Editing Contour integration (section)

===Contours===
Contours are the class of curves on which we define contour integration. A '''contour''' is a directed curve which is made up of a finite sequence of directed smooth curves whose endpoints are matched to give a single direction. This requires that the sequence of curves <math>\gamma_1,\dots,\gamma_n</math> be such that the terminal point of <math>\gamma_i</math> coincides with the initial point of <math>\gamma_{i+1}</math> for all <math>i</math> such that <math>1\leq i<n</math> . This includes all directed smooth curves. Also, a single point in the complex plane is considered a contour. The symbol <math>+</math> is often used to denote the piecing of curves together to form a new curve. Thus we could write a contour <math>\Gamma</math> that is made up of <math>n</math> curves as
<math display=block> \Gamma = \gamma_1 + \gamma_2 + \cdots + \gamma_n.</math>