| Igamma {UCS} | R Documentation |
Computes the incomplete Gamma function and its inverse. Both the lower and the upper incomplete Gamma function are supported, and the Gamma value can be scaled to a base 10 logarithm.
Igamma(a, x, lower=TRUE, log=FALSE) Igamma.inv(a, y, lower=TRUE, log=FALSE)
a |
a non-negative numeric vector, the parameter of the incomplete Gamma function |
x |
a non-negative numeric vector, the point at which the incomplete Gamma function is evaluated |
y |
a numeric vector, the values of the incomplete Gamma function
(or their base 10 logarithms if log=TRUE) |
lower |
if TRUE, computes the lower incomplete Gamma
function (default). Otherwise, computes the upper incomplete Gamma
function. |
log |
if TRUE, the Gamma values are base 10 logarithms
(default: FALSE) |
The upper incomplete Gamma function is defined by the Gamma integral
Gamma(a,x) = integral_x^Inf t^(a-1) exp(-t) dt
The lower incomplete Gamma function is defined by the complementary Gamma integral
gamma(a,x) = integral_0^x t^(a-1) exp(-t) dt
Igamma returns the (lower or upper) incomplete Gamma
function with parameter a evaluated at point x.
Igamma.inv returns the point x at which the (lower or
upper) incomplete Gamma function with parameter a evaluates to
y.
Cgamma, Rgamma, Cbeta,
Ibeta, Rbeta