Figure 1: The complex contour in which the singularity at the origin is avoided by bending the curve around it. It is closed from below to make sure exponential term,\(e^{-iz}\) , vanishes as \(R\rightarrow \infty.\)

Figure 2: The complex contour in which the singularity at the origin is avoided by bending the curve around it. It is closed from below to make sure exponential term,\(e^{-iz}\) , vanishes as \(R\rightarrow \infty.\)

Figure 3: The complex contour in which the singularity at the origin is avoided by bending the curve around it. It is closed from below to make sure exponential term,\(e^{-iz}\) , vanishes as \(R\rightarrow \infty.\)

Figure 4: The complex contour in which the singularity at the origin is avoided by bending the curve around it. It is closed from below to make sure exponential term,\(e^{-iz}\) , vanishes as \(R\rightarrow \infty.\)

Figure 5: The complex contour in which the singularity at the origin is avoided by bending the curve around it. It is closed from below to make sure exponential term,\(e^{-iz}\) , vanishes as \(R\rightarrow \infty.\)