| Logistic {stats} | R Documentation |
Density, distribution function, quantile function and random
generation for the logistic distribution with parameters
location and scale.
dlogis(x, location = 0, scale = 1, log = FALSE) plogis(q, location = 0, scale = 1, lower.tail = TRUE, log.p = FALSE) qlogis(p, location = 0, scale = 1, lower.tail = TRUE, log.p = FALSE) rlogis(n, location = 0, scale = 1)
x, q |
vector of quantiles. |
p |
vector of probabilities. |
n |
number of observations. If length(n) > 1, the length
is taken to be the number required. |
location, scale |
location and scale parameters. |
log, log.p |
logical; if TRUE, probabilities p are given as log(p). |
lower.tail |
logical; if TRUE (default), probabilities are P[X <= x], otherwise, P[X > x]. |
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 pi^2 /3 s^2.
dlogis gives the density,
plogis gives the distribution function,
qlogis gives the quantile function, and
rlogis generates random deviates.
Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988) The New S Language. Wadsworth & Brooks/Cole.
var(rlogis(4000, 0, s = 5))# approximately (+/- 3) pi^2/3 * 5^2