In mathematics, a Hankel contour is a path in the complex plane which extends from, around the origin counter clockwise and back to, where δ is an arbitrarily small positive number. The contour thus remains arbitrarily close to the real axis but without crossing the real axis except for negative values of x.
Use of Hankel contours is one of the methods of contour integration. This type of path for contour integrals was first used by Hermann Hankel in his investigations of the Gamma function.
The mirror image extending from −∞, circling the origin clockwise, and returning to −∞ is also called a Hankel contour.
Famous quotes containing the word contour:
“The living language is like a cowpath: it is the creation of the cows themselves, who, having created it, follow it or depart from it according to their whims or their needs. From daily use, the path undergoes change. A cow is under no obligation to stay in the narrow path she helped make, following the contour of the land, but she often profits by staying with it and she would be handicapped if she didn’t know where it was or where it led to.”
—E.B. (Elwyn Brooks)