Regularized Beta Function
The regularized beta function is defined by
where
is the incomplete Beta Function and 
is the complete Beta Function.See also Beta Function, Regularized Gamma Function- Robinson Projection
- Robust Estimation
- Rodrigues Formula
- Rodrigues's Curvature Formula
- Rogers-Ramanujan Continued Fraction
- Rogers-Ramanujan Identities
- Rolle's Theorem
- Roman Coefficient
- Roman Factorial
- Roman Numeral
- Roman Surface
- Roman Symbol
- Romberg Integration
- Rook Number
- Rook Reciprocity Theorem
- Rooks Problem
- Room Square
- Root
- Root Dragging Theorem
- Rooted Tree
- Root Linear Coefficient Theorem
- Root-Mean-Square
- Root of Unity
- Root (Radical)
- Root Test