Inverse DFT

The inverse DFT (the IDFT) is given by

$$x(t_n) = \frac{1}{N}\sum_{k=0}^{N-1}X(\omega_k )e^{j\omega_k t_n}, \qquad n=0,1,2,\ldots,N-1.$$

The inverse DFT is written using `$=$' instead of `$\isdef$' because the result follows from the definition of the DFT, as we will show in Chapter 6.