SSbeta5 {nlraa}

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)

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

.

Value

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

Examples

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))