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#include "lmer.h"
/* TODO
 * - The egsingle example with ~year|childid+schoolid shows an unusual
 *   drop in the deviance when switching from ECME to optim.  Is it real?
 *   (Apparently so.)
 * - Remove the fill_nnz function and the PAR and BLK macros.  Do the
 *   allocation of temporary storage once only.
 */

/**
 * Calculate the length of the parameter vector (historically called "coef"
 * even though these are not coefficients).
 *
 * @param nf number of factors
 * @param nc number of columns in the model matrices for each factor
 *
 * @return total length of the coefficient vector
 */
static R_INLINE
int coef_length(int nf, const int nc[])
{
    int i, ans = 0;
    for (i = 0; i < nf; i++) ans += (nc[i] * (nc[i] + 1))/2;
    return ans;
}

/**
 * Check validity of an lmer object.
 *
 * @param x Pointer to an lmer object
 *
 * @return TRUE if the object is a valid lmer object, else a string
 * describing the nature of the violation.
 */
SEXP lmer_validate(SEXP x)
{
    SEXP
    /* ZZxP = GET_SLOT(x, Matrix_ZZxSym), */
    ZtXP = GET_SLOT(x, Matrix_ZtXSym),
    XtXP = GET_SLOT(x, Matrix_XtXSym),
    RZXP = GET_SLOT(x, Matrix_RZXSym),
    RXXP = GET_SLOT(x, Matrix_RXXSym)
    /* , cnames = GET_SLOT(x, Matrix_cnamesSym) */
    ;
    int *ZtXd = INTEGER(getAttrib(ZtXP, R_DimSymbol)),
    *XtXd = INTEGER(getAttrib(XtXP, R_DimSymbol));

    if (!(isReal(ZtXP) && isReal(XtXP) && isReal(RZXP) && isReal(RXXP) ))
    return mkString(_("Slots ZtX, XtX, RZX, and RXX must be real matrices"));
    if (!match_mat_dims(ZtXd, INTEGER(getAttrib(RZXP, R_DimSymbol))))
    return mkString(_("Dimensions of slots ZtX and RZX must match"));
    if (!match_mat_dims(XtXd, INTEGER(getAttrib(RXXP, R_DimSymbol))))
    return mkString(_("Dimensions of slots XtX and RXX must match"));
    if (ZtXd[1] != XtXd[0] || XtXd[0] != XtXd[1])
    return mkString(_("Slots XtX must be a square matrix with same no. of cols as ZtX"));
    return ScalarLogical(1);
}

/**
 * Create the pairwise crosstabulation of the elements of flist.
 *
 * @param flist pointer to the factor list.
 * @param nobs number of observations.
 * @param nc number of columns in the model matrices.
 *
 * @return the pairwise crosstabulation in the form of the ZtZ array.
 */
static SEXP
lmer_crosstab(SEXP flist, int nobs, const int nc[])
{
    int i, nf = length(flist);
    int npairs = (nf * (nf + 1))/2;
    SEXP val = PROTECT(allocVector(VECSXP, npairs));
    SEXP cscbCl = PROTECT(MAKE_CLASS("dgBCMatrix"));
    int *Ti = Calloc(nobs, int),
    *nlevs = Calloc(nf, int),
    **zb = Calloc(nf, int*); /* zero-based indices */
    double *ones = Calloc(nobs, double),
    *Tx = Calloc(nobs, double);

    for (i = 0; i < nobs; i++) ones[i] = 1.;
    for (i = 0; i < nf; i++) {  /* populate the zb vectors */
    SEXP fi = VECTOR_ELT(flist, i);
    int j;

    zb[i] = Calloc(nobs, int);
    nlevs[i] = length(getAttrib(fi, R_LevelsSymbol));
    for (j = 0; j < nobs; j++) zb[i][j] = INTEGER(fi)[j] - 1;
    for (j = 0; j <= i; j++) {
        int *ijp, ind = Lind(i, j), nnz;
        SEXP ZZij;

        SET_VECTOR_ELT(val, ind, NEW_OBJECT(cscbCl));
        ZZij = VECTOR_ELT(val, ind);
        SET_SLOT(ZZij, Matrix_pSym, allocVector(INTSXP, nlevs[j] + 1));
        ijp = INTEGER(GET_SLOT(ZZij, Matrix_pSym));
        triplet_to_col(nlevs[i], nlevs[j], nobs, zb[i], zb[j], ones,
               ijp, Ti, Tx);
        nnz = ijp[nlevs[j]];
        SET_SLOT(ZZij, Matrix_iSym, allocVector(INTSXP, nnz));
        Memcpy(INTEGER(GET_SLOT(ZZij, Matrix_iSym)), Ti, nnz);
        SET_SLOT(ZZij, Matrix_xSym, alloc3Darray(REALSXP, nc[i], nc[j], nnz));
        /* The crosstab counts are copied into the first nnz elements */
        /* of the x slot.  These aren't the correct array positions */
        /* unless nc[i] == nc[j] == 1 but we don't use them. */
        Memcpy(REAL(GET_SLOT(ZZij, Matrix_xSym)), Tx, nnz);
    }
    }

    for (i = 0; i < nf; i++) Free(zb[i]);
    Free(zb); Free(nlevs); Free(ones); Free(Ti); Free(Tx);
    UNPROTECT(2);
    return val;
}


/**
 * Update the arrays ZtZ, ZtX, and XtX in an lme object
 * according to a list of model matrices.
 *
 * @param x pointer to an lmer object
 * @param mmats pointer to a list of model matrices
 *
 * @return NULL
 */
SEXP lmer_update_mm(SEXP x, SEXP mmats)
{
    SEXP
    ZtZP = GET_SLOT(x, Matrix_ZtZSym),
    ZtXP = GET_SLOT(x, Matrix_ZtXSym),
    flist = GET_SLOT(x, Matrix_flistSym);
    int *Gp = INTEGER(GET_SLOT(x, Matrix_GpSym)),
    *dims = INTEGER(getAttrib(ZtXP, R_DimSymbol)),
    *nc = INTEGER(GET_SLOT(x, Matrix_ncSym)),
    *status = LOGICAL(GET_SLOT(x, Matrix_statusSym)),
    nf = length(flist), nfp1 = nf + 1,
    i, ione = 1,
    nobs = nc[nfp1],
    pp1 = nc[nf];
    double
    *X,
    *XtX = REAL(GET_SLOT(x, Matrix_XtXSym)),
    *ZtX = REAL(ZtXP),
    one = 1.0, zero = 0.0;

    if (!isNewList(mmats) || length(mmats) != nfp1)
    error(_("mmats must be a list of %d model matrices"), nfp1);
    for (i = 0; i <= nf; i++) {
    SEXP mmat = VECTOR_ELT(mmats, i);
    int *mdims = INTEGER(getAttrib(mmat, R_DimSymbol));

    if (!isMatrix(mmat) || !isReal(mmat))
        error(_("element %d of mmats is not a numeric matrix"), i + 1);
    if (nobs != mdims[0])
        error(_("Expected %d rows in the %d'th model matrix. Got %d"),
          nobs, i+1, mdims[0]);
    if (nc[i] != mdims[1])
        error(_("Expected %d columns in the %d'th model matrix. Got %d"),
          nc[i], i+1, mdims[1]);
    }
                /* Create XtX */
    X = REAL(VECTOR_ELT(mmats, nf));
    F77_CALL(dsyrk)("U", "T", &pp1, &nobs, &one, X, &nobs, &zero, XtX, nc + nf);
                /* Zero an accumulator */
    AZERO(ZtX, pp1 * Gp[nf]);
    for (i = 0; i < nf; i++) {
    int *fac = INTEGER(VECTOR_ELT(flist, i)),
        j, k, nci = nc[i], ZtXrows = Gp[i+1] - Gp[i];
    int ncisqr = nci * nci, nlev = ZtXrows/nci;
    double *Z = REAL(VECTOR_ELT(mmats, i)), *ZZx;

    for (k = 0; k < i; k++) {
        SEXP ZZxM = VECTOR_ELT(ZtZP, Lind(i, k));
        int *rowind = INTEGER(GET_SLOT(ZZxM, Matrix_iSym)),
        *colptr = INTEGER(GET_SLOT(ZZxM, Matrix_pSym));
        int *f2 = INTEGER(VECTOR_ELT(flist, k)), nck = nc[k];
        double *Zk = REAL(VECTOR_ELT(mmats, k));

        ZZx = REAL(GET_SLOT(ZZxM, Matrix_xSym));
        AZERO(ZZx, length(GET_SLOT(ZZxM, Matrix_xSym)));
        for (j = 0; j < nobs; j++) {
        F77_CALL(dgemm)("T", "N", nc + i, nc + k, &ione, &one,
                Z + j, &nobs, Zk + j, &nobs, &one,
                ZZx + check_csc_index(colptr, rowind,
                              fac[j] - 1, f2[j] - 1, 0)
                * (nci * nck), &nci);
        }
    }
    ZZx = REAL(GET_SLOT(VECTOR_ELT(ZtZP, Lind(i, i)), Matrix_xSym));
    AZERO(ZZx, nci * nci * nlev);
    if (nci == 1) {     /* single column in Z */
        for (j = 0; j < nobs; j++) {
        int fj = fac[j] - 1; /* factor indices are 1-based */
        ZZx[fj] += Z[j] * Z[j];
        F77_CALL(daxpy)(&pp1, Z + j, X + j, &nobs, ZtX + fj, dims);
        }
    } else {
        for (j = 0; j < nobs; j++) {
        int fj = fac[j] - 1; /* factor indices are 1-based */

        F77_CALL(dsyr)("U", nc + i, &one, Z + j, &nobs,
                   ZZx + fj * ncisqr, nc + i);
        F77_CALL(dgemm)("T", "N", nc + i, &pp1, &ione,
                &one, Z + j, &nobs,
                X + j, &nobs, &one,
                ZtX + fj * nci, dims);
        }
    }
    ZtX += ZtXrows;
    }
    status[0] = status[1] = 0;
    return R_NilValue;
}

/**
 * Create an lmer object from a list of grouping factors and a list of model
 * matrices.  There is one more model matrix than grouping factor.  The last
 * model matrix is the fixed effects and the response.
 *
 * @param flist pointer to a list of grouping factors
 * @param mmats pointer to a list of model matrices
 *
 * @return pointer to an lmer object
 */
SEXP lmer_create(SEXP flist, SEXP mmats)
{
    SEXP val = PROTECT(NEW_OBJECT(MAKE_CLASS("lmer")));
    SEXP ZtZ, cnames, fnms, nms;
    int *nc, i, nf = length(flist), nobs;

                /* Check validity of flist */
    if (!(nf > 0 && isNewList(flist)))
    error(_("flist must be a non-empty list"));
    nobs = length(VECTOR_ELT(flist, 0));
    if (nobs < 1) error(_("flist[[0]] must be a non-null factor"));
    for (i = 0; i < nf; i++) {
    SEXP fi = VECTOR_ELT(flist, i);
    if (!(isFactor(fi) && length(fi) == nobs))
        error(_("flist[[%d]] must be a factor of length %d"),
          i + 1, nobs);
    }
    SET_SLOT(val, Matrix_flistSym, duplicate(flist));
                /* Check mmats; allocate and populate nc */
    if (!(isNewList(mmats) && length(mmats) == (nf + 1)))
    error(_("mmats must be a list of length %d"), nf + 1);
    SET_SLOT(val, Matrix_ncSym, allocVector(INTSXP, nf + 2));
    nc = INTEGER(GET_SLOT(val, Matrix_ncSym));
    nc[nf + 1] = nobs;
    for (i = 0; i <= nf; i++) {
    SEXP mi = VECTOR_ELT(mmats, i);
    int *dims;

    if (!(isMatrix(mi) && isReal(mi)))
        error(_("mmats[[%d]] must be a numeric matrix"), i + 1);
    dims = INTEGER(getAttrib(mi, R_DimSymbol));
    if (dims[0] != nobs)
        error(_("mmats[[%d]] must have %d rows"), i + 1, nobs);
    if (dims[1] < 1)
        error(_("mmats[[%d]] must have at least 1 column"), i + 1);
    nc[i] = dims[1];
    }   /* Arguments have now been checked for type, dimension, etc. */
                /* Create pairwise crosstabulation in ZtZ */
    SET_SLOT(val, Matrix_ZtZSym, lmer_crosstab(flist, nobs, nc));
    lmer_populate(val);
    ZtZ = GET_SLOT(val, Matrix_ZtZSym);
    /* FIXME: Check for possible reordering of the factors to maximize the
     * number of levels (columns?) in the leading nested sequence. */
    fnms = getAttrib(flist, R_NamesSymbol);
                /* Allocate and populate cnames */
    SET_SLOT(val, Matrix_cnamesSym, allocVector(VECSXP, nf + 1));
    cnames = GET_SLOT(val, Matrix_cnamesSym);
    setAttrib(cnames, R_NamesSymbol, allocVector(STRSXP, nf + 1));
    nms = getAttrib(cnames, R_NamesSymbol);
    for (i = 0; i <= nf; i++) {
    SEXP mi = VECTOR_ELT(mmats, i);
    SET_VECTOR_ELT(cnames, i,
               duplicate(VECTOR_ELT(getAttrib(mi, R_DimNamesSymbol),
                        1)));
    SET_STRING_ELT(nms, i, (i < nf) ? duplicate(STRING_ELT(fnms, i)) :
               mkChar(".fixed"));
    }
    lmer_update_mm(val, mmats);
    SET_SLOT(val, Matrix_bVarSym, duplicate(GET_SLOT(val, Matrix_DSym)));
    UNPROTECT(1);
    return val;
}

/**
 * Create and insert initial values for Omega.
 *
 * @param x pointer to an lmer object
 *
 * @return NULL
 */
SEXP lmer_initial(SEXP x)
{
    SEXP Omg = GET_SLOT(x, Matrix_OmegaSym);
    int *status = LOGICAL(GET_SLOT(x, Matrix_statusSym)), i, nf = length(Omg);

    for (i = 0; i < nf; i++) {
    SEXP ZZxP = GET_SLOT(VECTOR_ELT(GET_SLOT(x, Matrix_ZtZSym), Lind(i, i)),
                 Matrix_xSym);
    int *dims = INTEGER(getAttrib(ZZxP, R_DimSymbol));
    int j, k, nzc = dims[0], nlev = dims[2];
    int nzcsqr = nzc * nzc, nzcp1 = nzc + 1;
    double *Omega = REAL(VECTOR_ELT(Omg, i)),
        mi = 0.375 / ((double) nlev);

    AZERO(Omega, nzc * nzc);
    for (j = 0; j < nlev; j ++) {
        for (k = 0; k < nzc; k++) {
        Omega[k * nzcp1] += REAL(ZZxP)[k * nzcp1 + j * nzcsqr] * mi;
        }
    }
    }
    status[0] = status[1] = 0;
    return R_NilValue;
}

/**
 * Copy ZtZ to ZZpO and L.  Inflate diagonal blocks of ZZpO by Omega.
 * Update devComp[1].
 *
 * @param x pointer to an lmer object
 */
SEXP
lmer_inflate(SEXP x)
{
    SEXP Omg = GET_SLOT(x, Matrix_OmegaSym),
    ZZpO = GET_SLOT(x, Matrix_ZZpOSym),
    ZtZ = GET_SLOT(x, Matrix_ZtZSym),
    LP = GET_SLOT(x, Matrix_LSym);
    int *Gp = INTEGER(GET_SLOT(x, Matrix_GpSym)),
    *nc = INTEGER(GET_SLOT(x, Matrix_ncSym)),
    i, k, nf = length(Omg);
    double *dcmp = REAL(GET_SLOT(x, Matrix_devCompSym));

    for (i = 0; i < nf; i++) {
    SEXP ZZOel = VECTOR_ELT(ZZpO, i);
    SEXP ZZOm = GET_SLOT(ZZOel, Matrix_xSym);
    SEXP ZZel = VECTOR_ELT(ZtZ, Lind(i, i));
    int *Di = INTEGER(GET_SLOT(ZZOel, Matrix_iSym)),
        *Dp = INTEGER(GET_SLOT(ZZOel, Matrix_pSym)),
        *Si = INTEGER(GET_SLOT(ZZel, Matrix_iSym)),
        *Sp = INTEGER(GET_SLOT(ZZel, Matrix_pSym)),
        *dims = INTEGER(getAttrib(ZZOm, R_DimSymbol));
    int sz = dims[0] * dims[1];
    int ii, j, nci = nc[i], ncisqr = nci * nci;
    int nlev = (Gp[i + 1] - Gp[i])/nci;
    double *Omega = REAL(VECTOR_ELT(Omg, i)),
        *ZZ = REAL(GET_SLOT(ZZel, Matrix_xSym)),
        *tmp = Memcpy(Calloc(ncisqr, double), Omega, ncisqr);

    F77_CALL(dpotrf)("U", &nci, tmp, &nci, &j);
    if (j)
        error(_("Leading %d minor of Omega[[%d]] not positive definite"),
          j, i + 1);
                /* update dcmp[1] */
    for (j = 0; j < nci; j++) { /* nlev * logDet(Omega_i) */
        dcmp[1] += nlev * 2. * log(tmp[j * (nci + 1)]);
    }
    Free(tmp);
    AZERO(REAL(ZZOm), dims[0] * dims[1] * dims[2]);
    for (j = 0; j < nlev; j++) { /* copy diagonal block and inflate */
        double *ZZOkk = REAL(ZZOm) + check_csc_index(Dp, Di, j, j, 0) * sz;
        int kk, k2 = Sp[j + 1];
        for (kk = Sp[j]; kk < k2; kk++) {
        Memcpy(REAL(ZZOm) + check_csc_index(Dp, Di, Si[kk], j, 0) * sz,
               ZZ + kk * sz, sz);
        }
        for (kk = 0; kk < nci; kk++) {
        for (ii = 0; ii <= kk; ii++) {
            int ind = ii + kk * nci;
            ZZOkk[ind] += Omega[ind];
        }
        }
    }
    for (k = i + 1; k < nf; k++) {
        int ind = Lind(k, i);
        SEXP Lel = VECTOR_ELT(LP, ind),
        Lm = GET_SLOT(Lel, Matrix_xSym);
        double *L = REAL(Lm);

        dims = INTEGER(getAttrib(Lm, R_DimSymbol));
        ZZel = VECTOR_ELT(ZtZ, ind);
        ZZ = REAL(GET_SLOT(ZZel, Matrix_xSym));
        Di = INTEGER(GET_SLOT(Lel, Matrix_iSym));
        Dp = INTEGER(GET_SLOT(Lel, Matrix_pSym));
        Si = INTEGER(GET_SLOT(ZZel, Matrix_iSym));
        Sp = INTEGER(GET_SLOT(ZZel, Matrix_pSym));
        sz = dims[0] * dims[1];

        AZERO(L, sz * dims[2]); /* zero L  */
        for (j = 0; j < nlev; j++) { /* copy src blocks to dest */
        int kk, k2 = Sp[j + 1];
        for (kk = Sp[j]; kk < k2; kk++) {
            Memcpy(L + check_csc_index(Dp, Di, Si[kk], j, 0) * sz,
               ZZ + kk * sz, sz);
        }
        }
    }
    }
    return R_NilValue;
}

/**
 * Convert the extended parent pair (Parent, Block) to a parent array
 * for the jth diagonal block of size n.
 *
 * @param j index (0-based) of the diagonal outer block
 * @param n number of inner column blocks in the outer block
 * @param par array of length n to be filled with the parent array
 * @param ParP pointer to the extended parent structure
 *
 * @return par
 */
static R_INLINE
int *block_parent(int j, int n, int par[], SEXP ParP)
{
    SEXP Parj = VECTOR_ELT(ParP, j);
    int *Parent = INTEGER(VECTOR_ELT(Parj, 0)),
    *Block = INTEGER(VECTOR_ELT(Parj, 1)), i;
    for (i = 0; i < n; i++) par[i] = (Block[i] == j) ? Parent[i] : -1;
    return par;
}

/**
 * If status[["factored"]] is FALSE, create and factor Z'Z+Omega.  Also
 * create RZX and RXX, the deviance components, and the value of the
 * deviance for both ML and REML.
 *
 * @param x pointer to an lmer object
 *
 * @return NULL
 */
SEXP lmer_factor(SEXP x)
{
    int *status = LOGICAL(GET_SLOT(x, Matrix_statusSym));

    if (!status[0]) {
    SEXP DP = GET_SLOT(x, Matrix_DSym),
        LP = GET_SLOT(x, Matrix_LSym),
        RZXP = GET_SLOT(x, Matrix_RZXSym),
        ZZOP = GET_SLOT(x, Matrix_ZZpOSym),
        Parent = GET_SLOT(x, Matrix_ParentSym);
    int *dims = INTEGER(getAttrib(RZXP, R_DimSymbol)),
        *nc = INTEGER(GET_SLOT(x, Matrix_ncSym)),
        *Gp = INTEGER(GET_SLOT(x, Matrix_GpSym)),
        i, j, nf = length(DP);
    int nml = nc[nf + 1], nreml = nml + 1 - nc[nf];
    double
        *RXX = REAL(GET_SLOT(x, Matrix_RXXSym)),
        *RZX = REAL(RZXP),
        *dcmp = REAL(GET_SLOT(x, Matrix_devCompSym)),
        *deviance = REAL(GET_SLOT(x, Matrix_devianceSym)),
        minus1 = -1., one = 1.;


    dcmp[0] = dcmp[1] = dcmp[2] = dcmp[3] = 0.;
    Memcpy(RZX, REAL(GET_SLOT(x, Matrix_ZtXSym)), dims[0] * dims[1]);
    lmer_inflate(x);    /* initialize ZZpO and L */
    for (i = 0; i < nf; i++) {
        SEXP ZZOiP = VECTOR_ELT(ZZOP, i);
        SEXP DiP = VECTOR_ELT(DP, i);
        SEXP LiP = VECTOR_ELT(LP, Lind(i, i));
        int nlev = INTEGER(getAttrib(DiP, R_DimSymbol))[2];
        int jj, nci = nc[i], ncisqr = nci * nci;
        int *Pari = block_parent(i, nlev, Calloc(nlev, int), Parent);
        double *D = REAL(DiP);

        jj = cscb_ldl(ZZOiP, Pari, LiP, DiP);
        if (jj != nlev) error(_("cscb_ldl returned %d < nlev = %d"), jj, nlev);
        for (j = 0; j < nlev; j++) { /* accumulate dcmp[0] */
        double *Dj = D + j * ncisqr;
        for (jj = 0; jj < nci; jj++) /* accumulate determinant */
            dcmp[0] += 2. * log(Dj[jj * (nci + 1)]);
        }
        /* Solve L_{i,i} %*% RZX_i := RZX_i */
        cscb_trsm(LOW, NTR, UNT, 1., LiP,
              Gp[i+1] - Gp[i], dims[1], RZX + Gp[i], dims[0]);
        /* Solve D_i^{T/2} %*% RZX_i := RZX_i */
        for (jj = 0; jj < nlev; jj++) {
        F77_CALL(dtrsm)("L", "U", "T", "N", &nci, &dims[1],
                &one, D + jj * ncisqr, &nci,
                RZX + Gp[i] + jj * nci, dims);
        }
        for (j = i + 1; j < nf; j++) { /*  further blocks */
        SEXP Lji = VECTOR_ELT(LP, Lind(j, i));
        SEXP Lx = GET_SLOT(Lji, Matrix_xSym);
        double *L = REAL(Lx);
        int *xdims = INTEGER(getAttrib(Lx, R_DimSymbol)),
            *Lp = INTEGER(GET_SLOT(Lji, Matrix_pSym));
        int ntot = xdims[0] * xdims[1];

        /* L_{j,i} := L_{j,i} %*% L_{i,i}^{-T} %*% D_i^{-1/2} */
        cscb_trcbsm(RGT, LOW, TRN, UNT, 1.0, LiP, Pari, Lji);
        for (jj = 0; jj < nlev; jj++) {
            int k, k2 = Lp[jj + 1];
            for (k = Lp[jj]; k < k2; k++)
            F77_CALL(dtrsm)("R", "U", "N", "N", xdims, xdims + 1,
                    &one, D + jj * ncisqr, &nci,
                    L + k * ntot, xdims);
        }
        /* RZX_j := RZX_j - (L_{j,i} %*% D_i^{T/2}) %*% RZX_i */
        /* At this point Lji contains L_{j,i} %*% D_i^{T/2} */
        cscb_mm(LFT, NTR, Gp[j + 1] - Gp[j], dims[1], Gp[i+1] - Gp[i],
            -1.0, Lji, RZX + Gp[i], dims[0],
            1.0, RZX + Gp[j], dims[0]);
        }
        for (j = i + 1; j < nf; j++) { /* block pairs and final update */
        SEXP Lji = VECTOR_ELT(LP, Lind(j, i));
        SEXP Lx = GET_SLOT(Lji, Matrix_xSym);
        double *L = REAL(Lx);
        int *xdims = INTEGER(getAttrib(Lx, R_DimSymbol)),
            *Lp = INTEGER(GET_SLOT(Lji, Matrix_pSym));
        int ntot = xdims[0] * xdims[1];


        /* ZZpO_{j,j} := ZZpO_{j,j} - L{j,i} %*% L_{j,i}^T */
        cscb_syrk(UPP, NTR, -1.0, Lji, 1.0, VECTOR_ELT(ZZOP, j));
        for (jj = j+1; jj < nf; jj++) {
            /* L_{jj,j} := L_{jj,j} - L{jj,i} %*% L_{j,i}^T */
            cscb_cscbm(NTR, TRN, -1.0, VECTOR_ELT(LP, Lind(jj, i)),
                Lji, 1.0, VECTOR_ELT(LP, Lind(jj, j)));
        }
        /* L_{j,i} := L_{j,i} %*% D_i^{-T/2} */
        for (jj = 0; jj < nlev; jj++) {
            int k, k2 = Lp[jj + 1];
            for (k = Lp[jj]; k < k2; k++)
            F77_CALL(dtrsm)("R", "U", "T", "N", xdims, xdims + 1,
                    &one, D + jj * ncisqr, &nci,
                    L + k * ntot, xdims);
        }
        }
        Free(Pari);
    }
                /* downdate and factor XtX */
    Memcpy(RXX, REAL(GET_SLOT(x, Matrix_XtXSym)), dims[1] * dims[1]);
    F77_CALL(dsyrk)("U", "T", dims + 1, dims,
            &minus1, RZX, dims, &one, RXX, dims + 1);
    F77_CALL(dpotrf)("U", dims + 1, RXX, dims + 1, &j);
    if (j) {
        warning("Leading minor of size %d of downdated X'X is indefinite",
            j);
        dcmp[2] = dcmp[3] = deviance[0] = deviance[1] = NA_REAL;
    } else {
        for (j = 0; j < (dims[1] - 1); j++) /* 2 logDet(RXX) */
        dcmp[2] += 2 * log(RXX[j * (dims[1] + 1)]);
        dcmp[3] = 2. * log(RXX[dims[1] * dims[1] - 1]); /* 2 log(ryy) */
        deviance[0] =   /* ML criterion */
        dcmp[0] - dcmp[1] + nml*(1.+dcmp[3]+log(2.*PI/nml));
        deviance[1] = dcmp[0] - dcmp[1] + /* REML */
        dcmp[2] + nreml*(1.+dcmp[3]+log(2.*PI/nreml));
    }
    status[0] = 1; status[1] = 0; /* factored but not inverted */
    }
    return R_NilValue;
}

/**
 * Solve one of the matrix equations op(L)*X=alpha*B or
 * X*op(L)=alpha*B where L is a sparse, blocked, unit lower triangular matrix.
 *
 * @param side LFT or RGT for left or right
 * @param trans TRN or NTR for transpose or no transpose
 * @param nf number of grouping factors
 * @param Gp group pointers for the rows
 * @param n number of columns
 * @param alpha multiplier
 * @param L pointer to the L cscb object
 * @param B pointer to the matrix of right-hand sides
 * @param ldb leading dimension of array B as declared in the caller
 */
static void
lmer_sm(enum CBLAS_SIDE side, enum CBLAS_TRANSPOSE trans, int nf, const int Gp[],
    int n, double alpha, SEXP L, double B[], int ldb)
{
    int j, k;

    if (side == LFT) {
    if (trans == TRN) {
        for (j = nf - 1; j >= 0; j--) {
        int nrj = Gp[j + 1] - Gp[j];

        cscb_trsm(LOW, TRN, UNT, alpha, VECTOR_ELT(L, Lind(j, j)),
              nrj, n, B + Gp[j], ldb);
        for (k = 0; k < j; k++) {
            cscb_mm(LFT, TRN, Gp[k + 1] - Gp[k], n, nrj,
                -1., VECTOR_ELT(L, Lind(j, k)),
                B + Gp[j], ldb, alpha, B + Gp[k], ldb);
        }
        }
    } else error(_("Code for non-transpose case not yet written"));
    } else error(_("Code for right-side solutions not yet written"));
}

static 
int max_nnz(int j, SEXP Parent)
{
    SEXP lst = VECTOR_ELT(Parent, j);
    SEXP blk = VECTOR_ELT(lst, 1), par = VECTOR_ELT(lst, 0);
    int i, ncj = length(blk), val;
    int *nnz = Calloc(ncj, int);

    for (val = -1, i = ncj - 1; i >= 0; i--) {
        int thisnnz = (INTEGER(blk)[i] != j) ? 0 : nnz[INTEGER(par)[j]] + 1;
    if (thisnnz > val) val = thisnnz;
    nnz[i] = thisnnz;
    }
    return val;
}

#define BLK(i,j) INTEGER(VECTOR_ELT(VECTOR_ELT(Parent, i), 1))[j]
#define PAR(i,j) INTEGER(VECTOR_ELT(VECTOR_ELT(Parent, i), 0))[j]

/**
 * Fill the nnz array with the number of nonzero inner blocks in each
 * outer block of the jth inner column block of the ith outer block of
 * L^{-1}.  Also allocate the tmp and ind arrays and fill the ind array.
 *
 * @param i outer block index
 * @param j inner block index within the ith outer block
 * @param nf number of factors
 * @param Parent pointer to the extended parent pairs
 * @param nc
 * @param nnz array of length nf
 * @param tmp array of length nf of pointers to doubles
 * @param ind array of length nf of pointers to ints
 *
 */
static
void fill_nnz(int i, int j, int nf, SEXP Parent, const int nc[],
       int nnz[], double *tmp[], int *ind[])
{
    int *ik = Calloc(nf, int), blk, k, par;

    AZERO(nnz, nf);
    for (blk = BLK(i,j), par = PAR(i,j); blk >= 0;
     k = BLK(blk,par), par = PAR(blk,par), blk = k) nnz[blk]++;
    for (k = 0; k < nf; k++) {
    if (nnz[k]) {
        int sz = nc[i] * nc[k];
        tmp[k] = Calloc(sz * nnz[k], double);
        AZERO(tmp[k], sz * nnz[k]);
        ind[k] = Calloc(nnz[k], int);
    } else {
        tmp[k] = (double *) NULL;
        ind[k] = (int *) NULL;
    }
    }
    AZERO(ik, nf);
    for (blk = BLK(i,j), par = PAR(i,j); blk >= 0;
     k = BLK(blk,par), par = PAR(blk,par), blk = k) {
    ind[blk][ik[blk]++] = par;
    }
    Free(ik);
}

static R_INLINE
int fsrch(int target, const int vals[], int nvals)
{
    int i;
    for (i = 0; i < nvals; i++) if (vals[i] == target) return i;
    error(_("fsrch: unable to find target %d in nvals %d "), target, nvals);
    return -1;          /* -Wall */
}

/**
 * If necessary, factor Z'Z+Omega, ZtX, and XtX then, if necessary,
 * replace the RZX and RXX slots by the corresponding parts of the
 * inverse of the Cholesky factor.  Replace the elements of the D slot
 * by the blockwise inverses and evaluate bVar.
 *
 * @param x pointer to an lmer object
 *
 * @return NULL (x is updated in place)
 */
SEXP lmer_invert(SEXP x)
{
    int *status = LOGICAL(GET_SLOT(x, Matrix_statusSym));
    if (!status[0]) lmer_factor(x);
    if (!R_FINITE(REAL(GET_SLOT(x, Matrix_devianceSym))[0]))
    error(_("Unable to invert singular factor of downdated X'X"));
    if (!status[1]) {
    SEXP DP = GET_SLOT(x, Matrix_DSym),
        LP = GET_SLOT(x, Matrix_LSym),
        ParP = GET_SLOT(x, Matrix_ParentSym),
        RZXP = GET_SLOT(x, Matrix_RZXSym),
        bVarP = GET_SLOT(x, Matrix_bVarSym);
    int *Gp = INTEGER(GET_SLOT(x, Matrix_GpSym)),
        *dims = INTEGER(getAttrib(RZXP, R_DimSymbol)),
        *nc = INTEGER(GET_SLOT(x, Matrix_ncSym)),
        i, nf = length(DP);
    int **ind = Calloc(nf, int *),
        *nnz = Calloc(nf, int);
    double **tmp = Calloc(nf, double *),
        *RXX = REAL(GET_SLOT(x, Matrix_RXXSym)),
        *RZX = REAL(RZXP),
        minus1 = -1., one = 1., zero = 0.;

    /* RXX := RXX^{-1} */
    F77_CALL(dtrtri)("U", "N", dims + 1, RXX, dims + 1, &i);
    if (i)
        error(_("Leading minor of size %d of downdated X'X,is indefinite"),
            i + 1);

    /* RZX := - RZX %*% RXX */
    F77_CALL(dtrmm)("R", "U", "N", "N", dims, dims + 1, &minus1,
            RXX, dims + 1, RZX, dims);
    for(i = 0; i < nf; i++) {
        int info, j, jj, nci = nc[i];
        int ncisqr = nci * nci, nlev = (Gp[i+1] - Gp[i])/nci;
        double *Di = REAL(VECTOR_ELT(DP, i)),
        *RZXi = RZX + Gp[i];

        /* D_i := D_i^{-1}; RZX_i := D_i %*% RZX_i */
        if (nci == 1) {
        for (j = 0; j < nlev; j++) {
            Di[j] = 1./Di[j];
            for (jj = 0; jj < dims[1]; jj++)
            RZXi[j + jj * dims[0]] *= Di[j];
        }
        } else {
        for (j = 0; j < nlev; j++) {
            F77_CALL(dtrtri)("U", "N", &nci, Di + j * ncisqr, &nci, &info);
            if (info)
            error(_("D[,,%d] for factor %d is singular"), j + 1, i + 1);
            F77_CALL(dtrmm)("L", "U", "N", "N", &nci, dims + 1, &one,
                    Di + j * ncisqr, &nci, RZXi + j * nci, dims);
        }
        }
    }

    /* RZX := L^{-T} %*% RZX */
    lmer_sm(LFT, TRN, nf, Gp, dims[1], 1.0, LP, RZX, dims[0]);

    /* Create bVar arrays as crossprod of column blocks of D^{-T/2}%*%L^{-1} */
    for (i = 0; i < nf; i++) {
        int j, k, kj, nci = nc[i];
        int ncisqr = nci * nci, nlev = (Gp[i+1] - Gp[i])/nci;
        double *Di = REAL(VECTOR_ELT(DP, i)), *bVi = REAL(VECTOR_ELT(bVarP, i));

        AZERO(bVi, nlev * ncisqr); /* zero the accumulator */
        for (j = 0; j < nlev; j++) {
        double *bVij = bVi + j * ncisqr, *Dij = Di + j * ncisqr;

        F77_CALL(dsyrk)("U", "N", &nci, &nci, &one, Dij, &nci, &zero, bVij, &nci);
                /* count non-zero blocks; allocate and zero storage */
        fill_nnz(i, j, nf, ParP, nc, nnz, tmp, ind);
                /* kth row of outer blocks */
        for (k = i; k < nf; k++) {
            SEXP Lki = VECTOR_ELT(LP, Lind(k, i));
            int *Lkii = INTEGER(GET_SLOT(Lki, Matrix_iSym)),
            *Lkip = INTEGER(GET_SLOT(Lki, Matrix_pSym));
            double *Lkix = REAL(GET_SLOT(Lki, Matrix_xSym));
            int kk, sz = nc[i] * nc[k];

                /* initialize tmp from jth column of (k,i)th block */
                /* - sign in sol'n incorporated in dtrmm call below */
            for (kk = Lkip[j]; kk < Lkip[j + 1]; kk++)
            Memcpy(tmp[k] + fsrch(Lkii[kk], ind[k], nnz[k]) * sz,
                   Lkix + kk * sz, sz);
                /* columns in ind[kk] for (k,kk)th block */
            for (kk = i; kk <= k; kk++) {
            int szk = nc[k] * nc[kk];

            if (!nnz[kk]) continue; /* skip getting slots if not using them */
            Lki = VECTOR_ELT(LP, Lind(k, kk));
            Lkii = INTEGER(GET_SLOT(Lki, Matrix_iSym));
            Lkip = INTEGER(GET_SLOT(Lki, Matrix_pSym));
            Lkix = REAL(GET_SLOT(Lki, Matrix_xSym));
            for (kj = 0; kj < nnz[kk]; kj++) {
                int col = ind[kk][kj], k1;

                for (k1 = Lkip[col]; k1 < Lkip[col + 1]; k1++) {
                if ((kk == k) && col >= Lkii[k1]) break;
                F77_CALL(dgemm)("N", "N", nc+k, &nci, nc+kk,
                        &minus1, Lkix + k1 * szk, nc + k,
                        tmp[kk] + kj * szk, nc+k, &one,
                        tmp[k]+fsrch(Lkii[k1],ind[k],nnz[k])*sz,
                        nc + k);
                }
            }
            }
        }
        for (k = 0; k < nf; k++) {
            for (kj = 0; kj < nnz[k]; kj++) {
            F77_CALL(dtrmm)("L", "U", "T", "N", nc + k, &nci, &minus1,
                    REAL(VECTOR_ELT(DP, k))+ind[k][kj]*nc[k]*nc[k],
                    nc + k, tmp[k] + kj * nc[i] * nc[k], nc + k);
            }
            if (nnz[k] > 0) {
            kj = nc[k] * nnz[k];
            F77_CALL(dsyrk)("U", "T", &nci, &kj, &one, tmp[k], &kj,
                    &one, bVij, &nci);
            }
        }
        }
        for (k = 0; k < nf; k++) {
        if (tmp[k]) Free(tmp[k]);
        if (ind[k]) Free(ind[k]);
        }
    }
    Free(tmp); Free(nnz); Free(ind);
    }
    status[1] = 1;
    return R_NilValue;
}

/**
 * Extract the ML or REML conditional estimate of sigma
 *
 * @param x pointer to an lme object
 * @param REML logical scalar - TRUE if REML estimates are requested
 *
 * @return pointer to a numeric scalar
 */
SEXP lmer_sigma(SEXP x, SEXP REML)
{
    SEXP RXXsl = GET_SLOT(x, Matrix_RXXSym);
    int pp1 = INTEGER(getAttrib(RXXsl, R_DimSymbol))[1],
    nobs = INTEGER(GET_SLOT(x, Matrix_ncSym))
    [length(GET_SLOT(x, Matrix_OmegaSym)) + 1];

    lmer_invert(x);
    return ScalarReal(1./(REAL(RXXsl)[pp1*pp1 - 1] *
              sqrt((double)(asLogical(REML) ?
                    nobs + 1 - pp1 : nobs))));
}

/**
 * Extract the upper triangles of the Omega matrices.  These aren't
 * "coefficients" but the extractor is called coef for historical
 * reasons.  Within each group these values are in the order of the
 * diagonal entries first then the strict upper triangle in row
 * order.
 *
 * @param x pointer to an lme object
 * @param Unc pointer to a logical scalar indicating if the parameters
 * are in the unconstrained form.
 *
 * @return numeric vector of the values in the upper triangles of the
 * Omega matrices
 */
SEXP lmer_coef(SEXP x, SEXP Unc)
{
    SEXP Omega = GET_SLOT(x, Matrix_OmegaSym);
    int *nc = INTEGER(GET_SLOT(x, Matrix_ncSym)),
    i, nf = length(Omega), unc = asLogical(Unc), vind;
    SEXP val = PROTECT(allocVector(REALSXP, coef_length(nf, nc)));
    double *vv = REAL(val);

    vind = 0;           /* index in vv */
    for (i = 0; i < nf; i++) {
    int nci = nc[i], ncip1 = nci + 1;
    if (nci == 1) {
        vv[vind++] = (unc ?
              log(REAL(VECTOR_ELT(Omega, i))[0]) :
              REAL(VECTOR_ELT(Omega, i))[0]);
    } else {
        if (unc) {      /* L log(D) L' factor of Omega[,,i] */
        int j, k, ncisq = nci * nci;
        double *tmp = Memcpy(Calloc(ncisq, double),
                     REAL(VECTOR_ELT(Omega, i)), ncisq);
        F77_CALL(dpotrf)("U", &nci, tmp, &nci, &j);
        if (j)      /* should never happen */
            error(_("DPOTRF returned error code %d on Omega[[%d]]"),
              j, i+1);
        for (j = 0; j < nci; j++) {
            double diagj = tmp[j * ncip1];
            vv[vind++] = 2. * log(diagj);
            for (k = j + 1; k < nci; k++) {
            tmp[j + k * nci] /= diagj;
            }
        }
        for (j = 0; j < nci; j++) {
            for (k = j + 1; k < nci; k++) {
            vv[vind++] = tmp[j + k * nci];
            }
        }
        Free(tmp);
        } else {        /* upper triangle of Omega[,,i] */
        int j, k, odind = vind + nci;
        double *omgi = REAL(VECTOR_ELT(Omega, i));

        for (j = 0; j < nci; j++) {
            vv[vind++] = omgi[j * ncip1];
            for (k = j + 1; k < nci; k++) {
            vv[odind++] = omgi[k*nci + j];
            }
        }
        vind = odind;
        }
    }
    }
    UNPROTECT(1);
    return val;
}


/**
 * Assign the upper triangles of the Omega matrices.
 * (Called coef for historical reasons.)
 *
 * @param x pointer to an lme object
 * @param coef pointer to an numeric vector of appropriate length
 * @param Unc pointer to a logical scalar indicating if the parameters
 * are in the unconstrained form.
 *
 * @return R_NilValue
 */
SEXP lmer_coefGets(SEXP x, SEXP coef, SEXP Unc)
{
    SEXP Omega = GET_SLOT(x, Matrix_OmegaSym);
    int *nc = INTEGER(GET_SLOT(x, Matrix_ncSym)),
    *status = LOGICAL(GET_SLOT(x, Matrix_statusSym)),
    cind, i, nf = length(Omega),
    unc = asLogical(Unc);
    double *cc = REAL(coef);

    if (length(coef) != coef_length(nf, nc) || !isReal(coef))
    error(_("coef must be a numeric vector of length %d"),
          coef_length(nf, nc));
    cind = 0;
    for (i = 0; i < nf; i++) {
    int nci = nc[i];
    if (nci == 1) {
        REAL(VECTOR_ELT(Omega, i))[0] = (unc ?
                         exp(cc[cind++]) :
                         cc[cind++]);
    } else {
        int odind = cind + nci, /* off-diagonal index */
        j, k,
        ncip1 = nci + 1,
        ncisq = nci * nci;
        double
        *omgi = REAL(VECTOR_ELT(Omega, i));
        if (unc) {
        double
            *tmp = Calloc(ncisq, double),
            diagj, one = 1., zero = 0.;

        AZERO(omgi, ncisq);
        for (j = 0; j < nci; j++) {
            tmp[j * ncip1] = diagj = exp(cc[cind++]/2.);
            for (k = j + 1; k < nci; k++) {
            tmp[k*nci + j] = cc[odind++] * diagj;
            }
        }
        F77_CALL(dsyrk)("U", "T", &nci, &nci, &one,
                tmp, &nci, &zero, omgi, &nci);
        Free(tmp);
        } else {
        for (j = 0; j < nci; j++) {
            omgi[j * ncip1] = cc[cind++];
            for (k = j + 1; k < nci; k++) {
            omgi[k*nci + j] = cc[odind++];
            }
        }
        }
        cind = odind;
    }
    }
    status[0] = status[1] = 0;
    return x;
}

/**
 * Extract the conditional estimates of the fixed effects
 *
 * @param x Pointer to an lme object
 *
 * @return a numeric vector containing the conditional estimates of
 * the fixed effects
 */
SEXP lmer_fixef(SEXP x)
{
    SEXP RXXsl = GET_SLOT(x, Matrix_RXXSym),
    cnames = GET_SLOT(x, Matrix_cnamesSym);
    int j, pp1 = INTEGER(getAttrib(RXXsl, R_DimSymbol))[1];
    SEXP val = PROTECT(allocVector(REALSXP, pp1));
    double
    *beta = REAL(val),
    nryyinv;        /* negative ryy-inverse */

    lmer_invert(x);
    Memcpy(beta, REAL(RXXsl) + pp1 * (pp1 - 1), pp1);
    nryyinv = -REAL(RXXsl)[pp1*pp1 - 1];
    for (j = 0; j < pp1; j++) beta[j] /= nryyinv;
    setAttrib(val, R_NamesSymbol,
          duplicate(VECTOR_ELT(cnames, length(cnames) - 1)));
    UNPROTECT(1);
    return val;
}

/**
 * Extract the conditional modes of the random effects.
 *
 * @param x Pointer to an lme object
 *
 * @return a vector containing the conditional modes of the random effects
 */
SEXP lmer_ranef(SEXP x)
{
    SEXP RZXP = GET_SLOT(x, Matrix_RZXSym),
    cnames = GET_SLOT(x, Matrix_cnamesSym),
    flist = GET_SLOT(x, Matrix_flistSym);
    int *Gp = INTEGER(GET_SLOT(x, Matrix_GpSym)),
    *dims = INTEGER(getAttrib(RZXP, R_DimSymbol)),
    *nc = INTEGER(GET_SLOT(x, Matrix_ncSym)),
    i, ii, jj,
    nf = length(flist);
    SEXP val = PROTECT(allocVector(VECSXP, nf));
    double
    *b = REAL(RZXP) + dims[0] * (dims[1] - 1),
    nryyinv;        /* negative ryy-inverse */

    lmer_invert(x);
    setAttrib(val, R_NamesSymbol,
          duplicate(getAttrib(flist, R_NamesSymbol)));
    nryyinv = -REAL(GET_SLOT(x, Matrix_RXXSym))[dims[1] * dims[1] - 1];
    for (i = 0; i < nf; i++) {
    SEXP nms, rnms = getAttrib(VECTOR_ELT(flist, i), R_LevelsSymbol);
    int nci = nc[i], mi = length(rnms);
    double *bi = b + Gp[i], *mm;

    SET_VECTOR_ELT(val, i, allocMatrix(REALSXP, mi, nci));
    setAttrib(VECTOR_ELT(val, i), R_DimNamesSymbol, allocVector(VECSXP, 2));
    nms = getAttrib(VECTOR_ELT(val, i), R_DimNamesSymbol);
    SET_VECTOR_ELT(nms, 0, duplicate(rnms));
    SET_VECTOR_ELT(nms, 1, duplicate(VECTOR_ELT(cnames, i)));
    mm = REAL(VECTOR_ELT(val, i));
    for (jj = 0; jj < nci; jj++)
        for(ii = 0; ii < mi; ii++)
        mm[ii + jj * mi] = bi[jj + ii * nci]/nryyinv;
    }
    UNPROTECT(1);
    return val;
}

/**
 * Fill in four symmetric matrices for each level, providing the
 * information to generate the gradient or the ECME step.  The four
 * matrices are
 *  1) -m_i\bOmega_i^{-1}
 *  2) \bB_i\bB_i\trans
 *  3) \tr\left[\der_{\bOmega_i}\bOmega\left(\bZ\trans\bZ+\bOmega\right)\inv\right]
 *  4) The term added to 3) to get \tr\left[\der_{\bOmega_i}\bOmega\vb\right]
 *
 * @param x pointer to an lme object
 * @param val pointer to a list of matrices of the correct sizes
 *
 * @return val
 */
/* static */
SEXP lmer_firstDer(SEXP x, SEXP val)
{
    SEXP bVarP = GET_SLOT(x, Matrix_bVarSym),
    OmegaP = GET_SLOT(x, Matrix_OmegaSym),
    RZXP = GET_SLOT(x, Matrix_RZXSym);
    int *dims = INTEGER(getAttrib(RZXP, R_DimSymbol)),
    *Gp = INTEGER(GET_SLOT(x, Matrix_GpSym)),
    i, nf = length(OmegaP), p = dims[1] - 1;
    double *RZX = REAL(RZXP),
    *b = REAL(RZXP) + dims[0] * p;

    lmer_invert(x);
    /* FIXME: Why is this loop run backwards?  It appears it could run forwards. */
    for (i = nf - 1; i >= 0; i--) {
    SEXP bVPi = VECTOR_ELT(bVarP, i);
    int *ddims = INTEGER(getAttrib(bVPi, R_DimSymbol)), j, k;
    int nci = ddims[0];
    int ncisqr = nci * nci, RZXrows = Gp[i + 1] - Gp[i];
    int nlev = RZXrows/nci;
    double *RZXi = RZX + Gp[i], *bVi = REAL(bVPi),
        *bi = b + Gp[i], *mm = REAL(VECTOR_ELT(val, i)),
        *tmp = Memcpy(Calloc(ncisqr, double),
              REAL(VECTOR_ELT(OmegaP, i)), ncisqr),
        dlev = (double) nlev,
        one = 1., zero = 0.;

    if (nci == 1) {
        int ione = 1;
        mm[0] = ((double) nlev)/tmp[0];
        mm[1] = F77_CALL(ddot)(&nlev, bi, &ione, bi, &ione);
        mm[2] = 0.;
        for (k = 0; k < nlev; k++) mm[2] += bVi[k];
        mm[3] = 0.;
        for (j = 0; j < p; j++) {
        mm[3] += F77_CALL(ddot)(&RZXrows, RZXi + j * dims[0], &ione,
                    RZXi + j * dims[0], &ione);
        }
    } else {
        AZERO(mm, 4 * ncisqr);
        F77_CALL(dpotrf)("U", &nci, tmp, &nci, &j);
        if (j)
        error(_("Omega[[%d]] is not positive definite"), i + 1);
        F77_CALL(dtrtri)("U", "N", &nci, tmp, &nci, &j);
        if (j)
        error(_("Omega[[%d]] is not positive definite"), i + 1);
        F77_CALL(dsyrk)("U", "N", &nci, &nci, &dlev, tmp, &nci,
                &zero, mm, &nci);
        mm += ncisqr;   /* \bB_i term */
        F77_CALL(dsyrk)("U", "N", &nci, &nlev, &one, bi, &nci,
                &zero, mm, &nci);
        mm += ncisqr;     /* Sum of diagonal blocks of the inverse
                   * (Z'Z+Omega)^{-1} */
        for (j = 0; j < ncisqr; j++) {
        for (k = 0; k < nlev; k++) mm[j] += bVi[j + k*ncisqr];
        }
        mm += ncisqr;   /* Extra term for \vb */
        for (j = 0; j < p; j++) {
        F77_CALL(dsyrk)("U", "N", &nci, &nlev, &one,
                RZXi + j * dims[0], &nci,
                &one, mm, &nci);
        }
    }
    Free(tmp);
    }
    return val;
}

/**
 * Return a length nf list of arrays of dimension (nci, nci, 4).  The
 * values of these arrays are assigned in lmer_firstDer.
 *
 * @param nf number of factors
 * @param nc vector of number of columns per factor
 *
 * @return pointer to a list of REAL arrays
 */
static
SEXP EM_grad_array(int nf, const int nc[])
{
    SEXP val = PROTECT(allocVector(VECSXP, nf));
    int i;

    for (i = 0; i < nf; i++) {
    SET_VECTOR_ELT(val, i, alloc3Darray(REALSXP, nc[i], nc[i], 4));
    }
    UNPROTECT(1);
    return val;
}

/**
 * Fill in the 4-dimensional vector of linear combinations of the
 * firstDer array according to whether ECME steps or the gradient are
 * needed and to whether or not REML is being used.
 *
 * @param cc coefficient vector to be filled in
 * @param EM non-zero for ECME steps, zero for gradient
 * @param REML non-zero for REML, zero for ML
 * @param ns ns[0] is p+1, ns[1] is n
 *
 * @return cc with the coefficients filled in
 */
static
double *EM_grad_lc(double *cc, int EM, int REML, int ns[])
{
    cc[0] = EM ? 0. : -1.;
    cc[1] = (double)(ns[1] - (REML ? ns[0] - 1 : 0));
    cc[2] = 1.;
    cc[3] = REML ? 1. : 0.;
    return cc;
}


/**
 * Print the verbose output in the ECME iterations
 *
 * @param x pointer to an ssclme object
 * @param iter iteration number
 * @param REML non-zero for REML, zero for ML
 * @param firstDer arrays for calculating ECME steps and the first derivative
 * @param val Pointer to a list of arrays to receive the calculated values
 */
static
void EMsteps_verbose_print(SEXP x, int iter, int REML, SEXP firstDer, SEXP val)
{
    SEXP Omega = GET_SLOT(x, Matrix_OmegaSym),
    pMat = VECTOR_ELT(val, 2);
    int *nc = INTEGER(GET_SLOT(x, Matrix_ncSym)),
    *Its = INTEGER(VECTOR_ELT(val, 0)),
    i, ifour = 4, ii, ione = 1, jj, nf = length(Omega),
    niter = INTEGER(getAttrib(pMat, R_DimSymbol))[0];
    double
    *dev = REAL(GET_SLOT(x, Matrix_devianceSym)),
    *cc = EM_grad_lc(Calloc(4, double), 0, REML, nc + nf),
    *Devs = REAL(VECTOR_ELT(val, 1)),
    *pars = REAL(pMat) + iter,
    *grds = REAL(VECTOR_ELT(val, 3)) + iter,
    one = 1., zero = 0.;

    lmer_factor(x);
    if (iter == 0) Rprintf("  EM iterations\n");
    Rprintf("%3d %.3f", Its[iter] = iter, Devs[iter] = dev[REML ? 1 : 0]);
    for (i = 0; i < nf; i++) {
    int nci = nc[i], ncip1 = nci + 1, ncisqr = nci * nci;
    double
        *Omgi = REAL(VECTOR_ELT(Omega, i)),
        *Grad = Calloc(ncisqr, double);

                /* diagonals */
    Rprintf(" (%#8g", *pars = Omgi[0]);
    pars += niter;
    for (jj = 1; jj < nci; jj++, pars += niter) {
        Rprintf(" %#8g", *pars = Omgi[jj * ncip1]);
    }
    for (jj = 1; jj < nci; jj++) /* offdiagonals */
        for (ii = 0; ii < jj; ii++, pars += niter)
        Rprintf(" %#8g", *pars = Omgi[ii + jj * nci]);
                /* Evaluate and print the gradient */
    F77_CALL(dgemv)("N", &ncisqr, &ifour, &one,
            REAL(VECTOR_ELT(firstDer, i)), &ncisqr,
            cc, &ione, &zero, Grad, &ione);
    Rprintf(":%#8.3g", *grds = Grad[0]);
    grds += niter;
                /* diagonals */
    for (jj = 1; jj < nci; jj++, grds += niter) {
        Rprintf(" %#8.3g", *grds = Grad[jj * ncip1]);
    }
    for (jj = 1; jj < nci; jj++) /* offdiagonals */
        for (ii = 0; ii < jj; ii++, grds += niter)
        Rprintf(" %#8.3g", *grds = Grad[ii + jj * nci]);
    Rprintf(")");
    Free(Grad);
    }
    Rprintf("\n");
    Free(cc);
}

/**
 * Perform ECME steps for the REML or ML criterion.
 *
 * @param x pointer to an ssclme object
 * @param nsteps pointer to an integer scalar - the number of ECME steps to perform
 * @param REMLp pointer to a logical scalar indicating if REML is to be used
 * @param Verbp pointer to a logical scalar indicating verbose output
 *
 * @return R_NilValue if verb == FALSE, otherwise a list of iteration
 *numbers, deviances, parameters, and gradients.
 */
SEXP lmer_ECMEsteps(SEXP x, SEXP nsteps, SEXP REMLp, SEXP Verbp)
{
    SEXP Omega = GET_SLOT(x, Matrix_OmegaSym),
    flist = GET_SLOT(x, Matrix_flistSym),
    val = R_NilValue;
    int *nc = INTEGER(GET_SLOT(x, Matrix_ncSym)),
    *status = LOGICAL(GET_SLOT(x, Matrix_statusSym)),
    REML = asLogical(REMLp),
    i, ifour = 4, info, ione = 1, iter,
    nEM = asInteger(nsteps),
    nf = length(Omega),
    verb = asLogical(Verbp);
    double
    *cc = EM_grad_lc(Calloc(4, double), 1, REML, nc + nf),
    zero = 0.0;
    SEXP firstDer = PROTECT(EM_grad_array(nf, nc));

    lmer_firstDer(x, firstDer);
    if (verb) {
    int nEMp1 = nEM + 1, npar = coef_length(nf, nc);
    val = PROTECT(allocVector(VECSXP, 4));
    SET_VECTOR_ELT(val, 0, allocVector(INTSXP, nEMp1));
    SET_VECTOR_ELT(val, 1, allocVector(REALSXP, nEMp1));
    SET_VECTOR_ELT(val, 2, allocMatrix(REALSXP, nEMp1, npar));
    SET_VECTOR_ELT(val, 3, allocMatrix(REALSXP, nEMp1, npar));
    EMsteps_verbose_print(x, 0, REML, firstDer, val);
    }
    for (iter = 0; iter < nEM; iter++) {
    for (i = 0; i < nf; i++) {
        int nci = nc[i], ncisqr = nci * nci;
        double *Omgi = REAL(VECTOR_ELT(Omega, i)),
        mult = 1./
        ((double) length(getAttrib(VECTOR_ELT(flist, i),
                 R_LevelsSymbol)));

        F77_CALL(dgemm)("N", "N", &ncisqr, &ione, &ifour, &mult,
                REAL(VECTOR_ELT(firstDer, i)), &ncisqr,
                cc, &ifour, &zero, Omgi, &ncisqr);
        F77_CALL(dpotrf)("U", &nci, Omgi, &nci, &info);
        if (info)
        error(_("DPOTRF in ECME update gave code %d"), info);
        F77_CALL(dpotri)("U", &nci, Omgi, &nci, &info);
        if (info)
        error(_("Matrix inverse in ECME update gave code %d"), info);
    }
    status[0] = status[1] = 0;
    lmer_firstDer(x, firstDer);
    if (verb) EMsteps_verbose_print(x, iter + 1, REML, firstDer, val);
    }
    lmer_factor(x);
    if (verb) UNPROTECT(1);
    UNPROTECT(1);
    return val;
}

SEXP lmer_gradient(SEXP x, SEXP REMLp, SEXP Uncp)
{
    SEXP Omega = GET_SLOT(x, Matrix_OmegaSym);
    int *nc = INTEGER(GET_SLOT(x, Matrix_ncSym)),
    dind, i, ifour = 4, info, ione = 1, nf = length(Omega),
    odind, unc = asLogical(Uncp);
    SEXP
    firstDer = lmer_firstDer(x, PROTECT(EM_grad_array(nf, nc))),
    val = PROTECT(allocVector(REALSXP, coef_length(nf, nc)));
    double
    *cc = EM_grad_lc(Calloc(4, double), 0,
             asInteger(REMLp), nc + nf),
    one = 1.0, zero = 0.0;

    dind = 0;           /* index into val for diagonals */
    for (i = 0; i < nf; i++) {
    int nci = nc[i], ncisqr = nci * nci;
    double
        *Omgi = REAL(VECTOR_ELT(Omega, i)),
        *tmp = Calloc(ncisqr, double);

    F77_CALL(dgemm)("N", "N", &ncisqr, &ione, &ifour, &one,
            REAL(VECTOR_ELT(firstDer, i)), &ncisqr,
            cc, &ifour, &zero, tmp, &ncisqr);
    if (nci == 1) {
        REAL(val)[dind++] = (unc ? Omgi[0] : 1.) * tmp[0];
    } else {
        int ii, j, ncip1 = nci + 1;

        odind = dind + nci; /* index into val for off-diagonals */
        if (unc) {
        double *chol = Memcpy(Calloc(ncisqr, double),
                      REAL(VECTOR_ELT(Omega, i)), ncisqr),
            *tmp2 = Calloc(ncisqr, double);

        /* Overwrite the gradient with respect to positions in
         * Omega[[i]] by the gradient with respect to the
         * unconstrained parameters.*/

        F77_CALL(dpotrf)("U", &nci, chol, &nci, &info);
        if (info)
            error(_("Omega[[%d]] is not positive definite"), i + 1);
        /* tmp2 := chol %*% tmp using only upper triangle of tmp */
        F77_CALL(dsymm)("R", "U", &nci, &nci, &one, tmp, &nci,
                chol, &nci, &zero, tmp2, &nci);
        /* full symmetric product gives diagonals */
        F77_CALL(dtrmm)("R", "U", "T", "N", &nci, &nci, &one, chol, &nci,
                Memcpy(tmp, tmp2, ncisqr), &nci);
        /* overwrite upper triangle with gradients for positions in L' */
        for (ii = 1; ii < nci; ii++) {
            for (j = 0; j < ii; j++) {
            tmp[j + ii*nci] = chol[j*ncip1] * tmp2[j + ii*nci];
            tmp[ii + j*nci] = 0.;
            }
        }
        Free(chol); Free(tmp2);
        }
        for (j = 0; j < nci; j++) {
        REAL(val)[dind + j] = tmp[j * ncip1];
        for (ii = 0; ii < j; ii++) /* offdiagonals count twice */
            REAL(val)[odind++] = 2. * tmp[ii + j * nci];
        }
        dind = odind;
    }
    Free(tmp);
    }
    UNPROTECT(2);
    Free(cc);
    return val;
}

/**
 * Fill in five symmetric matrices, providing the
 * information to generate the Hessian.

 * @param x pointer to an lme object
 * @param Valp ignored at present
 *
 * @return Valp an array consisting of five symmetric faces
 */
static
SEXP lmer_secondDer(SEXP x, SEXP Valp)
{
    SEXP
    D = GET_SLOT(x, Matrix_DSym),
    Omega = GET_SLOT(x, Matrix_OmegaSym),
    RZXP = GET_SLOT(x, Matrix_RZXSym),
    levels = GET_SLOT(x, R_LevelsSymbol),
    val;
    int *dRZX = INTEGER(getAttrib(RZXP, R_DimSymbol)),
    *nc = INTEGER(GET_SLOT(x, Matrix_ncSym)),
    Q, Qsqr, RZXpos, facepos,
    i, ione = 1, j, nf = length(Omega), p = dRZX[1] - 1, pos;
    SEXP
    firstDer = lmer_firstDer(x, PROTECT(EM_grad_array(nf, nc)));
    double
    *RZX = REAL(RZXP),
    *b = REAL(RZXP) + dRZX[0] * p,
    *bbface,        /* vec of second faces of firstDer elts */
    one = 1.,
    zero = 0.;

    Q = 0;          /* number of rows and columns in the result */
    for (i = 0; i < nf; i++) Q += nc[i] * nc[i];
    Qsqr = Q * Q;
    bbface = Calloc(Q, double);
    val = PROTECT(alloc3Darray(REALSXP, Q, Q, 5));
    AZERO(REAL(val), Qsqr * 5);

    pos = 0;
    for (i = 0; i < nf; i++) {
    int nci = nc[i], ncisqr = nci * nci;
    double *fDi = REAL(VECTOR_ELT(firstDer, i)),
        mult = 1./((double) length(VECTOR_ELT(levels, i)));

    Memcpy(bbface + pos, fDi + ncisqr, ncisqr);
    /* outer product of the third face of firstDer on the diagonal
     * of the third face of val */
    F77_CALL(dsyr)("U", &ncisqr, &mult, fDi + 2 * ncisqr, &ione,
               REAL(val) + 2 * Qsqr + pos * Q, &Q);
    pos += ncisqr;
    }
                /* fifth face of val is outer product of bbface */
    F77_CALL(dsyr)("U", &Q, &one, bbface, &ione, REAL(val) + 4 * Qsqr, &Q);
                /* fourth face from \bb\trans\der\vb\der\bb */
    AZERO(REAL(val) + 3 * Qsqr, Qsqr); /* zero accumulator */
    RZXpos = 0;
    facepos = 0;
    for (i = 0; i < nf; i++) {
    int ii, jj, nci = nc[i], ncisqr = nci * nci, nctp = nci * p,
        nlev = length(VECTOR_ELT(levels, i));
    int maxpq = (p > nci) ? p : nci;
    double
        *Di = REAL(VECTOR_ELT(D, i)),
        *arr = Calloc(ncisqr * maxpq, double), /* tmp 3Darray */
        *face = REAL(val) + 3 * Qsqr,
        *mat = Calloc(nci * maxpq, double); /* tmp matrix */

    for (j = 0; j < nlev; j++) {
        F77_CALL(dgemm)("T", "T", &p, &nci, &nci,
                &one, RZX + j * nci, dRZX, Di + j * ncisqr, &nci,
                &zero, mat, &p);
        F77_CALL(dgemm)("N", "N", &nctp, &nci, &ione,
                &one, mat, &nctp, b + j * nci, &ione,
                &zero, arr, &nctp);
        F77_CALL(dsyrk)("U", "T", &ncisqr, &p, &one, arr, &p,
                &one, face + facepos, &Q);
                /* Add the D_{i,j}^{-T/2} term */
        Memcpy(mat, Di + j * ncisqr, ncisqr);
        for (jj = 1; jj < nci; jj++) { /* transpose mat */
        for (ii = 0; ii < jj; ii++) {
            mat[jj + ii * nci] = mat[ii + jj * nci];
            mat[ii + jj * nci] = 0.;
        }
        }
        F77_CALL(dgemm)("N", "N", &ncisqr, &nci, &ione,
                &one, mat, &ncisqr, b + j * nci, &ione,
                &zero, arr, &ncisqr);
        /* FIXME: Next call could be dsyr (it's rank one). */
        F77_CALL(dsyrk)("U", "T", &ncisqr, &nci, &one, arr, &nci,
                &one, face + facepos, &Q);

    }
    RZXpos += nci * nlev;
    facepos += ncisqr;
    Free(arr); Free(mat);
    }
    UNPROTECT(2);
    Free(bbface);
    return val;
}

/**
 * Return the unscaled variances
 *
 * @param x pointer to an lmer object
 *
 * @return a list similar to the Omega list with the unscaled variances
 */
SEXP lmer_variances(SEXP x)
{
    SEXP Omg = PROTECT(duplicate(GET_SLOT(x, Matrix_OmegaSym)));
    int *nc = INTEGER(GET_SLOT(x, Matrix_ncSym)),
    i, nf = length(Omg);

    for (i = 0; i < nf; i++) {
    double *mm = REAL(VECTOR_ELT(Omg, i));
    int j, nci = nc[i];

    F77_CALL(dpotrf)("U", &nci, mm, &nci, &j);
    if (j)          /* shouldn't happen */
        error(_("DPOTRF returned error code %d on Omega[%d]"),
          j, i + 1);
    F77_CALL(dpotri)("U", &nci, mm, &nci, &j);
    if (j)          /* shouldn't happen */
        error(_("DTRTRI returned error code %d on Omega[%d]"),
          j, i + 1);
    nlme_symmetrize(mm, nci);
    }
    UNPROTECT(1);
    return Omg;
}

SEXP lmer_Crosstab(SEXP flist)
{
    SEXP val;
    int i, nf = length(flist), nobs;
    int *nc = Calloc(nf, int);

    if (!(nf > 0 && isNewList(flist)))
    error(_("flist must be a non-empty list"));
    nobs = length(VECTOR_ELT(flist, 0));
    if (nobs < 1) error(_("flist[[0]] must be a non-null factor"));
    for (i = 0; i < nf; i++) {
    SEXP fi = VECTOR_ELT(flist, i);
    if (!(isFactor(fi) && length(fi) == nobs))
        error(_("flist[[%d]] must be a factor of length %d"),
          i + 1, nobs);
    nc[i] = 1;
    }
    val = lmer_crosstab(flist, nobs, nc);
    Free(nc);
    return val;
}

/** 
 * Calculate and return the fitted values.
 * 
 * @param x pointer to an ssclme object
 * @param mmats list of model matrices
 * @param useRf pointer to a logical scalar indicating if the random
 * effects should be used
 * 
 * @return pointer to a numeric array of fitted values
 */
SEXP lmer_fitted(SEXP x, SEXP mmats, SEXP useRf)
{
    SEXP flist = GET_SLOT(x, Matrix_flistSym);
    int *nc = INTEGER(GET_SLOT(x, Matrix_ncSym)), ione = 1,
    nf = length(flist), nobs = length(VECTOR_ELT(flist, 0));
    int p = nc[nf] - 1;
    SEXP val = PROTECT(allocVector(REALSXP, nobs));
    double one = 1.0, zero = 0.0;

    if (p > 0) {
    F77_CALL(dgemm)("N", "N", &nobs, &ione, &p, &one,
            REAL(VECTOR_ELT(mmats, nf)), &nobs,
            REAL(PROTECT(lmer_fixef(x))), &p,
            &zero, REAL(val), &nobs);
    UNPROTECT(1);
    } else {
    AZERO(REAL(val), nobs);
    }
    if (asLogical(useRf)) {
    int i;
    SEXP b = PROTECT(lmer_ranef(x));
    for (i = 0; i < nf; i++) {
        int *ff = INTEGER(VECTOR_ELT(flist, i)), j, nci = nc[i];
        double *bb = REAL(VECTOR_ELT(b, i)),
        *mm = REAL(VECTOR_ELT(mmats, i));
        for (j = 0; j < nobs; ) {
        int nn = 1, lev = ff[j];
        /* check for adjacent rows with same factor level */
        while ((j + nn) < nobs && ff[j + nn] == lev) nn++; 
        F77_CALL(dgemm)("N", "N", &nn, &ione, &nci,
                &one, mm + j, &nobs,
                bb + (lev - 1) * nci, &nci,
                &one, REAL(val) + j, &nobs);
        j += nn;
        }
    }
    UNPROTECT(1);
    }
    UNPROTECT(1);
    return val;
}