soilphysics (version 1.1)

maxcurv: Maximum Curvature Point

Description

Function to determine the maximum curvature point of an univariate nonlinear function of x.

Usage

maxcurv(x.range, fun, graph = TRUE, ...)

Arguments

x.range

a numeric vector of length two, the range of x.

fun

a function of x; it must be a one-line-written function, with no curly braces '{}'.

graph

logical; if TRUE (default) a curve of fun is plotted.

...

further graphical arguments.

Value

• A list of
• fun
  the function of x.
• x0
  the x critical value.
• y0
  the y critical value.

Warning

Numerical values into fun with three or more digits may cause miscalculation.

See Also

function, curve

Examples

# an exponential model
f <- function(x) exp(-x)
maxcurv(x.range = c(1, 5), fun = f)

# Load Bearing Capacity Model
b0 = 2.79
b1 = -2.34
lbc <- function(x) 10^(b0 + b1*x)
maxcurv(x.range = c(0, 1), fun = lbc)

# Gompertz Growth Model
Asym <- 8.5
b2 <- 2.3
b3 <- 0.6
g <- function(x) Asym * exp(-b2 * b3 ^ x)
maxcurv(x.range = c(0, 20), fun = g)

# Lessman & Atkins (1963) model for optimum plot size
a = 40.1
b = 0.72
cv <- function(x) a * x^-b
maxcurv(x.range = c(1, 50), fun = cv)

# End (not run)