Centroid (Function)
By analogy with the Geometric Centroid, the centroid of an arbitrary function 
is defined as
References
Bracewell, R. The Fourier Transform and Its Applications. New York: McGraw-Hill, pp. 139-140 and 156, 1965.
- Rotation Operator
- Roth's Removal Rule
- Roth's Theorem
- Rotkiewicz Theorem
- Rotoinversion
- Rotor
- Rotunda
- Rouché's Theorem
- Roulette
- Round
- Rounding
- Routh-Hurwitz Theorem
- Routh's Theorem
- RSA Encryption
- RSA Number
- Rubber-Sheet Geometry
- Rubik's Clock
- Rubik's Cube
- Rudin-Shapiro Sequence
- Rudvalis Group
- Rule
- Ruled Surface
- Rule of 72
- Ruler
- Ruler Function