Wiener-Hopf factorization
= Wiener-Hopf factorization
{c}
{title2=$K=K^+K^-$}
The plus factor is analytic and nonzero above the transform contour, and the minus factor below it. Their continuations inherit singularities and zeros in the opposite half-planes. Allocation of branch cuts and modal poles must agree with the physical outgoing continuation; no factor may have a zero inside its designated analytic domain.