Wikipediabetai(a,b,x)
Returns the Incomplete Beta function evaluated from zero to x where:
a is the alpha parameter of the beta distribution, 0≤a.
b is the beta parameter of the beta distribution, 0≤b.
x is the final integration point 0<x<1.
See also beta gamma gammai gammaic
Example
betai(3,5,0.7)
0.9712