Long description

This figure is in two parts: (a) and (b). Part (a) starts with a horizontal line with two points labelled a and b with a being furthest left and a bold line joining the two points. A curved arrow labelled gamma links this to an unlabelled copy of the complex plane concentrated in the upper-right quadrant. A contour labelled capital gamma is labelled and has labelled initial point gamma of a and final point gamma of b. A direction arrow is shown. The contour travels from the point gamma of a near the origin in a left to right and upwards direction to gamma of b. Part (b) again starts with a horizontal line with two points labelled a and b with a being furthest left and a bold line joining the two points. A curved arrow labelled gamma tilde links this to an unlabelled copy of the complex plane concentrated in the upper-right quadrant. A contour labelled capital gamma tilde is labelled and has labelled initial point gamma tilde of a and final point gamma tilde of b and gamma tilde of b is closest to the origin. A direction arrow is shown. The contour travels from point gamma tilde of a to gamma tilde of b right to left and downwards direction.