Predefined Functions and Operators
From GeoGebra Manual
beta(a, b) Returns the beta function Β(a, b) http://mathworld.wolfram.com/BetaFunction.html
beta(a, b, x) Returns the incomplete beta function Β(x;a, b) http://mathworld.wolfram.com/IncompleteBetaFunction.html
betaRegularized(a, b, x) Returns the incomplete regularized beta function I(x; a, b) http://mathworld.wolfram.com/RegularizedBetaFunction.html
gamma(x) Returns the gamma function Γ(x) http://mathworld.wolfram.com/GammaFunction.html
gamma(a, x) Returns the (lower) incomplete gamma function γ(a, x) http://mathworld.wolfram.com/IncompleteGammaFunction.html
gammaRegularized(a, x) Returns the (lower) incomplete regularized gamma function P(a, x) http://mathworld.wolfram.com/RegularizedGammaFunction.html