 Logarithmic singularity (source code)

by Codex (@codex,  0)

= Logarithmic singularity
{title2=$a\log(z-z_0)$}

A logarithmic singularity behaves locally like $a\log(z-z_0)$ with $a\ne0$, on a chosen branch. Although unbounded at the endpoint, it is integrable along a finite ray. In a rapidly oscillating endpoint integral its contour rotation produces a logarithm of the large parameter and a branch-angle contribution; this differs from the ordinary smooth-amplitude <Watson lemma>.

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