R/interPlagiophile.R

In RLeafAngle: Estimates, Plots and Evaluates Leaf Angle Distribution Functions, Calculates Extinction Coefficients

#' Compute the fraction leaf area of Plagiophile distribution given leaf angle intervals (in degree).
#' @description Compute the fraction leaf area of Plagiophile distribution given leaf angle intervals (in degree).
#' @param AngleLower The lower limit of leaf angle intervals in degree.
#' @param AngleUpper The upper limit of leaf angle intervals in degree.
#' @return Compute the fraction leaf area of Plagiophile function.
#' @author Wei-Min Wang (wmwang AT gmail.com)
#' @references  Wang, W. M., Li, Z. L., & Su, H. B. (2007). 
#' Comparison of leaf angle distribution functions: effects on extinction coefficient and 
#' fraction of sunlit foliage. Agricultural and Forest Meteorology, 143(1), 106-122.
#' @examples
#' interPlagiophile(40,50)
#' @export
#' 


interPlagiophile<-function(AngleLower, AngleUpper)
{
  plagiophileLAD<-function(LeafAngle)
  {
    #plagiophile- oblique leaves most frequent
    2*(1-cos(4*LeafAngle))/pi
  }      
  pi180<-pi/180.0
  fraction<-integrate(plagiophileLAD, lower=AngleLower*pi180, upper=AngleUpper*pi180)
  fraction[[1]]
}