BETAI Function
Evaluates the real incomplete beta function.
Usage
result = BETAI(x, a, b)
Input Parameters
x—Upper limit of integration.
a—First beta distribution parameter.
b—Second beta distribution parameter.
Returned Value
result—The value of the incomplete beta function.
Input Keywords
Double—If present and nonzero, double precision is used.
Discussion
The incomplete beta function is defined as:
requiring that 0 ≤ x ≤ 1, a > 0, and b > 0. It underflows for sufficiently small x and large a. This underflow is not reported as an error. Instead, the value zero is returned.
Example
In this example, I0.61(2.2, 3.7) is computed and printed.
PM, BETAI(.61, 2.2, 3.7) ; PV-WAVE prints: 0.882172
