  We study the entropy production rate in systems described by linear Langevin
equations, containing mixed even and odd variables under time reversal. Exact
formulas are derived for several important quantities in terms only of the
means and covariances of the random variables in question. These include the
total rate of change of the entropy, the entropy production rate, the entropy
flux rate and the three components of the entropy production. All equations are
cast in a way suitable for large-scale analysis of linear Langevin systems. Our
results are also applied to different types of electrical circuits, which
suitably illustrate the most relevant aspects of the problem.
