DFT and IDFT using Matrix Multiplication Method in Matlab

clc
clear all
close all

X=input('Enter the Input Sequence');
N=input('Enter the value of N such taht N-point DFT is to be calculated');
%Inputs are taken%

n=0:1:N-1;
k=0:1:N-1;
nk=n'*k; %n transpose * k gives us a N*N matrix%

W=exp(-(j*2*pi)/N); % Twiddle Factor %

Wnk=W.^nk; % Twiddle Factor matrix is generated %

Y= Wnk*X' ; % Twiddle factor matrix multiplied by X transpose%

%Reason behing going to Transopose of the input matrix is : when we enter a matrix sequence we usually use ROW Matrix, in order to convert ROW to COLUMN we are using Transpose%


L=length(Y);
n=0:1:L-1;

figure,plot(n,abs(Y)),title('Magnitude Response of DFT')
figure, plot(n, angle(Y)), title('Phase Response of DFT')
%MAGNITUDE and PHASERESPONSE OF DFT SIGNAL IS PLOTTED%


W=exp((j*2*pi)/N); % Twiddle Factor %

Wnk=(W.^nk)/N; % Twiddle Factor matrix is generated %

Yinv= Wnk*Y ; % Twiddle factor matrix multiplied by Y%

L=length(Y);
n=0:1:L-1;

figure,plot(n,abs(Yinv)),title('Magnitude Response of IDFT')
figure, plot(n, angle(Yinv)), title('Phase Response of IDFT')
%MAGNITUDE and PHASERESPONSE OF ORIGINAL SIGNAL IS PLOTTED%

Error using input
Cannot call INPUT from EVALC.

Error in dftidft3 (line 5)
X=input('Enter the Input Sequence');

Published with MATLAB® R2013b