Topic summary
Branch cut
Extracted from the Wikipedia article Branch point.
Branch cuts
Roughly speaking, branch points are the points where the various sheets of a multivalued function come together. The branches of the function are the various sheets of the function. For example, the function w = z has two branches: one where the square root comes in with a plus sign, and the other with a minus sign. A branch cut is a curve in the complex plane such that it is possible to define a single analytic branch of a multi-valued function on the plane minus that curve. Branch cuts are usually, but not always, taken between pairs of branch points.