[ top | up ]

The Gamma Distribution

Syntax

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) = 1/(b^a Gamma(a)) x^(a-1) e^-(x/b)

((Equations will(?) come with HTML 3.x ))
for x > 0, a > 0 and b > 0.

See Also

gamma.

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))