GammaDist {base}

R Documentation

The Gamma Distribution

Usage

dgamma(x, shape, scale=1)
pgamma(q, shape, scale=1)
qgamma(p, shape, scale=1)
rgamma(n, shape, scale=1)

Arguments

x, q	vector of quantiles.
p	vector of probabilites.
n	number of observations.
shape, scale	shape and scale parameters.

Value

These functions provide information about the gamma distribution with parameters shape and scale. dgamma gives the density, pgamma gives the distribution function qgamma gives the quantile function and rgamma generates random deviates.

The gamma distribution with parameters shape = a and scale = b has density

f(x) = \frac{1}{{b}^{a} \Gamma (a)} {x}^{a-1} {e}^{-x/b}

for x > 0, a > 0 and b > 0.

See Also

gamma, dbeta.

Examples

-log(dgamma(1:4, shape=1))
p <- (1:9)/10
pgamma(qgamma(p,shape=2), shape=2)
1 - 1/exp(qgamma(p, shape=1))

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