taper_bi {timbeR}

Bi (2004) Taper Function.

Description

Bi (2004) Taper Function.

Usage

taper_bi(dbh, h, hih, b0, b1, b2, b3, b4, b5, b6)

Arguments

dbh

tree diameter at breast height, in centimeters.

h

total tree height, in meters.

hih

ratio between the height of the section (hi) and the total height (h) .

b0, b1, b2, b3, b4, b5, b6

model parameters.

Value

a numeric value indicating the diameter at the section.

References

Bi, H. (2000). Trigonometric variable-form taper equations for Australian eucalypts. Forest Science, 46(3), 397-409.

Examples

library(dplyr)
library(minpack.lm)
library(timbeR)

tree_scaling <- tree_scaling %>%
mutate(did = di/dbh,
       hih = hi/h)

bi <-  nlsLM(di ~ taper_bi(dbh, h, hih, b0, b1, b2, b3, b4, b5, b6),
data=tree_scaling,
start=list(b0=1.8,b1=-0.2,b2=-0.04,b3=-0.9,b4=-0.0006,b5=0.07,b6=-.14))