Simple harmonic motion refers to the periodic sinusoidal oscillation of an object or quantity. Simple harmonic motion is executed by any quantity obeying the differential equation x^¨ + ω_0^2 x = 0, where x^¨ denotes the second derivative of x with respect to t, and ω_0 is the angular frequency of oscillation. This ordinary differential equation has an irregular singularity at ∞.