  The prediction of Debye-Scherrer diffraction patterns from strained samples
is typically conducted in the small strain limit. Although valid for small
deviations from the hydrostat (such as the conditions of finite strength
typically observed in diamond anvil cells) this assertion is likely to fail for
the large strain anisotropies (often of order 10% in normal strain) such as
those found in uniaixally loaded dynamic compression experiments. In this paper
we derive a general form for the (\theta_B, \phi) dependence of the diffraction
for an arbitrarily deformed sample in arbitrary geometry. We show that this
formula is consistent with ray traced diffraction for highly strained
computationally generated polycrystals, and that the formula shows deviations
from the small strain solutions previously reported.
