An argument at which identical points in the Complex Plane are mapped to different points. For example, consider

Then , but , despite the fact that . Pinch Points are also called branch points.

**References**

Arfken, G. *Mathematical Methods for Physicists, 3rd ed.* Orlando, FL: Academic Press, pp. 397-399, 1985.

Morse, P. M. and Feshbach, H. *Methods of Theoretical Physics, Part I.* New York: McGraw-Hill,
pp. 391-392 and 399-401, 1953.

© 1996-9

1999-05-26