#### Triangular Matrices -- Coercion and Methods

## or rather setIs() {since test can fail }?
setAs("dgeMatrix", "dtrMatrix",
      function(from) {
          ## FIXME: also check for unit-diagonal: 'diag = "U"'
	  if(isTriangular(from, upper = TRUE))
	      new("dtrMatrix", x = from@x, Dim = from@Dim, uplo = "U",
		  Dimnames = from@Dimnames)
	  else if(isTriangular(from, upper = FALSE))
	      new("dtrMatrix", x = from@x, Dim = from@Dim, uplo = "L",
		  Dimnames = from@Dimnames)
	  else stop("not a triangular matrix")
      })

setAs("dgeMatrix", "triangularMatrix", function(from) as(from, "dtrMatrix"))

setAs("dtrMatrix", "dtpMatrix",
      function(from) .Call(dtrMatrix_as_dtpMatrix, from))

setAs("dtrMatrix", "sparseMatrix", .dense2C)
setAs("dtrMatrix", "CsparseMatrix", .dense2C)


## needed for t() method
setAs("dtrMatrix", "matrix",
      function(from) .Call(dtrMatrix_as_matrix, from))

setAs("matrix", "dtrMatrix",
      function(from) as(.Call(dup_mMatrix_as_dgeMatrix, from), "dtrMatrix"))

setAs("Cholesky", "lMatrix",
      function(from) as(as(from, "dtrMatrix"), "lMatrix"))
setAs("BunchKaufman", "lMatrix",
      function(from) as(as(from, "dtrMatrix"), "lMatrix"))


## Group Methods:
## TODO: carefully check for the cases where the result remains triangular
## instead : inherit them from "dgeMatrix" via definition in ./dMatrix.R

## Note: Just *because* we have an explicit  dtr -> dge coercion,
##       show( <ddenseMatrix> ) is not okay, and we need our own:
setMethod("show", "dtrMatrix", function(object) prMatrix(object))

setMethod("%*%", signature(x = "dtrMatrix", y = "ddenseMatrix"),
	  function(x, y) .Call(dtrMatrix_matrix_mm, x, y, FALSE),
          valueClass = "dgeMatrix")

setMethod("%*%", signature(x = "dtrMatrix", y = "matrix"),
	  function(x, y) .Call(dtrMatrix_matrix_mm, x, y, FALSE),
          valueClass = "dgeMatrix")

setMethod("%*%", signature(x = "dgeMatrix", y = "dtrMatrix"),
	  function(x, y) .Call(dtrMatrix_matrix_mm, y, x, TRUE),
          valueClass = "dgeMatrix")

setMethod("%*%", signature(x = "matrix", y = "dtrMatrix"),
	  function(x, y) .Call(dtrMatrix_matrix_mm, y, x, TRUE),
          valueClass = "dgeMatrix")

## no longer needed
## setMethod("%*%", signature(x = "dtrMatrix", y = "dtrMatrix"),
## 	  function(x, y) callGeneric(x = x, y = as(y, "dgeMatrix")),
##           valueClass = "dgeMatrix")

setMethod("crossprod", signature(x = "dtrMatrix", y = "missing"),
	  function(x, y = NULL) callGeneric(x = as(x, "dgeMatrix")),
	  valueClass = "dpoMatrix")

setMethod("determinant", signature(x = "dtrMatrix", logarithm = "missing"),
	  function(x, logarithm, ...) callGeneric(x, TRUE))

setMethod("determinant", signature(x = "dtrMatrix", logarithm = "logical"),
	  function(x, logarithm, ...) {
	      dg <- diag(x)
	      if (logarithm) {
		  modulus <- sum(log(abs(dg)))
		  sgn <- prod(sign(dg))
	      } else {
		  modulus <- prod(dg)
		  sgn <- sign(modulus)
		  modulus <- abs(modulus)
	      }
	      attr(modulus, "logarithm") <- logarithm
	      val <- list(modulus = modulus, sign = sgn)
	      class(val) <- "det"
	      val
	  })

setMethod("diag", signature(x = "dtrMatrix"),
          function(x, nrow, ncol = n) .Call(dtrMatrix_getDiag, x),
          valueClass = "numeric")

setMethod("norm", signature(x = "dtrMatrix", type = "character"),
	  function(x, type, ...)
	  .Call(dtrMatrix_norm, x, type),
	  valueClass = "numeric")

setMethod("norm", signature(x = "dtrMatrix", type = "missing"),
	  function(x, type, ...)
	  .Call(dtrMatrix_norm, x, "O"),
	  valueClass = "numeric")

setMethod("rcond", signature(x = "dtrMatrix", type = "character"),
	  function(x, type, ...)
	  .Call(dtrMatrix_rcond, x, type),
	  valueClass = "numeric")

setMethod("rcond", signature(x = "dtrMatrix", type = "missing"),
	  function(x, type, ...)
	  .Call(dtrMatrix_rcond, x, "O"),
	  valueClass = "numeric")

setMethod("solve", signature(a = "dtrMatrix", b="missing"),
	  function(a, b, ...)
	  .Call(dtrMatrix_solve, a),
	  valueClass = "dtrMatrix")

setMethod("solve", signature(a = "dtrMatrix", b="ddenseMatrix"),
	  function(a, b, ...)
          .Call(dtrMatrix_matrix_solve, a, b),
	  valueClass = "dgeMatrix")

setMethod("solve", signature(a = "dtrMatrix", b="matrix"),
	  function(a, b, ...)
          .Call(dtrMatrix_matrix_solve, a, b),
	  valueClass = "dgeMatrix")

setMethod("t", signature(x = "dtrMatrix"), t_trMatrix)