R/method_is_zero.R

In polyMatrix: Infrastructure for Manipulation Polynomial Matrices

#' Tests if something is zero or not
#'
#' Generic function to check if we can treat on object as being zero.
#' For matrices the result is a matrix of the same size.
#'
#' @param x An \R object
#' @param eps The minimal numerical value which will not be treated as zero
#' @return TRUE if the object can be treat as zero
#'
#' @details
#' Different type of objects can be treated as zero in different ways:
#' * Numerical types can be compared by absolute value with `eps`.
#' * Other types should define its own method.
#'
#' By befault `eps` = `{r} ZERO_EPS`
#'
#' @seealso [zero.round()]
#'
#' @examples
#'
#' # numericals and matrices
#' is.zero(0)  ## TRUE
#'
#' is.zero(0.0001, eps=0.01)  ## TRUE
#'
#' is.zero(c(0, 1, 0))  ## TRUE, FALSE, TRUE
#'
#' is.zero(matrix(c(1, 9, 0, 0), 2, 2))
#' ## FALSE TRUE
#' ## FALSE TRUE
#'
#' @export
setGeneric("is.zero", function (x, eps=ZERO_EPS) {abs(x) < eps})

#' @describeIn is.zero a polynomial can be treated as zero
#' if all its coefficients can be treated as zero
#'
#' @examples
#'
#' # polynomials
#' is.zero(parse.polynomial("0.1 - 0.5 x")) ## FALSE
#' is.zero(parse.polynomial("0.0001 - 0.0005 x + 0.00002 x^2"), eps=0.01) ## TRUE
#'
#' @export
setMethod("is.zero", signature(x=P), function (x, eps=ZERO_EPS) {all(abs(as.numeric(x)) < eps)})

#' @describeIn is.zero for a polynomial matrix every item is checked if it is zero polynomial
#'
#' @export
setMethod("is.zero", signature(x=PM), function (x, eps=ZERO_EPS) {
  return(polyMatrix.apply(x, function(x) {is.zero(x, eps=eps)}))
})