logit: Logit and inverse-logit functions

In CGMossa/rbatteries: Help write R with all the batteries included

Description

An alias for qlogis as logit, and alias for plogis as inv_logis.

Usage

logit(p, location = 0, scale = 1, lower.tail = TRUE, log.p = FALSE)

inv_logit(q, location = 0, scale = 1, lower.tail = TRUE,
  log.p = FALSE)

Arguments

p	vector of probabilities.
location	location and scale parameters.
scale	location and scale parameters.
lower.tail	logical; if TRUE (default), probabilities are P[X ≤ x], otherwise, P[X > x].
log.p	logical; if TRUE, probabilities p are given as log(p).
q	vector of quantiles.

Details

If location or scale are omitted, they assume the default values of 0 and 1 respectively.

The Logistic distribution with location = m and scale = s has distribution function

F(x) = 1 / (1 + exp(-(x-m)/s))

and density

f(x) = 1/s exp((x-m)/s) (1 + exp((x-m)/s))^-2.

It is a long-tailed distribution with mean m and variance π^2 /3 s^2.

Value

dlogis gives the density, plogis gives the distribution function, qlogis gives the quantile function, and rlogis generates random deviates.

The length of the result is determined by n for rlogis, and is the maximum of the lengths of the numerical arguments for the other functions.

The numerical arguments other than n are recycled to the length of the result. Only the first elements of the logical arguments are used.

References

Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988) The New S Language. Wadsworth & Brooks/Cole.

Johnson, N. L., Kotz, S. and Balakrishnan, N. (1995) Continuous Univariate Distributions, volume 2, chapter 23. Wiley, New York.

See Also

Distributions for other standard distributions.

Examples

var(rlogis(4000, 0, scale = 5))  # approximately (+/- 3)
pi^2/3 * 5^2

CGMossa/rbatteries documentation built on Oct. 30, 2019, 5:29 a.m.