irstep) ;			/* make sure irstep is >= 0 */

    W = (Entry *) SolveWork ;			/* Entry W [0..n-1] */

    Z = (Entry *) NULL ;	/* unused if no iterative refinement */
    S = (Entry *) NULL ;
    Y = (double *) NULL ;
    Z2 = (double *) NULL ;
    B2 = (double *) NULL ;

#ifdef COMPLEX
    if (irstep > 0)
    {
	if (!Ap || !Ai || !Ax)
	{
	    return (UMFPACK_ERROR_argument_missing) ;
	}
	/* A, B, and X in split format if Az, Bz, and Xz present */
	AXsplit = SPLIT (Az) || SPLIT(Xz);
	Z = (Entry *) (SolveWork + 4*n) ;	/* Entry Z [0..n-1] */
	S = (Entry *) (SolveWork + 6*n) ;	/* Entry S [0..n-1] */
	Y = (double *) (SolveWork + 8*n) ;	/* double Y [0..n-1] */
	B2 = (double *) (SolveWork + 9*n) ;	/* double B2 [0..n-1] */
	Z2 = (double *) Z ;		/* double Z2 [0..n-1], equiv. to Z */
    }
    else
    {
      /* A is ignored, only  look at X for split/packed cases */
      AXsplit = SPLIT(Xz);
    }
    Bsplit = SPLIT (Bz);

    if (AXsplit)
    {
	X = (Entry *) (SolveWork + 2*n) ;	/* Entry X [0..n-1] */
    }
    else
    {
	X = (Entry *) Xx ;			/* Entry X [0..n-1] */
    }
#else
    X = (Entry *) Xx ;				/* Entry X [0..n-1] */
    if (irstep > 0)
    {
	if (!Ap || !Ai || !Ax)
	{
	    return (UMFPACK_ERROR_argument_missing) ;
	}
	Z = (Entry *) (SolveWork + n) ;		/* Entry Z [0..n-1] */
	S = (Entry *) (SolveWork + 2*n) ;	/* Entry S [0..n-1] */
	Y = (double *) (SolveWork + 3*n) ;	/* double Y [0..n-1] */
	B2 = (double *) (SolveWork + 4*n) ;	/* double B2 [0..n-1] */
	Z2 = (double *) Z ;		/* double Z2 [0..n-1], equiv. to Z */
    }
#endif

    /* ---------------------------------------------------------------------- */
    /* determine which system to solve */
    /* ---------------------------------------------------------------------- */

    if (sys == UMFPACK_A)
    {

	/* ------------------------------------------------------------------ */
	/* solve A x = b with optional iterative refinement */
	/* ------------------------------------------------------------------ */

	if (irstep > 0)
	{

	    /* -------------------------------------------------------------- */
	    /* using iterative refinement:  compute Y and B2 */
	    /* -------------------------------------------------------------- */

	    nz = Ap [n] ;
	    Info [UMFPACK_NZ] = nz ;

	    /* A is stored by column */
	    /* Y (i) = ||R A_i||, 1-norm of row i of R A */
	    for (i = 0 ; i < n ; i++)
	    {
		Y [i] = 0. ;
	    }
	    flops += (ABS_FLOPS + 1) * nz ;
	    p2 = Ap [n] ;
	    for (p = 0 ; p < p2 ; p++)
	    {
		/* Y [Ai [p]] += ABS (Ax [p]) ; */
	        ASSIGN (aij, Ax, Az, p, AXsplit) ;
		ABS (d, aij) ;
		Y [Ai [p]] += d ;
	    }

	    /* B2 = abs (B) */
	    flops += ABS_FLOPS * n ;
	    for (i = 0 ; i < n ; i++)
	    {
		/* B2 [i] = ABS (B [i]) ; */
		ASSIGN (bi, Bx, Bz, i, Bsplit) ;
		ABS (B2 [i], bi) ;
	    }

	    /* scale Y and B2. */
	    if (do_scale)
	    {
		/* Y = R Y */
		/* B2 = R B2 */
#ifndef NRECIPROCAL
		if (do_recip)
		{
		    /* multiply by the scale factors */
		    for (i = 0 ; i < n ; i++)
		    {
			Y [i]  *= Rs [i] ;
			B2 [i] *= Rs [i] ;
		    }
		}
		else
#endif
		{
		    /* divide by the scale factors */
		    for (i = 0 ; i < n ; i++)
		    {
			Y [i]  /= Rs [i] ;
			B2 [i] /= Rs [i] ;
		    }
		}

		flops += 2 * n ;
	    }

	}

	for (step = 0 ; step <= irstep ; step++)
	{

	    /* -------------------------------------------------------------- */
	    /* Solve A x = b (step 0): */
	    /*  x = Q (U \ (L \ (P R b))) */
	    /* and then perform iterative refinement (step > 0): */
	    /*  x = x + Q (U \ (L \ (P R (b - A x)))) */
	    /* -------------------------------------------------------------- */

	    if (step == 0)
	    {
		if (do_scale)
		{
		    /* W = P R b, using X as workspace, since Z is not
		     * allocated if irstep = 0. */
#ifndef NRECIPROCAL
		    if (do_recip)
		    {
			/* multiply by the scale factors */
			for (i = 0 ; i < n ; i++)
			{
			    ASSIGN (X [i], Bx, Bz, i, Bsplit) ;
			    SCALE (X [i], Rs [i]) ;
			}
		    }
		    else
#endif
		    {
			/* divide by the scale factors */
			for (i = 0 ; i < n ; i++)
			{
			    ASSIGN (X [i], Bx, Bz, i, Bsplit) ;
			    SCALE_DIV (X [i], Rs [i]) ;
			}
		    }
		    flops += SCALE_FLOPS * n ;
		    for (i = 0 ; i < n ; i++)
		    {
			W [i] = X [Rperm [i]] ;
		    }
		}
		else
		{
		    /* W = P b, since the row scaling R = I */
		    for (i = 0 ; i < n ; i++)
		    {
			/* W [i] = B [Rperm [i]] ; */
			ASSIGN (W [i], Bx, Bz, Rperm [i], Bsplit) ;
		    }
		}
	    }
	    else
	    {
		for (i = 0 ; i < n ; i++)
		{
		    /* Z [i] = B [i] ; */
		    ASSIGN (Z [i], Bx, Bz, i, Bsplit) ;
		}
		flops += MULTSUB_FLOPS * nz ;
		for (i = 0 ; i < n ; i++)
		{
		    xi = X [i] ;
		    p2 = Ap [i+1] ;
		    for (p = Ap [i] ; p < p2 ; p++)
		    {
			/* Z [Ai [p]] -= Ax [p] * xi ; */
			ASSIGN (aij, Ax, Az, p, AXsplit) ;
			MULT_SUB (Z [Ai [p]], aij, xi) ;
		    }
		}
		/* scale, Z = R Z */
		if (do_scale)
		{
#ifndef NRECIPROCAL
		    if (do_recip)
		    {
			/* multiply by the scale factors */
			for (i = 0 ; i < n ; i++)
			{
			    SCALE (Z [i], Rs [i]) ;
			}
		    }
		    else
#endif
		    {
			/* divide by the scale factors */
			for (i = 0 ; i < n ; i++)
			{
			    SCALE_DIV (Z [i], Rs [i]) ;
			}
		    }
		    flops += SCALE_FLOPS * n ;
		}
		for (i = 0 ; i < n ; i++)
		{
		    W [i] = Z [Rperm [i]] ;
		}
	    }

	    flops += UMF_lsolve (Numeric, W, Pattern) ;
	    flops += UMF_usolve (Numeric, W, Pattern) ;

	    if (step == 0)
	    {
		for (i = 0 ; i < n ; i++)
		{
		    X [Cperm [i]] = W [i] ;
		}
	    }
	    else
	    {
		flops += ASSEMBLE_FLOPS * n ;
		for (i = 0 ; i < n ; i++)
		{
		    /* X [Cperm [i]] += W [i] ; */
		    ASSEMBLE (X [Cperm [i]], W [i]) ;
		}
	    }

	    /* -------------------------------------------------------------- */
	    /* sparse backward error estimate */
	    /* -------------------------------------------------------------- */

	    if (irstep > 0)
	    {

		/* ---------------------------------------------------------- */
		/* A is stored by column */
		/* W (i) = R (b - A x)_i, residual */
		/* Z2 (i) = R (|A||x|)_i */
		/* ---------------------------------------------------------- */

		for (i = 0 ; i < n ; i++)
		{
		    /* W [i] = B [i] ; */
		    ASSIGN (W [i], Bx, Bz, i, Bsplit) ;
		    Z2 [i] = 0. ;
		}
		flops += (MULT_FLOPS + DECREMENT_FLOPS + ABS_FLOPS + 1) * nz ;
		for (j = 0 ; j < n ; j++)
		{
		    xj = X [j] ;
		    p2 = Ap [j+1] ;
		    for (p = Ap [j] ; p < p2 ; p++)
		    {
			i = Ai [p] ;

			/* axx = Ax [p] * xj ; */
			ASSIGN (aij, Ax, Az, p, AXsplit) ;
			MULT (axx, aij, xj) ;

			/* W [i] -= axx ; */
			DECREMENT (W [i], axx) ;

			/* Z2 [i] += ABS (axx) ; */
			ABS (d, axx) ;
			Z2 [i] += d ;
		    }
		}

		/* scale W and Z2 */
		if (do_scale)
		{
		    /* Z2 = R Z2 */
		    /* W = R W */
#ifndef NRECIPROCAL
		    if (do_recip)
		    {
			/* multiply by the scale factors */
			for (i = 0 ; i < n ; i++)
			{
			    SCALE (W [i], Rs [i]) ;
			    Z2 [i] *= Rs [i] ;
			}
		    }
		    else
#endif
		    {
			/* divide by the scale factors */
			for (i = 0 ; i < n ; i++)
			{
			    SCALE_DIV (W [i], Rs [i]) ;
			    Z2 [i] /= Rs [i] ;
			}
		    }
		    flops += (SCALE_FLOPS + 1) * n ;
		}

		flops += (2*ABS_FLOPS + 5) * n ;
		if (do_step (omega, step, B2, X, W, Y, Z2, S, n, Info))
		{
		    /* iterative refinement is done */
		    break ;
		}

	    }

	}

    }
    else if (sys == UMFPACK_At)
    {

	/* ------------------------------------------------------------------ */
	/* solve A' x = b with optional iterative refinement */
	/* ------------------------------------------------------------------ */

	/* A' is the complex conjugate transpose */

	if (irstep > 0)
	{

	    /* -------------------------------------------------------------- */
	    /* using iterative refinement:  compute Y */
	    /* -------------------------------------------------------------- */

	    nz = Ap [n] ;
	    Info [UMFPACK_NZ] = nz ;

	    /* A' is stored by row */
	    /* Y (i) = ||(A' R)_i||, 1-norm of row i of A' R */

	    if (do_scale)
	    {
		flops += (ABS_FLOPS + 2) * nz ;
#ifndef NRECIPROCAL
		if (do_recip)
		{
		    /* multiply by the scale factors */
		    for (i = 0 ; i < n ; i++)
		    {
			yi = 0. ;
			p2 = Ap [i+1] ;
			for (p = Ap [i] ; p < p2 ; p++)
			{
			    /* yi += ABS (Ax [p]) * Rs [Ai [p]] ; */
			    /* note that abs (aij) is the same as
			     * abs (conj (aij)) */
			    ASSIGN (aij, Ax, Az, p, AXsplit) ;
			    ABS (d, aij) ;
			    yi += (d * Rs [Ai [p]]) ;
			}
			Y [i] = yi ;
		    }
		}
		else
#endif
		{
		    /* divide by the scale factors */
		    for (i = 0 ; i < n ; i++)
		    {
			yi = 0. ;
			p2 = Ap [i+1] ;
			for (p = Ap [i] ; p < p2 ; p++)
			{
			    /* yi += ABS (Ax [p]) / Rs [Ai [p]] ; */
			    /* note that abs (aij) is the same as
			     * abs (conj (aij)) */
			    ASSIGN (aij, Ax, Az, p, AXsplit) ;
			    ABS (d, aij) ;
			    yi += (d / Rs [Ai [p]]) ;
			}
			Y [i] = yi ;
		    }
		}
	    }
	    else
	    {
		/* no scaling */
		flops += (ABS_FLOPS + 1) * nz ;
		for (i = 0 ; i < n ; i++)
		{
		    yi = 0. ;
		    p2 = Ap [i+1] ;
		    for (p = Ap [i] ; p < p2 ; p++)
		    {
			/* yi += ABS (Ax [p]) ; */
			/* note that abs (aij) is the same as
			 * abs (conj (aij)) */
			ASSIGN (aij, Ax, Az, p, AXsplit) ;
			ABS (d, aij) ;
			yi += d ;
		    }
		    Y [i] = yi ;
		}
	    }

	    /* B2 = abs (B) */
	    for (i = 0 ; i < n ; i++)
	    {
		/* B2 [i] = ABS (B [i]) ; */
		ASSIGN (bi, Bx, Bz, i, Bsplit) ;
		ABS (B2 [i], bi) ;
	    }

	}

	for (step = 0 ; step <= irstep ; step++)
	{

	    /* -------------------------------------------------------------- */
	    /* Solve A' x = b (step 0): */
	    /*	x = R P' (L' \ (U' \ (Q' b))) */
	    /* and then perform iterative refinement (step > 0): */
	    /*	x = x + R P' (L' \ (U' \ (Q' (b - A' x)))) */
	    /* -------------------------------------------------------------- */

	    if (step == 0)
	    {
		/* W = Q' b */
		for (i = 0 ; i < n ; i++)
		{
		    /* W [i] = B [Cperm [i]] ; */
		    ASSIGN (W [i], Bx, Bz, Cperm [i], Bsplit) ;
		}
	    }
	    else
	    {
		/* Z = b - A' x */
		for (i = 0 ; i < n ; i++)
		{
		    /* Z [i] = B [i] ; */
		    ASSIGN (Z [i], Bx, Bz, i, Bsplit) ;
		}
		flops += MULTSUB_FLOPS * nz ;
		for (i = 0 ; i < n ; i++)
		{
		    zi = Z [i] ;
		    p2 = Ap [i+1] ;
		    for (p = Ap [i] ; p < p2 ; p++)
		    {
			/* zi -= conjugate (Ax [p]) * X [Ai [p]] ; */
			ASSIGN (aij, Ax, Az, p, Bsplit) ;
			MULT_SUB_CONJ (zi, X [Ai [p]], aij) ;
		    }
		    Z [i] = zi ;
		}
		/* W = Q' Z */
		for (i = 0 ; i < n ; i++)
		{
		    W [i] = Z [Cperm [i]] ;
		}
	    }

	    flops += UMF_uhsolve (Numeric, W, Pattern) ;
	    flops += UMF_lhsolve (Numeric, W, Pattern) ;

	    if (step == 0)
	    {

		/* X = R P' W */
		/* do not use Z, since it isn't allocated if irstep = 0 */

		/* X = P' W */
		for (i = 0 ; i < n ; i++)
		{
		    X [Rperm [i]] = W [i] ;
		}
		if (do_scale)
		{
		    /* X = R X */
#ifndef NRECIPROCAL
		    if (do_recip)
		    {
			/* multiply by the scale factors */
			for (i = 0 ; i < n ; i++)
			{
			    SCALE (X [i], Rs [i]) ;
			}
		    }
		    else
#endif
		    {
			/* divide by the scale factors */
			for (i = 0 ; i < n ; i++)
			{
			    SCALE_DIV (X [i], Rs [i]) ;
			}
		    }
		    flops += SCALE_FLOPS * n ;
		}

	    }
	    else
	    {

		/* Z = P' W */
		for (i = 0 ; i < n ; i++)
		{
		    Z [Rperm [i]] = W [i] ;
		}
		if (do_scale)
		{
		    /* Z = R Z */
#ifndef NRECIPROCAL
		    if (do_recip)
		    {
			/* multiply by the scale factors */
			for (i = 0 ; i < n ; i++)
			{
			    SCALE (Z [i], Rs [i]) ;
			}
		    }
		    else
#endif
		    {
			/* divide by the scale factors */
			for (i = 0 ; i < n ; i++)
			{
			    SCALE_DIV (Z [i], Rs [i]) ;
			}
		    }
		    flops += SCALE_FLOPS * n ;
		}

		flops += ASSEMBLE_FLOPS * n ;
		/* X += Z */
		for (i = 0 ; i < n ; i++)
		{
		    /* X [i] += Z [i] ; was +=W[i] in v4.3, which is wrong */
		    ASSEMBLE (X [i], Z [i]) ;	/* bug fix, v4.3.1 */
		}
	    }

	    /* -------------------------------------------------------------- */
	    /* sparse backward error estimate */
	    /* -------------------------------------------------------------- */

	    if (irstep > 0)
	    {

		/* ---------------------------------------------------------- */
		/* A' is stored by row */
		/* W (i) = (b - A' x)_i, residual */
		/* Z2 (i) = (|A'||x|)_i */
		/* ---------------------------------------------------------- */

		flops += (MULT_FLOPS + DECREMENT_FLOPS + ABS_FLOPS + 1) * nz ;
		for (i = 0 ; i < n ; i++)
		{
		    /* wi = B [i] ; */
		    ASSIGN (wi, Bx, Bz, i, Bsplit) ;
		    z2i = 0. ;
		    p2 = Ap [i+1] ;
		    for (p = Ap [i] ; p < p2 ; p++)
		    {
			/* axx = conjugate (Ax [p]) * X [Ai [p]] ; */
			ASSIGN (aij, Ax, Az, p, AXsplit) ;
			MULT_CONJ (axx, X [Ai [p]], aij) ;

			/* wi -= axx ; */
			DECREMENT (wi, axx) ;

			/* z2i += ABS (axx) ; */
			ABS (d, axx) ;
			z2i += d ;
		    }
		    W [i] = wi ;
		    Z2 [i] = z2i ;
		}

		flops += (2*ABS_FLOPS + 5) * n ;
		if (do_step (omega, step, B2, X, W, Y, Z2, S, n, Info))
		{
		    /* iterative refinement is done */
		    break ;
		}

	    }

	}

    }
    else if (sys == UMFPACK_Aat)
    {

	/* ------------------------------------------------------------------ */
	/* solve A.' x = b with optional iterative refinement */
	/* ------------------------------------------------------------------ */

	/* A' is the array transpose */

	if (irstep > 0)
	{

	    /* -------------------------------------------------------------- */
	    /* using iterative refinement:  compute Y */
	    /* -------------------------------------------------------------- */

	    nz = Ap [n] ;
	    Info [UMFPACK_NZ] = nz ;

	    /* A.' is stored by row */
	    /* Y (i) = ||(A.' R)_i||, 1-norm of row i of A.' R */

	    if (do_scale)
	    {
		flops += (ABS_FLOPS + 2) * nz ;
#ifndef NRECIPROCAL
		if (do_recip)
		{
		    /* multiply by the scale factors */
		    for (i = 0 ; i < n ; i++)
		    {
			yi = 0. ;
			p2 = Ap [i+1] ;
			for (p = Ap [i] ; p < p2 ; p++)
			{
			    /* yi += ABS (Ax [p]) * Rs [Ai [p]] ; */
			    /* note that A.' is the array transpose,
			     * so no conjugate */
			    ASSIGN (aij, Ax, Az, p, AXsplit) ;
			    ABS (d, aij) ;
			    yi += (d * Rs [Ai [p]]) ;
			}
			Y [i] = yi ;
		    }
		}
		else
#endif
		{
		    /* divide by the scale factors */
		    for (i = 0 ; i < n ; i++)
		    {
			yi = 0. ;
			p2 = Ap [i+1] ;
			for (p = Ap [i] ; p < p2 ; p++)
			{
			    /* yi += ABS (Ax [p]) / Rs [Ai [p]] ; */
			    /* note that A.' is the array transpose,
			     * so no conjugate */
			    ASSIGN (aij, Ax, Az, p, AXsplit) ;
			    ABS (d, aij) ;
			    yi += (d / Rs [Ai [p]]) ;
			}
			Y [i] = yi ;
		    }
		}
	    }
	    else
	    {
		/* no scaling */
		flops += (ABS_FLOPS + 1) * nz ;
		for (i = 0 ; i < n ; i++)
		{
		    yi = 0. ;
		    p2 = Ap [i+1] ;
		    for (p = Ap [i] ; p < p2 ; p++)
		    {
			/* yi += ABS (Ax [p]) */
			/* note that A.' is the array transpose,
			 * so no conjugate */
			ASSIGN (aij, Ax, Az, p, AXsplit) ;
			ABS (d, aij) ;
			yi += d ;
		    }
		    Y [i] = yi ;
		}
	    }

	    /* B2 = abs (B) */
	    for (i = 0 ; i < n ; i++)
	    {
		/* B2 [i] = ABS (B [i]) ; */
		ASSIGN (bi, Bx, Bz, i, Bsplit) ;
		ABS (B2 [i], bi) ;
	    }

	}

	for (step = 0 ; step <= irstep ; step++)
	{

	    /* -------------------------------------------------------------- */
	    /* Solve A.' x = b (step 0): */
	    /*	x = R P' (L.' \ (U.' \ (Q' b))) */
	    /* and then perform iterative refinement (step > 0): */
	    /*	x = x + R P' (L.' \ (U.' \ (Q' (b - A.' x)))) */
	    /* -------------------------------------------------------------- */

	    if (step == 0)
	    {
		/* W = Q' b */
		for (i = 0 ; i < n ; i++)
		{
		    /* W [i] = B [Cperm [i]] ; */
		    ASSIGN (W [i], Bx, Bz, Cperm [i], Bsplit) ;
		}
	    }
	    else
	    {
		/* Z = b - A.' x */
		for (i = 0 ; i < n ; i++)
		{
		    /* Z [i] = B [i] ; */
		    ASSIGN (Z [i], Bx, Bz, i, Bsplit) ;
		}
		flops += MULTSUB_FLOPS * nz ;
		for (i = 0 ; i < n ; i++)
		{
		    zi = Z [i] ;
		    p2 = Ap [i+1] ;
		    for (p = Ap [i] ; p < p2 ; p++)
		    {
			/* zi -= Ax [p] * X [Ai [p]] ; */
			ASSIGN (aij, Ax, Az, p, AXsplit) ;
			MULT_SUB (zi, aij, X [Ai [p]]) ;
		    }
		    Z [i] = zi ;
		}
		/* W = Q' Z */
		for (i = 0 ; i < n ; i++)
		{
		    W [i] = Z [Cperm [i]] ;
		}
	    }

	    flops += UMF_utsolve (Numeric, W, Pattern) ;
	    flops += UMF_ltsolve (Numeric, W, Pattern) ;

	    if (step == 0)
	    {

		/* X = R P' W */
		/* do not use Z, since it isn't allocated if irstep = 0 */

		/* X = P' W */
		for (i = 0 ; i < n ; i++)
		{
		    X [Rperm [i]] = W [i] ;
		}
		if (do_scale)
		{
		    /* X = R X */
#ifndef NRECIPROCAL
		    if (do_recip)
		    {
			/* multiply by the scale factors */
			for (i = 0 ; i < n ; i++)
			{
			    SCALE (X [i], Rs [i]) ;
			}
		    }
		    else
#endif
		    {
			/* divide by the scale factors */
			for (i = 0 ; i < n ; i++)
			{
			    SCALE_DIV (X [i], Rs [i]) ;
			}
		    }
		    flops += SCALE_FLOPS * n ;
		}

	    }
	    else
	    {

		/* Z = P' W */
		for (i = 0 ; i < n ; i++)
		{
		    Z [Rperm [i]] = W [i] ;
		}
		if (do_scale)
		{
		    /* Z = R Z */
#ifndef NRECIPROCAL
		    if (do_recip)
		    {
			/* multiply by the scale factors */
			for (i = 0 ; i < n ; i++)
			{
			    SCALE (Z [i], Rs [i]) ;
			}
		    }
		    else
#endif
		    {
			/* divide by the scale factors */
			for (i = 0 ; i < n ; i++)
			{
			    SCALE_DIV (Z [i], Rs [i]) ;
			}
		    }
		    flops += SCALE_FLOPS * n ;
		}

		flops += ASSEMBLE_FLOPS * n ;
		/* X += Z */
		for (i = 0 ; i < n ; i++)
		{
		    /* X [i] += Z [i] ; was +=W[i] in v4.3, which is wrong */
		    ASSEMBLE (X [i], Z [i]) ;	/* bug fix, v4.3.1 */
		}
	    }

	    /* -------------------------------------------------------------- */
	    /* sparse backward error estimate */
	    /* -------------------------------------------------------------- */

	    if (irstep > 0)
	    {

		/* ---------------------------------------------------------- */
		/* A.' is stored by row */
		/* W (i) = (b - A.' x)_i, residual */
		/* Z (i) = (|A.'||x|)_i */
		/* ---------------------------------------------------------- */

		flops += (MULT_FLOPS + DECREMENT_FLOPS + ABS_FLOPS + 1) * nz ;
		for (i = 0 ; i < n ; i++)
		{
		    /* wi = B [i] ; */
		    ASSIGN (wi, Bx, Bz, i, Bsplit) ;
		    z2i = 0. ;
		    p2 = Ap [i+1] ;
		    for (p = Ap [i] ; p < p2 ; p++)
		    {
			/* axx = Ax [p] * X [Ai [p]] ; */
			ASSIGN (aij, Ax, Az, p, AXsplit) ;
			MULT (axx, aij, X [Ai [p]]) ;

			/* wi -= axx ; */
			DECREMENT (wi, axx) ;

			/* z2i += ABS (axx) ; */
			ABS (d, axx) ;
			z2i += d ;
		    }
		    W [i] = wi ;
		    Z2 [i] = z2i ;
		}

		flops += (2*ABS_FLOPS + 5) * n ;
		if (do_step (omega, step, B2, X, W, Y, Z2, S, n, Info))
		{
		    /* iterative refinement is done */
		    break ;
		}

	    }

	}

    }
    else if (sys == UMFPACK_Pt_L)
    {

	/* ------------------------------------------------------------------ */
	/* Solve P'Lx=b:  x = L \ Pb */
	/* ------------------------------------------------------------------ */

	for (i = 0 ; i < n ; i++)
	{
	    /* X [i] = B [Rperm [i]] ; */
	    ASSIGN (X [i], Bx, Bz, Rperm [i], Bsplit) ;
	}
	flops = UMF_lsolve (Numeric, X, Pattern) ;
	status = UMFPACK_OK ;

    }
    else if (sys == UMFPACK_L)
    {

	/* ------------------------------------------------------------------ */
	/* Solve Lx=b:  x = L \ b */
	/* ------------------------------------------------------------------ */

	for (i = 0 ; i < n ; i++)
	{
	    /* X [i] = B [i] ; */
	    ASSIGN (X [i], Bx, Bz, i, Bsplit) ;
	}
	flops = UMF_lsolve (Numeric, X, Pattern) ;
	status = UMFPACK_OK ;

    }
    else if (sys == UMFPACK_Lt_P)
    {

	/* ------------------------------------------------------------------ */
	/* Solve L'Px=b:  x = P' (L' \ b) */
	/* ------------------------------------------------------------------ */

	for (i = 0 ; i < n ; i++)
	{
	    /* W [i] = B [i] ; */
	    ASSIGN (W [i], Bx, Bz, i, Bsplit) ;
	}
	flops = UMF_lhsolve (Numeric, W, Pattern) ;
	for (i = 0 ; i < n ; i++)
	{
	    X [Rperm [i]] = W [i] ;
	}
	status = UMFPACK_OK ;

    }
    else if (sys == UMFPACK_Lat_P)
    {

	/* ------------------------------------------------------------------ */
	/* Solve L.'Px=b:  x = P' (L.' \ b) */
	/* ------------------------------------------------------------------ */

	for (i = 0 ; i < n ; i++)
	{
	    /* W [i] = B [i] ; */
	    ASSIGN (W [i], Bx, Bz, i, Bsplit) ;
	}
	flops = UMF_ltsolve (Numeric, W, Pattern) ;
	for (i = 0 ; i < n ; i++)
	{
	    X [Rperm [i]] = W [i] ;
	}
	status = UMFPACK_OK ;

    }
    else if (sys == UMFPACK_Lt)
    {

	/* ------------------------------------------------------------------ */
	/* Solve L'x=b:  x = L' \ b */
	/* ------------------------------------------------------------------ */

	for (i = 0 ; i < n ; i++)
	{
	    /* X [i] = B [i] ; */
	    ASSIGN (X [i], Bx, Bz, i, Bsplit) ;
	}
	flops = UMF_lhsolve (Numeric, X, Pattern) ;
	status = UMFPACK_OK ;

    }
    else if (sys == UMFPACK_Lat)
    {

	/* ------------------------------------------------------------------ */
	/* Solve L.'x=b:  x = L.' \ b */
	/* ------------------------------------------------------------------ */

	for (i = 0 ; i < n ; i++)
	{
	    /* X [i] = B [i] ; */
	    ASSIGN (X [i], Bx, Bz, i, Bsplit) ;
	}
	flops = UMF_ltsolve (Numeric, X, Pattern) ;
	status = UMFPACK_OK ;

    }
    else if (sys == UMFPACK_U_Qt)
    {

	/* ------------------------------------------------------------------ */
	/* Solve UQ'x=b:  x = Q (U \ b) */
	/* ------------------------------------------------------------------ */

	for (i = 0 ; i < n ; i++)
	{
	    /* W [i] = B [i] ; */
	    ASSIGN (W [i], Bx, Bz, i, Bsplit) ;
	}
	flops = UMF_usolve (Numeric, W, Pattern) ;
	for (i = 0 ; i < n ; i++)
	{
	    X [Cperm [i]] = W [i] ;
	}

    }
    else if (sys == UMFPACK_U)
    {

	/* ------------------------------------------------------------------ */
	/* Solve Ux=b:  x = U \ b */
	/* ------------------------------------------------------------------ */

	for (i = 0 ; i < n ; i++)
	{
	    /* X [i] = B [i] ; */
	    ASSIGN (X [i], Bx, Bz, i, Bsplit) ;
	}
	flops = UMF_usolve (Numeric, X, Pattern) ;

    }
    else if (sys == UMFPACK_Q_Ut)
    {

	/* ------------------------------------------------------------------ */
	/* Solve QU'x=b:  x = U' \ Q'b */
	/* ------------------------------------------------------------------ */

	for (i = 0 ; i < n ; i++)
	{
	    /* X [i] = B [Cperm [i]] ; */
	    ASSIGN (X [i], Bx, Bz, Cperm [i], Bsplit) ;
	}
	flops = UMF_uhsolve (Numeric, X, Pattern) ;

    }
    else if (sys == UMFPACK_Q_Uat)
    {

	/* ------------------------------------------------------------------ */
	/* Solve QU.'x=b:  x = U.' \ Q'b */
	/* ------------------------------------------------------------------ */

	for (i = 0 ; i < n ; i++)
	{
	    /* X [i] = B [Cperm [i]] ; */
	    ASSIGN (X [i], Bx, Bz, Cperm [i], Bsplit) ;
	}
	flops = UMF_utsolve (Numeric, X, Pattern) ;

    }
    else if (sys == UMFPACK_Ut)
    {

	/* ------------------------------------------------------------------ */
	/* Solve U'x=b:  x = U' \ b */
	/* ------------------------------------------------------------------ */

	for (i = 0 ; i < n ; i++)
	{
	    /* X [i] = B [i] ; */
	  ASSIGN (X [i], Bx, Bz, i, Bsplit) ;
	}
	flops = UMF_uhsolve (Numeric, X, Pattern) ;

    }
    else if (sys == UMFPACK_Uat)
    {

	/* ------------------------------------------------------------------ */
	/* Solve U'x=b:  x = U' \ b */
	/* ------------------------------------------------------------------ */

	for (i = 0 ; i < n ; i++)
	{
	    /* X [i] = B [i] ; */
	    ASSIGN (X [i], Bx, Bz, i, Bsplit) ;
	}
	flops = UMF_utsolve (Numeric, X, Pattern) ;

    }
    else
    {
	return (UMFPACK_ERROR_invalid_system) ;
    }

#ifdef COMPLEX
    /* copy the solution back, from Entry X [ ] to double Xx [ ] and Xz [ ] */
    if (AXsplit)
    {
	for (i = 0 ; i < n ; i++)
	{
	    Xx [i] = REAL_COMPONENT (X [i]) ;
	    Xz [i] = IMAG_COMPONENT (X [i]) ;
	}
    }
#endif

    /* return UMFPACK_OK, or UMFPACK_WARNING_singular_matrix */
    /* Note that systems involving just L will return UMFPACK_OK */
    Info [UMFPACK_SOLVE_FLOPS] = flops ;
    return (status) ;
}