R/logsd_of_lognorm_function.R

In niknap/ScalingFunctions: Collection of functions for scaling of distributions

# Copyright (C) 2019 Dr. Nikolai Knapp, UFZ
#
# This file is part of the ScalingFunctions R package.
#
# The ScalingFunctions R package is free software: you can redistribute
# it and/or modify it under the terms of the GNU General Public License
# as published by the Free Software Foundation, either version 3 of the
# License, or (at your option) any later version.
#
# ScalingFunctions 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 General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with ScalingFunctions. If not, see <http://www.gnu.org/licenses/>.



#' Lognormal SD of lognormal distribution
#'
#' Calculation of the logarithmic standard deviation parameter (sigma)
#' of a lognormal distribution from distribution moments
#' @param arithmean Arithmetic mean
#' @param arithsd Arithmetic standard deviation
#' @return Logarithmic standard deviation of lognormal distribution (sigma parameter)
#' @author Nikolai Knapp, nikolai.knapp@ufz.de

logsd_of_lognorm <- function(arithmean, arithsd){
  logsd <- (log(1 + arithsd^2/arithmean^2))^0.5
  names(logsd) <- "logsd"
  return(logsd)
}