R/ops_multiplication.R

In polyMatrix: Infrastructure for Manipulation Polynomial Matrices

# Title     : multiplication
# Created by: namezys
# Created on: 2020. 10. 16.

.mult.polyMatrix.numeric <- function(e1, e2) {
  return(polyMatrix(e1@coef * e2, nrow(e1), ncol(e1), degree(e1)))
}

.mult.polyMatrix.polynomial <- function(e1, e2) {
  res_d <- degree(e1) + degree(e2)
  src_c_idx <- seq_len(ncol(e1@coef))
  nc <- ncol(e1)
  coef <- matrix(0, nrow(e1), nc * (res_d + 1))
  for(i in 0:degree(e2)) {
    column_idxs <- src_c_idx + nc * i
    coef[, column_idxs] <- coef[, column_idxs] + e1@coef * e2[i + 1]
  }
  return(polyMatrix(coef, nrow(e1), nc, res_d))
}

.mult.matrix.polynomial <- function (e1, e2) {
  return(.mult.polyMatrix.polynomial(polyMatrix(e1, nrow(e1), ncol(e1), 0), e2))
}

#' @rdname polyMatrix-Arith
#'
#' @return Binary `*` is elementwise multiplication with matrix or scalar operands.
#'
#' @export
setMethod("*", signature(e1 = PM, e2 = "numeric"), .mult.polyMatrix.numeric)
#' @rdname polyMatrix-Arith
#'
#' @export
setMethod("*", signature(e1 = PM, e2 = P), .mult.polyMatrix.polynomial)
#' @rdname polyMatrix-Arith
#'
#' @export
setMethod("*", signature(e1 = PM, e2 = PM), function(e1, e2) {
  stop("Per element multiplication for polyMatrix isn't supported")
})
#' @rdname polyMatrix-Arith
#'
#' @export
setMethod("*", signature(e1 = "ANY", e2 = PM), function(e1, e2) { e2 * e1 })