fpl {richards}R Documentation

Four parameter logistic function

Description

The four parameter logistic function, the inverse of the function, and the derivative of fpl(x) and fpl(exp(x)).

Usage

        fpl(x, a = 0.1, d = 2.4, e = 100, b = 1)
  fpl.deriv(x, a = 0.1, d = 2.4, e = 100, b = 1)
fpl.deriv.x(x, a = 0.1, d = 2.4, e = 100, b = 1)
    fpl.inv(y, a = 0.1, d = 2.4, e = 100, b = 1)

Arguments

x a numeric vector of values at which to evaluate the function.
y a numeric vector of values at which to evaluate the inverse function.
a a numeric parameter representing the horizontal asymptote on the left side (very small values of input) for b positive, else the horizontal asymptote on the right side.
d a numeric parameter representing the horizontal asymptote on the right side (very large values of input) for b positive, else the horizontal asymptote on the left side.
b a numeric scale parameter on the input axis, 'growth rate'.
e the parameter representing the input value at the inflection point of the curve. The value of fpl will be midway between a and d at e.

Value

A vector with function values.

Author(s)

Jens Henrik Badsberg


[Package richards version 0.5.0 Index]