(mechanics, analytical mechanics) A differential equation which describes a function mathbf q(t) which describes a stationary point of a functional, S( mathbf q)=∫L(t, mathbf q(t), mathbf ̇q(t)),dt, which represents the action of mathbf q(t), with L representing the Lagrangian. The said equation (found through the calculus of variations) is ∂L/∂ mathbf q=d/dt∂L/∂ mathbf ̇q and its solution for mathbf q(t) represents the trajectory of a particle or object, and such trajectory should satisfy the principle of least action.

plural of ordinary differential equation

plural of partial differential equation

plural of magnetic equator

plural of celestial equator

(military) A line drawn on a map or chart connecting all points at which the magnetic inclination (dip) is zero for a specified epoch.

(astronomy) A great circle on the celestial sphere, coincident with the plane of earth's equator.

the equation ̂H𝜓(⃑r)=E𝜓(⃑r), for some constant E; applies to separable solutions 𝛹(⃑r,t)=𝜓(⃑r)𝜙(t) to the Schrödinger equation

Resembling or characteristic of an equation.

In terms of equations.