  We study matrix factorizations of a section W of a line bundle on an
algebraic stack. We relate the corresponding derived category (the category of
D-branes of type B in the Landau-Ginzburg model with potential W) with the
singularity category of the zero locus of W generalizing a theorem of Orlov. We
use this result to construct push-forward functors for matrix factorizations
with relatively proper support.
