We study the L-functions
associated to Siegel modular forms—equivalently, automorphic representations of
GSp(4, 𝔸ℚ)—both theoretically and numerically. For the L-functions of degrees
10, 14, and 16 we perform representation theoretic calculations to cast the
Langlands L-function in classical terms. We develop a precise notion of what it
means to test a conjectured functional equation for an L-function, and we
apply this to the degree-10 adjoint L-function associated to a Siegel modular
form.