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Diffstat (limited to 'R/SFORB.solution.R')
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diff --git a/R/SFORB.solution.R b/R/SFORB.solution.R deleted file mode 100644 index 2abe4577..00000000 --- a/R/SFORB.solution.R +++ /dev/null @@ -1,35 +0,0 @@ -#' Single First-Order Reversible Binding kinetics -#' -#' Function describing the solution of the differential equations describing -#' the kinetic model with first-order terms for a two-way transfer from a free -#' to a bound fraction, and a first-order degradation term for the free -#' fraction. The initial condition is a defined amount in the free fraction -#' and no substance in the bound fraction. -#' -#' @param t Time. -#' @param parent.0 Starting value for the response variable at time zero. -#' @param k_12 Kinetic constant describing transfer from free to bound. -#' @param k_21 Kinetic constant describing transfer from bound to free. -#' @param k_1output Kinetic constant describing degradation of the free -#' fraction. -#' @return The value of the response variable, which is the sum of free and -#' bound fractions at time \code{t}. -#' @references FOCUS (2006) \dQuote{Guidance Document on Estimating Persistence -#' and Degradation Kinetics from Environmental Fate Studies on Pesticides in -#' EU Registration} Report of the FOCUS Work Group on Degradation Kinetics, -#' EC Document Reference Sanco/10058/2005 version 2.0, 434 pp, -#' \url{http://esdac.jrc.ec.europa.eu/projects/degradation-kinetics} -#' @examples -#' -#' \dontrun{plot(function(x) SFORB.solution(x, 100, 0.5, 2, 3), 0, 2)} -#' -#' @export -SFORB.solution = function(t, parent.0, k_12, k_21, k_1output) { - sqrt_exp = sqrt(1/4 * (k_12 + k_21 + k_1output)^2 + k_12 * k_21 - (k_12 + k_1output) * k_21) - b1 = 0.5 * (k_12 + k_21 + k_1output) + sqrt_exp - b2 = 0.5 * (k_12 + k_21 + k_1output) - sqrt_exp - - parent = parent.0 * - (((k_12 + k_21 - b1)/(b2 - b1)) * exp(-b1 * t) + - ((k_12 + k_21 - b2)/(b1 - b2)) * exp(-b2 * t)) -} |