Editing Hankel contour (section)

== General Principles ==
The Hankel contour, in its general form is always split in 3 partial paths :
[[File:ColoredHankelContour.png|thumb|Hankel Contour in coloured sections]]
Integration must be carried out on the green semi-axis above the Ox axis from right to left from infinity to point M, then following the part of the red circle counter-clockwise to point N and finally on the blue semi-axis below the Ox axis from left to right to infinity. M (and all the horizontal axis to its right) has a complex part iδ. Conversely, N (and all the axis to its right) has the complex part -iδ.
The integral is thus calculated along each path separately before summing them.