Mode Locking
A phenomenon in which a system being forced at an Irrational period undergoes rational, periodicmotion which persists for a finite range of forcing values. It may occur for strong couplings between natural and forcingoscillation frequencies.
The phenomenon can be exemplified in the Circle Map when, after 
iterations of the map, the new angle differs fromthe initial value by a Rational Number
This is the form of the unperturbed Circle Map with the Winding Number
For
not a Rational Number, the trajectory is Quasiperiodic.See also Chaos, Quasiperiodic Function- Müller-Lyer Illusion
- Müntz Space
- Müntz's Theorem
- N
- Nabla
- Nagel Point
- Naive Set Theory
- Napierian Logarithm
- Napier's Analogies
- Napier's Bones
- Napier's Constant
- Napier's Inequality
- Napkin Ring
- Napoleon Points
- Napoleon's Problem
- Napoleon's Theorem
- Napoleon Triangles
- Nappe
- Narcissistic Number
- Nash Equilibrium
- Nash's Theorem
- Nasik Square
- Nasty Knot
- Natural Density
- Natural Equation