half_norm_key {EstimationTools}

Half normal key function

Description

This function provides the half normal key function for model fitting in distance sampling.

Usage

half_norm_key(x, sigma)

Arguments

x

vector of perpendicular distances from the transect.

sigma

scale parameter.

Details

This is the half normal key function with parameter sigma. Its expression is given by

g(x) = \exp(\frac{-x^2}{2*\sigma^2},

for x > 0.

Value

A numeric value corresponding to a given value of x and sigma.

Author(s)

Jaime Mosquera Gutiérrez, [e-mail]

See Also

Other key functions: hazard_rate_key(), uniform_key()

Examples

library(EstimationTools)

#----------------------------------------------------------------------------
# Example: Half normal function
half_norm_key(x=1, sigma=4.1058)
curve(half_norm_key(x, sigma=4.1058), from=0, to=20, ylab='g(x)')

#----------------------------------------------------------------------------