# computeG: Compute the mean projection of unit leaf area on the plane... In RLeafAngle: Estimates, Plots and Evaluates Leaf Angle Distribution Functions, Calculates Extinction Coefficients

## Description

Compute the mean projection of unit leaf area on the plane perpendicular to beam direction, namely, G parameter.

## Usage

 `1` ```computeG(LeafAngleZ, FractionZ, LeafAngleA, FractionA, theta, alpha) ```

## Arguments

 `LeafAngleZ` The center angles list of leaf zenith angle intervals. `FractionZ` The leaf area fraction list given leaf zenith angle intervals list. `LeafAngleA` The center angles list of leaf azimuth angle intervals. `FractionA` The leaf area fraction list given leaf azimuth angle intervals list. `theta` The zenith angle of beam direction. `alpha` The azimuth angle of beam direction.

## Value

The mean projection of unit leaf area on the plane perpendicular to beam direction, namely, G value.

## Author(s)

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

 ```1 2 3 4 5 6 7 8``` ```angleZ<-c(4.5, 13.5, 22.5, 31.5, 40.5, 49.5, 58.5, 67.5, 76.5, 85.5) angleA<-c(10,30,50,70,90,110,130,150,170,190,210,230,250,270,290,310,330,350) sADis<-sysAziDis() sZDis<-sphericalDis() for(solarZenith in 10:80) { print(computeG(angleZ,sZDis,angleA,sADis,solarZenith,40)) } ```

RLeafAngle documentation built on June 20, 2017, 9:10 a.m.