scipy.special.betainc(a, b, x) = <ufunc 'betainc'>

Compute the incomplete beta integral of the arguments, evaluated from zero to x:

gamma(a+b) / (gamma(a)*gamma(b)) * integral(t**(a-1) (1-t)**(b-1), t=0..x).


The incomplete beta is also sometimes defined without the terms in gamma, in which case the above definition is the so-called regularized incomplete beta. Under this definition, you can get the incomplete beta by multiplying the result of the scipy function by beta(a, b).