The Mathieu functions of even order are the characteristic functions of this system on the quantum l
The Mathieu functions of even order are the characteristic functions of this system on the quantum level.  Braginsky, Polnarev and Thorne proposed using it to measure the earth's general relativistic gravitomagnetic field. When modeling this system, a common approximation is for sin theta to equal theta; this only holds for small amplitudes.  The "physical" version differs from the "simple" version in that the "string" of the "mass on a string" has some mass.  For 10 points, name this physical system, often used to demonstrate simple harmonic motion?
The Mathieu functions of even order are the characteristic functions of this system on the quantum level.  