In electric circuits analysis, nodal analysis, node-voltage
analysis, or the branch current method is a method of
determining the voltage (potential difference) between "nodes"
(points where elements or branches connect) in an electrical
circuit in terms of the branch currents. In analyzing a circuit
using Kirchhoff's circuit laws, one can either do nodal analysis
using Kirchhoff's current law (KCL) or mesh analysis using
Kirchhoff's voltage law (KVL). Nodal analysis writes an equation
at each electrical node, requiring that the branch currents
incident at a node must sum to zero. The branch currents are
written in terms of the circuit node voltages. As a consequence,
each branch constitutive relation must give current as a
function of voltage; an admittance representation. For instance,
for a resistor, Ibranch = Vbranch * G, where G (=1/R) is the
admittance (conductance) of the resistor. Nodal analysis is
possible when all the circuit elements' branch constitutive
relations have an admittance representation.