N-Point DFT and IDFT

N-Point DFT of a Function and its IDFT

• Discrete Fourier Transform
• Inverse Discrete Fourier Transform

DFT is defined as X(k)= summation from n=0 to N-1 of E-j*2*pi*k*(n/N)

% program to find N-point DFT of a given function x(n) and also its IDFT

clear all ; % close all

x=input('enter the sequence ');

N=input('Enter the length of the DFT');

xk=fft(x, N); %find DFT

magnitude=abs(xk); %find magnitude

subplot(2,2,1);

n=0:N-1;

stem(n,magnitude); % plot magnitude response.

phaseplot=angle(xk); %find phase angle

subplot(2,2,2);

stem(n,phaseplot); %plot phaseplot

%To find IDFT

xn=ifft(xk); %find IDFT

subplot(2,2,3);

stem(xn); %plot IDFT sequence