I am seeking the method for calculating the following integral
$$\int_{-\infty}^\infty\frac{e^{-2ix\pi\psi}}{1+x^2} dx $$
Ideas I have are:
1) substition (however which one?) 2) integration by parts
The integral comes from the Fourier transform of $$\frac{1}{1+x^2}$$
$$\int_{-\infty}^\infty\frac{e^{-2ix\pi\psi}}{1+x^2} dx =\int_{-\infty}^\infty\frac{\cos(2\pi\psi\,x)}{1+x^2}dx-i\int_{-\infty}^\infty\frac{\sin(2\pi\psi\,x)}{1+x^2}dx$$ Please check this question
Now set $\lambda=2\pi\psi$