Dstart {HydroMe} | R Documentation |
Determine starting values for nonlinear parameter estimation in the water retention models
Description
This function determines the starting values for estimation of parameters in the water retention models. The input data must contain at least the x (suction potential) and y(moisture contents) variables. It gives the starting values as close to the expected estimates as possible.
Usage
Dstart(data)
Arguments
data |
This is the water retention data with at least x (suction potential) and y(moisture contents) variables. The number of rows of the data should be at least 4 entries/levels of suction potential |
Details
The data contains x columns and y columns which are used by the function. The initial x value should not be zero but something close like 0.001
Value
A vector of five values: pars[1]: thr- The residual moisture content, pars[2]: ths- The saturated moisture content, Pars[3]: alp- Inverse of air entry potential, pars[4]: nscal-index of pore-size distribution, and pars[5]: mscal-scaling parameter related to nscal
Author(s)
Christian Thine Omuto
See Also
Examples
data(isric)
pf=subset(isric, Sample=="Benin3")
Dstart(pf)[1]## thr initial value