Gaussian Hypergeometric Function

HYPERGEOMETRIC2F1 Computes a hypergeometric function using the series expansion:

f(a,b;c;x)=
1 + [ab/1!c]x + [a(a+1)b(b+1)/2!c(c+1)]x^2 +[a(a+1)(a+2)b(b+1)(b+2)/3!c(c+1)(c+2)]x^3 + ...

This function solves the Gaussian Hypergeometric Differential Equation:

x(1-x)y'' + {c-(a+b+1)x}y' - aby = 0