1 files changed, 27 insertions, 5 deletions
diff --git a/R/DFOP.solution.R b/R/DFOP.solution.R
index 8531cfed..608e7e18 100644
--- a/R/DFOP.solution.R
+++ b/R/DFOP.solution.R
@@ -1,5 +1,27 @@
-DFOP.solution <- function(t, parent.0, k1, k2, g)
-{
-	parent = g * parent.0 * exp(-k1 * t) +
-		 (1 - g) * parent.0 * exp(-k2 * t)
-}
+#' Double First-Order in Parallel kinetics
+#' 
+#' Function describing decline from a defined starting value using the sum of
+#' two exponential decline functions.
+#' 
+#' @param t Time.
+#' @param parent.0 Starting value for the response variable at time zero.
+#' @param k1 First kinetic constant.
+#' @param k2 Second kinetic constant.
+#' @param g Fraction of the starting value declining according to the first
+#'   kinetic constant.
+#' @return The value of the response variable 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
+#' 
+#'   plot(function(x) DFOP.solution(x, 100, 5, 0.5, 0.3), 0, 4, ylim = c(0,100))
+#' 
+#' @export
+DFOP.solution <- function(t, parent.0, k1, k2, g)
+{
+	parent = g * parent.0 * exp(-k1 * t) +
+		 (1 - g) * parent.0 * exp(-k2 * t)
+}