gompertz: R optmisation of Nemes et al (1999) four-parameter particle...

In gowusu/vadose: The estimation of saturated hydraulic conductivity and soil water retention Curves in the vadose zone

Description

The function optimises 4 parameters of Nemes et al (1999) particle size distribution function

Usage

gompertz(data = NULL, D = NULL, fr = NULL, p = NULL, group = NULL,
  a = 1, b = 1, e = 1, z = 1)

## Default S3 method:
gompertz(data = NULL, D = NULL, fr = NULL, p = NULL,
  group = NULL, a = 1, b = 1, e = 1, z = 1)

## S3 method for class 'gompertz'
plot(x, main = "Particle Size Distribution Function",
  xlab = "Particle Diameter", ylab = "Fraction", ...)

## S3 method for class 'gompertz'
coef(object, ...)

## S3 method for class 'gompertz'
predict(object, D, ...)

Arguments

data	dataframe. It can contain data with column names of "time" and "I"
D	character. The corresponding diameter in the data.
fr	character. The corresponding fraction of the particles.
p	porosity[g/m^3]
group	character. The name of the group variables if the data is from different areas.
a	an initial value of 'a' parameter to be optimised
b	an initial value of 'b' parameter to be optimised
e	an initial value of 'e' parameter to be optimised
z	an initial value of 'z' parameter to be optimised
x	a return object of the function.
main	Title of the plot
xlab	x label of the plot
ylab	y label of the plot
...	Any other graphical parameter
object	Model output object

Value

• PD: predicted fraction by mass of particles passing a particular diameter

• sand: percentage of sand

• clay: percentage of clay

• silt: percentage of silt

• a: optimised a parameter

• b: optimised b parameter

• e: optimised e parameter

• z: optimised z parameter

Author(s)

George Owusu

References

Nemes, A., Wosten, J. H. M., Lilly, A., & Voshaar, J. H. O. (1999). Evaluation of different procedures to interpolate particle-size distributions to achieve compatibility within soil databases. Geoderma., 90, 187-202.

See Also

zhuang3, zhuang4,lass3,logarithmic, logistic2, logistic3,fredlund3,fredlund4, jaky,andersson,gompertz, haverkamp

Examples

data=read.csv(system.file("ext","sys","soil2.csv",package="vadose"))
single<- subset(data, ID=="30B20_1")
mod=gompertz (data=single,p="sand",D="D",fr="Sand.")
plot(mod)
## Not run: 
#group simulation
mod2=gompertz (data=data,D="D",fr="FractionSand",group="ID")
mod2$coef

## End(Not run)
#generic function

gowusu/vadose documentation built on May 17, 2019, 7:59 a.m.