Chi {adehabitatLT}  R Documentation 
Density, distribution function, quantile function and random
generation for the chi distribution with df
degrees of
freedom.
dchi(x, df = 2) pchi(q, df = 2, lower.tail = TRUE, ...) qchi(p, df = 2, lower.tail = TRUE) rchi(n, df = 2)
x,q 
vector of quantiles. 
p 
vector of probabilities. 
n 
number of observations. If 
df 
degrees of freedom (nonnegative, but can be noninteger). 
lower.tail 
logical; if TRUE (default), probabilities are P[X <= x], otherwise, P[X > x]. 
... 
additional arguments to be passed to the function

The chi distribution with df
= n > 0 degrees of freedom
has density
f_n (x) = 2^(1n/2) x^(n1) e^((x^2)/2) / Gamma(n/2)
for x > 0. This distribution is used to describe the square root of a variable distributed according to a chisquare distribution.
dchi
gives the density, pchi
gives the distribution
function, qchi
gives the quantile function, and rchi
generates random deviates.
Clement Calenge clement.calenge@ofb.gouv.fr
Evans, M., Hastings, N. and Peacock, B. (2000) Statistical Distributions, 3rd ed. Wiley, New York.
opar < par(mfrow = c(2,2)) hist(rchi(100), ncla = 20, main="The Chi distribution") plot(tutu < seq(0, 5, length=20), dchi(tutu, df = 2), xlab = "x", ylab = "probability density", type = "l") plot(tutu, pchi(tutu), xlab = "x", ylab = "Repartition function", type = "l") par(opar)