nlraa (version 1.2)

SSbeta5: self start for Beta 5-parameter function

Description

Self starter for Beta 5-parameter function

Usage

beta5(temp, mu, tb, a, tc, b)
SSbeta5(temp, mu, tb, a, tc, b)

Value

beta5: vector of the same length as x (temp) using the beta5 function

Arguments

temp

input vector which is normally ‘temperature’

mu

mu parameter (see equation)

tb

base (low) temperature at which no expansion accurs

a

parameter describing the initial increasing phase

tc

critical (high) temperature at which no expasion occurs

b

parameter describing the decreasing phase

Details

For details see the publication by Yin et al. (1995) “A nonlinear model for crop development as a function of temperature ”. Agricultural and Forest Meteorology 77 (1995) 1-16

The form of the equation is: $$exp(mu) * (temp - tb)^a * (tc - temp)^b$$.

Examples

# \donttest{
require(minpack.lm)
require(ggplot2)
## Temperature response example
data(maizeleafext)
## Fit model
fit <- nlsLM(rate ~ SSbeta5(temp, mu, tb, a, tc, b), data = maizeleafext)
## Visualize
ndat <- data.frame(temp = 0:45)
ndat$rate <- predict(fit, newdata = ndat)
ggplot() + 
   geom_point(data = maizeleafext, aes(temp, rate)) + 
   geom_line(data = ndat, aes(x = temp, y = rate))
# }