Hello, How would i go by doing a Discrete fourier transform?

I am trying to create a discrete Fourier transform but without using fft and then plotting it, taking into consideration it is a simple matrix with numerous data points, how would i go by creating the function? i am somewhat lost in where to begin. thank you for your time.

Answer 1

[Naga Sai]

Include below give program in your working directory when ever you execute program

    function X = dft(xn,N)
%To compute the DFT of the sequence x(n)
L = length(xn);%length of the sequence
%Checking for the length of the DFT
if(N<L)
error('N must be >=L')
end 
x1 = [xn zeros(1,N-L)];%Appending zeros
%Computation of twiddle factors
for k=0:1:N-1;
for n=0:1:N-1;
p = exp(-i*2*pi*n*k/N);
x2(k+1,n+1)=p;
end
end
 X = x1*x2;