Nodal

Nodal is an adjective used across science and engineering to describe things related to a node. A node is a point of connection, a junction in a network, or a location where a function or wave vanishes. The meaning thus varies with context.

In physics and mathematics, the term commonly appears with wave phenomena. A nodal point or nodal line is a location where the amplitude of a wave is zero. For vibrating membranes and drums, nodal lines delineate regions that do not move. In quantum mechanics and the study of eigenfunctions, nodal sets are the collection of points where the wavefunction vanishes. Nodal domains are the regions separated by these sets.

In electrical engineering and circuit analysis, nodal analysis is a standard method for determining voltages at circuit nodes relative to a reference point, by applying Kirchhoff's current law to the node equations.

In botany, nodal refers to nodes on plant stems—the points where leaves, buds, or branches attach. Nodal regions are used to describe segments of the stem with specific growth or anatomical features, and the distance between nodes (internode) is a common measurement in plant morphology.

In astronomy and orbital mechanics, nodal points and lines describe where an orbit crosses a reference plane. The ascending node is where the orbit passes upward through the plane, and the descending node is where it passes downward.

In geometry and algebraic geometry, a nodal curve or node is a type of singularity where two branches meet at a point. Nodality can also describe sets of zeros of a function in partial differential equations, known as nodal sets.