BAST1-R-Library: BAST R function library.

#' For testing equivalence of numbers.
#'
#' Operator that is similar to ==, for comparing two numeric vectors.
#'
#' @author Aaron Hayman
#' @param a numeric vector to be tested for equivalence.
#' @param b numeric vector to be tested against \eqn{a} for equivalence.
#' @return TRUE if all but the insignificant parts are identical.
#' @details This operator works with the option insigbits, which should be an integer between 1 and 8. The option insigbits defines how many bits
#'          (from least significant) will be considered as insignificant in deciding upon equality.
#' @note Default for insigbits is 6, it can be changed by using \deqn{options(insigbits = #),} where \eqn{#} is the desired value.
#' @examples
#' a = 90
#' b = 100*(0.95 - 0.05)  # 90
#' a == b  # FALSE
#' a - b  # 1.421085e-14
#' a %==% b  # TRUE
#' @usage a \%==\% b
#' @rdname EqualsEquals
#' @export



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####                                         %==%                                                  ####
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# Operator that is similar to ==, for comparing two numeric vectors.
# This operator works with the option insigbits, which should be an integer between 1 and 8. The option
# insigbit defines how many bits (from least significant) will be considered as insignificant in deciding upon equallity.
#
# Operator returns TRUE if all but the insignificant bits are identical.
# Default for insigbits is 6, it can be chaged by using options(insigbits= )


"%==%" = function(a,b)
{
  if(mode(a)!='numeric' | mode(b)!='numeric' )
  { return(a==b)}
  a=as.numeric(a)					# a and b are converted to numeric
  b=as.numeric(b)

  if(is.null(options()$sigfigs)) options(sigfigs=13)

  # new code
  a=signif(a,options()$sigfigs)
  b=signif(b,options()$sigfigs)
  return(a==b)

  # previous code below has problems
  #ra=raw()					# empty raw vectors are prepared
  #rb=raw()
  #ra=writeBin(a,ra)				# a and b are converted to raw (byte) format
  #rb=writeBin(b,ra)
  #ind=seq(1L,length(ra),by=8L)			# index for every first byte in numbers, (R uses little endian format, numerics are 8 bytes long)
  #ra[ind]=ra[ind]|as.raw(2^options()$insigbits-1) # first bytes of a and b have the insignifant bits all changed to 1
  #rb[ind]=rb[ind]|as.raw(2^options()$insigbits-1)					# or operator, |, also and operator, &, have very interesting behaviours with raw vectors
  #tr=readBin(ra,'numeric',length(a))==readBin(rb,'numeric',length(b))	# raw vectors are coverted back to numbers and checked for equality
  #return(tr)
}

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###################### END OF %==% operator ########################
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