poly5_di {timbeR}

Estimate the diameter at a given height based on a 5th degree polynomial function.

Description

Estimates the diameter at a given height of a tree from the diameter at breast height, total height and the coefficients of the 5th degree polynomial function that describes the tree's taper.

Usage

poly5_di(dbh, h, hi, coef)

Arguments

dbh

tree diameter at breast height, in centimeters.

h

total tree height, in meters.

hi

height at which the diameter will be calculated, in meters.

coef

numerical vector containing six coefficients of the 5th degree polynomial function that describes the tree's taper.

Value

a numeric value indicating the diameter at the given height.

Examples

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

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

poli5 <- lm(did~hih+I(hih^2)+I(hih^3)+I(hih^4)+I(hih^5),tree_scaling)

coef_poli <- coef(poli5)

dbh <- 25
h <- 20
di <- 5

poly5_di(dbh, h, di, coef_poli)