####--- All "Ops" group methods for all Matrix classes (incl sparseVector) ------
####         ===   but diagonalMatrix  -> ./diagMatrix.R and  abIndex.R
####                                        ~~~~~~~~~~~~      ~~~~~~~~~

### Note that the "Ops" group consists of
### sub-groups   "Arith", "Compare", and "Logic"
###               -----    -------        -----
### where 'Arith'   :=  '"+"', '"-"', '"*"', '"^"', '"%%"', '"%/%"', '"/"'
###       'Compare' := '"=="', '">"', '"<"', '"!="', '"<="', '">="'
###       'Logic'   :=  '"&"', '"|"'
###		but *not* '"!"' since that has only one argument : >>>>> ./not.R

## cache them [rather in package 'methods' ??]
.ArithGenerics   <- getGroupMembers("Arith")
.CompareGenerics <- getGroupMembers("Compare")
.LogicGenerics   <- getGroupMembers("Logic")

## find them with M-x grep -E 'Method\("(Ops|Compare|Arith|Logic)"' *.R
##                --------

### Design decision for *sparseMatrix*:
### work via Csparse  since Tsparse are not-unique (<-> slots not compatible)

### Dimnames: (partly) via  dimNamesCheck()  [ ./Auxiliaries.R ]

### --  0 -- (not dense *or* sparse) -----------------------------------

##-------- originally from ./Matrix.R --------------------

## Some ``Univariate'' "Arith" (univariate := 2nd argument 'e2' is missing)
setMethod("+", signature(e1 = "Matrix", e2 = "missing"), function(e1,e2) e1)

## "fallback":
setMethod("-", signature(e1 = "Matrix", e2 = "missing"),
	  function(e1, e2) {
	      warning("inefficient method used for \"- e1\"")
	      0-e1
	  })
setMethod("-", signature(e1 = "denseMatrix", e2 = "missing"),
	  function(e1, e2) { e1@x <- -e1@x; e1 })

## "diagonalMatrix" -- only two cases -- easiest to do both
setMethod("-", signature(e1 = "ddiMatrix", e2 = "missing"),
	  function(e1, e2) {
		  if(e1@diag == "U") {
                      e1@x <- rep.int(-1., e1@Dim[1])
                      e1@diag <- "N"
                  }
		  else ## diag == "N" -> using 'x' slot
                      e1@x <- -e1@x
	      e1
	  })
setMethod("-", signature(e1 = "ldiMatrix", e2 = "missing"),
	  function(e1, e2) {
	      d <- e1@Dim
	      new("ddiMatrix", Dim = d, Dimnames = e1@Dimnames, diag = "N",
		  x = if(e1@diag == "U") rep.int(-1, d[1]) else -e1@x)
	  })



## old-style matrices are made into new ones
setMethod("Ops", signature(e1 = "Matrix", e2 = "matrix"),
	  function(e1, e2) callGeneric(e1, Matrix(e2)))

setMethod("Ops", signature(e1 = "matrix", e2 = "Matrix"),
	  function(e1, e2) callGeneric(Matrix(e1), e2))
## Note: things like  callGeneric(Matrix(e1, sparse=is(e2,"sparseMatrix")), e2))
##   may *not* be better: e.g. Matrix(.) can give *diagonal* instead of sparse

##  NULL  should be treated as logical(0) {which often will be coerced to numeric(0)}:
setMethod("Ops", signature(e1 = "Matrix", e2 = "NULL"),
	  function(e1, e2) callGeneric(e1, logical()))
setMethod("Ops", signature(e1 = "NULL", e2 = "Matrix"),
	  function(e1, e2) callGeneric(logical(), e2))

## bail-outs -- on highest possible level, hence "Ops", not "Compare"/"Arith" :
.bail.out.Ops <- function(e1, e2) {
    if(is(e1, "mMatrix") && is(e2, "mMatrix"))
	dimCheck(e1,e2)
    .bail.out.2(.Generic, class(e1), class(e2))
}
setMethod("Ops", signature(e1 = "Matrix", e2 = "ANY"),
	  function(e1, e2) {
	      if(is(e1, "mMatrix") && is(e2, "mMatrix")) dimCheck(e1,e2)
	      if(is.matrix(e2) && identical(e2, as.matrix(e2)) &&
		 is.object(e2) && !isS4(e2)) # e.g. for "table"
		  callGeneric(e1, unclass(e2))
	      else
		  .bail.out.2(.Generic, class(e1), class(e2))
	  })
setMethod("Ops", signature(e1 = "ANY", e2 = "Matrix"),
	  function(e1, e2) {
	      if(is(e1, "mMatrix") && is(e2, "mMatrix")) dimCheck(e1,e2)
	      if(is.matrix(e1) && identical(e1, as.matrix(e1)) &&
		 is.object(e1) && !isS4(e1)) # e.g. for "table"
		  callGeneric(unclass(e1), e2)
	      else
		  .bail.out.2(.Generic, class(e1), class(e2))
	  })
rm(.bail.out.Ops)

## "General principle"
##  - - - - - - - - -
## For "Arith" it is sufficient (though not optimal, once we have "iMatrix"!)
## to define "dMatrix" methods and coerce all other "[nli]Matrix" to "dMatrix"
setMethod("Arith", signature(e1 = "Matrix", e2 = "Matrix"),
          function(e1, e2) callGeneric(as(e1, "dMatrix"), as(e2, "dMatrix")))

## For "Compare", this would be feasible too, but is clearly suboptimal,
## particularly for "==" and "!="
## and for "lMatrix" and "nMatrix"  should not coerce at all
if(FALSE)
setMethod("Compare", signature(e1 = "Matrix", e2 = "Matrix"),
          function(e1, e2) {
              if(is.na(match(.Generic, c("==", "!="))))
                  callGeneric(as(e1, "dMatrix"), as(e2, "dMatrix"))
              else { ## no coercion needed for "==" or "!="
                  ##
                  ## what now ?  <<<<<<<<<<< FIXME >>>>>>>>>
                  .bail.out.2(.Generic, class(e1), class(e2))
              }
          })


## Working entirely on "matching" x slot:
## can be done for matching-dim "*geMatrix", and also
## matching-{dim + uplo} for *packed* (only!) symmetric+triangular
.Ops.via.x <- function(e1,e2) {
    dimCheck(e1, e2)
    e1@x <- callGeneric(e1@x, e2@x)
    e1
}


###-------- originally from ./dMatrix.R --------------------
##
## Note that there extra methods for <sparse> o <sparse> !
##
## "Compare" -> returning  logical Matrices;  .Cmp.swap() is in ./Auxiliaries.R
setMethod("Compare", signature(e1 = "numeric", e2 = "dMatrix"), .Cmp.swap)
setMethod("Compare", signature(e1 = "logical", e2 = "dMatrix"), .Cmp.swap)
setMethod("Compare", signature(e1 = "numeric", e2 = "lMatrix"), .Cmp.swap)
setMethod("Compare", signature(e1 = "logical", e2 = "lMatrix"), .Cmp.swap)
setMethod("Compare", signature(e1 = "numeric", e2 = "nMatrix"), .Cmp.swap)
setMethod("Compare", signature(e1 = "logical", e2 = "nMatrix"), .Cmp.swap)


## This is parallel to Logic.Mat.atomic() below --->  __keep parallel__ !
Cmp.Mat.atomic <- function(e1, e2) { ## result will inherit from "lMatrix"
    n1 <- prod(d <- e1@Dim)
    cl <- class(e1)
    if((l2 <- length(e2)) == 0)
	return(if(n1 == 0)
		   as(e1, class2(cl, "l"))# more expensive than (but working for "dgC*"):
		   ## new(class2(cl, "l"), Dim = d, Dimnames = e1@Dimnames)
               else
		   as.logical(e2))
    ## else
    if(n1 && n1 < l2)
	stop(sprintf(
	    "dim [product %d] do not match the length of object [%d]", n1, l2))
    cl1 <- getClassDef(cl)
    slots1 <- names(cl1@slots)
    has.x <- any("x" == slots1)# *fast* check for "x" slot presence
    if(l2 > 1 && has.x)
	return(if(n1 == 0)
		   new(class2(cl, "l"), x = callGeneric(e1@x, e2),
		       Dim = d, Dimnames = e1@Dimnames)
	       else ## e2 cannot simply be compared with e1@x --> use another method
		   callGeneric(e1, Matrix(e2, nrow=d[1], ncol=d[2])))
    ## else
    Udg <- extends(cl1, "triangularMatrix") && e1@diag == "U"
    r0 <- callGeneric(0, e2)
    ## Udg: append the diagonal at *end*, as diagU2N():
    r  <- callGeneric(if(Udg) c(e1@x,..diag.x(e1)) else if(has.x) e1@x else TRUE, e2)
    ## trivial case first (beware of NA)
    if(isTRUE(all(r0) && all(r))) {
        r <- new(if(d[1] == d[2]) "lsyMatrix" else "lgeMatrix")
        r@Dim <- d
        r@Dimnames <- e1@Dimnames
        r@x <- rep.int(TRUE, n1)
    }
    else if(extends(cl1, "denseMatrix")) {
	full <- !.isPacked(e1)	   # << both "dtr" and "dsy" are 'full'
	if(full || allFalse(r0) || extends(cl1, "symmetricMatrix")) {
            isTri <- extends(cl1, "triangularMatrix")
            if(isTri) {
                if(extends1of(cl1, c("Cholesky","BunchKaufman")))
                    cl1 <- getClassDef(cl <- class(e1 <- as(e1, "dtrMatrix")))
            }
            ## FIXME? using copyClass() to copy "relevant" slots
            r <- new(class2(cl, "l"), x = r, Dim = d, Dimnames = e1@Dimnames)
            if(extends(cl1, "symmetricMatrix")) {
                r@uplo <- e1@uplo
            } else if(isTri) {
                r@uplo <- e1@uplo
                r@diag <- e1@diag
            }
        }
        else { ## packed matrix with structural 0 and r0 is not all FALSE:
            ##--> result cannot be packed anymore
            ## [dense & packed & not symmetric ] ==> must be "dtp*" :
            if(!extends(cl1, "dtpMatrix"))
                stop("internal bug in \"Compare\" method (Cmp.Mat.atomic); please report")
	    rx <- rep_len(r0, n1)
	    rx[indTri(d[1], upper = (e1@uplo == "U"), diag=TRUE)] <- r
	    r <- new("lgeMatrix", x = rx, Dim = d, Dimnames = e1@Dimnames)
	}

    }
    else { ##---- e1 is(. , sparseMatrix) -----------------
        ## FIXME: remove this test eventually
        if(extends(cl1, "diagonalMatrix")) stop("Cmp.Mat.atomic() should not be called for diagonalMatrix")
        remainSparse <- allFalse(r0) ## <==> things remain sparse
        if(Udg) {          # e1 *is* unit-diagonal (triangular sparse)
            r1 <- callGeneric(1, e2)
            Udg <- all(r1)       # maybe Unit-diagonal (sparse) result
            ## if(!remainSparse) we'll use non0ind() which *has* unit-diag. indices at end
            ##
            if(Udg && remainSparse) {
            } else { ## result will not be unit-diagonal sparse
                e1 <- .diagU2N(e1, cl = cl1) # otherwise, result is U-diag
                if(extends(cl1, "CsparseMatrix")) {
                    ## repeat computation if e1 has changed
                    r <- callGeneric(if(has.x) e1@x else TRUE, e2)
                }
            }
        }

        if(remainSparse) {
            if(!anyNA(r) && ((Ar <- all(r)) || !any(r))) {
                lClass <- class2(cl, "l") # is "lsparse*"
                r <- new(lClass)
                r@Dim <- d
                r@Dimnames <- e1@Dimnames
                if(Ar) {       # 'TRUE' instead of 'x': same sparsity:
		    for(n in intersect(c("i","j","p","uplo","diag"), slots1))
			slot(r, n) <- slot(e1, n)
		    n <- if(has.x) length(e1@x) else if(any("p" == slots1))
			e1@p[d[2]+1L] else length(e1@i)
		    r@x <- rep.int(TRUE, n)
                }
                else { ## !any(r): all FALSE: keep empty 'r' matrix
                    ## but may need a valid 'pointer' slot:
                    if(extends(lClass, "CsparseMatrix"))
                        r@p <- rep.int(0L, 1+ncol(r))
                    else if(extends(lClass, "RsparseMatrix"))
                        r@p <- rep.int(0L, 1+nrow(r))
                }
            } else {  # some TRUE, FALSE, NA : go via unique 'Tsparse'
                M <- asTuniq(e1)
                nCl <- class2(class(M), 'l') # logical Tsparse
                sN <- slotNames(nCl)
                ## copy "the other slots" (important for "tr"/"sym"):
                r <- copyClass(M, nCl, sNames = sN[is.na(match(sN, "x"))])
                r@x <- callGeneric(if(has.x) M@x else 1, e2)
                if(extends(cl1, "CsparseMatrix"))
                    r <- as(r, "CsparseMatrix")
                else if(extends(cl1, "RsparseMatrix"))
                    r <- as(r, "RsparseMatrix")
            }
        }
        else { ## non sparse result; triangularity also gone, typically
            lClass <- if(extends(cl1, "symmetricMatrix")) "lsyMatrix" else "lgeMatrix"
            Matrix.msg(sprintf("sparse to dense (%s) coercion in '%s' -> %s",
                               lClass, .Generic, "Cmp.Mat.atomic"), .M.level = 2)
	    rx <- rep_len(r0, n1)

            ## Here, we assume that 'r' and the indices align (!)
            encI <- .Call(m_encodeInd,
                          non0ind(e1, cl1, uniqT=FALSE, xtendSymm=FALSE),
                          di = d, orig1=FALSE, checkBounds=FALSE)
            rx[1L + encI] <- r
            r <- new(lClass, x = rx, Dim = d, Dimnames = e1@Dimnames)
        }
    }
    r
}
setMethod("Compare", signature(e1 = "dMatrix", e2 = "numeric"), Cmp.Mat.atomic)
setMethod("Compare", signature(e1 = "dMatrix", e2 = "logical"), Cmp.Mat.atomic)
setMethod("Compare", signature(e1 = "lMatrix", e2 = "numeric"), Cmp.Mat.atomic)
setMethod("Compare", signature(e1 = "lMatrix", e2 = "logical"), Cmp.Mat.atomic)
setMethod("Compare", signature(e1 = "nMatrix", e2 = "numeric"), Cmp.Mat.atomic)
setMethod("Compare", signature(e1 = "nMatrix", e2 = "logical"), Cmp.Mat.atomic)


## "xMatrix <-> work with 'x' slot {was originally just for "Compare"}:
##  -------  {also used for "Arith"}:
Ops.x.x <- function(e1, e2)
{
    d <- dimCheck(e1,e2)
    if((dens1 <- extends(c1 <- class(e1), "denseMatrix")))
	gen1 <- extends(c1, "generalMatrix")
    if((dens2 <- extends(c2 <- class(e2), "denseMatrix")))
	gen2 <- extends(c2, "generalMatrix")
    if(dens1 && dens2) { ## both inherit from ddense*
	geM <- TRUE
	if(!gen1) {
	    if(!gen2) { ## consider preserving "triangular" / "symmetric"
		geM <- FALSE
		le <- prod(d)
		isPacked <- function(x) length(x@x) < le
		Mclass <-
		    if(extends(c1, "symmetricMatrix") &&
		       extends(c2, "symmetricMatrix")) {
			if(e1@uplo != e2@uplo)
			    ## one is upper, one is lower
			    e2 <- t(e2)
			if((p1 <- isPacked(e1)) | (p2 <- isPacked(e2))) { ## at least one is packed
			    if(p1 != p2) { # one is not packed --> *do* pack it:
				pack.sy <- function(x)
				    if(is.numeric(x@x))
					 .Call(dsyMatrix_as_dspMatrix, x)
				    else .Call(lsyMatrix_as_lspMatrix, x, 0L)
				if(p1) e2 <- pack.sy(e2)
				else   e1 <- pack.sy(e1)
			    }
			    "spMatrix"
			} else
			    "syMatrix"
		    }
		    else if(extends(c1, "triangularMatrix") &&
			    extends(c2, "triangularMatrix")) {
			if(!(geM <- e1@uplo != e2@uplo || isN0(callGeneric(0,0)))) {
			    p1 <- isPacked(e1)
			    p2 <- isPacked(e2)
			    if(e1@diag == "U") e1 <- .dense.diagU2N(e1, isPacked=p1)
			    if(e2@diag == "U") e2 <- .dense.diagU2N(e2, isPacked=p2)
			    if(p1 | p2) { ## at least one is packed
				if(p1 != p2) { # one is not packed --> *do* pack it:
				    pack.tr <- function(x)
					if(is.numeric(x@x)) .Call(dtrMatrix_as_dtpMatrix, x)
					else .Call(ltrMatrix_as_ltpMatrix, x, 0L)
				    if(p1) e2 <- pack.tr(e2)
				    else   e1 <- pack.tr(e1)
				}
				"tpMatrix"
			    } else
				"trMatrix"
			}
		    }
		    else { ## not symmetric, not triangular  ==> "general"
			geM <- TRUE
		    }
		if(geM)
		    e2 <- as(e2, "generalMatrix")
	    }
	    if(geM)
		e1 <- as(e1, "generalMatrix") # was "dgeMatrix"
	} else { ## gen1
	    if(!gen2) e2 <- as(e2, "generalMatrix")
	}
	## now, in all cases @x should be matching & correct {only "uplo" part is used}
	r <- callGeneric(e1@x, e2@x)
	kr <- .M.kind(r)
	if(kr == "d" && !is.double(r)) ## as "igeMatrix" does not yet exist!
	    r <- as.double(r)
	if(geM)
	    new(paste0(kr, "geMatrix"), x = r, Dim = d, Dimnames = e1@Dimnames)
	else
	    new(paste0(kr, Mclass), x = r, Dim = d, Dimnames = e1@Dimnames, uplo = e1@uplo)
    }
    else {
	r <- if(!dens1 && !dens2)
	    ## both e1 _and_ e2 are sparse.
	    ## Now (new method dispatch, 2009-01) *does* happen
	    ## even though we have <sparse> o <sparse> methods
	    callGeneric(as(e1, "CsparseMatrix"), as(e2, "CsparseMatrix"))
	else if(dens1 && !dens2) ## go to dense
	    callGeneric(e1, as(e2, "denseMatrix"))
	else ## if(!dens1 && dens2)
	    callGeneric(as(e1, "denseMatrix"), e2)

	## criterion "2 * nnz(.) < ." as in sparseDefault() in Matrix()	 [./Matrix.R] :
	if(2 * nnzero(r, na.counted = TRUE) < prod(d))
	    as(r, "sparseMatrix") else r
    }
}

setMethod("Ops", signature(e1 = "dMatrix", e2 = "dMatrix"), Ops.x.x)
setMethod("Ops", signature(e1 = "lMatrix", e2 = "lMatrix"), Ops.x.x)
## n*: for "Arith" go via dMatrix, for "Logic" via "lMatrix"
setMethod("Compare", signature(e1 = "nMatrix", e2 = "nMatrix"), Ops.x.x)

## l o d : depends on *kind* of Ops -- but Ops.x.x works on slots - correctly:
setMethod("Ops", signature(e1="lMatrix", e2="dMatrix"), Ops.x.x)
setMethod("Ops", signature(e1="dMatrix", e2="lMatrix"), Ops.x.x)

## lMatrix & nMatrix ... probably should also just use "Matrix" ?
##
## Hmm, the coercion should differ, depending on subgroup ("Logic", "Arith",..)
## --> try to get rid of these
setMethod("Ops", signature(e1="lMatrix", e2="numeric"),
	  function(e1,e2) callGeneric(as(e1,"dMatrix"), e2))
setMethod("Ops", signature(e1="numeric", e2="lMatrix"),
	  function(e1,e2) callGeneric(e1, as(e2,"dMatrix")))
setMethod("Ops", signature(e1="nMatrix", e2="numeric"),
	  function(e1,e2) callGeneric(as(e1,"dMatrix"), e2))
setMethod("Ops", signature(e1="numeric", e2="nMatrix"),
	  function(e1,e2) callGeneric(e1, as(e2,"dMatrix")))
## setMethod("Ops", signature(e1="Matrix", e2="logical"),
## 	  function(e1,e2) callGeneric(as(e1,"lMatrix"), e2))
## setMethod("Ops", signature(e1="logical", e2="Matrix"),
## 	  function(e1,e2) callGeneric(e1, as(e2,"lMatrix")))

## "dpoMatrix" / "dppMatrix" :
## Positive-definiteness is lost with all "Ops" but some "Arith" cases
for(cl in c("numeric", "logical")) { # "complex", "raw" : basically "replValue"

setMethod("Arith", signature(e1 = cl, e2 = "dpoMatrix"),
	  function(e1, e2) if(!(l1 <- length(e1))) numeric()
			   else if(l1 == 1 && any(.Generic == c("*","/","+")) && (e1 > 0)) {
	      e2@x <- callGeneric(e1, e2@x) ; e2 # remains "dpo"
	  } else ## in all other cases
	  callGeneric(e1, as(e2, "dsyMatrix")))
setMethod("Arith", signature(e1 = cl, e2 = "dppMatrix"),
	  function(e1, e2) if(!(l1 <- length(e1))) numeric()
			   else if(l1 == 1 && any(.Generic == c("*","/","+")) && (e1 > 0)) {
	      e2@x <- callGeneric(e1, e2@x) ; e2 # remains "dpp"
	  } else ## in all other cases
	  callGeneric(e1, as(e2, "dspMatrix")))
setMethod("Arith", signature(e1 = "dpoMatrix", e2 = cl),
	  function(e1, e2) if(!(l2 <- length(e2))) numeric()
			   else if(l2 == 1 && any(.Generic == c("*","/","+")) && (e2 > 0)) {
	      e1@x <- callGeneric(e1@x, e2) ; e1 # remains "dpo"
	  } else ## in all other cases
	  callGeneric(as(e1, "dsyMatrix"), e2))
setMethod("Arith", signature(e1 = "dppMatrix", e2 = cl),
	  function(e1, e2) if(!(l2 <- length(e2))) numeric()
			   else if(l2 == 1 && any(.Generic == c("*","/","+")) && (e2 > 0)) {
	      e1@x <- callGeneric(e1@x, e2) ; e1 # remains "dpp"
	  } else ## in all other cases
	  callGeneric(as(e1, "dspMatrix"), e2))

setMethod("Ops", signature(e1 = cl, e2 = "dpoMatrix"),
	  function(e1, e2) callGeneric(e1, as(e2, "dsyMatrix")))
setMethod("Ops", signature(e1 = cl, e2 = "dppMatrix"),
	  function(e1, e2) callGeneric(e1, as(e2, "dspMatrix")))
setMethod("Ops", signature(e1 = "dpoMatrix", e2 = cl),
	  function(e1, e2) callGeneric(as(e1, "dsyMatrix"), e2))
setMethod("Ops", signature(e1 = "dppMatrix", e2 = cl),
	  function(e1, e2) callGeneric(as(e1, "dspMatrix"), e2))
}# for(cl...)


### --  I -- dense -----------------------------------------------------------

##-------- originally from ./dgeMatrix.R --------------------

## ----- only work with NAMESPACE importFrom(methods, ..)

setMethod("Arith", signature(e1 = "dgeMatrix", e2 = "dgeMatrix"),
	  ##  "+", "-", "*", "^", "%%", "%/%", "/"
	  function(e1, e2) {
	      ## NB:  triangular, symmetric, etc may need own method
	      d1 <- e1@Dim
	      d2 <- e2@Dim
	      eqD <- d1 == d2
	      if (!eqD[1])
		  stop("Matrices must have same number of rows for arithmetic")
	      same.dim <- eqD[2]
	      if (same.dim) {
		  d <- d1
		  dn <- dimNamesCheck(e1, e2)
	      }
	      else { # nrows differ ----> maybe recycling
		  if(d2[2] %% d1[2] == 0) { # nrow(e2) is a multiple
		      e1@x <- rep.int(e1@x, d2[2] %/% d1[2])
		      d <- d2
		      dn <- e2@Dimnames
		  } else if(d1[2] %% d2[2] == 0) { # nrow(e1) is a multiple
		      e2@x <- rep.int(e2@x, d1[2] %/% d2[2])
		      d <- d1
		      dn <- e1@Dimnames
		  } else
		      stop(gettextf("number of rows are not compatible for %s",
				    .Generic), domain=NA)
	      }
	      new("dgeMatrix", Dim = d, Dimnames = dn, x = callGeneric(e1@x, e2@x))
	  })

A.M.n <- function(e1, e2) {
    d <- e1@Dim
    le <- length(e2)
    if(le == 0)
	if(prod(d) == 0)
	    new(class2(class(e1), "d"), Dim = d, Dimnames = e1@Dimnames)
	else
	    as.numeric(e2)
    else if(le == 1 || le == d[1] || any(prod(d) == c(le, 0L))) { # matching dim
        e1@x <- callGeneric(e1@x, as.vector(e2))
        e1
    } else stop ("length of 2nd arg does not match dimension of first")
}
setMethod("Arith", signature(e1 = "dgeMatrix", e2 = "numeric"), A.M.n)
setMethod("Arith", signature(e1 = "dgeMatrix", e2 = "logical"), A.M.n)
setMethod("Arith", signature(e1 = "dgeMatrix", e2 = "sparseVector"), A.M.n)

A.n.M <- function(e1, e2) {
    d <- e2@Dim
    le <- length(e1)
    if(le == 0)
	if(prod(d) == 0)
	    new(class2(class(e2), "d"), Dim = d, Dimnames = e2@Dimnames)
	else
	    as.numeric(e1)
    else if(le == 1 || le == d[1] || any(prod(d) == c(le, 0L))) { # matching dim
        e2@x <- callGeneric(as.vector(e1), e2@x)
        e2
    } else stop ("length of 1st arg does not match dimension of 2nd")
}
setMethod("Arith", signature(e1 = "numeric", e2 = "dgeMatrix"), A.n.M)
setMethod("Arith", signature(e1 = "logical", e2 = "dgeMatrix"), A.n.M)
setMethod("Arith", signature(e1 = "sparseVector", e2 = "dgeMatrix"), A.n.M)
##
rm(A.M.n, A.n.M)

##-------- originally from ./ddenseMatrix.R --------------------

## Cheap version: work via "dgeMatrix" and use the group methods there:
if(FALSE)## preserve "symmetric", "triangular", --> rather use Ops.x.x
setMethod("Arith", signature(e1 = "ddenseMatrix", e2 = "ddenseMatrix"),
          function(e1, e2) callGeneric(as(e1, "dgeMatrix"),
                                       as(e2, "dgeMatrix")))

.Arith.denseM.atom <- function(e1, e2) {
    ## since e1 = "dgeMatrix" has its own method, we have
    ## either symmetric or triangular !
    n1 <- prod(d <- e1@Dim)
    le <- length(e2 <- as.vector(e2))
    if(n1 && n1 < le)
	stop(sprintf(
	    "dim [product %d] do not match the length of object [%d]", n1, le))
    if(le == 0)
	if(prod(d) == 0)
	    new(class2(class(e1), "d"), Dim = d, Dimnames = e1@Dimnames)
	else
	    as.numeric(e2)
    else if(le == 1 || le == d[1] || any(prod(d) == c(le, 0L))) { # matching dim
        if(is(e1, "triangularMatrix")) {
            r0 <- callGeneric(0, e2)
            if(all0(r0)) {              # result remains triangular
                if(e1@diag == "U" && !all(1 == callGeneric(1,e2)))
                    e1 <- diagU2N(e1)
                e1@x <- callGeneric(e1@x, e2)
                e1
            } else { ## result *general*
                callGeneric(as(e1,"dgeMatrix"), e2)
            }
        } else {                    ## symmetric
            if(le == 1) {           ## result remains symmetric
                e1@x <- callGeneric(e1@x, e2)
                e1
            } else { ## (le == d[1] || prod(d) == le)
                ## *might* remain symmetric, but 'x' may contain garbage
                ## *testing* for symmetry is also a bit expensive ==> simple:
                callGeneric(as(e1,"dgeMatrix"), e2)
            }
        }
    } else stop ("length of 2nd arg does not match dimension of first")
}
setMethod("Arith", signature(e1 = "ddenseMatrix", e2 = "numeric"), .Arith.denseM.atom)
setMethod("Arith", signature(e1 = "ddenseMatrix", e2 = "logical"), .Arith.denseM.atom)
setMethod("Arith", signature(e1 = "ddenseMatrix", e2 = "sparseVector"), .Arith.denseM.atom)

.Arith.atom.denseM <- function(e1, e2) {
    d <- e2@Dim
    ## note that e2 is either symmetric or triangular here
    le <- length(e1 <- as.vector(e1))
    if(le == 0)
	if(prod(d) == 0)
	    new(class2(class(e2), "d"), Dim = d, Dimnames = e2@Dimnames)
	else
	    as.numeric(e1)
    else if(le == 1 || le == d[1] || any(prod(d) == c(le, 0L))) { # matching dim
	if(is(e2, "triangularMatrix")) {
	    r0 <- callGeneric(e1, 0)
	    if(all0(r0)) {		# result remains triangular
		if(e2@diag == "U" && !all(1 == callGeneric(e1,1)))
		    e2 <- diagU2N(e2)
		e2@x <- callGeneric(e1, e2@x)
		e2
	    } else {			# result *general*
		callGeneric(e1, as(e2,"dgeMatrix"))
	    }
	} else { ## symmetric
	    if(le == 1) {		# result remains symmetric
		e2@x <- callGeneric(e1, e2@x)
		e2
	    } else { ## (le == d[1] || prod(d) == le)
		## *might* remain symmetric, but 'x' may contain garbage
		## *testing* for symmetry is also a bit expensive ==> simple:
		callGeneric(e1, as(e2,"dgeMatrix"))
	    }
	}
    } else stop ("length of 1st arg does not match dimension of 2nd")
}
## setMethod("Arith", signature(e1 = "numeric", e2 = "ddenseMatrix"),
##	     function(e1, e2) callGeneric(e1, as(e2, "dgeMatrix")))
setMethod("Arith", signature(e1 = "numeric", e2 = "ddenseMatrix"), .Arith.atom.denseM)
setMethod("Arith", signature(e1 = "logical", e2 = "ddenseMatrix"), .Arith.atom.denseM)
setMethod("Arith", signature(e1 = "sparseVector", e2 = "ddenseMatrix"), .Arith.atom.denseM)


## "Logic"
## -------

##-------- originally from ./ldenseMatrix.R --------------------

## These all had "Logic", now also for "Compare",
## but "Arith" differs: result will be "dgeMatrix' :
.Ops2dge.via.x <- function(e1,e2) {
    dimCheck(e1, e2)
    r <- copyClass(e1, "dgeMatrix", sNames = c("Dim","Dimnames"))
    r@x <- as.numeric(callGeneric(e1@x, e2@x))
    r
}

setMethod("Compare", signature(e1="lgeMatrix", e2="lgeMatrix"), .Ops.via.x)
setMethod("Logic",   signature(e1="lgeMatrix", e2="lgeMatrix"), .Ops.via.x)
setMethod("Arith",   signature(e1="lgeMatrix", e2="lgeMatrix"), .Ops2dge.via.x)

setMethod("Compare", signature(e1="ngeMatrix", e2="ngeMatrix"), .Ops.via.x)
setMethod("Logic",   signature(e1="ngeMatrix", e2="ngeMatrix"), .Ops.via.x)
setMethod("Arith",   signature(e1="ngeMatrix", e2="ngeMatrix"), .Ops2dge.via.x)


## FIXME: These lose symmmetry & triangularity
setMethod("Ops", signature(e1="ldenseMatrix", e2="ldenseMatrix"),
	  function(e1,e2) {
	      dimCheck(e1, e2)
	      callGeneric(as(e1, "lgeMatrix"), as(e2, "lgeMatrix"))
	  })

setMethod("Ops", signature(e1="ndenseMatrix", e2="ndenseMatrix"),
	  function(e1,e2) {
	      dimCheck(e1, e2)
	      callGeneric(as(e1, "ngeMatrix"), as(e2, "ngeMatrix"))
	  })

## nMatrix -> lMatrix  conversions when "the other" is not nMatrix
## Use Ops.x.x unless both are sparse
setMethod("Ops", signature(e1="nMatrix", e2="lMatrix"), Ops.x.x)
setMethod("Ops", signature(e1="lMatrix", e2="nMatrix"), Ops.x.x)
setMethod("Ops", signature(e1="nMatrix", e2="dMatrix"), Ops.x.x)
setMethod("Ops", signature(e1="dMatrix", e2="nMatrix"), Ops.x.x)
## ... both are sparse: cannot use Ops.x.x
setMethod("Ops", signature(e1="nsparseMatrix", e2="lsparseMatrix"),
	  function(e1,e2) callGeneric(as(e1,"lMatrix"), e2))
setMethod("Ops", signature(e1="lsparseMatrix", e2="nsparseMatrix"),
	  function(e1,e2) callGeneric(e1, as(e2,"lMatrix")))
setMethod("Ops", signature(e1="nsparseMatrix", e2="dsparseMatrix"),
	  function(e1,e2) callGeneric(as(e1,"lMatrix"), e2))
setMethod("Ops", signature(e1="dsparseMatrix", e2="nsparseMatrix"),
	  function(e1,e2) callGeneric(e1, as(e2,"lMatrix")))


## Have this for "Ops" already above
## setMethod("Logic", signature(e1 = "logical", e2 = "Matrix"),
##           function(e1, e2) callGeneric(e1, as(e2, "lMatrix")))
## setMethod("Logic", signature(e1 = "Matrix", e2 = "logical"),
##           function(e1, e2) callGeneric(as(e1, "lMatrix"), e2))

.ll <- function(e1, e2) callGeneric(as(e1,"lMatrix"), as(e2, "lMatrix"))
setMethod("Logic", signature(e1 = "nMatrix", e2 =  "Matrix"), .ll)
setMethod("Logic", signature(e1 =  "Matrix", e2 = "nMatrix"), .ll)
setMethod("Logic", signature(e1 = "nMatrix", e2 = "nMatrix"), .ll)
rm(.ll)

### "ANY" here means "any non-Matrix" (since "Ops"(ANY) has already bailout above):
setMethod("Logic", signature(e1 = "ANY", e2 = "Matrix"),
          function(e1, e2) callGeneric(as.logical(e1), as(e2, "lMatrix")))
setMethod("Logic", signature(e1 = "Matrix", e2 = "ANY"),
          function(e1, e2) callGeneric(as(e1, "lMatrix"), as.logical(e2)))

## "swap RHS and LHS" and use the method below -- can do this, since
## 	"Logic" := { "&" , "|" } and both are commutative
for(Mcl in c("lMatrix","nMatrix","dMatrix"))
    for(cl in c("logical", "numeric", "sparseVector"))
    setMethod("Logic", signature(e1 = cl, e2 = Mcl),
              function(e1,e2) callGeneric(e2, e1))
## conceivably "numeric" could use  callGeneric(e2, as.logical(e1))
## but that's not useful at the moment, since Logic.Mat.atomic() does as.logical()

## This is parallel to Cmp.Mat.atomic() above --->  __keep parallel__ !
Logic.Mat.atomic <- function(e1, e2) { ## result will typically be "like" e1:
    l2 <- length(e2 <- as.logical(e2))
    n1 <- prod(d <- e1@Dim)
    if(n1 && n1 < l2)
	stop(sprintf(
	    "dim [product %d] do not match the length of object [%d]", n1, l2))
    if(.Generic == "&" && l2 && allTrue (e2)) return(as(e1, "lMatrix"))
    if(.Generic == "|" && l2 && allFalse(e2)) return(as(e1, "lMatrix"))
    cl <- class(e1)
    if(l2 == 0)
	return(if(n1 == 0)
		   as(e1, class2(cl, "l"))# more expensive than (but working for "dgC*"):
		   ## new(class2(cl, "l"), Dim = d, Dimnames = e1@Dimnames)
	       else
		   as.logical(e2))
    ## else
    cl1 <- getClassDef(cl)
    slots1 <- names(cl1@slots)
    has.x <- any("x" == slots1)# *fast* check for "x" slot presence
    if(l2 > 1 && has.x)
	return(if(prod(d) == 0)
		   new(class2(cl, "l"), x = callGeneric(e1@x, e2),
		       Dim = d, Dimnames = e1@Dimnames)
	       else ## e2 cannot simply be compared with e1@x --> use another method
		   callGeneric(e1, Matrix(e2, nrow=d[1], ncol=d[2])))
    ## else
    Udg <- extends(cl1, "triangularMatrix") && e1@diag == "U"
    r0 <- callGeneric(0, e2)
    ## Udg: append the diagonal at *end*, as diagU2N():
    r  <- callGeneric(if(Udg) c(e1@x,..diag.x(e1)) else if(has.x) e1@x else TRUE, e2)
    ## trivial case first (beware of NA)
    if(isTRUE(all(r0) && all(r))) {
        r <- new(if(d[1] == d[2]) "lsyMatrix" else "lgeMatrix")
        r@Dim <- d
        r@Dimnames <- e1@Dimnames
        r@x <- rep.int(TRUE, prod(d))
    }
    else if(extends(cl1, "denseMatrix")) {
	full <- !.isPacked(e1)	   # << both "dtr" and "dsy" are 'full'
	if(full || allFalse(r0) || extends(cl1, "symmetricMatrix")) {
            isTri <- extends(cl1, "triangularMatrix")
            if(isTri) {
                if(extends1of(cl1, c("Cholesky","BunchKaufman")))
                    cl1 <- getClassDef(cl <- class(e1 <- as(e1, "dtrMatrix")))
            }
            ## FIXME? using copyClass() to copy "relevant" slots
            r <- new(class2(cl, "l"), x = r, Dim = d, Dimnames = e1@Dimnames)
            if(extends(cl1, "symmetricMatrix")) {
                r@uplo <- e1@uplo
            } else if(isTri) {
                r@uplo <- e1@uplo
                r@diag <- e1@diag
            }
        }
        else { ## packed matrix with structural 0 and r0 is not all FALSE:
            ##--> result cannot be packed anymore
            ## [dense & packed & not symmetric ] ==> must be "ltp*" :
            if(!extends(cl1, "ltpMatrix"))
                stop("internal bug in \"Logic\" method (Logic.Mat.atomic); please report")
	    rx <- rep_len(r0, prod(d))
	    rx[indTri(d[1], upper = (e1@uplo == "U"), diag=TRUE)] <- r
	    r <- new("lgeMatrix", x = rx, Dim = d, Dimnames = e1@Dimnames)
	}

    }
    else { ##---- e1 is(. , sparseMatrix) -----------------
        ## FIXME: remove this test eventually
        if(extends(cl1, "diagonalMatrix"))
            stop("Logic.Mat.atomic() should not be called for diagonalMatrix")
        remainSparse <- allFalse(r0) ## <==> things remain sparse
        if(Udg) {          # e1 *is* unit-diagonal (triangular sparse)
            r1 <- callGeneric(1, e2)
            Udg <- all(r1)       # maybe Unit-diagonal (sparse) result
            ## if(!remainSparse) we'll use non0ind() which *has* unit-diag. indices at end
            ##
            if(Udg && remainSparse) {
            } else { ## result will not be unit-diagonal sparse
                e1 <- .diagU2N(e1, cl = cl1) # otherwise, result is U-diag
                if(extends(cl1, "CsparseMatrix")) {
                    ## repeat computation if e1 has changed
                    r <- callGeneric(if(has.x) e1@x else TRUE, e2)
                }
            }
        }

        if(remainSparse) {
            if(!anyNA(r) && ((Ar <- all(r)) || !any(r))) {
                lClass <- class2(cl, "l") # is "lsparse*"
                r <- new(lClass)
                r@Dim <- d
                r@Dimnames <- e1@Dimnames
                if(Ar) {       # 'TRUE' instead of 'x': same sparsity:
		    for(n in intersect(c("i","j","p","uplo","diag"), slots1))
			slot(r, n) <- slot(e1, n)
		    n <- if(has.x) length(e1@x) else if(any("p" == slots1))
			e1@p[d[2]+1L] else length(e1@i)
		    r@x <- rep.int(TRUE, n)
                }
                else { ## !any(r): all FALSE: keep empty 'r' matrix
                    ## but may need a valid 'pointer' slot:
                    if(extends(lClass, "CsparseMatrix"))
                        r@p <- rep.int(0L, 1+ncol(r))
                    else if(extends(lClass, "RsparseMatrix"))
                        r@p <- rep.int(0L, 1+nrow(r))
                }
            } else {  # some TRUE, FALSE, NA : go via unique 'Tsparse'
                M <- asTuniq(e1)
                nCl <- class2(class(M), 'l') # logical Tsparse
                sN <- slotNames(nCl)
                ## copy "the other slots" (important for "tr"/"sym"):
                r <- copyClass(M, nCl, sNames = sN[is.na(match(sN, "x"))])
		r@x <- callGeneric(if(has.x) M@x else TRUE, e2)
                if(extends(cl1, "CsparseMatrix"))
                    r <- as(r, "CsparseMatrix")
                else if(extends(cl1, "RsparseMatrix"))
                    r <- as(r, "RsparseMatrix")
            }
        }
        else { ## non sparse result
            lClass <- if(extends(cl1, "symmetricMatrix"))
                "lsyMatrix" else "lgeMatrix"
            Matrix.msg(sprintf("sparse to dense (%s) coercion in '%s' -> %s",
                               lClass, .Generic, "Logic.Mat.atomic"), .M.level = 2)
	    rx <- rep_len(r0, prod(d))

            ## Here, we assume that 'r' and the indices align (!)
            encI <- .Call(m_encodeInd,
                          non0ind(e1, cl1, uniqT=FALSE, xtendSymm=FALSE),
                          di = d, orig1=FALSE, checkBounds=FALSE)
            rx[1L + encI] <- r
            r <- new(lClass, x = rx, Dim = d, Dimnames = e1@Dimnames)
        }
    }
    r
}
for(Mcl in c("lMatrix","nMatrix","dMatrix"))
    for(cl in c("logical", "numeric", "sparseVector"))
    setMethod("Logic", signature(e1 = Mcl, e2 = cl), Logic.Mat.atomic)


### -- II -- sparse ----------------------------------------------------------

## Have lgC o lgC  and then lgT o lgT  Logic - quite similarly -
## also lsC o *  and ltC o * :

## Here's the common functionality
.do.Logic.lsparse <- function(e1,e2, d, dn, isOR, ij1, ij2) {

    ## NB non-diagonalMatrix := Union{ general, symmetric, triangular}
    gen1 <- extends(cD1 <- getClassDef(class(e1)), "generalMatrix")
    gen2 <- extends(cD2 <- getClassDef(class(e2)), "generalMatrix")
    sym1 <- !gen1 && extends(cD1, "symmetricMatrix")
    sym2 <- !gen2 && extends(cD2, "symmetricMatrix")
    tri1 <- !gen1 && !sym1
    tri2 <- !gen2 && !sym2
    G <- gen1 && gen2
    S <- sym1 && sym2 && e1@uplo == e2@uplo
    T <- tri1 && tri2 && e1@uplo == e2@uplo
    if(T && e1@diag != e2@diag) {
	## one is "U" the other "N"
	if(e1@diag == "U")
	    e1 <- diagU2N(e1)
	else ## (e2@diag == "U"
	    e2 <- diagU2N(e2)
	shape <- "t"
    }
    else if(!G && !S && !T) {
	## e.g. one symmetric, one general
	## coerce to generalMatrix and go :
	if(!gen1) e1 <- as(e1, "generalMatrix", strict = FALSE)
	if(!gen2) e2 <- as(e2, "generalMatrix", strict = FALSE)
	shape <- "g"
    } else {
	shape <- if(T) "t" else if(S) "s" else "g"
    }

    ii <- WhichintersectInd(ij1, ij2, di=d)
    I1 <- ii[[1]] ; has1 <- length(I1) > 0
    I2 <- ii[[2]] ; has2 <- length(I2) > 0

    ## 1) common indices
    i <- ij1[I1, 1]
    j <- ij1[I1, 2]

    if(isOR) { ## i.e. .Generic == "|" i.e. not "&"
	x <- e1@x[I1] | e2@x[I2]

	## 2) "e1 o  FALSE":
	x2 <- if(has1) e1@x[- I1] else e1@x # == callGeneric(e1@x[- I1], FALSE)
	## 3) "0  o e1":
	x3 <- if(has2) e2@x[- I2] else e2@x # == callGeneric(FALSE, e2@x[- I2])
	i <- c(i,
	       if(has1) ij1[-I1, 1] else ij1[, 1],
	       if(has2) ij2[-I2, 1] else ij2[, 1])
	j <- c(j,
	       if(has1) ij1[-I1, 2] else ij1[, 2],
	       if(has2) ij2[-I2, 2] else ij2[, 2])
	x <- c(x, x2, x3)
    } else { ## AND
	x <- e1@x[I1] & e2@x[I2]
    }


    if(any(!(x. <- x | is.na(x)))) { ## drop 'FALSE's
	i <- i[x.]
	j <- j[x.]
	x <- x[x.]
    }
    new(paste0("l",shape,"TMatrix"), Dim = d, Dimnames = dn,
        i = i, j = j, x = x)
}

Logic.lCMat <- function(e1, e2, isOR) {
    stopifnot(is.logical(isOR))
    d <- dimCheck(e1, e2)
    dn <- dimNamesCheck(e1, e2)
    ## Very easy case first :
    if(identical(e1@i, e2@i) && identical(e1@p, e2@p)) {
        e1@x <- if(isOR) e1@x | e2@x else e1@x & e2@x
        return(e1)
    }
    ## else :

    .Call(Tsparse_to_Csparse,
          .do.Logic.lsparse(e1, e2, d = d, dn = dn, isOR = isOR,
                            ij1 = .Call(compressed_non_0_ij, e1, TRUE),
                            ij2 = .Call(compressed_non_0_ij, e2, TRUE)),
          FALSE)
}

m.Logic.lCMat <- function(e1, e2) Logic.lCMat(e1, e2, isOR = .Generic == "|")

Logic.lTMat <- function(e1,e2) {
    d <- dimCheck(e1, e2)
    dn <- dimNamesCheck(e1, e2)
    ## Very easy case first :
    if(identical(e1@i, e2@i) && identical(e1@j, e2@j)) {
        e1@x <- callGeneric(e1@x, e2@x)
        return(e1)
    }
    ## else :
    cld <- getClassDef(class(e1))
    .do.Logic.lsparse(e1, e2, d = d, dn = dn,
                      isOR = .Generic == "|",
                      ij1 = non0ind(e1, cld),
                      ij2 = non0ind(e2, cld))
}

setMethod("Logic", signature(e1="lgCMatrix", e2="lgCMatrix"), m.Logic.lCMat)

setMethod("Logic", signature(e1="lgTMatrix", e2="lgTMatrix"), Logic.lTMat)

setMethod("Logic", signature(e1 = "lsCMatrix", e2 = "lsCMatrix"),
	  function(e1, e2) {
	      if(e1@uplo == e2@uplo) Logic.lCMat(e1, e2, isOR = .Generic == "|")
	      else Logic.lCMat(e1, t(e2), isOR = .Generic == "|")
	  })

setMethod("Logic", signature(e1 = "ltCMatrix", e2 = "ltCMatrix"),
	  function(e1, e2) {
	      if(e1@uplo == e2@uplo) {
		  if(e1@diag == e2@diag) ## both "N" or both "U" (!)
		      Logic.lCMat(e1, e2, isOR = .Generic == "|")
		  else if(e1@diag == "U")
		      Logic.lCMat(diagU2N(e1), e2, isOR = .Generic == "|")
		  else ## e1@diag == "N"  *and*	 e2@diag == "U"
		      Logic.lCMat(e1, diagU2N(e2), isOR = .Generic == "|")
	      }
	      else {
		  d <- dimCheck(e1, e2)
		  ## differing triangle (upper <-> lower):
		  ## all will be FALSE apart from diagonal
		  as(.diag2tT(new("ldiMatrix", Dim=d,
				  x = get(.Generic)(diag(e1), diag(e2))),
			      uplo = e1@uplo, kind = "l"),
		     "dtCMatrix")
	      }
	  })



## Now the other "Ops" for the "lgT" and "lgC" cases:
setMethod("Arith", signature(e1="lgCMatrix", e2="lgCMatrix"),
	  function(e1, e2) callGeneric(as(e1, "dgCMatrix"), as(e2, "dgCMatrix")))
setMethod("Arith", signature(e1="lgTMatrix", e2="lgTMatrix"),
	  function(e1, e2) callGeneric(as(e1, "dgTMatrix"), as(e2, "dgTMatrix")))

## More generally:  Arith: l* and n*  via  d*
setMethod("Arith", signature(e1="lsparseMatrix", e2="Matrix"),
	  function(e1, e2) callGeneric(as(e1, "dMatrix"), as(e2,"dMatrix")))
setMethod("Arith", signature(e1="Matrix", e2="lsparseMatrix"),
	  function(e1, e2) callGeneric(as(e1, "dMatrix"), as(e2,"dMatrix")))
setMethod("Arith", signature(e1="nsparseMatrix", e2="Matrix"),
	  function(e1, e2) callGeneric(as(e1, "dMatrix"), as(e2,"dMatrix")))
setMethod("Arith", signature(e1="Matrix", e2="nsparseMatrix"),
	  function(e1, e2) callGeneric(as(e1, "dMatrix"), as(e2,"dMatrix")))
##
for(cl in c("numeric", "logical")) # "complex", "raw" : basically "replValue"
  for(Mcl in c("lMatrix", "nMatrix")) {
      setMethod("Arith", signature(e1=Mcl, e2=cl),
		function(e1, e2) callGeneric(as(e1, "dMatrix"), e2))
      setMethod("Arith", signature(e1=cl, e2=Mcl),
		function(e1, e2) callGeneric(e1, as(e2,"dMatrix")))
  }
rm(cl, Mcl)

## FIXME: These are really too cheap: currently almost all go via dgC*() :
## setMethod("Compare", signature(e1="lgCMatrix", e2="lgCMatrix"),
## setMethod("Compare", signature(e1="lgTMatrix", e2="lgTMatrix"),
## setMethod("Compare", signature(e1="lsparseMatrix", e2="lsparseMatrix"),
## 	  function(e1, e2) callGeneric(as(e1, "dgCMatrix"), as(e2, "dgCMatrix")))
##. Have "Ops" below which only goes *conditionally* via Csparse
##. setMethod("Compare", signature(e1="lsparseMatrix", e2="lsparseMatrix"),
##. 	  function(e1, e2) callGeneric(as(e1, "CsparseMatrix"),
##. 				       as(e2, "CsparseMatrix")))

## setMethod("Compare", signature(e1="lgTMatrix", e2="lgTMatrix"), ## coerce to Csparse

## 	  function(e1, e2) callGeneric(as(e1, "dgCMatrix"), as(e2, "dgCMatrix")))


###--- Sparse ... ----------


setMethod("Ops", signature(e1="lsparseMatrix", e2="lsparseMatrix"),
          function(e1,e2) callGeneric(as(e1, "CsparseMatrix"), as(e2, "CsparseMatrix")))

setMethod("Logic", signature(e1="lsparseMatrix", e2="ldenseMatrix"),
	  function(e1,e2) callGeneric(as(e1, "generalMatrix"), as(e2, "sparseMatrix")))

setMethod("Logic", signature(e1="ldenseMatrix", e2="lsparseMatrix"),
	  function(e1,e2) callGeneric(as(e1, "sparseMatrix"), as(e2, "generalMatrix")))

setMethod("Logic", signature(e1="lsparseMatrix", e2="lsparseMatrix"),
	  function(e1,e2) {
	      if(!is(e1,"generalMatrix"))
		  callGeneric(as(as(e1, "generalMatrix"), "CsparseMatrix"), e2)
	      else if(!is(e2,"generalMatrix"))
		  callGeneric(e1, as(as(e2, "generalMatrix"), "CsparseMatrix"))
	      else callGeneric(as(e1, "lgCMatrix"), as(e2, "lgCMatrix"))
	  })


## FIXME: also want (symmetric o symmetric) , (triangular o triangular)
## -----
setMethod("Arith", signature(e1 = "dsCMatrix", e2 = "dsCMatrix"),
	  function(e1, e2) {
	      Matrix.msg("suboptimal 'Arith' implementation of  'dsC*  o  dsC*'")
	      forceSymmetric(callGeneric(as(e1, "dgCMatrix"), as(e2, "dgCMatrix")))
	  })


##-------- originally from ./dgCMatrix.R --------------------

.Arith.Csparse <- function(e1, e2, Generic, class., triangular = FALSE, check.dimnames = TRUE)
{
    ## Generic is one of  "+", "-", "*", "^", "%%", "%/%", "/"

    ## triangular:  TRUE  iff e1,e2 are triangular  _and_  e1@uplo == e2@uplo
    d <- dimCheck(e1, e2)
    dn <- dimNamesCheck(e1, e2, check = check.dimnames)
    if(triangular) {
	## need these for the 'x' slots in any case
	if (e1@diag == "U") e1 <- .Call(Csparse_diagU2N, e1)
	if (e2@diag == "U") e2 <- .Call(Csparse_diagU2N, e2)
        ## slightly more efficient than non0.i() or non0ind():
	ij1 <- .Call(compressed_non_0_ij, e1, isC=TRUE)
	ij2 <- .Call(compressed_non_0_ij, e2, isC=TRUE)

	newTMat <- function(i,j,x)
	    new("dtTMatrix", Dim = d, Dimnames = dn, i = i, j = j, x = x,
		uplo = e1@uplo)
	dmat <- "dtrMatrix"
    } else {
        cld <- getClassDef(class.)
	ij1 <- non0ind(e1, cld)
	ij2 <- non0ind(e2, cld)

	newTMat <- function(i,j,x)
	    new("dgTMatrix", Dim = d, Dimnames = dn, i = i, j = j, x = x)
	dmat <- "dgeMatrix"
    }

    switch(Generic,
	   "+" = , "-" = {
	       ## care for over-allocated 'x' slot:
	       nc1 <- d[2] + 1L
	       if((nz <- e1@p[nc1]) < length(e1@x)) e1@x <- e1@x[seq_len(nz)]
	       if((nz <- e2@p[nc1]) < length(e2@x)) e2@x <- e2@x[seq_len(nz)]
	       ## special "T" convention: repeated entries are *summed*
	       .Call(Tsparse_to_Csparse,
		     newTMat(i = c(ij1[,1], ij2[,1]),
			     j = c(ij1[,2], ij2[,2]),
			     x = if(Generic == "+") c(e1@x, e2@x) else c(e1@x, - e2@x)),
		     triangular)
	   },

	   "*" =
       { ##  X * 0 == 0 * X == 0 --> keep common non-0
	   ii <- WhichintersectInd(ij1, ij2, di=d)
	   ij <- ij1[ii[[1]], , drop = FALSE]
	   .Call(Tsparse_to_Csparse,
		 newTMat(i = ij[,1],
			 j = ij[,2],
			 x = e1@x[ii[[1]]] * e2@x[ii[[2]]]),
		 triangular)
       },

	   "^" =
       {
	   ii <- WhichintersectInd(ij1, ij2, di=d)
	   ## 3 cases:
	   ## 1) X^0 := 1  (even for X=0) ==> dense
	   ## 2) 0^Y := 0  for Y != 0	      =====
	   ## 3) x^y :

	   ## FIXME:	dgeM[cbind(i,j)] <- V  is not yet possible
	   ##	    nor dgeM[ i_vect   ] <- V
	   ## r <- as(e2, "dgeMatrix")
	   ## ...
	   r <- as(e2, "matrix")
	   Yis0 <- is0(r)
	   r[complementInd(ij1, dim=d)] <- 0 ## 2)
	   r[1L + ij2[ii[[2]], , drop=FALSE]] <-
	       e1@x[ii[[1]]] ^ e2@x[ii[[2]]] ## 3)
	   r[Yis0] <- 1			     ## 1)
	   as(r, dmat)
       },

	   "%%" = , "%/%" = , "/" = ## 0 op 0	 |-> NaN => dense
	   get(Generic)(as(e1, dmat), e2)

	   )# end{switch(..)}
}

setMethod("Arith", signature(e1 = "dgCMatrix", e2 = "dgCMatrix"),
	  function(e1,e2) .Arith.Csparse(e1,e2, .Generic, class.= "dgCMatrix"))

setMethod("Arith", signature(e1 = "dtCMatrix", e2 = "dtCMatrix"),
	  function(e1, e2) {
	      U1 <- e1@uplo
	      isTri <- U1 == e2@uplo && .Generic != "^" # will the result definitely be triangular?
	      if(isTri) {
		  .Arith.Csparse(e1,e2, .Generic, class. = "dtCMatrix",
				 triangular = TRUE)
	      }
	      else { ## lowerTri  o  upperTri: |--> "all 0" {often} -- FIXME?
		  .Arith.Csparse(as(e1, "dgCMatrix"), as(e2, "dgCMatrix"),
				 .Generic, class.= "dgCMatrix")
	      }
	  })

## TODO : Consider going a level up, and do this for all "Ops"
##
## NB: For "dgCMatrix" have special method ==> this is for dsC*, lgC*, ...
##     now also for Tsparse etc {*must* as method directly: "callGeneric()"}
.Arith.CM.atom <- function(e1, e2) {
    if(length(e2) == 1) { ## e.g.,  Mat ^ a
	f0 <- callGeneric(0, e2)
	if(is0(f0)) { ## remain sparse, symm., tri.,...
	    e1 <- as(e1, "dMatrix")
            if(!extends(cld <- getClassDef(class(e1)), "CsparseMatrix"))
                cld <- getClassDef(class(e1 <- as(e1, "CsparseMatrix")))
	    if(extends(cld, "triangularMatrix") &&
	       e1@diag == "U" && !all(1 == callGeneric(1, e2)))
		e1 <- .diagU2N(e1, cld)
	    e1@x <- callGeneric(e1@x, e2)
	    if(extends(cld, "compMatrix") && length(e1@factors))
                ## TODO: be much smarter and try *updating* (some) 'factors':
		e1@factors <- list()
	    return(e1)
	}
    }
    ## all other (potentially non-sparse) cases: give up symm, tri,..
    callGeneric(as(as(as(e1, "dMatrix"), "CsparseMatrix"), "dgCMatrix"), e2)
}
## The same,  e1 <-> e2 :
.Arith.atom.CM <- function(e1, e2) {
    if(length(e1) == 1) {
	f0 <- callGeneric(e1, 0)
	if(is0(f0)) {
	    e2 <- as(e2, "dMatrix")
            if(!extends(cld <- getClassDef(class(e2)), "CsparseMatrix"))
                cld <- getClassDef(class(e2 <- as(e2, "CsparseMatrix")))
	    if(extends(cld, "triangularMatrix") &&
	       e2@diag == "U" && !all(1 == callGeneric(e1, 1)))
		e2 <- .diagU2N(e2, cld)
	    e2@x <- callGeneric(e1, e2@x)
	    if(extends(cld, "compMatrix") && length(e2@factors))
                ## TODO: be much smarter and try *updating* (some) 'factors':
		e2@factors <- list()
	    return(e2)
	}
    }
    callGeneric(e1, as(as(as(e2, "dMatrix"), "CsparseMatrix"), "dgCMatrix"))
}
setMethod("Arith", signature(e1 = "CsparseMatrix", e2 = "numeric"), .Arith.CM.atom)
setMethod("Arith", signature(e1 = "numeric", e2 = "CsparseMatrix"), .Arith.atom.CM)

##' compute indices for recycling <numeric> of length 'len' to match sparseMatrix 'spM'
.Ops.recycle.ind <- function(spM, len) {
    n <- prod(d <- dim(spM))
    if(n && n < len) stop("vector too long in Matrix - vector operation")
    if(n %% len != 0) ## identical warning as in main/arithmetic.c
        warning("longer object length\n\tis not a multiple of shorter object length")
    ## TODO(speedup!): construction of [1L + in0 %%len] via one .Call()
    in0 <- .Call(m_encodeInd, .Call(compressed_non_0_ij, spM, TRUE),
                 d, FALSE, FALSE)
    1L + in0 %% len
}

A.M.n <- function(e1, e2) {
    if((l2 <- length(e2)) == 0) # return 0-vector of e1's kind, as matrix()+<0>
	return(if(length(e1)) vector(.type.kind[.M.kind(e1)]) else e1)
    is0f <- is0(f0 <- callGeneric(0, e2)) #
    if(all(is0f)) { ## result keeps sparseness structure of e1
	if(l2 > 1) {  #	 "recycle" e2 "carefully"
	    e2 <- e2[.Ops.recycle.ind(e1, len = l2)]
	}
	e1@x <- callGeneric(e1@x, e2)
	if(length(e1@factors)) # TODO: be smarter and try *updating* (some) 'factors':
	    e1@factors <- list()
	e1
    } else if(mean(is0f) > 7/8) { ## remain sparse ['7/8' is *somewhat* arbitrary]
	if(l2 > 1) ## as not all callGeneric(0, e2) is 0, e2 is typically sparse
	    callGeneric(e1, as(e2, "sparseVector"))
	else { ## l2 == 1: e2 is "scalar"
	    e1@x <- callGeneric(e1@x, e2)
	    if(length(e1@factors)) # TODO: be smarter (see above)
		e1@factors <- list()
	    e1
	}
    }
    else { ## non-sparse, since '0 o e2' is not (all) 0
	r <- as(e1, "matrix")
	if(l2 == 1) {
	    r[] <- f0
	    r[non0ind(e1, getClassDef("dgCMatrix")) + 1L] <- callGeneric(e1@x, e2)
	    ..2dge(r)
	} else {
	    as(callGeneric(r, e2), "dgeMatrix")
	}
    }
}
setMethod("Arith", signature(e1 = "dgCMatrix", e2 = "numeric"), A.M.n)
setMethod("Arith", signature(e1 = "dgCMatrix", e2 = "logical"), A.M.n)
## coercing to "general*" / "dgC*"  would e.g. lose symmetry of  'S * 3'
setMethod("Arith", signature(e1 = "dsparseMatrix", e2 = "numeric"), .Arith.CM.atom)
setMethod("Arith", signature(e1 = "dsparseMatrix", e2 = "logical"), .Arith.CM.atom)

A.n.M <- function(e1, e2) {
    if((l1 <- length(e1)) == 0) # return 0-vector of e2's kind, as <0> + matrix()
	return(if(length(e2)) vector(.type.kind[.M.kind(e2)]) else e2)
    is0f <- is0(f0 <- callGeneric(e1, 0))
    if(all(is0f)) { ## result keeps sparseness structure of e2
	if(l1 > 1) {  #	 "recycle" e1 "carefully"
	    e1 <- e1[.Ops.recycle.ind(e2, len = l1)]
	}
	e2@x <- callGeneric(e1, e2@x)
	if(length(e2@factors))# TODO: be much smarter and try *updating* (some) 'factors':
	    e2@factors <- list()
	e2
    } else if(mean(is0f) > 7/8) { ## remain sparse ['7/8' is *somewhat* arbitrar
	if(l1 > 1) ## as not all callGeneric(e1, 0) is 0, e1 is typically sparse
	    callGeneric(as(e1, "sparseVector"), e2)
	else { ## l1 == 1: e1 is "scalar"
	    e2@x <- callGeneric(e1, e2@x)
	    if(length(e2@factors))# TODO: be much smarter (see above)
		e2@factors <- list()
	    e2
	}
    }
    else { ## non-sparse, since '0 o e2' is not (all) 0
	r <- as(e2, "matrix")
	if(l1 == 1) {
	    r[] <- f0
	    r[non0ind(e2, getClassDef("dgCMatrix")) + 1L] <-
		callGeneric(e1, e2@x)
	    ..2dge(r)
	} else {
	    as(callGeneric(e1, r), "dgeMatrix")
	}
    }
}
setMethod("Arith", signature(e1 = "numeric", e2 = "dgCMatrix"), A.n.M)
setMethod("Arith", signature(e1 = "logical", e2 = "dgCMatrix"), A.n.M)
## coercing to "general*" / "dgC*"  would e.g. lose symmetry of  '3 * S'
setMethod("Arith", signature(e1 = "numeric", e2 = "dsparseMatrix"), .Arith.atom.CM)
setMethod("Arith", signature(e1 = "logical", e2 = "dsparseMatrix"), .Arith.atom.CM)
rm(A.M.n, A.n.M)

##-------- originally from ./Csparse.R --------------------

setMethod("Arith", signature(e1 = "CsparseMatrix", e2 = "CsparseMatrix"),
	  function(e1, e2) {
	      ## go via "symmetric" if both are symmetric, etc...
	      s1 <- .M.shape(e1, getClassDef(class(e1)))
	      s2 <- .M.shape(e2, getClassDef(class(e2)))
	      viaCl <- paste0("d", if(s1 == s2) s1 else "g", "CMatrix")
	      callGeneric(as(as(e1, "dMatrix"), viaCl),
			  as(as(e2, "dMatrix"), viaCl))
	  })

setMethod("Logic", signature(e1 = "CsparseMatrix", e2 = "CsparseMatrix"),
	  function(e1, e2) {
	      ## go via "symmetric" if both are symmetric, etc...
	      s1 <- .M.shape(e1, getClassDef(class(e1)))
	      s2 <- .M.shape(e2, getClassDef(class(e2)))
	      viaCl <- paste0("l", if(s1 == s2) s1 else "g", "CMatrix")
	      callGeneric(as(as(e1, "lMatrix"), viaCl),
			  as(as(e2, "lMatrix"), viaCl))
	  })



setMethod("Compare", signature(e1 = "CsparseMatrix", e2 = "CsparseMatrix"),
	  function(e1, e2) {
	      d <- dimCheck(e1,e2)

	      ## How do the "0" or "FALSE" entries compare?
	      ## Depends if we have an "EQuality RELation" or not:
	      EQrel <- switch(.Generic,
			      "==" =, "<=" =, ">=" = TRUE,
			      "!=" =, "<"  =, ">"  = FALSE)
	      if(EQrel) {
		  ## The (0 op 0) or  (FALSE op FALSE) comparison gives TRUE
		  ## -> result becomes *dense*; the following may be suboptimal
		  return( callGeneric(as(e1, "denseMatrix"),
				      as(e2, "denseMatrix")))
	      }

	      ## else: INequality:   0 op 0 gives FALSE ---> remain sparse!

              cD1 <- getClassDef(class(e1))
              cD2 <- getClassDef(class(e2))
	      Matrix.msg(sprintf("Compare <Csparse> -- \"%s\" %s \"%s\" :\n",
				 cD1@className, .Generic,
				 cD2@className), .M.level = 2)

	      ## NB non-diagonalMatrix := Union{ general, symmetric, triangular}
	      gen1 <- extends(cD1, "generalMatrix")
	      gen2 <- extends(cD2, "generalMatrix")
	      sym1 <- !gen1 && extends(cD1, "symmetricMatrix")
	      sym2 <- !gen2 && extends(cD2, "symmetricMatrix")
	      tri1 <- !gen1 && !sym1
	      tri2 <- !gen2 && !sym2
	      G <- gen1 && gen2
	      S <- sym1 && sym2 && e1@uplo == e2@uplo
	      T <- tri1 && tri2 && e1@uplo == e2@uplo

	      if(T && e1@diag != e2@diag) {
		  ## one is "U" the other "N"
		  if(e1@diag == "U")
		      e1 <- diagU2N(e1)
		  else ## (e2@diag == "U"
		      e2 <- diagU2N(e2)
		  shape <- "t"
	      }
	      else if(!G && !S && !T) {
		  ## e.g. one symmetric, one general
		  ## coerce to generalMatrix and go :
		  if(!gen1) e1 <- as(e1, "generalMatrix", strict = FALSE)
		  if(!gen2) e2 <- as(e2, "generalMatrix", strict = FALSE)
		  shape <- "g"
	      } else {
		  shape <- if(T) "t" else if(S) "s" else "g"
	      }

	      dn <- dimNamesCheck(e1, e2) ## <- FIXME: for 'S'; allow staying
              ## the result object:
	      newC <- sub("^.", "l", MatrixClass(class(e1)))
              ## FIXME: "n" result when e1 & e2 are "n", or even whenever possible
	      r <- new(newC)
              e1is.n <- extends(cD1, "nMatrix")
              e2is.n <- extends(cD2, "nMatrix")
              ## Easy case: identical sparsity pattern
	      if(identical(e1@i, e2@i) && identical(e1@p, e2@p)) {
		  if(e1is.n) {
		      if(e2is.n)
			  ## non-equality of identical pattern matrices: all FALSE
			  r@p <- rep.int(0L, d[2]+1L) # and r@i, r@x remain empty
		      else { ## e1 pattern, e2@x
			  rx <- callGeneric(TRUE, e2@x)
			  if(allFalse(rx))
			      r@p <- rep.int(0L, d[2]+1L) # and r@i, r@x remain empty
			  else {
			      r@x <- rx
			      r@i <- e2@i
			      r@p <- e2@p
			  }
		      }
		  } else if(e2is.n) { ## e1@x, e2 pattern
		      rx <- callGeneric(e1@x, TRUE)
		      if(allFalse(rx))
			  r@p <- rep.int(0L, d[2]+1L) # and r@i, r@x remain empty
		      else {
			  r@x <- rx
			  r@i <- e1@i
			  r@p <- e1@p
		      }
		  } else {		# both have 'x' slot
		      r@x <- callGeneric(e1@x, e2@x)
		      ## and all others are  '0 op 0' which give FALSE
		      r@i <- e1@i
		      r@p <- e1@p
		  }
		  r@Dim <- d
		  r@Dimnames <- dn
		  r
	      }
              else {
                  ## now the 'x' slots ``match'' insofar as they are for the
                  ## same "space" (triangle for tri* and symm*; else rectangle)

                  ## not non0ind() which gives more;
                  ## want only those which correspond to 'x' slot
                  ij1 <- .Call(compressed_non_0_ij, e1, TRUE)
                  ij2 <- .Call(compressed_non_0_ij, e2, TRUE)
                  ii <- WhichintersectInd(ij1, ij2, di=d)
                  I1 <- ii[[1]]; has1 <- length(I1) > 0
                  I2 <- ii[[2]]; has2 <- length(I2) > 0

		  ## potentially could be faster for 'nsparse' but this is simple:
		  e1x <- if(e1is.n) rep.int(1L, length(e1@i)) else e1@x
		  e2x <- if(e2is.n) rep.int(1L, length(e2@i)) else e2@x

		  ## 1) common
		  x <- callGeneric(e1x[I1],
				   e2x[I2])
		  ## 2) "e1 o  0":
		  x2 <- callGeneric(if(has1) e1x[- I1] else e1x, 0)
		  ## 3) "0  o e2":
		  x3 <- callGeneric(0, if(has2) e2x[- I2] else e2x)

		  i <- c(ij1[I1, 1],
			 if(has1) ij1[-I1, 1] else ij1[, 1],
			 if(has2) ij2[-I2, 1] else ij2[, 1])
		  j <- c(ij1[I1, 2],
			 if(has1) ij1[-I1, 2] else ij1[, 2],
			 if(has2) ij2[-I2, 2] else ij2[, 2])
		  x <- c(x, x2, x3)
		  if(any(i0x <- is0(x))) { # drop 'FALSE's
		      n0 <- !i0x
		      i <- i[n0]
		      j <- j[n0]
		      x <- x[n0]
		  }
		  .Call(Tsparse_to_Csparse,
			if(e1is.n && e2is.n)
			new(paste0("n",shape,"TMatrix"), Dim = d,
			    Dimnames = dn, i = i, j = j)
			else new(paste0("l",shape,"TMatrix"), Dim = d,
				 Dimnames = dn, i = i, j = j, x = x),
			FALSE)
              }
	  })


##-------- originally from ./sparseMatrix.R --------------------

## "Arith" short cuts / exceptions
setMethod("-", signature(e1 = "sparseMatrix", e2 = "missing"),
	  function(e1, e2) {
	      e1 <- diagU2N(e1)
	      e1@x <- -e1@x
	      e1@factors <- list()# Drop Cholesky factors; TODO: Consider to modify & keep LU
	      e1
	  })
## with the following exceptions:
setMethod("-", signature(e1 = "nsparseMatrix", e2 = "missing"),
	  function(e1,e2) callGeneric(as(as(as(e1, "CsparseMatrix"), "dMatrix"), "dgCMatrix")))
setMethod("-", signature(e1 = "pMatrix", e2 = "missing"),
          function(e1,e2) callGeneric(as(e1, "ngTMatrix")))

## Group method  "Arith"

## have CsparseMatrix methods above
## which may preserve "symmetric", "triangular" -- simply defer to those:

setMethod("Ops", signature(e1 = "sparseMatrix", e2 = "nsparseMatrix"),
	  function(e1, e2) callGeneric(as(e1, "CsparseMatrix"),
				       as(e2, "lsparseMatrix")))
setMethod("Ops", signature(e1 = "nsparseMatrix", e2 = "sparseMatrix"),
	  function(e1, e2) callGeneric(as(e1, "lsparseMatrix"),
				       as(e2, "CsparseMatrix")))

## these were 'Arith', now generalized:
if(FALSE) { ## just shifts the ambiguity warnings ..
## <sparse> o <sparse> more complicated - against PITA disambiguation warnings:
setMethod("Ops", signature(e1 = "TsparseMatrix", e2 = "TsparseMatrix"),
	  function(e1, e2) callGeneric(as(e1, "CsparseMatrix"),
				       as(e2, "CsparseMatrix")))
setMethod("Ops", signature(e1 = "TsparseMatrix", e2 = "CsparseMatrix"),
	  function(e1, e2) callGeneric(as(e1, "CsparseMatrix"), e2))
setMethod("Ops", signature(e1 = "CsparseMatrix", e2 = "TsparseMatrix"),
	  function(e1, e2) callGeneric(e1, as(e2, "CsparseMatrix")))
}
## catch the rest:  Rsparse*  and  T*  o  R*
setMethod("Ops", signature(e1 = "sparseMatrix", e2 = "sparseMatrix"),
	  function(e1, e2) callGeneric(as(e1, "CsparseMatrix"),
				       as(e2, "CsparseMatrix")))

setMethod("Ops", signature(e1 = "sparseMatrix", e2 = "numeric"),
	  function(e1, e2) callGeneric(as(e1, "CsparseMatrix"), e2))
setMethod("Ops", signature(e1 = "numeric", e2 = "sparseMatrix"),
	  function(e1, e2) callGeneric(e1, as(e2, "CsparseMatrix")))

## setMethod("Compare", signature(e1 = "sparseMatrix", e2 = "sparseMatrix"),
## 	  function(e1, e2) callGeneric(as(e1, "CsparseMatrix"),
## 				       as(e2, "CsparseMatrix")))

###-------- sparseVector -------------
###-------- ============ -------------

## Catch all remaining
setMethod("Ops", signature(e1 = "sparseVector", e2 = "ANY"),
          function(e1, e2) .bail.out.2(.Generic, class(e1), class(e2)))
setMethod("Ops", signature(e1 = "ANY", e2 = "sparseVector"),
          function(e1, e2) .bail.out.2(.Generic, class(e1), class(e2)))

## 1)  spVec  o  (sp)Vec : -------------

## FIXME:
##   2. <spVec>  o  <non-NA numeric>  should also happen directly and
##                                    |-> sparse for o = {'*', "/", '&&', '==', ...

setMethod("Ops", signature(e1 = "sparseVector", e2 = "atomicVector"),
	  function(e1, e2) {
	      if(length(e2) == 1) { ## scalar ------ special case - "fast"
		  if(all0(callGeneric(FALSE, e2))) { # result remains sparse
		      if(is(e1, "nsparseVector")) { # no 'x' slot, i.e. all TRUE
			  r <- callGeneric(TRUE, e2)
			  if(is.logical(r)) {
			      if(isTRUE(all(r))) # (could be NA)
				  e1	# result unchanged
			      else
				  newSpVec("lsparseVector", x = r, e1)
			  } else {
			      newSpVec(paste0(if(is.integer(r)) "i" else "d", "sparseVector"),
				       x = r, e1)
			  }
		      } else { # has x slot
			  r <- callGeneric(e1@x, e2)
			  if(identical(class(r), class(e1@x))) {
			      e1@x <- r
			      e1
			  } else {
			      newSpVec(paste0(.V.kind(r), "sparseVector"), x = r, e1)
			  }
		      }
		  }
		  else ## non-sparse result
		      callGeneric(sp2vec(e1), e2)
	      }
	      else ## e2 is not scalar
		  callGeneric(e1, as(e2, "sparseVector"))
	  })

setMethod("Ops", signature(e1 = "atomicVector", e2 = "sparseVector"),
	  function(e1, e2) {
	      if(length(e1) == 1) { ## scalar ------ special case - "fast"
		  if(all0(callGeneric(e1, FALSE))) { # result remains sparse
		      if(is(e2, "nsparseVector")) { # no 'x' slot, i.e. all TRUE
			  r <- callGeneric(e1, TRUE)
			  if(is.logical(r)) {
			      if(isTRUE(all(r))) # (could be NA)
				  e2	# result unchanged
			      else
				  newSpVec("lsparseVector", x = r, e2)
			  } else {
			      newSpVec(paste0(if(is.integer(r)) "i" else "d", "sparseVector"),
				       x = r, e2)
			  }
		      } else { # has x slot
			  r <- callGeneric(e1, e2@x)
			  if(identical(class(r), class(e2@x))) {
			      e2@x <- r
			      e2
			  } else {
			      newSpVec(paste0(.V.kind(r), "sparseVector"), x = r, e2)
			  }
		      }
		  }
		  else ## non-sparse result
		      callGeneric(e1, sp2vec(e2))
	      }
	      else ## e1 is not scalar
		  callGeneric(as(e1, "sparseVector"), e2)
	  })


Ops.spV.spV <- function(e1, e2) {
    n1 <- e1@length
    n2 <- e2@length
    if(!n1 || !n2) ## return 0-length :
	return(if(is.na(match(.Generic, .ArithGenerics))) logical() else numeric())
    ## else  n1, n2 >= 1 :
    if(n1 != n2) {
	if(n1 < n2) {
	    n <- n1 ; N <- n2
	} else {
	    n <- n2 ; N <- n1
	}
        if(n == 1L) { # simple case, do not really recycle
	    if(n1 < n2) return(callGeneric(sp2vec(e1), e2))
	    else	return(callGeneric(e1, sp2vec(e2)))
	}
	## else : 2 <= n < N
	if(N %% n != 0)
	    warning("longer object length is not a multiple of shorter object length")
        ## recycle the shorter one
	if(n1 < n2) {
            e1 <- rep(e1, length = N)
	} else {
            e2 <- rep(e2, length = N)
	}
    } else { ## n1 == n2
	N <- n1
    }
    ## ---- e1 & e2 now are both of length 'N' ----

    ## First check the (0  o  0) result
    is1n <- extends(class(e1), "nsparseVector")
    is2n <- extends(class(e2), "nsparseVector")
    r00 <- callGeneric(if(is1n) FALSE else as0(e1@x),
		       if(is2n) FALSE else as0(e2@x))
    if(is0(r00)) { ## -> sparseVector
	e1x <- if(is1n) TRUE else e1@x
	e2x <- if(is2n) TRUE else e2@x
	sp <- .setparts(e1@i, e2@i)
	## Idea: Modify 'e2' and return it :
	new.x <- c(callGeneric(e1x[sp[["ix.only"]]], 0), # e1-only
		   callGeneric(0, e2x[sp[["iy.only"]]]), # e2-only
		   callGeneric(e1x[sp[["my"]]],          # common to both
			       e2x[sp[["mx"]]]))
	i. <- c(sp[["x.only"]], sp[["y.only"]], sp[["int"]])
	cl2x <- typeof(e2x) ## atomic "class"es - can use in is(), as(), too:
	if(!is2n && is(new.x, cl2x)) {
	    i. <- sort.int(i., method = "quick", index.return=TRUE)
	    e2@x <- as(new.x, cl2x)[i.$ix]
	    e2@i <- i.$x
	    e2
	} else {
	    newSpV(paste0(.kind.type[typeof(new.x)],"sparseVector"),
		   x = new.x, i = i., length = e2@length)
	}
    } else { ## 0 o 0  is NOT in {0 , FALSE} --> "dense" result
	callGeneric(sp2vec(e1),	 sp2vec(e2))
    }
} ## {Ops.spV.spV}

## try to use it in all cases
setMethod("Ops", signature(e1 = "sparseVector", e2 = "sparseVector"),
	  Ops.spV.spV)
## was    function(e1, e2) .bail.out.2(.Generic, class(e1), class(e2)))

setMethod("Arith", signature(e1 = "sparseVector", e2 = "sparseVector"),
	  function(e1, e2) callGeneric(as(e1, "dsparseVector"),
				       as(e2, "dsparseVector")))
setMethod("Arith", signature(e1 = "dsparseVector", e2 = "dsparseVector"),
	  Ops.spV.spV)

## "Arith"  exception (shortcut)
setMethod("-", signature(e1 = "dsparseVector", e2 = "missing"),
	  function(e1) { e1@x <- -e1@x ; e1 })


setMethod("Logic", signature(e1 = "sparseVector", e2 = "sparseVector"),
	  ## FIXME: this is suboptimal for "nsparseVector" !!
	  function(e1, e2) callGeneric(as(e1, "lsparseVector"),
				       as(e2, "lsparseVector")))

setMethod("Logic", signature(e1 = "lsparseVector", e2 = "lsparseVector"),
	  Ops.spV.spV)

## "nsparse" have no 'x' slot --> version of Ops.spV.spV..
## --------  but also for (nsp.. o lsp..) etc, when  lsp... has no NA
if(FALSE) ### FIXME
setMethod("Logic", signature(e1 = "nsparseVector", e2 = "nsparseVector"),
	  function(e1, e2) {
	      .bail.out.2(.Generic, class(e1), class(e2))
	  })


## 2)  spVec  o  [Mm]atrix : -------------

Ops.M.spV <- function(e1, e2) {
    d <- e1@Dim
    n1 <- prod(d)
    n2 <- e2@length
    if(n1 != n2) {
	if(n1 && n1 < n2) { # 0-extent matrix + vector is fine
	    stop(sprintf(
		"dim [product %d] do not match the length of object [%d]",
			 n1, n2))
	}
	## else	 n1 > n2 [vector]
	N <- n1
	if(n2 == 1) ## simple case, do not really recycle
	    return(callGeneric(e1, sp2vec(e2)))
	if(N %% n2 != 0)
	    warning("longer object length is not a multiple of shorter object length")
	## else : 2 <= n < N --- recycle the vector
        e2 <- rep(e2, length = N)
    } else { ## n1 == n2
	N <- n1
    }
    ## ---- e1 & e2 now are both of length 'N' ----
    dim(e2) <- d #-> sparseMatrix (!)
    callGeneric(e1, e2)
}## {Ops.M.spV}

Ops.spV.M <- function(e1, e2) {
    n1 <- e1@length
    d <- e2@Dim
    n2 <- prod(d)
    if(n2 != n1) {
	if(n2 && n2 < n1) { # vector + 0-extent matrix  is fine
	    stop(sprintf(
		"dim [product %d] do not match the length of object [%d]",
			 n2, n1))
	}
	## else	 n2 > n1 [vector]
	N <- n2
	if(n1 == 1) ## simple case, do not really recycle
	    return(callGeneric(sp2vec(e1), e2))
	if(N %% n1 != 0)
	    warning("longer object length is not a multiple of shorter object length")
	## else : 2 <= n < N --- recycle the vector
        e1 <- rep(e1, length = N)
    } else { ## n2 == n1
	N <- n2
    }
    ## ---- e2 & e1 now are both of length 'N' ----
    dim(e1) <- d #-> sparseMatrix (!)
    callGeneric(e1, e2)
}## {Ops.spV.M}

## try to use it in all cases
setMethod("Ops", signature(e1 = "Matrix", e2 = "sparseVector"), Ops.M.spV)
setMethod("Ops", signature(e1 = "sparseVector", e2 = "Matrix"), Ops.spV.M)
