FuzzyNumbers: Tools to Deal with Fuzzy Numbers

## This file is part of the FuzzyNumbers package
##
## Copyright 2012-2019 Marek Gagolewski
##
##
## FuzzyNumbers is free software: you can redistribute it and/or modify
## it under the terms of the GNU Lesser General Public License as published by
## the Free Software Foundation, either version 3 of the License, or
## (at your option) any later version.
##
## FuzzyNumbers is distributed in the hope that it will be useful,
## but WITHOUT ANY WARRANTY; without even the implied warranty of
## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
## GNU Lesser General Public License for more details.
##
## You should have received a copy of the GNU Lesser General Public License
## along with FuzzyNumbers. If not, see <http://www.gnu.org/licenses/>.



#' @title
#' Calculate the Value of a Fuzzy Number
#'
#' @description
#' The calculation of the so-called value is one of possible methods to
#' deffuzify a fuzzy number.
#'
#' @details
#' The value of \eqn{A} (Delgrado et al, 1998) is defined as
#' \eqn{val(A) := \int_0^1 \alpha\left(A_L(\alpha)+A_U(\alpha)\right)\,d\alpha}{val(A) := int_0^1 \alpha(A_L(\alpha) + A_U(\alpha))d\alpha}.
#'
#' @param object a fuzzy number
#' @param ... additional arguments passed to \code{\link{alphaInterval}}
#' 
#' @return Returns a single numeric value.
#'
#' @exportMethod value
#' @docType methods
#' @name value
#' @family FuzzyNumber-method
#' @family deffuzification
#' @family characteristics
#' @rdname value-methods
#' @aliases value,FuzzyNumber-method
#' @usage
#' \S4method{value}{FuzzyNumber}(object, ...)
#' @references
#' Delgado M., Vila M.A., Voxman W. (1998), On a canonical representation of a fuzzy number,
#' Fuzzy Sets and Systems 93, pp. 125-135.
setGeneric("value",
           function(object, ...) standardGeneric("value"))



setMethod(
   f="value",
   signature(object="FuzzyNumber"),
   definition=function(object, ...)
   {
      return(sum(alphaInterval(object, ...)))
   }
)