A theory of equivalent fields, analogous to equivalent circuits in net
work theory, is developed. It extends diakoptic analysis and permits s
olution of two (or more) coupled boundary-value problems independently
, representing their mutual coupling by appropriate influence constrai
nts and functions. Analytical models are derived, and their impact on
numerical methods is explored. This technique is particularly valuable
where detailed results are sought only in a small portion of a large
field problem.